USE OF FLY-ASH OR SILICA FUME TO INCREASE THE RESISTANCE OF CONCRETE TO FEED ACIDS

Concrete in animal houses is subject to aggressive substances from fee d and manure. Chemical attack by the most important feed acids, lactic and acetic acids, and abrasion caused by animals and cleaning were si mulated and studied using accelerated corrosion tests. The resistance of concrete prisms with different percentages of fly ash or silica fum e to simulation liquids with different pH values was investigated. The decrease in volume in terms of percentage and the mass loss per unit area were measured, as well as the pH change and calcium content of th e liquids. It appeared that the addition of fly ash and, even more so, the addition of silica fume helped to increase the resistance of conc rete to highly and very highly aggressive simulation liquids. A percen tage of fly ash below 30% by weight of cement seemed to be best. The d ifference between using silica fume as an addition or as a cement repl acement was small. A correlation was found between the mass of the dis solved material and the calcium content of the liquid.