Self-compacting concrete with limestone powder for transport infrastructure
At the beginning of XXI century in civil engineering and buildings of transport infrastructure, such as tunnels, elements of bridges, viaducts and roads, it is more expedient to use conventionally vibrated concretes which have almost universally replaced prefabricated constructions. However, in objects with high congested reinforcement or in cases where vibration is impossible it is more preferable to apply self-compacting concrete (SSC) mixtures. SCC possesses the ability to take form shape without any mechanical aid. The most important requirement for SCC is high flowability without the segregation of aggregate during placement. Despite the low water-cement ratio of the fresh self-compacting concrete mixture the bleeding is still possible. That is why fillers such as natural pozzolana, calcined clay (metakaolin), silica fume, fly-ash, slag, and quarry dusts should be used. Furthermore, mineral admixtures can improve energy efficiency and particle packing, decrease cost and permeability of self-compacting concrete. In this study, the properties of SCC with limestone powder as partial replacement of Portland cement was established by applying mathematical experiment planning method. The obtained SCC gave high early compressive strength within 3 days in the range of 41.3 MPa while its 28 day strength ranged of 69.0 MPa. The result of this study indicated the possibility of adding limestone powder in SCC with optimum percentage content around 38 %. The researched SCC had density of hardened and fresh concrete mix in the ranges of 2438 kg/m3 and 2452 kg/m3 respectively. The investigated SCC concrete with limestone powder showed high rate of water permeability in the range of 1.6 MPa (W16) and high frost resistance in the ranges of F2400. It can be explained by additive’s high water retention capacity and increase of hydration degree and, as a consequence, decrease of capillary porosity. That is why the developed SCC with limestone powder has high compressive strength and excellent durability performance.