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Lingyun You, Dongzhao Jin, Shuaicheng Guo, Jiaqing Wang, Qingli Dai, and Zhanping You
Journal of Cleaner Production, ISSN: 09596526, Volume: 279, Published: 10 January 2021 Elsevier BV
Abstract This study intends to evaluate the feasibility of the use of recycled cathode ray tube (CRT) glass in water-foamed asphalt mixtures used in low volume roads. In the asphalt mixture samples, 21.5% (wt.) aggregates were replaced by the recycled CRT glass to evaluate the mechanical performance and leaching potential. First, the leaching test was used to characterize the leaching potential of the CRT mixes since there is high lead content in CRT glass, which may be harmful to the groundwater if the hazardous lead leaches from the CRT mixes. Second, the high-temperature rutting and the low-temperature cracking performance of the asphalt mixtures were measured via the Hamburg Wheel Tracking Test (HWTT) and the Disk-Shape Compact Tension (DCT) test, respectively. In addition, the Moisture-Induced Stress Tester (MIST) was used to simulate the pore pressure generated in a wet pavement under moving traffic loading. The experimental results showed that, although the measured lead leaching of the pure CRT glass particles was higher than the regulatory level of 5 mg/L, the coated asphalt could effectively insulate the contact between CRT glass and the external environment, resolving the leaching issues. In summary, from the view of the mechanical performance of the water-foamed asphalt mixtures containing recycled CRT glass, the performance is acceptable in various temperatures when used in low volume roads. Recycling CRT glass in asphalt mixture should be carried out with extreme caution because if not done correctly, the potential leaching may eliminate the benefits of recycling unwanted waste materials.
Jiaqing Wang, Qingli Dai, Ruizhe Si, Yunxiang Ma, and Shuaicheng Guo
Journal of Cleaner Production, ISSN: 09596526, Volume: 277, Published: 20 December 2020 Elsevier BV
Abstract The self-compacting concrete (SCC) with the replacement of recycled rubber aggregates is limited for the field application due to high-performance requirements. The steel fiber was introduced to the rubberized SCC (RSCC) to enhance its performance and promote its application. The fresh and mechanical properties and durability performance of steel fiber-reinforced rubber self-compacting concrete (SRSCC) were evaluated. The SRSCC samples were prepared with replaced rubber aggregate based on fine aggregate volume percentages of 10%, 15%, and 25% and a consistent steel fiber ratio of 0.2%. The plain SCC and rubberized SCC samples were also produced for comparison. The fresh performance was evaluated with slump flow, J-ring flow, V-funnel, and U-box tests. The results showed that both filling and passing ability could be affected by the added steel fiber and rubber aggregate. However, the SRSCC could still meet most of the recommended criteria for passing and filling abilities when the rubber content is lower than 25%. Regarding the hardened properties, the compressive strength was reduced in rubber SCC samples with increased rubber contents by comparing with the control SCC samples. Nevertheless, SRSCC samples with 10% rubbers have higher splitting tensile strength than RSCC and plain SCC. Also, the SRSCC specimens showed excellent freeze-thaw resistance after 600 F-T cycles. The relative dynamic modulus of elasticity slightly increased without any dimensional expansion in SRSCC samples. In summary, the proposed SRSCC can meet required flowability, filling and passing abilities along with good mechanical and freeze-thaw performance. This study will provide lab test data for the applications of recycling waste tire aggregates in steel fiber-reinforced SCC.
Songtao Lv, Jiang Yuan, Xinghai Peng, Milkos Borges Cabrera, Shuaicheng Guo, Xinzi Luo, and Junfeng Gao
Construction and Building Materials, ISSN: 09500618, Volume: 264, Published: 20 December 2020 Elsevier BV
Abstract Applying bio-asphalt in road engineering can effectively resolve its shortage of petroleum asphalt, and enhance its environmental friendliness and sustainability. However, the poor high-temperature stability with added bio-oil is a key obstacle restricting its wide utilization. To broaden the application of bio-asphalt in road engineering, in this research was used rock asphalt to further improve bio-asphalt through the Box-Behnken Design (BBD). During the optimization of the design, bio-oil content, rock asphalt content, and shear time were defined as independent variables. Penetration, softening point, creep rate, stiffness modulus, and irrecoverable creep compliance of the modified asphalt were considered response values. Response surface method (RSM) model and Genetic algorithm optimization artificial neural network (GA-ANN) model were utilized to analyze the behavior of bio-oil/rock asphalt composite modified asphalt. Furthermore, the feasibility of both models was verified through experimental results. The results indicated that the incorporation of bio-oil and rock asphalt improved the low-temperature and high-temperature resistance of neat asphalt, respectively. Besides, the low-temperature crack resistance of composite modified asphalt was remarkably enhanced, and the high-temperature performance was similar to the one related to neat asphalt. GA-ANN model had higher feasibility for composite modified asphalt performance optimization. The optimal bio-oil content, rock asphalt content, and shear time determined by using RSM and GA-ANN model were equal to 6.3%, 11.2%, 52.8 min, and 6.3%, 12.9%, 76.6 min, respectively. The bio-oil/rock asphalt composite modified asphalt with targeted performance requirements can be achieved by combining the proposed weight function with the RSM model and GA-ANN model. Optimization with GA-ANN can further promote the recycling of both bio-oil and Buton rock asphalt, save energy, and lead to a greener construction material. This study can serve as a solid base for more efficient utilization of bio-asphalt in road engineering.
Songtao Lv, Long Hu, Chengdong Xia, Xiaofeng Wang, Milkos Borges Cabrera, Shuaicheng Guo, and Jie Chen
Construction and Building Materials, ISSN: 09500618, Volume: 260, Published: 10 November 2020 Elsevier BV
Abstract As the primary surface type for high-grade Chinese highways, the long-term performance of asphalt pavement can affect significantly transportation efficiency. It has been confirmed that fatigue cracking is one of the major failure modes for asphalt pavement, which can cause a great reduction of asphalt pavement durability. Currently, the fatigue properties of asphalt mixtures are evaluated mainly based on traditional laboratory fatigue tests, such as bending fatigue tests and indirect tensile fatigue tests. However, none of these fatigue test methods can realistically evaluate the fatigue performance of asphalt pavement under the repeated wheel load. To resolve this issue, the model mobile load simulator (MMLS3), which is a small-scale accelerated pavement test device, was utilized to evaluate the fatigue life of six kinds of asphalt mixtures. The fatigue damage variable was defined as stiffness reduction. Based on the small-scale accelerated pavement test, a stiffness reduction model for asphalt mixtures was determined. A stiffness reduction law for asphalt mixtures during the fatigue process was proposed. The stiffness evolution process could be divided into three phases, which are the adaptation phase, the quasi-stationary phase, and the failure phase. A maximum value of the rate of stiffness reduction from the quasi-stationary phase into the failure phase was proposed as the failure threshold. Besides the fatigue life obtained from the failure criteria had a good agreement with the test results. The results from this research can be used as a theoretical reference for evaluating the fatigue life of asphalt mixtures and improving the durability of asphalt pavement.
Sai Liu, Prashant Rawat, Zheng Chen, Shuaicheng Guo, Caijun Shi, and Deju Zhu
Composites Part B: Engineering, ISSN: 13598368, Volume: 199, Published: 15 October 2020 Elsevier BV
Abstract Textile reinforced concretes (TRCs) have many extraordinary features that make them a future-ready material exposed to complex environmental situations. However, current knowledge related to TRCs under mechanical loading and environmental conditions is not fully explored as compared to conventional fiber reinforced concretes. The present work investigates the quasi-static pullout performance of single-yarn and textile type (AR-glass and basalt fiber) reinforced cement mortars under different temperatures (25 °C, 100 °C, 300 °C and 600 °C). The pullout testes were carried out at loading rates of 0.25, 2.5 and 25 mm/min on a MTS load frame setup. The reinforcement embedded length in the cement matrix was 30 mm. The pullout testing results were evaluated in terms of first-crack load and maximum pullout (or peak) load, displacement at first-crack, and energy absorption. The experimental results indicated that the textile type reinforcement was better than the yarn type reinforcement. The mechanical properties of TRCs were sensitive to loading rate and temperatures. In addition, the scanning electronic microscopy (SEM) images of the fractured samples tested at different loading rate and temperatures highlighted that quasi-static loading rate variations did not affect the fracture pattern. However, the temperature variation highly affected the epoxy resins used for filament bonding or coating) in the reinforcements which may critically affect their interfacial performances.
