Polymers are used for modification of the cement-based composites and others building materials since the thirties of 20th century. Based on the conclusions of recent studies, it is assumed that even water soluble polymers could be used as an admixture for such modification. Currently, there exist and are exploited several possibilities for polymer modification of mortars, wood-based products or bituminous asphalts. Various options differ in the way of modification, which can be basically applied to the entire volume or just a surface, but also in the form of the polymer used – either in the form of solution or fibers. The aim of our study was to investigate the influence of volume modification by the water soluble polymers, such as polyvinyl alcohol (PVA), on the properties of cement paste and find an optimum additive. It turned out that the addition of PVA solution into fresh cement paste results in an increase of porosity and therefore a stiffness and compressive strength reduction. On the other hand, the bending strength of PVA-rich specimens was significantly higher and their water absorption decreased, which may consequently result in enhanced frost resistance.
Abstract. The disposal and further recycling of concrete is being investigated worldwide, because the issue of complete recycling has not yet been fully resolved. A fundamental difficulty faced by researchers is the reuse of the recycled concrete fines which are very small (< 1 mm). Currently, full recycling of such waste fine fractions is highly energy intensive and resulting in production of CO 2 . Because of this, the only recycling methods that can be considered as sustainable and environmentally friendly are those which involve recycled concrete powder (RCP) in its raw form. This article investigates the performance of RCP with the grain size < 0.25 mm as a potential binder replacement, and also as a microfiller in cement-based composites. Here, the RCP properties are assessed, including how mechanical properties and the microstructure are influenced by increasing the amount of the RCP in a cement paste (≤ 25 wt%).
The presented study addresses the mechanical performance of micro-filler cement-based material produced from recycled concrete sleepers. Such material can be considered both, as a binder and filler at the same time. The main advantage of such material is the energy efficiency of the production process, since there is no demand for increased temperature. Compression and flexural strength parameters of such material are compared with those of a composite based on commonly used Portland cement. Moreover, the influence of curing conditions on the strength parameters was investigated as well. The results indicate that the recycled sleepers can be used in the form of micro-filler cement-based to replace a certain portion of cement in concrete and reduce cost of concrete structures.
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