RESISTANCE OF CONCRETE WITH LIMESTONE SAND OR POLYMER ADDITIONS TO FEED ACIDS

By using limestone sand or polymer additions in the concrete mix, it w as attempted to reduce the deterioration of concrete floors in pig hou ses by lactic and acetic acid. To simulate in a standardized and autom ated way chemical attack by those acids and abrasion caused by animals and cleaning, a testing apparatus for accelerated degradation tests w as developed. Concrete cylinders mounted on rotating axles were turnin g through containers with simulation liquid After each attack cycle th e concrete was brushed with rotary brushes. Concrete degradation wars measured with laser sensors connected to a computer and the average at tack depth and the Ra-value, which is a measure of surface roughness w ere calculated Results of previous experiments, showing that concrete with blast furnace slag cement was much more resistant than the refere nce concrete with ordinary portland cement, were confirmed The use of limestone sand and possibly limestone aggregates led to a quicker neut ralization of the aggressive liquid, but was insufficient to reduce th e average attack depth. When limestone sand and limestone aggregates w ere used, the increase in concrete roughness was smaller than for conc rete with limestone sand and gravel aggregates. Addition of 10% polyme rs to the concrete mix increased the resistance significantly, when ca re was taken that the polymer cement concrete (PCC) didn't contain too much air voids. The most resistant PCC, containing a styrol acrylic a cid ester showed after six cycles an average attack depth 12 times sma ller than the reference concrete. Furthermore the potential benefit of the polymers was probably underestimated, as an investigation with th e scanning electron microscope showed that the emulsified polymer had not completely formed a film.