Genādijs Šahmenko
@rtu.lv
Faculty of Civil Engineering
Riga Technical University
EDUCATION
2005 Doctor’s degree of engineering sciences, Riga Technical University, ISCED 2011 – 8.lev.;
1994 Master’s degree of engineering sciences, Riga Technical University, ISCED 2011 – 7.level;
1991 Bachelor’s degree engineering sciences, Riga Technical University, ISCED 2011 – 6.level;
RESEARCH INTERESTS
High Performance Concrete, Cement Composite, Concrete non-destructive testing, Eco-materials, Hemp concrete
Scopus Publications
Scopus Publications
Girts Bumanis, Pauls Pavils Argalis, Genadijs Sahmenko, Deniss Mironovs, Sandris Rucevskis, Aleksandrs Korjakins, and Diana Bajare
MDPI AG
Up to now, primary resources have been the main choice of raw material selection for production. Now, global market tendencies have brought significant attention to secondary resources as the price has been raised for primary materials, and there is a shortage of their delivery. This could bring an additional effort to increase the recycling level of construction and demolition waste, including expanded polystyrene (EPS). Efforts have been made to develop new efficient building materials with a high content of recycled EPS. In this paper, composite insulation material made of gypsum hemihydrate and recycled EPS beads by casting and compression methods were evaluated, and properties were compared. Thermal and sound insulation properties were characterized. Density from 48 to 793 kg/m3 was obtained and the thermal conductivity coefficient from 0.039 to 0.246 W/(m·K) was measured. Compression strength was from 18 kPa to 2.5 MPa. Composites produced with the compression method have a sound absorption coefficient α > 0.9 in the range from 600 to 700 Hz, while the samples produced by casting showed poor sound absorption with wide deviation. Compression methods had an advantage over the casting method as more homogenous and lightweight materials were produced with improved insulation properties.
Girts Kolendo, Aziza Kuldasheva, Aleksandrs Korjakins, Genadijs Sahmenko, and Diana Bajare
Walter de Gruyter GmbH
Abstract The number of end-of-life tyres recycled into crumb rubber varies widely across different countries and regions, depending on factors such as local regulations, infrastructure, and demand for the product. According to the International Rubber Study Group (IRSG), the global production of crumb rubber from end-of-life tires was estimated to be around 12.7 million metric tons. This study is devoted to the development of cement composites where the sand was partially and fully replaced with a specially prepared fine fraction of crumb rubber. Partial replacement of sand with crumb rubber changes the workability of the concrete. The lighter concrete composite may also have improved acoustic and thermal insulation properties. Complete substitution of sand with crumb rubber leads to a lighter concrete composite, featuring reduced densities and enhanced ductility. In these experiments, prisms of dimensions 40×40×160 mm were produced, with various mixes where we changed the amount of replaced sand with crumb rubber and water-cement ratios. These samples were tested for strength in flexure and compression, simultaneously producing force-deflection curves indicating that the rubber granules prevent brittle failure. By full sand replacement, a lightweight cementitious composite was obtained, with the potential for use as acoustic absorption materials and shock energy absorbing layers, but careful consideration of the specific application and mix design is necessary to ensure optimal performance and sustainability. Replacing sand entirely resulted in a lightweight cementitious composite, with densities of 2222 kg/m3 for 10 % replacement and 1525 kg/m3 for 100 % replacement by volume. This material holds promise for applications in acoustic absorption and shock energy absorption. However, achieving optimal performance and sustainability requires thoughtful consideration of the specific application and mix design.
Ervins Blumbergs, Viktors Mironovs, and Genadijs Sahmenko
Rezekne Academy of Technologies
The relevance of the topic of the work was shown by the accident of a multi-storey residential building in Miami, which was caused by corrosion of steel reinforcement in reinforced concrete.There is a need to maintain the bearing capacity of structures for a long time in a humid climate, aggressive environmental influences and temperature fluctuations with a lower consumption of materials used.The use of titanium will allow changing some parameters of titanium concrete structures in comparison with reinforced concrete structures. The protective layer of concrete, which serves to protect the reinforcement from the effects of the external environment, will be significantly reduced. This will help to reduce the mass of concrete structures while maintaining strength properties and will allow you to create lighter structures that can withstand heavy loads.Strength tests were carried out on concrete blocks reinforced with smooth iron or titanium rods Ø10 mm, which showed the prospects of replacing steel reinforcement with titanium reinforcement in reinforced concrete.