Shuaicheng Guo, Pegah Kord Forooshani, Qingli Dai, Bruce P. Lee, Ruizhe Si, and Jiaqing Wang
Composites Part B: Engineering, ISSN: 13598368, Volume: 199, Published: 15 October 2020 Elsevier BV
The crack development is considered to be one of the most severe threats to the durability of concrete infrastructure. This study aims to enhance the durability performance of cementitious material with the pH-responsive Superabsorbent Polymer (SAP). The SAP was synthesized with acrylic acid (AA)-methyl acrylate (MA) precursors, and three type samples with different crosslinking levels were prepared. The examination on the pH sensitivity indicated that the swelling capacity of the prepared SAP would first increase and then decrease with solution alkalinity, and the peak swelling potential was achieved around pH value of 12 for all the three type SAP with solution/gel mass ratio of 500. Further examination indicated the alkalinity of the buffer solution was reduced during the adsorption test, which can be caused by the hydrolysis of the amide groups and the crosslinker. Besides that, it was also found the solution/gel ratio and the Ca(OH)2 content could affect the swelling potential of the SAP. After that, the performance tests were conducted for the evaluation of concrete with SAP. A wax-coating protocol for the SAP was designed by using the hot-water method to prevent its swelling during mixing process. It was found that the strength reduction for samples with wax-coated SAP was insignificant compared to that of the control samples. Furthermore, durability tests supported the wax-shell could be broken by the crack propagation in concrete. And further experimental studies are needed to optimize the wax-size and shell thickness for enhanced self-sealing efficiency.
Yong Yi, Deju Zhu, Shuaicheng Guo, Zuhua Zhang, and Caijun Shi
Cement and Concrete Composites, ISSN: 09589465, Volume: 113, Published: October 2020 Elsevier BV
Abstract This paper presents a review of the deterioration of concrete under seawater attack with particular interests in field exposure. The research reported in the literature has shown that salinity of seawater in different areas varies considerably but the type of ions and their proportion are similar. Because of this variation, laboratory studies should use specific artificial seawater to simulate on field environments. The phase changes induced by chloride, magnesium and sulfate ions contained in seawater are reviewed. The interaction between hydrates and chloride ion can lead to the formation Friedel's and Kuzel's salts. Magnesium ion can replace the calcium in Portlandite, and lowers the alkalinity of pore solution and eventually destabilizes C-S-H gel. The expansive ettringite is inhibited at the presence of chloride ions. At the tidal zone, the phase change mainly occurs on the surface of concrete, which weakens the structure and leads to spalling and delamination under the physical attack of the wave. Based on the existing deterioration mechanisms, the protocols to enhance the durability performance of marine concrete are also reviewed, such as using supplementary cementitious materials (SCMs) to mitigate rate of chloride penetration and, more promisingly, to use alternative binder systems. This paper also proposes a concept of designing a more durable concrete cover system by enhancing the chemical stability of cement hydrates, rapid self-healing and intelligent alkalinity control.
Azzam Ahmed, Shuaicheng Guo, Zuhua Zhang, Caijun Shi, and Deju Zhu
Construction and Building Materials, ISSN: 09500618, Volume: 256, Published: 30 September 2020 Elsevier BV
Abstract FRP reinforced seawater sea sand concrete (FRP-SWSSC) combines the advantages of corrosion-free FRP bars in the marine environment and the direct utilization of seawater and sea sand, which can lead to a more sustainable and economic-efficient construction material. This paper reports a comprehensive overview of the current works on workability, mechanical properties (tensile, interlaminar shear, transverse shear, and flexural strength), bond behavior, durability, and applications of FRP-SWSSCs. The results indicated that exposure to the saline/alkaline environment is the main threat to the long-term performance of SWSSC. Furthermore, durability performance can also be affected by the type of FRP, surface protection, and concrete. Normally, the surface enhancement of the FRP bars can enhance its durability performance under saline environment. The current study mainly focuses on the application of glass fiber reinforced polymer (GFRP) in SWSSC, while the basalt fiber reinforced polymer (BFRP) bars have gained less attention. Also, GFRP demonstrated better resistance to both simulated concrete pore solution and saline condition than BFRP. Also, the exposure test under real conditions is essential to validate the results obtained from experiments in the simulated environment. The future research directions on FRP-SWSSC systems are recommended based on the summarization of current studies and field application.
Ruizhe Si, Shuaicheng Guo, Qingli Dai, and Jiaqing Wang
Construction and Building Materials, ISSN: 09500618, Volume: 254, Published: 10 September 2020 Elsevier BV
Abstract This objective of this study is to utilize recycled glass powder as a partial replacement precursor of the metakaolin-based geopolymer to develop a sustainable geopolymer material. Four glass powder replacement ratios were selected for the metakaolin-based geopolymer preparation (0%, 5%, 10%, and 20% by the total precursor weight). The pair distribution function (PDF) analysis indicated that a higher amount of the four-membered ring structures in the formed gel with the added glass powder. Both PDF and EDX analysis showed that the Si/Al ratio of the binder phase increased with glass powder content in the mixtures. The added glass powder can improve the workability of the geopolymer binder and prolong the setting time of the synthesized geopolymer samples. The nanoindentation test results showed that the elastic modulus of the formed gel increased with replaced 10% and 20% glass powder. In addition, the samples with 5% of glass powder achieved the highest compressive strength among tested samples. The test results indicated that the appropriate glass powder replacement can affect the geopolymerization process and modify the formed gels in the metakaolin-based geopolymer to improve the mechanical properties of the mixture. The information obtained in this study can promote the utilization of waste glass powder as a partial replacement of the precursor for the production of sustainable alkali-activated materials.
Wenbo Ma, Wenhao Gao, Shuaicheng Guo, Yanbing Zhao, Zhiren Wu, and Caiqian Yang
Cold Regions Science and Technology, ISSN: 0165232X, Volume: 177, Published: September 2020 Elsevier BV
Abstract Stabilization of the loose and fragile Pisha with the hydrophilic polyurethane material has been proved to be a time and cost-efficient protocol for the conservation of soil and water. However, the undesirable durability performance of the original W-OH binder material deteriorate its long-term conservation ability, especially under the freeze-thaw cycles. This study aims to improve the freeze-thaw durability performance of the W-OH composites through mixture design optimization and material modification. This study first investigates the correlation between the freeze-thaw resistance of the W-OH/Pisha sandstone composites and the concentration of the applied W-OH solution. The test results indicated both the compressive strength and elastic modulus of the W-OH based composites would decrease with freeze-thaw cycles and the samples prepared with higher concentration W-OH solution own better freeze-thaw resistance. Meanwhile, the elastic modulus of the W-OH composites decreased almost linearly with the freeze-thaw cycles, which is in accordance with the linear increase of the porosity of samples determined with the ultra-depth-of-field microscope. Based on these mechanism analyses, the modification of the W-OH material was further conducted with the Ethylene-vinyl acetate (EVA) and air entrainer. The compressive strength test results indicate both the added EVA can enhance the freeze-thaw durability of the W-OH composites, which can be caused by the improved cohesion strength of the W-OH binder due to enhanced density. Similarly, the freeze-thaw durability of the W-OH composites was also enhanced with added air entrainer, which provided extra space for the freezing expansion. The research results of this study can enhance the freeze-thaw durability of the stabilized Pisha sandstone and its long-term conservation ability on soil and water.
