Tomass Kozlovskis

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, and Arnaud Castel
Applied Sciences (Switzerland), eISSN: 20763417, Published: September 2021 MDPI AG
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
Crystals, eISSN: 20734352, Published: July 2021

Long-term properties of cement mortar under compression, tension, and 3-point bending
N. Vatin, A. Sprince, R. Gailitis, L. Pakrastins and T. Kozlovskis
Magazine of Civil Engineering, eISSN: 27128172, Volume: 105, Published: 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, and Tomass Kozlovskis
RILEM Bookseries, ISSN: 22110844, eISSN: 22110852, Pages: 13-24, Published: 2021 Springer International Publishing

Drying Shrinkage Deformation Comparison between Foam Concrete, Geopolymer Concrete, Disintegrated, and Non-disintegrated Cement Mortar
R Gailitis, A Sprince, L Pakrastins, G Sahmenko, and T Kozlovskis
IOP Conference Series: Materials Science and Engineering, ISSN: 17578981, eISSN: 1757899X, Volume: 660, Published: 5 December 2019 IOP Publishing

Comparison of the long-term properties in compression of different size foamed concrete
Rihards Gailītis, Andina Sprince, Leonids Pakrastins, Genadijs Shakhmenko, and Tomass Kozlovskis
Vide. Tehnologija. Resursi - Environment, Technology, Resources, ISSN: 16915402, Pages: 41-44, Published: 2019 Rezekne Academy of Technologies
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.

Tomass Kozlovskis

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