Attack of Concrete Floors in Pig Houses by Feed Acids: Influence of Fly Ash Addition and Cement-bound Surface Layers

Concrete floors in pig houses are subject to attack by lactic and acetic acid, formed in spilled and soured meal–water mixtures. Accelerated degradation tests, comprising cyclical exposure to acidic liquids and detachment of the unstable concrete by brushing, were used to simulate the attack of concrete floors and of cement-bound surface layers. It is estimated that the effect of one attack cycle on the reference concrete is more or less equivalent to the floor degradation observed in houses for fattening pigs at the most vulnerable place in front of a wetfeeder after one to two years. It was found that the addition of about 10% low-calcium coal fly ash by weight of cement to a high-quality concrete made with ordinary portland cement (OPC), reduced the degradation significantly. The addition of fly ash to concrete made with sulphate-resisting portland cement (0%C3A) mostly resulted in less deterioration than addition to concrete made with ordinary portland cement during the first stage of the attack. However, the differences were seldom significant after two attack cycles. Under very highly aggressive exposure, a surface layer (mortar) consisting of the product S (based on ground tuff) and blast-furnace slag cement showed the best resistance.