Songtao Lv, Chengdong Xia, Qing Yang, Shuaicheng Guo, Lingyun You, Yanpeng Guo, and Jianlong Zheng
Journal of Cleaner Production, ISSN: 09596526, Volume: 264, Published: 10 August 2020 Elsevier BV
Abstract The quickly accumulated crayfish shell waste in China has led to severe environmental issues and recycling pressure. This study aims to build an efficient protocol by utilizing waste crayfish shell powder in the production of high-performance and sustainable asphalt binder. The asphalt binder modified with different contents of crayfish shell powder (5%, 10% and 20% mass ratio to control asphalt, respectively) were first prepared at the temperature of 140oC–150 °C. Then the softening point and the penetration of the prepared samples were implemented to compare the stiffness difference between the modified and original asphalt binder. The results indicated that the added shell powder increased the softening point and decreased the penetration of the control asphalt. Furthermore, the high-temperature stability of the asphalt binder was examined by the dynamic shear rheometer (DSR) tests. The DSR results revealed that adding shell powder could enhance the rutting resistance of the asphalt binder by decreasing the phase angle δ, increasing the dynamic shear modulus |G∗| and finally enhancing the rutting factor |G∗|/sinδ. After that, to compare the creep performance between the control and modified asphalt binder, the multiple stress creep recovery (MSCR) tests were employed. The results of the MSCR test showed that at the same temperature, the percent recovery was higher while the non-recoverable creep compliance Jnr of modified asphalt was lower than those of the control binder. These results indicated that the added crayfish shell powder could increase the stiffness, improve the high-temperature stability and creep resistance of the asphalt binder. Finally, fourier transform infrared spectroscopy (FT-IR) test results implied that the added CS would not affect the chemical structure of the asphalt binder, and the modification was mainly a physical process. The novelty and limitation of this study have also been detailedly explained in the discussion part. The test results could provide a reference for the engineering application of the crayfish shell powder modified asphalt material and lead to both a cleaner and greener product.
Fang Liu, Zhanping You, Aboelkasim Diab, Zhuangzhuang Liu, Chao Zhang, and Shuaicheng Guo
Construction and Building Materials, ISSN: 09500618, Volume: 249, Published: 20 July 2020 Elsevier BV
Abstract The concrete transportation infrastructures will undergo both fatigue traffic loading and environmental impacts during the whole service life, including rigid pavements, bridges decks, airfield runways, railway bridges, even high-speed railways and concrete structures in the ocean. This study aims to investigate the effects of external sulfate attack on concrete under flexural fatigue loading and drying-wetting cycles. The changes of mass loss rate and relative dynamic elastic modulus were measured to indicate the influence of the coupled effects on the integrity and mechanical performance of concrete, also the sulfate content inside concrete was determined to indicate the permeability of sulfate ion under different experimental conditions. Moreover, the phase composition of samples was analyzed using X-ray diffraction (XRD). In addition, the effect of fly ash on sulfate attack was duly studied. Fatigue loading causes cracking in the interfaces of various phases and forms cracks in the concrete. Within the influence depth of drying-wetting cycles, concrete is subjected to both water convection due to capillary action and diffusion due to concentration gradients. The results indicate the fatigue loading and drying-wetting cycles can accelerate the transportation of sulfate ion inside concrete and the deterioration degree of concrete subjected to sulfate. The findings in this study can help to understand the influence of fatigue loading and drying-wetting cycles on the development of sulfate attack.
Wenbo Ma, Zenggang Zhao, Shuaicheng Guo, Yanbing Zhao, Zhiren Wu, and Caiqian Yang
Materials, eISSN: 19961944, Published: 1 February 2020 MDPI AG
Currently the investigation on recycled cement concrete aggregate has been widely conducted, while the understanding of the recycled polymer concrete aggregate is still limited. This study aims to fill this knowledge gap through the experimental investigation on mechanical and durability performance. Specifically, the remolded polyurethane stabilized Pisha sandstone was collected as the recycled polymer concrete aggregate. The remolded Pisha sandstone was then applied to re-prepare the polyurethane-based composites. After that, the mechanical performance of the prepared composites was first examined with unconfined and triaxial compressive tests. The results indicated that the Pisha sandstone reduces the composite’s compressive strength. The reduction is caused by the remained polyurethane material on the surface of the remolded aggregate, which reduces its bond strength with the new polyurethane material. Aiming at this issue, this study applied the ethylene-vinyl acetate (EVA) to enhance the bond performance between the polyurethane and remolded sandstone. The test results indicated both the unconfined and triaxle compressive strength of the polyurethane composites were enhanced with the added EVA content. Furthermore, the durability performance of the EVA-modified composites were examined through freeze-thaw and wet-dry cycle tests. The test results indicated the EVA could enhance the polyurethane composites’ resistance to both wet-dry and freeze-thaw cycles. Overall, the modification with EVA can compensate for the strength loss of polyurethane composites because of the applied remolded aggregate and enhance its sustainability.
Ruizhe Si, Qingli Dai, Shuaicheng Guo, and Jiaqing Wang
Journal of Cleaner Production, ISSN: 09596526, Volume: 242, Published: 1 January 2020 Elsevier BV
Abstract This paper investigates the mechanical properties, nanopore structure and drying shrinkage behavior of the metakaolin-based geopolymer mixtures containing 0%–20% waste glass powder. The prepared samples were cured under ambient temperature and high temperature (60 °C), respectively. The mechanical properties of the samples can be improved by introducing the low content of glass powder (5%–10%). Microstructure and nanopore structure analysis indicated that a denser gel phase was formed in the glass powder modified geopolymer samples. The added glass powder reduced the water loss rate of the samples under drying condition, leading to a reduction of drying shrinkage at early ages. The capillary stress in the prepared geopolymer samples was analyzed based on the pore size distribution of the mixtures. The magnitude of capillary stress generated in glass powder containing samples was similar to that of geopolymers without glass powder. The improved creep modulus with added glass powder facilitated the reduction of the shrinkage of the samples at later ages. This study can facilitate the recycling of waste glass into geopolymer for sustainable construction applications.
Jiaqing Wang, Qingli Dai, Ruizhe Si, and Shuaicheng Guo
Journal of Cleaner Production, ISSN: 09596526, Volume: 234, Pages: 1351-1364, Published: 10 October 2019 Elsevier BV
Abstract In this study, the synergistic effect of combining macro polypropylene (PP) fiber and rubberized concrete was evaluated based on mechanical and durability performance, as well as microstructure. The specimens were prepared with two different rubber volume contents at 10% and 15%, incorporating with a consistent fiber volume fraction of 0.5%. The plain concrete specimens and specimens with only PP fiber were also produced for comparison. The mechanical test results indicated that the fracture energy of plain concrete could be enhanced with both macro PP fiber and rubber aggregates. Besides, all specimens achieved compressive strength higher than 40 Mpa, and the ultrasonic pulse velocity demonstrated the good quality of concrete specimens. The fracture morphology and ESEM imaging showed the positive function of rubber aggregates and PP fibers on the post-crack propagation. The durability performance, including drying shrinkage, ASR expansion, and frost resistance were also strengthened in macro PP fiber-reinforced rubber concrete compared with plain concrete. The macro PP fiber-reinforced rubber concrete will enlarge the post-failure flexural residual load capacity and deformation and distribute stress for multiple crack propagation, thus increasing overall fracture toughness and reducing brittleness. The sustainable applications can be further explored with the combination of macro PP fiber and recycled rubber aggregate.
