[ramyeeen]

Hello everyone, I am working in cement industry right at the moment and we are testing ecological alternatives for cement production. One of recent ideas in scientific field was to combine a steel slag powder with ammonium dihydrogen phosphate in different proportions and add water with reaction retarder (Borax) to produce concrete from this combination. But combining all the products with water results in very fast setting (it became hard for less than a minute) and the final product is very low in strength. Chemical composition of steel slag powder is 39% Ca, 38% Fe, 9.74% Si, 5.21% Mn, 2.80% Al, 1.97% Mg, and less than 1% of such elements as P, Ti, S, V, Na, K, Cl, Zn, Sr, Nb, Cu, Ni. Experiment was conducted with varying proportions of steel slag/adp. On attached files you can see proportions of products used (1), hydration temperature and pH variation depending on steel slag/adp ratio and the last picture is the chemical composition of steel slag in another experiment which was done successfuly and resulted in concrete with higher compressive strength. The question is what you think had an effect on alterations in setting time and strength, and what possible internal reactions had an effect on this?