Genadijs Sahmenko, Maris Sinka, Ugis Paurins, and Diana Bajare
IOP Publishing
Abstract Eco materials derived from natural plant fibres and mineral binders are an alternative solution for modern ecological construction. This research is devoted to developing production technology for ecological high-performance fibre composite materials based on hemp shives and magnesium binder. The proposed composite wall structures consist of outer envelope layers made from dense hemp composite and middle insulation layer made from a lightweight hemp composite. The article describes the process of manufacturing a hemp composite boadr and the process of creating a three-layer structure of the outer wall. Used mix compositions are based on previously elaborated mix compositions based on magnesium oxychloride cement (MOC) binder and hemp shives. This study presents the case study of testing samples from hemp composite boards produced in actual industrial conditions. During an experiment, 20% magnesium oxide was replaced as an alternative binder, such as metakaolin and fly ash. The purpose of modifying the compositions of the composite is to increase the water resistance of the material and improvement of the hydraulic properties of the material, as it was previously found that this material is hygroscopic concerning the high humidity of the ambient air.
Jelizaveta Zorica, Maris Sinka, Genadijs Sahmenko, Laura Vitola, Aleksandrs Korjakins, and Diana Bajare
MDPI AG
The share of bio-based materials in modern construction needs to grow more rapidly due to increasingly stringent environmental requirements as a direct result of the climate emergency. This research aims to expand the use of hemp concrete in construction by replacing traditional lime binder with magnesium oxychloride cement, which provides a faster setting and higher strength, opening the door for industrial production. However, the negative feature of this binder is its low water resistance. In this work, the water resistance of magnesium cement was studied, and the possibilities of improving it by adding fly ash, various acids and nano-silica were considered. Nano-silica and citric acid showed the most significant impact, increasing the binder water resistance up to four times, reaching softening coefficient of 0.80 while reducing the compressive strength of the magnesium cement in a dry state by only 2–10%. On the downside, citric and phosphoric acid significantly extended the setting of the binder, delaying it 2–4 times. Regarding board production, prototype samples of hemp magnesium biocomposite demonstrated compressive strength of more than 3.8 MPa in the dry state but only 1.1–1.6 MPa in the wet state. These results did not correlate with binder tests, as the additives did not increase the strength in the wet state.
Michał Kubiś, Piotr Łapka, Łukasz Cieślikiewicz, Genadijs Sahmenko, Maris Sinka, and Diana Bajare
MDPI AG
The evolution of bio-based composites in the building industry is strongly linked with the growing demand for sustainable development, which is relevant nowadays. Hemp shives are a large group of organic residues that are obtained in the process of oil extraction as well as straw processing. These residues could be utilized along with a binder as constituents in the manufacture of bio-based building composites. This study is focused on the impact of density and relative humidity on the effective thermal conductivity of hemp shive-based bio-composites with a magnesium binder. For this reason, a series of samples with variable densities was manufactured and subjected to conditioning in a climatic chamber at a constant temperature and different relative humidity settings. As soon as samples were stabilized, the guarded hot plate method was applied to determine their thermal conductivities. Before each measurement, great care was taken during sample preparation to ensure minimum moisture loss during long-lasting measurements. The results showed that an increase in sample density from 200 kg/m3 to 600 kg/m3 corresponded to up to a three-fold higher composite thermal conductivity. In the case of sample conditioning, a change in relative humidity from a very low value to 90% also resulted in almost 60% average higher thermal conductivity.
Rihards Gailitis, Beata Figiela, Kalvis Abelkalns, Andina Sprince, Genadijs Sahmenko, Marta Choinska, and Martin Duarte Guigou
MDPI AG
One way to prevent cement from ending up in landfills after its shelf life is to regain its activity and reuse it as a binder. As has been discovered, milling by planetary ball mill is not effective. Grinding by collision is considered a more efficient way to refine brittle material and, in the case of cement, to regain its activity. There has been considerable research regarding the partial replacement of cement using disintegrated cement in mortar or concrete in the past few decades. This article determines and compares the creep and shrinkage properties of cement mortar specimens made from old disintegrated, old non-disintegrated, and new non-disintegrated Portland cement. The tests show that the creep strains for old disintegrated and old non-disintegrated cement mortars are close, within a 2% margin of each other. However, the creep strains for new non-disintegrated cement mortar are 30% lower. Shrinkage for old disintegrated and non-disintegrated cement mortar is 20% lower than for new non-disintegrated cement mortar. The research shows that disintegration is a viable procedure to make old cement suitable for structural application from a long-term property standpoint. Additionally, it increases cement mortar compressive strength by 49% if the cement is disintegrated together with sand.