Shuaicheng Guo, Ruizhe Si, Qingli Dai, Zhanping You, Yunxiang Ma, and Jiaqing Wang
Journal of Cleaner Production, ISSN: 09596526, Volume: 233, Pages: 126-146, Published: 1 October 2019 Elsevier BV
Abstract Corrosion is one of the most severe threats to the stability of steel bridges and regular rust removal techniques is needed for the maintenance of steel bridges. Currently the correlation between rust development/removal process and the structural/environmental performance of the steel bridges has not been fully understood. This study intends to fill this knowledge gap through critically reviewing. The characteristic analysis of the rust on the corroded steel bridges was first introduced, which provided information that was needed to understand the corrosion mechanisms and classify the rust type. Then the related rust removal techniques (chemical and physical methods) are analyzed by considering the environmental impact and cleaning efficiency. Based on the discussion, the laser cleaning method is proposed due to its cleaning efficiency and environmentally friendliness. After that, the influence of developed rust (uniform and pitting) on the structural performance (static and dynamic) of steel members were summarized. Through the discussion, the potential environmental impact of the corroded steel bridges was identified, including runoff of heavy metal and bacteria growth caused by iron rust. Besides that, an improved kinetic model was proposed by considering the influence of rust removal on the corrosion rate. Furthermore, the structural impact of laser cleaning was simulated with the finite element analysis. This study will serve as solid base for the future studies of corrosion development and rust removal on steel bridges, and the proposed technical routes can be proceeded during future studies to better understand the environmental and structural performance of the steel bridges.
Fangyuan Gong, Shuaicheng Guo, Siyu Chen, Zhanping You, Yu Liu, and Qingli Dai
Construction and Building Materials, ISSN: 09500618, Volume: 214, Pages: 475-483, Published: 30 July 2019 Elsevier BV
Abstract Application of rubber particle from the scrap tire through dry-process is a practical and economical efficient way to resolve the recycling problem and environmental concern of the disposed tires. However, the added rubber aggregate reduces both the strength and durability of the rubberized asphalt mixture. This study aims to improve the strength and durability of dry-processed asphalt mixture by using the cement (Portland Type Ⅰ) coating methods and gap-gradation system (Stone Matrix Asphalt (SMA)). The cement coating was applied to enhance the bonding performance between rubber aggregate and asphalt binder, and limits its expansion due to swelling in hot asphalt binder. The SMA mixtures were prepared with different sizes and proportions of mineral aggregates. The samples with conventional aggregate and untreated rubber aggregate both serve as control samples for the sample evaluation. Finally, tests on tensile strength, moisture susceptibility, rutting resistance, anti-stripping resistance, fatigue cracking resistance, and bonding between rubber particles and asphalt binder of SMA mixtures were conducted. The results showed that SMA mixture with pre-coated rubber aggregate owns similar performance comparing to the samples prepared with conventional aggregate and also has higher strength and better performance than that of the mixture with untreated rubber aggregate. Results also clearly indicated that the asphalt mixtures with 50% of No.16 mineral aggregates replaced by pre-coated rubber aggregates performed the best-satisfied performances; while, with a further increase in replaced size or proportion, the satisfied performances of SMA mixtures would be degenerated.
Jiaqing Wang, Shuaicheng Guo, Qingli Dai, Ruizhe Si, and Yunxiang Ma
Journal of Cleaner Production, ISSN: 09596526, Volume: 226, Pages: 85-95, Published: 20 July 2019 Elsevier BV
Abstract Using the crushed waste Cathode Ray Tube (CRT) glass as fine aggregate to produce concrete can be an efficient method to resolve the recycling issue. However, the mediocre mechanical properties of CRT concrete obstructed its wide application. This study aims to resolve this issue based on the study on concrete/mortar specimen incorporating with an innovated surface treatment method. Specifically, a two-step surface treatment method was proposed to improve the performance of CRT concrete by modifying the surface layer of CRT glass sands with NaOH solution and Al(NO3)3 solution. About 30% of the portland cement was replaced with class-F fly ash to mitigate possible ASR damage by the reactive CRT aggregate. The mechanical performance (Compressive/flexural strength, dynamic modulus of elasticity, and flexural fracture energy) and the durability performance (Drying shrinkage and ASR expansion) was examined and compared among different specimens. In addition, the leaching levels of lead in different concrete specimens was evaluated by toxicity characteristic leaching procedure (TCLP). The results showed that the surface treatment method of CRT glass sands could obviously improve both the mechanical properties and durability performance. Particularly, the leaching of lead (Pb) level in all concrete specimens was much lower than the TCLP heavy metals limit of 5 mg/L. This experimental study will facilitate the production of CRT glass concrete for secondary structural applications.
Wenbo Ma, Cong Hu, Shuaicheng Guo, Zenggang Zhao, and Tianbao Huang
Journal of Materials in Civil Engineering, ISSN: 08991561, Published: 1 July 2019 American Society of Civil Engineers (ASCE)
AbstractPolyurethane materials have been widely applied in the mending of cementitious materials, and the mending efficiency is highly impacted by the bond strength between the polyurethane materia...
Zhi Wang, Long Li, Linjian Song, Shuaicheng Guo, and Qingli Dai
International Journal of Geomechanics, ISSN: 15323641, Published: 1 May 2019 American Society of Civil Engineers (ASCE)
Yanping Sheng, Haichuan Jia, Shuaicheng Guo, Assaad Taoum, Bowen Guan, Haibin Li, and Xiong Rui
International Journal of Pavement Research and Technology, ISSN: 19966814, eISSN: 19971400, Pages: 315-324, Published: 1 May 2019 Springer Science and Business Media LLC
This paper aims to study the mechanical performance and durability properties of the brucite fiber reinforced cement stabilized base at the low-temperature condition. Five type samples with different fiber content were prepared, and the related mechanical performance and durability properties were examined. The test results indicated that the added brucite fiber could enhance both the mechanical and durability performance of the cement stabilized base. Specifically, it was found that the unconfined compressive/splitting tensile strength can reach at 3-day age and 7-day age could reach 41%/37% and 67%/67% respectively compared to the results at 28-day age. Furthermore, the added brucite fiber can reduce the drying shrinkage of the cementitious material and also improve its resistance to frost damage. The X-ray diffraction and Scanning Electron Microscopy tests were further conducted to examine the improvement mechanism of the brucite fiber reinforcement. It is found that the hydration degree of cement paste was enhanced with the added brucite fiber. The designed brucite fiber cement stabilized sample in this study is suitable for pavement construction in alpine regions.
Wenbo Ma, Tianbao Huang, Shuaicheng Guo, Caiqian Yang, Yanhuai Ding, and Cong Hu
Construction and Building Materials, ISSN: 09500618, Volume: 205, Pages: 642-655, Published: 30 April 2019 Elsevier BV
Abstract Asphalt aging is one of the most severe threats to the asphalt pavement durability and rejuvenation with cooking oil can help to resolve this issue. Currently, the influence of aging/rejuvenation on the bonding performance of asphalt binder has not been fully understood. This study aims to unveil the influence of aging/rejuvenation on the adhesion performance under both micro and macro scale tests. Three type asphalt binders were examined in this study, including the original, aged and rejuvenated samples. The atomic force microscope (AFM) was first applied to examine the surface morphology and adhesion performance of the three type asphalt samples. It is found that the aging effect can increase the adhesion between asphalt binder and silica particles and the adhesion force can be further enhanced through rejuvenation. Then the three-point bending was further conducted to examine adhesion performance at the macroscale, and the obtained results are in accordance with those obtained at the microscale. However, the slant shear test indicated the shear bond strength can be reduced due to the rejuvenation with vegetable oil, which can be generated due to the lubrication effect of the oil. The results in this study can help to better understand the influence of aging and rejuvenation on the bond performance between asphalt binder and mineral aggregate.
