Tomass Kozlovskis

EDUCATION

Bachelor of Civil Engineering, Riga Technical University, Faculty of Civil Engineering, Riga, Latvia (September 2017 — Present: Professional Bachelor's Degree)
Bachelor of Architectural Technology and Construction Management, Copenhagen School of Design and Technology, Copenhagen, Denmark (September 2013 — February 2016: Professional Bachelor's Degree)
Architectural Technology, George Brown College, Toronto, Ontario, Canada (September 2013 — December 2013: Exchange studies abroad, 1 semester)

RESEARCH INTERESTS

Innovative cement composites, digital image correlations (DIC), long-term properties of materials, creep, concrete

Scopus Publications

Tensile creep of cement and concrete composites: Monitoring by means of 2D-digital image correlation
Andina Sprince, Tomass Kozlovskis, Rihards Gailitis, Juozas Valivonis, Kinga Korniejenko, Arnaud Castel
Applied Sciences Switzerland, 2021
Creep and shrinkage of Cement and Concrete Composites (CCC) are significant properties that need to be considered to use these materials in practice. Many previous scientific studies revealed CCC creep characteristics under sustained compression and shrinkage, using traditional test methods from design standards. Because of the complexity of experimental procedures, CCC creep in tension has not been studied as close. Furthermore, there is no unified standard that proposes applicable testing methods or specific testing apparatus. This study examines the suitability of 2D—Digital Image Correlation (DIC) to observe the creep deformations of specimens under tension. Ordinary Portland cement (OPC) mortar with 1% polyvinyl alcohol (PVA) fibres has been investigated in the research. Compact tension (CT) specimens 150 × 150 × 12 mm (with a notch) were used. Creep deformations under sustained uniaxial tension (applied loading corresponding to 60% of the ultimate strength) were measured. DIC images were captured using an entry/mid-level DSLR camera. Results show that DIC is suitable for studying uniaxial tensile creep of cement and concrete composites. Deformation of specimens in tension was similar to that measured using the conventional method (using surface-attached gauges).
Long-term properties of different fiber reinforcement effect on fly ash-based geopolymer composite
Rihards Gailītis, Andīna Sprince, Tomass Kozlovskis, Līga Radiņa, Leonīds Pakrastiņš, et al.
Crystals, 2021
Geopolymer composites have been around only for 40 years. Nowadays, they are used in buildings and infrastructures of various kinds. A geopolymer’s main benefit is that it is a green material that is partially made by utilizing waste products. The carbon footprint from geopolymer matrix manufacturing is at least two times less than Portland cement manufacturing. Due to the nature of the geopolymer manufacturing process, there is a high risk of shrinkage that could develop unwanted micro-cracks that could reduce strength and create higher creep strains. Because of this concern, a common strategy to reduce long-term strains of the material, such as shrinkage and creep, is to add fiber reinforcement that would constrain crack development in the material. This article aims to determine how various kinds and amounts of different fiber reinforcement affect fly ash-based geopolymer composites’ creep strains in compression. Specimen mixes were produced with 1% steel fibers, 1% polypropylene fibers, 5% polypropylene fibers, and without fibers (plain geopolymer). For creep and shrinkage testing, cylindrical specimens Ø46 × 190 mm were used. The highest creep resistance was observed in 5% polypropylene fiber specimens, followed by 1% polypropylene fiber, plain, and 1% steel fiber specimens. The highest compressive strength was observed in 1% polypropylene fiber specimens, followed by plain specimens, 1% steel fiber specimens, and 5% polypropylene fiber-reinforced specimens. The only fiber-reinforced geopolymer mix with improved long-term properties was observed with 1% polypropylene fiber inclusion, whereas other fiber-introduced mixes showed significant decreases in long-term properties. The geopolymer composite mix with 1% polypropylene fiber reinforcement showed a reduction in creep strains of 31% compared to the plain geopolymer composite.
Long-term properties of cement mortar under compression, tension, and 3-point bending
N. Vatin, A. Sprince, R. Gailitis, L. Pakrastins, T. Kozlovskis
Magazine of Civil Engineering, 2021
Cement composite long-term property assessment usually is limited to the compression strain state due to the difficulty of performing long-term tests in tension and 3-point bending. This paper shows the difference in long-term properties in compression, tension, and 3-point bending for plain ordinary Portland cement mortar (OPC). The obtained results were compared to reinforced specimen results to determine whether the PVA refibres improve the long-term properties of OPC mortar in various stress-strain conditions. Cylinders, compact tension specimens (CT), and beams – plates were prepared to evaluate material properties and the role of fibre reinforcement in these different stress states. Additionally, to conventional surface-attached strain gauges, 2D-DIC was employed to observe the creep strain of specimens in tension. This paper aim to determine long-term property differences in compression, tension and 3-point bending and, also, to see if low amount PVA fibre incorporation improve long-term properties in previously stated stress-strain states. It was determined that the usage of 1 % of PVA fibres increases creep strains in compression on average by 15 % and reduced by 7 % in tension. It reduces shrinkage strain by 18 % in compression and 8 % in tension. The long-term deflection for the PVA fibre-reinforced specimens are, on average by 55 % higher than for plain OPC mortar specimens in 3-point bending.
Plain Geopolymer Concrete Cross-Section Surface Analysis After Creep and Shrinkage Tests in Compression and Tension