Donatas Sikarskas, Valentin Antonovič, Jurgita Malaiškienė, Renata Boris, Rimvydas Stonys, and Genadijs Šahmenko
MDPI AG
This study addresses the application of polyvinyl alcohol (PVA) fibers to improve the performance of lightweight cement composites with pozzolans. Blended cement mixes based on expanded glass granules were modified with PVA fibers (Type A: Ø40 µm, L = 8 mm and Type B: Ø200 µm, L = 12 mm). The following research methods were used to analyse the effect of the fibers on the structure of cement matrix and physical-mechanical properties of lightweight composite: SEM, XRD, DTG, calorimetry tests, and standard test methods of physical and mechanical properties. Results from the tests showed that a denser layer of hydrates was formed around the PVA fiber and the amounts of portlandite, CSH, and CASH formed in the specimens with PVA were found to be higher. PVA fibers of Type A accelerated hydration of the cement paste, slightly increased the compressive strength of the lightweight composite, but had no significant effect on the values of density, ultrasonic pulse velocity and flexural strength. The shrinkage of cement composite was significantly reduced using both types of PVA fiber and both types of PVA fibers increased the fracture energy of lightweight cement composite with expanded granules.
Modests Elemba, Videvuds-Arijs Lapsa, Genadijs Šahmenko, and Aleksandrs Korjakins
IOP Publishing
This work proposes an original and active method for non-destructive testing of concrete and can also be used for other building materials. The proposed method includes the successive steps of: drilling holes into samples of building material with use of rotation or percussion drilling machine and simultaneously determining the power consumption necessary for drilling; strength determination of building material by destructive failure of samples; obtaining a positive empiric correlation between the power consumption necessary for drilling and determined strength values of material; control during drilling the holes in structure material being tested and simultaneously determining the power consumption necessary for drilling; determining the actual strength of structure material being tested by use of correlation between power consumption and material strength values derived in testing process. The application of the method makes strength determination of building materials simpler and faster and also increases the accuracy of testing.
Elvija Namsone, Genadijs Sahmenko, and Aleksandrs Korjakins
Trans Tech Publications, Ltd.
Increasing energy consumption is forcing the building sector to seek and use building materials and products that would be environmentally friendly. As one such material should be noted magnesium based cements, which production requires much lower calcination temperature than the traditional Portland cement. During the experimental research part of this work, two types of magnesia cement were produced (using magnesium chloride and magnesium sulphate brine solutions) and physical, mechanical properties of obtained cement composites were determined.
G. Šahmenko, M. Sinka, Eva Namsone, A. Korjakins and D. Bajare
Abstract This work is devoted to developing an energy-efficient solution for the external wall and evaluating its environmental impact. Several types of innovative single-layer and sandwich-type wall solutions were analysed and compared. Different constructive and thermal insulation materials were used, including traditional wall materials such as AAC (autoclaved aerated concrete) and normal concrete. Advanced materials, such as high-performance foamed concrete (HPFC) and natural biofibre composites, have been evaluated as an alternative solution. Ultra-light foam concrete was applied as an alternative for polymer-based insulation. The next development was sandwich three-layer wall constructions consisting of foam concrete and natural biofibre composites. A prototype of a wall panel was elaborated with outer layers of high-density bio-composite and a middle layer of high porosity hemp composite. Basic properties of sandwich blocks, such as density and thermal conductivity, were evaluated and compared. The environmental impact of the studied wall systems was analysed using a life-cycle assessment (LCA) to assess carbon dioxide emissions during the production phase of the material. The results show that replacing traditional insulation with bio-based materials has greatly reduced the negative environmental impact of the wall elements. A combination of natural fibre bio-composite and mineral insulating foam makes it possible to obtain an eco-friendly and sustainable sandwich-type wall system.