Jiaqing Wang, Qingli Dai, Shuaicheng Guo, and Ruizhe Si
Construction and Building Materials, ISSN: 09500618, Volume: 203, Pages: 469-480, Published: 10 April 2019 Elsevier BV
Abstract The epoxy-based polymer concrete has been widely used for concrete repairing and overlays due to good mechanical properties and durability. To reduce environmental landfill problems with the accumulation of tire rubbers, scrap tire rubbers were added to epoxy polymer concrete in this investigation. The crumb rubber (with mesh size #50, 0.279 mm) were introduced into epoxy concrete with two different contents of 5% and 10% based on the epoxy monomer weight. The mechanical properties including direct tensile strength, compressive strength, splitting tensile strength and interface bond strength. Thermal- and moisture-related durability performance of rubberized epoxy concrete were measured and compared with the control samples. The compressive strength and splitting tensile strength were improved with the added 5% solid rubbers, and slightly reduced with 10% content. With a specially-designed testing method, the interface tensile bonding strength between the epoxy concrete overlay and concrete slab were measured as higher than 250 psi for both control and rubberized samples. The thermal conductivity of polymer concrete was reduced with the increase of rubber contents. In addition, very low water absorption rates (
Ruizhe Si, Shuaicheng Guo, and Qingli Dai
Journal of the American Ceramic Society, ISSN: 00027820, eISSN: 15512916, Volume: 102, Pages: 1479-1494, Published: March 2019 Wiley
Jiaqing Wang, Qingli Dai, Shuaicheng Guo, and Ruizhe Si
ACI Materials Journal, ISSN: 0889325X, Volume: 116, Pages: 21-31, Published: March 2019 American Concrete Institute
Shuaicheng Guo, Qingli Dai, Liang Chang, Yunhang Hu, Xinfeng Xie, Ruizhe Si, and Jiaqing Wang
Journal of the American Ceramic Society, ISSN: 00027820, eISSN: 15512916, Volume: 102, Pages: 1463-1478, Published: March 2019 Wiley
Shuaicheng Guo, Qingli Dai, and Ruizhe Si
Cement and Concrete Research, ISSN: 00088846, Volume: 115, Pages: 220-229, Published: January 2019 Elsevier BV
Abstract This study aims to investigate the influence of lithium and calcium content on the alkali-silica reaction kinetics and phase formation processes at atomic scales. The atomic structure of the reacted ASR gels was analyzed with the Pair Distribution Function (PDF) measurement. The analysis results can explain the expansion potential difference of gels with different chemical composition. The in situ PDF characterizations of the samples containing lithium compounds identified the formation of the Li Si phase, and thus both the alkali-silica reaction and the reaction between dissolved silica and Ca(OH)2 were suppressed. The alkali-silica reaction kinetics was further indicated with the changes of Si O peak intensity. The amorphous structure of the generated Li Si phase was confirmed with in situ XRD tests. The results strongly support the formed amorphous Li Si phase can act as a surface barrier for silica dissolution, and thus prohibit both the alkali-silica reaction and pozzolanic reaction in hardened concrete.
Jiaqing Wang, Qingli Dai, Ruizhe Si, and Shuaicheng Guo
Construction and Building Materials, ISSN: 09500618, Volume: 193, Pages: 631-642, Published: 30 December 2018 Elsevier BV
Abstract In this study, the Polyvinyl Alcohol (PVA) fiber was introduced to improve the performance of the rubberized concrete. This study experimentally investigated the mechanical performance and durability of Polyvinyl Alcohol (PVA) fiber-reinforced rubber concrete. The waste rubber particles (mesh size #10–#30) were selected to partially replace fine aggregates in the plain concrete. In addition, the rubber particles were pre-treated with an alkali solution to enhance the interface bond with cement paste. The fiber-reinforced rubber concrete samples were prepared with different fine aggregate replacement ratios based on the volume of fine aggregate (15%, 20%, and 25%) and a selected fiber content (0.5% based on the total volume of the mixture). For those samples, the mechanical properties, including compressive strength, flexural behavior, and fracture energy were evaluated to compare with control samples. The results showed that fiber-reinforced samples can largely improve the post-cracking extension and fracture energy. The results of electrical resistivity test indicated the reduced permeability in the fiber-reinforced rubber concrete. The durability performance including Alkali-Silica reaction (ASR) expansion, drying shrinkage and freeze-thaw resistance were also investigated and compared with the control samples. All the durability performances were enhanced through rubber stress release and fiber crack bridging. Therefore, the PVA-fiber reinforced rubber concrete can improve durability and ductility of cementitious materials for structure construction and also can facilitate the recycling of waste rubber into cementitious materials.
Lingyun You, Zhanping You, Qingli Dai, Shuaicheng Guo, Jiaqing Wang, and Meghan Schultz
Journal of Materials in Civil Engineering, ISSN: 08991561, Published: 1 November 2018 American Society of Civil Engineers (ASCE)
AbstractA major concern with the application of water-foamed asphalt mixtures is the possible performance degradation caused by the presence of inclusion water during production. Inclusion water le...
Zigeng Wang, Qingli Dai, and Shuaicheng Guo
Construction and Building Materials, ISSN: 09500618, Volume: 187, Pages: 865-875, Published: 30 October 2018 Elsevier BV
Abstract This paper computationally and experimentally investigated the microwave healing performance of graphite (flake graphite and exfoliated graphite nanoplatelet (xGNP)) modified asphalt mixture. The original fracture energy and strength were first measured for the modified asphalt mixture through the disk-shaped compact tension test. Then the micro-wave healing performance (recovered fracture energy and strength) were further examined. All these were enhanced with the added carbon materials. The recovered fracture strengths were also compared with FE cohesive zone model (CZM) simulation with digital image correlation (DIC) calibrated parameters. The predicted recovered fracture strength had good agreement with the experimental measurement.
Zhi Wang, Long Li, Shuaicheng Guo, and Qingli Dai
Applied Sciences (Switzerland), eISSN: 20763417, Published: 9 July 2018 MDPI AG
Grouting reinforcement is an important part of modern engineering and has grown in popularity due to the benefits of grouting enhancement on cyclic loading. Understanding the fatigue mechanism of grouting-enhanced structures is vital to the design and the long-term stability analysis of such structures. In this study, the fatigue mechanical properties of cracked cement paste after epoxy resin grouting enhancement under different cyclic conditions were investigated in the laboratory and an inverted S-shaped curve was proposed to describe the damage accumulation. The test results indicated that the fatigue axial deformation can be divided into three stages: the initial stage, constant velocity stage and accelerating stage. The irreversible deformation can be used to describe the damage accumulation. The fatigue process is significantly affected by the upper limit stress level and the stress amplitude. In addition, the exponential relationship between stress amplitude and fatigue life was obtained. The proposed S-shaped curve was validated by an experimental fatigue strain test. The tests result upon various load conditions and crack types represented a good agreement with the predicted data.
Shuaicheng Guo, Jiong Hu, and Qingli Dai
Journal of Cleaner Production, ISSN: 09596526, Volume: 188, Pages: 92-112, Published: 1 July 2018 Elsevier BV
Abstract The quick accumulation of recycled organic components with the modern society development has caused serious environment issues, and the utilization of these recycled organic components in concrete production can effectively mitigate recycling pressure. Portland cement concrete mixes containing recycled organic components behave differently in both fresh and hardened stages compared to conventional concrete, which need to be thoroughly studied before a large-scale field application. This paper aims to critically review the currently-reported performance of concrete with recycled organic components and to identify the knowledge gap for future sudies. This paper first conducted the characteristic investigation of recycled organic components, which provided the needed information for the classification of recycled organic components. Then the property performance, including workability, mechanical properties, and durability of concrete containing recycled organic component was evaluated. It has been concluded that both the workability and concrete strength will decrease with the added recycled organic components. However the durability performance, including freeze-thaw, impact resistance, and the resistance to alkali-silica reaction can be enhanced with the added recycled organic components. Aiming at the decreased strength, surface treatment methods have been reviewed. The current finding demonstrated the NaOH surface treatment for rubber particles and oxidation method for reclaimed asphalt mixture aggregates can enhance the concrete performance, respectively. Finally, the practice of applying recycled organic components in high strength and self-consolidating concrete was summarized, which demonstrated the potential of high performance concrete production with recycled organic component. Current knowledge gaps were identified to point out the challenges for the further study, including the difficulties to produce high strength and self-consolidating concrete with replacement ratio of recycled organic components higher than 50%. This study will provide the firm base for the application and future study on concrete containing recycled organic components, including reclaimed asphalt pavement (RAP), recycled asphalt shingles (RAS) and recycled crumb rubber (RCR).