Rihards Gailitis, Andina Sprince, Leonids Pakrastins, Kinga Korniejenko, Tomass Kozlovskis
Rilem Bookseries, 2021
Drying Shrinkage Deformation Comparison between Foam Concrete, Geopolymer Concrete, Disintegrated, and Non-disintegrated Cement Mortar
R Gailitis, A Sprince, L Pakrastins, G Sahmenko, T Kozlovskis
Iop Conference Series Materials Science and Engineering, 2019
Abstract Foamed concrete has been known as a building material for nearly 100 years. In the beginning, it was used as an insulation material with very low density. Since then there have been attempts to make this material more load-bearing and structural. In present-day foamed concrete is being used in soil reinforcement, building blocks and in other sorts of building applications [1]. Another innovative material - the geopolymer concrete has been around only for 40 years. It is being used in buildings and infrastructures objects such as railroads, reservoirs, and houses and others. The main benefit of the geopolymer is that it is green material that is partially made by utilizing waste products. The geopolymer manufacturing carbon footprint is 2 times less than the Portland cement carbon footprint. Another way to reduce Portland cement carbon footprint is to reuse old cement. In the past few decades, there has been a considerable amount of researches regarding the partial replacement of cement using disintegrated cement in cement mortar or concrete. As it is known to obtain powder mineral filler material planetary ball milling is applied, but it is ineffective. It has been discovered that grinding by collision is a more effective method for refining brittle material. One of the ways to refine is to disintegrate with disintegrator. This raises the question of whether old cement disintegration together with sand can improve its long-term properties and what differences do these different cement and alkaline activated compounds have. The aim of this article is to determine the difference of shrinkage deformation for foamed concrete and disintegrated cement mortar which is Portland cement based cement composites and geopolymer concrete which represents alkali-activated cement composites. The size of all shrinkage specimens was 46mm in the diameter and 190mm in height. The shrinkage deformations of the specimen were determined by consistently measuring specimen deformation displacement. Shrinkage deformation values for foamed concrete in the 81st day did reach 11.85mm *10 −2 , disintegrated old cement mortar 4.88mm *10 −2 , non-disintegrated new cement mortar 5.02mm *10 −2 , non-disintegrated old cement mortar 4.33mm *10 −2 , but for geopolymer concrete, on the 81st day, it was 3.73mm *10 −2 .
Comparison of the long-term properties in compression of different size foamed concrete
Rihards Gailītis, Andina Sprince, Leonids Pakrastins, Genadijs Shakhmenko, Tomass Kozlovskis
Vide Tehnologija Resursi Environment Technology Resources, 2019
Foamed concrete has been used as a building material since the early 1920s. In the beginning, it was used as an insulation material with very low density. Since then there have been attempts to make this material more load-bearing and structural. In the present-day foamed concrete is being used in soil reinforcement, manufacturing of building blocks and other sorts of construction materials. [1] The aim of this article is to determine long-term properties and strength of foamed concrete specimens as well as compare the results between two differently sized foamed concrete specimens. The size of creep and shrinkage specimens were Ø46x190 mm and Ø75x180 mm. The creep properties of the specimens were determined by loading them with 20% of the ultimate stress value. [2] The compressive strength, creep and specific creep of specimens were determined as well as specimen size factor to creep deformations.
Long-term properties of foamed concrete
Rihards Gailitis, Andina Sprince, Leonids Pakrastins, Genadijs Shakhmenko, Tomass Kozlovskis, Liga Radina
Selected Papers of the 13th International Conference Modern Building Materials Structures and Techniques Mbmst 2019, 2019
Foamed concrete has been used as a building material since the early 1920s. In the beginning, it was used as an insulation material with very low density. Since then there have been attempts to improve the structural properties in order to increase materials load-bearing capacity. In the present-day foamed concrete is being used in soil reinforcement, manufacturing of building blocks and other sorts of construction materials (Mugahed Amran, Farzadnia, & Abang Ali, 2015). The aim of this article is to determine the behaviour and long-term properties of foamed concrete. Cylindrical specimens (Ø46×190 mm) were used for creep and shrinkage testing. The creep properties of the specimens were determined by loading them with 20% and 60% of the ultimate compressive stress value (Sprince, 2015). The compressive strength, creep, shrinkage and specific creep of the material were examined. It was determined that during 90 days of creep testing the non-linear creep deformations (specimens loaded with 60% of the ultimate stress) are 4 times larger than linear creep deformations (specimens loaded with 20% of the ultimate stress). Also, changes in the modulus of elasticity of foamed concrete were researched over time. Foamed concrete modulus of elasticity reached 12.21 GPa on the 28th day, 12.49 GPa on the 62nd and 14.23 GPa on the 144th day since the specimens were made.

INDUSTRY EXPERIENCE

Research Assistant at Riga Technical University, Institute of Civil Engineering and Renovation, Riga, Latvia (April 2019 — Present)
Designer, CAD Tracer at SIA JaunRigaECO, Riga, Latvia (October 2018 — October 2019)
Designer, CAD Tracer at Wolf System SIA, Cesis, Latvia (July 2018 — August 2018)
Designer, CAD Tracer at Wolf System SIA, Cesis, Latvia (April 2016 — August 2017)