Mechanical and durability behaviour of self-compacting concretes for application in the manufacture of hazardous waste containers

Abstract

In self-compacting concrete (SCC), the amount of coarse aggregates, use of fillers, and type of additives play important roles in its self-compaction, including mechanical and durability properties. The use of SCC is widespread in the precast concrete industry and it can also be employed in the manufacture of containers for the storage of hazardous waste. In addition to the requirements for self-compaction, strict mechanical and durability requirements must be considered. In this work, a study on the effect of variation in the amounts of coarse and fine aggregates, and fillers on the properties of the fresh state (self-compactability) and hardened state (microstructural, mechanical, and durability behaviours) of different dosages is carried out. The factors that have more significant influences on the density of the mixes are the presence of fillers and water-cement ratio. This is because mixes with fillers and low water-cement ratios have higher densities, which agree with the lower porosity and finer porous structure observed in mixes that incorporate fillers. Mixes incorporating siliceous fillers presented better performances in the absorption of water by immersion and capillarity than mixes without them. Measuring the depth of penetration of water under pressure in various mixes makes it possible to identify those that have high compactness and impermeability. Mixes with fillers and higher microstructural densities have lower water penetration depths. After exposure to aggressive environments, none of the mixes, with and without fillers, showed signs of wearing out or deterioration. The presence of fillers in SCCs had a more significant influence on its shrinkage than the amount of coarse aggregates. Thus, it is possible to obtain high performance SCC in relation to its mechanical and durability properties by reducing the coarse aggregate content and incorporating siliceous fillers in the dosage. Moreover, for applications where high mechanical requirements are not necessary, it is possible to produce an SCC with high performance against the attack of aggressive agents such Cl− and SO3 without using siliceous fillers.