Shuaicheng Guo, Qingli Dai, and Jacob Hiller
Frontiers of Structural and Civil Engineering, ISSN: 20952430, eISSN: 20952449, Pages: 227-238, Published: 1 June 2018 Springer Science and Business Media LLC
Freeze-thaw damage is one of the main threats to the long time performance of the concrete pavement in the cold regions. This project aims to evaluate the influence of the freeze-thaw damages on pavement distresses under different climate conditions. Based on the Long-Term Pavement Performance (LTPP) data base, the freeze-thaw damage generated by four different kinds of climate conditions are considered in this project: wet-freeze, wet-non freeze, dryfreeze and dry-non freeze. The amount of the transverse crack and the joint spalling, along with the International Roughness Index (IRI) are compared among the test sections located in these four different climate conditions. The back calculation with the Falling Weight Deflectometer (FWD) test results based on the ERES and the Estimation of Concrete Pavement Parameters (ECOPP) methods are conducted to obtain concrete slab elastic modulus and the subgrade k-value. These two parameters both decrease with service time under freeze condition. Finally, MEPDG simulation is conducted to simulate the IRI development with service year. These results showed the reasonable freeze-thaw damage development with pavement service life and under different climate conditions.
Ruizhe Si, Jiaqing Wang, Shuaicheng Guo, Qingli Dai, and Song Han
Journal of Cleaner Production, ISSN: 09596526, Volume: 180, Pages: 823-831, Published: 10 April 2018 Elsevier BV
Abstract This study investigated the performance of early-aged and hardened self-consolidating concrete (SCC). Rubber-modified SCC mixtures were prepared with 15% as-received crumb rubber and 15% and 25% NaOH-treated crumb rubber based on volume of fine aggregates. The SCC sampled without rubber aggregates were cast as the control groups. The slump test, V-flannel flow test, and U-box test were conducted to evaluate the fresh properties of different types of rubber modified SCC. The fresh properties showed slightly reduced flowability with replaced rubber particles. The measured compressive and splitting tensile strength of rubber-modified SCC concrete were reduced in comparison with the control mixture. However, the surface-treated rubberized concrete had higher mechanical strength than as-received rubberized concrete due to better bonding at the interface. The measured ultrasonic transmission speed decreased with the increasing rubber content in concrete and these results also indicated the reduced dynamic modulus. The transport property evaluated from the electrical resistivity measurement indicated the decreased permeability with added rubber content. The durability performances (including alkali-silica reaction and drying shrinkage) of SCC mortar samples were generally improved with rubber-modified samples. Overall study showed that the rubber-modified SCC can maintain good workability and mechanical properties and enhance durability with reduced environmental impacts.
Shuaicheng Guo, Qingli Dai, Xiao Sun, and Xinfeng Xie
Materials Characterization, ISSN: 10445803, Volume: 136, Pages: 165-174, Published: February 2018 Elsevier BV
Abstract Recent studies demonstrated that the added glass powder with high-alumina content could significantly reduce Alkali-Silica Reaction (ASR) damage in cement concrete. This paper aims to investigate the gel water content, chemical composition and expansion behavior of the alkali-glass powder reacted gel by using neutron scattering and other characterization techniques. Three types of samples were prepared with glass powder, sodium oxide and deuteroxide/hydrogen water with different molar ratios. The swelling potential of this alkali-glass powder reacted gel was much lower than that of the reported alkali-silica reacted gel. The gel water content and chemical compositions were characterized with small-angle neutron scattering (SANS) technique, supported by small-angle X-ray scattering (SAXS), prompt-gamma ray neutron activation analysis (PGAA) measurement. The SAXS test results showed the close scattering intensities, and thus similar internal microstructures among these samples. The elemental molar ratios of gels were obtained from the PGAA test results. Then the gel water molar ratio and mass density were determined by neutron scattering contrast calculation. The determined gel water content from neutron scattering analysis was validated with zero contrast analysis and TGA experimental measurement. Overall, this paper demonstrated the feasibility of using SANS technique to determine the water content of alkali-glass powder reacted gel.
Xiao Sun, Antonio Faraone, Qingli Dai, and Shuaicheng Guo
Materials Characterization, ISSN: 10445803, Volume: 136, Pages: 134-143, Published: February 2018 Elsevier BV
Abstract The three-component model is typically used to analyze the quasi-elastic neutron scattering data and study the water dynamics of hydrating cementitious system. Its application to the hardened cement paste is hindered due to the inaccuracy in evaluating free water at normal ambient temperature. This paper presents a novel approach to quantifying the amount of free water through conducting neutron scattering under freeze-thaw cycling. Disk-like cement paste samples were prepared and applied with four freeze-thaw cycles by varying temperatures in the range of 240 K to 300 K. Quasi-elastic neutron scattering data collected before and after the freeze-thaw cycles and elastic neutron scattering data was collected during each cycle. The signal intensity associated with the free water was obtained by combining QENS and ENS data analysis and a mathematical deduction. We introduced the index of the total immobile water to quantitatively demonstrate water content. The fractional change of the immobile water after freeze-thaw cycle was also studied. The significance of this method is that it is not limited to be applied to cement paste system but also compatible with other systems where the amount of free water cannot be accurately quantified by the standard QENS analysis.
Shuaicheng Guo, Qingli Dai, Xiao Sun, Xianghui Xiao, Ruizhe Si, and Jiaqing Wang
Journal of Cleaner Production, ISSN: 09596526, Volume: 172, Pages: 3621-3633, Published: 20 January 2018 Elsevier BV
Abstract Recycling waste glass aggregate into concrete can reduce environmental impacts but also may lead to serious alkali silica reaction (ASR) damage. This study aims to characterize ASR damage development in the mortar samples containing reactive glass aggregates and investigate the damage reduction effect of the waste supplementary cementitious materials (SCMs), including recycled glass powders and fly ash. The recycled glass aggregate mortar samples with/without SCMs were prepared in this study. The length change tests were first conducted with the prepared mortar samples based on the ASTM C1260 standard. The results demonstrated the added SCMs can largely decrease early-age ASR expansion rate. The optical microscope and Scanning Electron Microscope (SEM) with Energy Dispersive X-ray Spectroscopy (EDS) were further conducted to characterize the ASR damage in mortar samples and investigate the damage mitigation mechanism with added SCMs. The combined SEM imaging and chemical analysis indicated added SCMs can decrease both the alkali and calcium content of the generated ASR gel. In addition, the ASR damage development inside mortar samples were monitored with dynamic micron X-ray CT (μCT) over a reaction period of 63 h at the temperature of 80 °C. The scanning patterns demonstrated the ASR damage can be easily developed from the area with initial cracks and sharp corners. The images of glass power and fly ash samples showed significantly reduced ASR damage. This study showed that adding of SCMs can largely reduce ASR deterioration and thus facilitate the recycling glass particles into concrete.
Shuaicheng Guo, Xu Yang, Zigeng Wang, Lingyun You, Qingli Dai, and Zhanping You
Nanotechnology in Eco-efficient Construction: Materials, Processes and Applications, Pages: 187-201, Published: 1 January 2018 Elsevier
Abstract This chapter aims to summarize the current research and findings on performance enhancement of the nanomodification on asphalt mixture. The study first summed up the main nanomaterials applied for the modification, including the nanomineral and nanocarbon materials. The dispersion protocol for these nanomaterials into the asphalt binder was further introduced, including mixing temperature, shear speed, and mixing time. Then the enhanced performance of the nanomodified asphalt mixture was concluded based on the reference review, including mechanical, electrical, thermal, and optical performance. It is found that the added nanomaterials can enhance the stiffness and high temperature stability of the asphalt mixture and reduce its permanent deflection. Similar findings on mechanical performance can be found for the asphalt mixture with different nanomaterials mainly due to the similar reinforcing mechanism (filler effect). The added carbon nanomaterials can further enhance the thermal conductivity, electrical conductivity, and absorbance for sunlight, which can lead to promising self-sensing and self-healing materials.