Elvija Namsone, Genadijs Sahmenko, and Aleksandrs Korjakins
Rezekne Academy of Technologies
Building sector is known as one of the biggest polluters, causing environmental pollution and carbon dioxide emissions, most of which are generated during the production process of building materials. Therefore, researchers and manufacturers have become increasingly interested in environmentally friendly materials with low energy consumption. Magnesium based cements are being studied as an alternative to a widespread material as Portland cement, thus reducing the temperature required for calcination. During this research, magnesium binder-based composites using two types of magnesium (local dolomite waste material and caustic magnesia) were produced. Within the framework of this study, several regimes of thermal treatment were used to produce low carbon dioxide and environmentally friendly magnesium binder composites. Physical, mechanical and thermal properties of obtained specimens were tested.
Eva Namsone, Genadijs Sahmenko, Elvija Namsone, and Aleksandrs Korjakins
Trans Tech Publications, Ltd.
Unlike traditional materials, the development of high-performance foamed concrete with a compressive strength of up to 20 MPa and a density of up to 1400 kg/m3 allows the use of foamed concrete as a constructive material with additional functions including good thermal insulation properties, sound insulation and capillary porosity needed to ensure hydrothermal conditions. Unlike autoclaved aerated concrete, foamed concrete can also be used in monolithic construction.The studies of high strength foamed concrete were performed by using mostly local mineral components and mixing technology by using planetary activator which provides a fundamentally new mixing mode that combines intensive mixing, foaming and activation of components. To realize the experimental part of the research, turbulence type foamed concrete mixer SPBU-LUKS was used.
Elvija Namsone, Genadijs Sahmenko, Irina Shvetsova, and Aleksandrs Korjakins
Trans Tech Publications, Ltd.
Because of low calcination temperature, magnesia binders are attributed as low-CO2 emission materials that can benefit the environment by reducing the energy consumption of building sector. Portland cement in different areas of construction can be replaced by magnesia binder which do not require autoclave treatment for hardening, it has low thermal conductivity and high strength properties. Magnesium-based materials are characterized by decorativeness and ecological compatibility.The experimental part of this research is based on the preparation of magnesia binders by adding raw materials and calcinated products and caustic magnesia. The aim of this study was to obtain low-CO2 emission and eco-friendly material using local dolomite waste materials, comparing physical, mechanical, thermal properties of magnesium binders.
Maris Sinka, Jelizaveta Zorica, Diana Bajare, Genadijs Sahmenko, and Aleksandrs Korjakins
MDPI AG
The construction industry is one of the largest emitters of CO2 because the production of traditional building materials is highly energy-intensive and uses considerable amounts of raw materials. This research aims to decrease the negative environmental impact of the construction industry by providing biocomposites with a low environmental impact due to their bio-based components and efficient use of the materials through 3D printing. Agricultural waste products—hemp shives—are used in these materials as a filler together with three different types of fast-setting binders—magnesium, calcium sulphoaluminate (CSA) and those that are gypsum-based. The study determines the setting time and compressive strength of these binders, as well as the formation of biocomposites of different densities for different applications; extrusion tests and preliminary life cycle assessment (LCA) are also performed. Results show that biocomposites with hemp shives and fast setting binders have a possible application in 3D printing due to their shape stability and buildability, as well as relatively high compressive strength, which allows for load-bearing use at high densities and thermal insulation use at low densities, although printability at low binder content remains a significant challenge. Preliminary LCA results show that CSA and gypsum binders have the lowest environmental impact from the binders considered.
Elvija Namsone, Irina Shvetsova, Genadijs Sahmenko, and Aleksandrs Korjakins
Trans Tech Publications, Ltd.
The experimental research work is dedicated to magnesium-based binders. Two types of magnesium oxide were added in the compositions of binders – caustic magnesia and raw materials and calcinated products. Dolomite waste material (dolomite powder) from three quarries (two in Latvia, one in Russia) was tested. Magnesium-based binders are described as low-CO2 emission materials, helping to reduce the energy consumption in building sector. The aim of this study is to investigate the possibility to obtain eco-friendly, low-CO2 emission binding material from local dolomite waste materials and research the physical, mechanical and thermal properties of obtained samples.
Eva Namsone, Genadijs Sahmenko, Elvija Namsone, and Aleksandrs Korjakins
Trans Tech Publications, Ltd.
