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 acet ic 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 blushing, were used to simulat e the attack of concrete floors and of cement-bound surface layers. It is estimated that the effect of one attack cycle on the reference con crete is more or less equivalent to the floor degradation observed in houses for fattening pigs at the most vulnerable place in front of a w etfeeder after one to two years. It was found that the addition of abo ut 10% low-calcium coal fly ash by weight of cement to a high-duality concrete made with ordinary portland cement (OPC), reduced the degrada tion significantly. The addition of fly ash to concrete made with sulp hate-resisting portland cement (0%C(3)A) mostly resulted in less deter ioration than addition to concrete made with ordinary portland cement during the first stage of the attack. However, the differences were se ldom 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 resista nce. (C) 1997 Silsoe Research Institute.