Shuaicheng Guo, Qingli Dai, Xiao Sun, and Xianghui Xiao
Theoretical and Applied Fracture Mechanics, ISSN: 01678442, Pages: 76-88, Published: December 2017 Elsevier BV
Abstract The alkali-silica reaction (ASR) damage in reactive aggregates affects the long-term durability of the concrete infrastructure. The generated ASR gel can expand by imbibing water from the pore solution and the resulting expansion pressure causes the aggregate fracture. This study aims to simulate the development of ASR damage in glass particles of two types of samples (glass in alkali solution and glass mortars). The dynamic micro X-ray CT technique was conducted to monitor the crack propagation in glass aggregates at different reaction stages (up to 64 h). The Boundary Element Method (BEM) and Displacement Discontinuity Method (DDM) were used to efficiently simulate the crack propagation within irregular glass particles under gel expansion pressures. The aggregate boundaries were built with the BEM elements and the initial cracks were meshed with the DDM elements. The estimated expansion pressure was applied to the initial crack surfaces. The discontinuous displacements and stresses were calculated along the crack path and crack tip. The mixed-mode Stress Intensity Factors (SIFs) were calculated based on plane stress conditions. The maximum circumferential stress criteria were used to simulate the propagation of cracks along a specific angle. The simulation results include the simulated crack path and the combined SIFs changing with the increments. With the estimate expansion pressure, the glass particle damages were simulated within conditions of alkali solution and confined mortar samples. The predicted crack propagation path was compared with the X-ray CT imaging data. The comparison results demonstrate the DDM has the ability to predicting the ASR damage propagation inside aggregates.
Ruizhe Si, Shuaicheng Guo, and Qingli Dai
Construction and Building Materials, ISSN: 09500618, Volume: 153, Pages: 496-505, Published: 30 October 2017 Elsevier BV
Abstract This study experimentally investigated the durability of rubberized mortar and concrete samples with NaOH-solution treated rubber particles. The concrete samples without rubber particles were cast as control samples. The rubberized mortar or concrete samples were prepared with 15% as-received rubber and different contents of NaOH treated rubber (15%, 25%, 35% and 50% by volume of fine aggregate). The electrical resistivity, air-void measurement, and absorption tests were first conducted to evaluate the transport properties of rubberized concrete samples. The freeze-thaw durability tests on different concrete samples showed that the added rubber particles improved the freeze-thaw resistance of concrete. The effect was more significant for NaOH treated rubber particles than that of as-received rubber particles. The results of the alkali-silicate reaction (ASR) expansion test suggested that the ASR expansion was decreased in rubberized mortar compared to plain mortar. The 15% NaOH treated rubber replacement was most effective on reducing the ASR expansion among all of the rubberized mortar samples. The drying shrinkage increased with the content of rubber particles in mortar; however, the increased shrinkage in rubberized mortar appeared to be reduced when the additional rubber was treated with NaOH solution. These test results indicated that the rubberized concrete or mortar (with 15% or 25% NaOH-treated rubber replacement) samples have improved durability.
Zigeng Wang, Qingli Dai, and Shuaicheng Guo
Construction and Building Materials, ISSN: 09500618, Volume: 149, Pages: 515-524, Published: 15 September 2017 Elsevier BV
Abstract This paper presents a laboratory investigation of the thermal, electrical, rheological and mechanical properties and performance of control and graphite (flake graphite and exfoliated graphite nanoplatelet (xGNP)) modified asphalt binder and mixture. For the graphite modified asphalt binder, the rolling thin film oven (RTFO) test and pressure aging vessel (PAV) test were utilized to simulate the short-term and long-term aging process of control and graphite modified asphalt binder, respectively. The bending beam rheometer (BBR) test and dynamic shear rheometer (DSR) test were conducted to evaluate the rheological properties of the control and graphite modified asphalt binder at low and high temperatures, respectively. The Fourier transform infrared spectroscopy (FTIR) was used to evaluate the oxidation group content in these asphalt binders. The thermal conductivity of the graphite modified asphalt binder increased with graphite content. For the graphite modified asphalt mixtures, both thermal and electrical conductivities also increased with added graphite modifiers. The measured dynamic modulus results of mixture performance tests indicated that the added graphite particles were capable of increasing their moduli at both high and low temperatures. The Hamburg wheel tracking device (HWTD) test results also showed an improved rutting resistance. As a result, the graphite modified asphalt mixture can improve multiple physical properties and high-temperature performance as promising conductive materials for many applications.
Xiao Sun, Shuaicheng Guo, Qingli Dai, and Xianghui Xiao
Materials Characterization, ISSN: 10445803, Volume: 131, Pages: 98-107, Published: September 2017 Elsevier BV
Abstract The major obstacles of the incorporation of recycled waste glass in concrete infrastructures are the deteriorations caused by alkali-silica reaction (ASR). Previous research found the concrete containing glass powder does not suffer from ASR. This indicates the size-effect, which is the main focus of this study, is crucial for the incorporation of waste glass in concrete. In order to gather the information for the proposed analytical models, the microstructure and morphology of the synthetic alkali-glass particle and alkali-glass powder reacted gels were characterized by using ultra small angle/small angle neutron scattering (USANS/SANS) and scanning electron microscope (SEM) techniques. The radius of gyration and the power-law constant of different gel samples were obtained by fitting the scattering intensity with a unified Guinier/power-law approach. The power-law constants were in the range from 3 to 4 for the condensed gel sample, indicating the gel particles are surface fractals with different roughness. The SEM images show that the gel particles were spherical-like with sizes around 2 to 3 μm, which is close to the characteristic size (3.4 μm) calculated from the radius of gyration. The dynamic alkali-glass particle reaction was captured with the synchrotron X-ray micro-computed tomography (X-ray micro-CT). The reacted gel particle distributions at different reaction stages were analyzed (up to 64 h). At earlier reaction stage, the majority of gel particles has a size ranged from 2 to 3 μm. At later reaction stages, more large-sized particles were observed in the reaction solution, indicating the volume change of the glass-particle reaction gel.
Shuaicheng Guo, Qingli Dai, Zigeng Wang, and Hui Yao
Composites Part B: Engineering, ISSN: 13598368, Volume: 124, Pages: 134-143, Published: 1 September 2017 Elsevier BV
Abstract Due to its superior mechanical properties, carbon nanotubes (CNTs) can be applied for material reinforcement and modification. However, the relatively high cost for CNTs synthesis limits their large application in construction materials. This study employed the microwave irradiation method to produce CNTs with low cost and high efficiency. The ferrocene powder was mixed with graphite surfaces and irradiated with the microwave. Particularly, the flake graphite and exfoliated graphite nanoplatelets (xGNP) were applied in this study as substrate. The high temperature generated by the microwave irradiation can decompose ferrocene into iron and hydrocarbons, which serve as the catalyst and carbon source for the CNTs growth, respectively. The morphology, internal structure and chemical composition of the synthesized CNTs were then examined with SEM, TEM and EDS. The Raman test was also conducted to investigate the defect level of synthesized CNTs. Then the adhesion energy between the CNTs and substrate was evaluated with the MD simulation. The obtained adhesion energy between CNTs and non-oxidized graphene layers was slightly higher than the calculated results between CNTs and oxidized graphene layers. Finally, the hybrid CNTs-graphite powders were used for the modification of asphalt binder. The test results of viscosity and dynamic shear modulus tests demonstrate that the hybrid CNTs-graphite powders can further improve the mechanical properties of asphalt, especially at high service temperatures.
