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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.

This study investigates the cyclic load application impact on fly-ash-based geopolymer composites that are reinforced with a low amount of fibre reinforcement. For reinforcement purposes, polyvinyl alcohol and steel fibres are used. For testing purposes, four geopolymer composite mixes were made, three of which had fibre reinforcement. Simultaneously, specimens were tested for shrinkage, static-load-induced creep, and cyclic-load-induced creep. For static and cyclic creep testing, specimens were loaded with 20% of their strength. For cyclic creep testing, load application and release cycles were seven days long. When each cycle was introduced, the load was applied in steps. Necessary load application or unloading lasted for 5 min and consisted of four steps, each 25% of the necessary load. From the long-term static and cyclic creep tests, it was seen that only the plain specimens showed that static creep strains are within cyclic creep strains. For all the other specimens, the static load was higher than the cyclic-load-induced creep amplitude. Also, 1% polyvinyl alcohol fibre-reinforced specimens showed the most elastic characteristics under cyclic load, and 1% steel fibre-reinforced specimens appeared to be the most resistant to the cyclic load introduction. [ABSTRACT FROM AUTHOR]

This study examines foamed geopolymer composites based on fly ash from the Skawina coal-fired power plant in Poland. The paper presents the effect of adding 3% and 5% by weight of glass wool waste on selected properties of foamed geopolymers. The scope of the tests carried out included density measurements, compressive and bending strength tests, measurements of the heat conduction coefficient, and the results of measurements of changes in thermal radiation in samples subjected to a temperature of 800 °C. The obtained results indicate that glass wool waste can be successfully used to lower the density and heat conduction coefficient of foamed geopolymer composites with a fly ash matrix. In addition, the results of changes in thermal radiation in the samples subjected to the temperature of 800 °C showed a positive effect of the addition of glass wool waste. Moreover, the introduction of the addition of glass wool waste made it possible to increase the compressive strength of the examined foamed geopolymers. For the material modified with 3% by weight of mineral wool, the increase in compressive strength was about 10%, and the increase in fibers in the amount of 5% by weight resulted in an increase of 20% concerning the base material. The obtained results seem promising for future applications. Such materials can be used in technical constructions as thermal insulation materials. [ABSTRACT FROM AUTHOR]