Nowadays, the type of foamed concrete performs a group of cemented composite materials that can compete with conventionally used autoclaved aerated concrete. Improving microstructure of the foamed concrete by inventive mixing technology allows to homogenizate the mix of foamed concrete. This original research is applied to inspection on mixing technology of foamed concrete by using a planetary ball mill. The objective of this paper is to clarify the correlation between physical-mechanical properties and intensive mixing time.
G. Sahmenko, A. Korjakins, and D. Bajare
Springer International Publishing
Dolomite is the widespread sedimentary rock that finds a wide application in building industry and road engineering. During the treatment of dolomite rocks, a huge amount of fine fractions (0…8 mm) are produced and classified as by-products due to the limited range of applications. For example, nowadays more than 400 000–450 000 t dolomite by-products are deposited in a single quarry and the annual increase of this material is 50 000 t.
Rimvydas Moceikis, Asta Kičaitė, Genadijs Sahmenko, and Aušra Selsekienė
Kaunas University of Technology (KTU)
Resistance to freezing and thawing of glass fibre reinforced concrete (GRC) modified with silica fume and metakaolin was tested according to scaling at freezing test method with de-icing salt after 112 cycles. Surface mass loss was obtained, flexural strain energies calculated from load- deformation curves and ductile/ brittle behavior of GRC composite explained. SEM micrograph analysis was used to identify possible flaws on the surface of filaments and fiber-matrix contact zone due to freeze-thaw influence.
K Buka-Vaivade, J Sliseris, D Serdjuks, G Sahmenko, and L Pakrastins
IOP Publishing
V Markin, G Sahmenko, V N Nerella, M Näther, and V Mechtcherine
IOP Publishing
R Moceikis, A Kičaitė, G Sahmenko, and A Korjakins
IOP Publishing
R Gailitis, A Sprince, L Pakrastins, G Sahmenko, and T Kozlovskis
IOP Publishing
Zinta Zimele, Maris Sinka, Aleksandrs Korjakins, Diana Bajare, and Genadijs Sahmenko
Walter de Gruyter GmbH
Abstract Global warming being increasingly discussed, solutions for reducing emission greenhouse gases become more important in all industry sectors. The total energy consumed in the construction sector contribute up to 1/3 from all greenhouse gases emissions. Large part of it comes from the cement production – 5 % of the total global emissions. The foam concrete is lightweight concrete with good thermal properties and ability to reduce CO2 emissions by reducing the use of cement due to its low density. The aim of this study is to determine impact on the environment with the use of Life Cycle Assessment (LCA) with focus on Global Warming Potential (GWP) for two different compressive strength foam concrete mixtures produced in Latvia by unique intensive mixing technology – turbulence with cavitation effect. Afterwards, the selected foam concrete mixtures are compared with alternative materials with similar compressive strength – aerated concrete and hollow ceramic blocks. The foam concrete mixture having 12.5 MPa compressive strength showed higher CO2 emissions than hallow ceramic block. The majority of CO2 emissions comes from the Portland cement, which is a key element in its composition. On the other hand, the foam concrete mixture having 2.4 MPa compressive strength showed higher CO2 emissions than aerated concrete block. The majority of CO2 emissions are due to foam glass granules, which is the main element contributing to the increased insulation properties of the material. Comparison of each foam concrete with analogue building material by compressive strength shows that the chosen foam concrete mixtures produce greater GWP than alternative materials. This research allows to identify the environmental impacts of different foam concrete mixture components and to improve these mixtures to achieve similar properties with less impact, for example, by replacing foam glass granules with granules made from recycled glass or replacing cement with flay ash, silica fume or recycled glass powder.
GRANT DETAILS
Participation at the Latvian Council of Science funding project “Long-term properties of innovative cement composites in various stress-strain conditions” (No. lzp-2018/2-0249")
INDUSTRY EXPERIENCE
Development production technology in paving brick plant, foam concrete plant. Work in testing laboratory.
SOCIAL, ECONOMIC, or ACADEMIC BENEFITS
2008. Member of Latvian Concrete Society (LCA), from 2017. chairman of the board of LCA. duties: the advancement of science in the concrete industry, development of recommendation for new specification, standards and lows in the field of concrete industry.
2016. Member of American Concrete Institute (ACI) Committee 523 – Cellular Concrete.