Shuaicheng Guo, Qingli Dai, Ruizhe Si, Xiao Sun, and Chao Lu
Journal of Cleaner Production, ISSN: 09596526, Volume: 148, Pages: 681-689, Published: 1 April 2017 Elsevier BV
Abstract Using rubber particles as concrete aggregates can reduce the environmental impacts caused by the large accumulation of scrap tires. However, the added rubber particles can decrease concrete strength due to their low stiffness and surface bonding with cement paste. This study aims to improve the rubber concrete performance by employing different surface treatment and coating methods. Particularly, two surface treatment methods (NaOH, and Silane Coupling Agent) and three coating techniques (coated with normal cement, blended cement with silica fume, and blended cement plus sodium silicate) were used to improve rubber-cement bonding. Totally, ten groups of rubber concrete samples were prepared by using difference treatment or rubber replacement ratio. In addition, the control concrete samples without rubber particles or with as-received rubber particles were prepared for the comparison. The compressive strength tests demonstrated the NaOH-solution treatment can significantly improve the rubber concrete strength by comparing with normal and as-received rubber concrete. Further tests indicated that the samples with 25% replacement can still fulfil the strength requirements for rigid pavement construction. The measured electrical resistivity of rubber concrete were higher than the normal concrete, which indicates lower permeability and better durability. The decreased thermal conductivity and sound transmission attenuation can increase building energy efficiency and reduce noise, respectively. Overall, this study demonstrated NaOH-treated methods can improve the mechanical performance of rubber concrete and enhance its long-term durability. This modified rubber concrete can be potentially applied to the pavement and structure construction applications.
Zigeng Wang, Qingli Dai, Shuaicheng Guo, Ronghua Wang, Mingxiao Ye, and Yoke Khin Yap
Construction and Building Materials, ISSN: 09500618, Volume: 134, Pages: 412-423, Published: 1 March 2017 Elsevier BV
Abstract This presented research investigated the physical properties and accelerated sunlight-healing performance of graphite modified asphalt materials. Two types of graphite materials, flake graphite and exfoliated graphite nanoplatelets (xGNP), were added to asphalt with different contents by weight. Asphalt binder tests were conducted to evaluate the performance of modified asphalt, including rotational viscosity, light absorbance, and thermal conductivity. The tests results of graphite modified asphalt showed increased viscosities, decreased activation energies, and increased light absorbance and thermal conductivity in comparison to the control asphalt. Afterwards, the graphite modified asphalt mixture beams (5% flake graphite and 2% xGNP) were prepared and used for cyclic fracture-light healing tests. The digital image correlation (DIC) was utilized to characterize the displacement changes in the fracture zone during the light healing process. The DIC results indicated that the improved healing performance of graphite modified asphalt mixtures and decreased healing displacement with light healing cycles. Finally, the measured recovered strength after each cycle was used to evaluate the healing performance of both the graphite modified and control samples. The results of cyclic fracture-light healing tests indicated that the graphite modified asphalt materials have significantly improved healing performance and therefore these materials have promises in promoting new light healing applications.
Shuaicheng Guo, Qingli Dai, Xiao Sun, Ye Sun, and Zhen Liu
Applied Sciences (Switzerland), eISSN: 20763417, Published: 2017 MDPI AG
Entrained air voids can improve the freeze-thaw durability of concrete, and also affect its mechanical and transport properties. Therefore, it is important to measure the air void structure and understand its influence on concrete performance for quality control. This paper aims to measure air void structure evolution at both early-age and hardened stages with the ultrasonic technique, and evaluates its influence on concrete properties. Three samples with different air entrainment agent content were specially prepared. The air void structure was determined with optimized inverse analysis by achieving the minimum error between experimental and theoretical attenuation. The early-age sample measurement showed that the air void content with the whole size range slightly decreases with curing time. The air void size distribution of hardened samples (at Day 28) was compared with American Society for Testing and Materials (ASTM) C457 test results. The air void size distribution with different amount of air entrainment agent was also favorably compared. In addition, the transport property, compressive strength, and dynamic modulus of concrete samples were also evaluated. The concrete transport decreased with the curing age, which is in accordance with the air void shrinkage. The correlation between the early-age strength development and hardened dynamic modulus with the ultrasonic parameters was also evaluated. The existence of clustered air voids in the Interfacial Transition Zone (ITZ) area was found to cause severe compressive strength loss. The results indicated that this developed ultrasonic technique has potential in air void size distribution measurement, and demonstrated the influence of air void structure evolution on concrete properties during both early-age and hardened stages.
Hui Yao, Qingli Dai, Zhanping You, Andreas Bick, Min Wang, and Shuaicheng Guo
Applied Sciences (Switzerland), eISSN: 20763417, Published: 2017 MDPI AG
This Molecular Dynamics (MD) simulation paper presents a physical property comparison study between exfoliated graphite nanoplatelets (xGNP) modified and control asphalt models, including density, glass transition temperature, viscosity and thermal conductivity. The three-component control asphalt model consists of asphaltenes, aromatics, and saturates based on previous references. The xGNP asphalt model was built by incorporating an xGNP and control asphalt model and controlling mass ratios to represent the laboratory prepared samples. The Amber Cornell Extension Force Field (ACEFF) was used with assigned molecular electro-static potential (ESP) charge from NWChem analysis. After optimization and ensemble relaxation, the properties of the control and xGNP modified asphalt models were computed and analyzed using the MD method. The MD simulated results have a similar trend as the test results. The property analysis showed that: (1) the density of the xGNP modified model is higher than that of the control model; (2) the glass transition temperature of the xGNP modified model is closer to the laboratory data of the Strategic Highway Research Program (SHRP) asphalt binders than that of the control model; (3) the viscosities of the xGNP modified model at different temperatures are higher than those of the control model, and it coincides with the trend in the laboratory data; (4) the thermal conductivities of the xGNP modified asphalt model are higher than those of the control asphalt model at different temperatures, and it is consistent with the trend in the laboratory data.
Shuaicheng Guo, Qingli Dai, Xiao Sun, and Ye Sun
Construction and Building Materials, ISSN: 09500618, Volume: 113, Pages: 415-422, Published: 15 June 2016 Elsevier BV
Abstract The size distribution of air voids in concrete has significant impacts on freeze-thaw damage. This study presented a non-destructive ultrasonic scattering technique to determine the air void size distribution in hardened concrete samples. The ultrasonic scattering theory was applied to calculate the theoretical attenuation of concrete by including the effects of the viscoelastic matrix and different sizes of air voids and aggregates. The air void size distribution was determined by using an inverse analysis to minimize the difference between theoretical and experimental attenuation of concrete. The logarithm normal distribution for large-size air voids and normal distribution for small-size air voids were selected to better represent the air void size distribution in concrete. Both the large-size range and small-size air void distributions were obtained with ultrasonic scattering techniques for hardened concrete specimens. These results were favorably compared with the petrography-based ASTM C 457 method. The comparisons indicated that the developed ultrasonic scattering technique can measure the size distribution of air voids in concrete for the evaluation of freeze-thaw durability.
Wen-bo Ma, Qiu-hua Rao, Peng Li, Shuai-cheng Guo, and Kang Feng
Journal of Central South University, ISSN: 20952899, eISSN: 22275223, Pages: 4682-4689, Published: 2014 Springer Science and Business Media LLC
Based on mineral component and in-situ vane shear strength of deep-sea sediment, four kinds of simulative soils were prepared by mixing different bentonites with water in order to find the best simulative soil for the deep-sea sediment collected from the Pacific C-C area. Shear creep characteristics of the simulative soil were studied by shear creep test and shear creep parameters were determined by Burgers creep model. Research results show that the shear creep curves of the simulative soil can be divided into transient creep, unstable creep and stable creep, where the unstable creep stage is very short due to its high water content. The shear creep parameters increase with compressive stress and change slightly or fluctuate to approach a constant value with shear stress, and thus average creep parameters under the same compressive stress are used as the creep parameters of the simulative soil. Traction of the deep-sea mining machine walking at a constant velocity can be calculated by the shear creep constitutive equation of the deep-sea simulative soil, which provides a theoretical basis for safe operation and optimal design of the deep-sea mining machine.
Yantu Lixue/Rock and Soil Mechanics, ISSN: 10007598, Pages: 1641-1646, Published: June 2014