The influence of polyfunctional modifier additives on properties of cement-ash fine-grained concrete
The object of the study is the properties of cement-ash concrete with the addition of a polyfunctional modifier (PFM) intended for floors of industrial enterprises. The PFM composition includes a naphthalene-formaldehyde type superplasticizer and a vinyl acetate-vinylversatate copolymer. A prerequisite for the use of PFM additives in cement-ash concrete is the ability to actively influence the structure formation processes and, as a consequence, the properties of concrete with it. Using well-known chemical and physical methods, experimental data have been obtained on the effect of PFM additives on the degree of cement hydration, the kinetics of changes in the plastic strength of cement-ash stone during hardening. It was found that the introduction of the PFM additive allows one to reduce the open porosity and average pore sizes of cement-ash stone and also increase the pore size uniformity index. To study the properties of cement-ash concrete with PFM additive, the method of mathematical planning of experiments was applied, as a result of which a complex of mathematical models of water demand, water separation, volume of air involved, concrete strength under compression and bending was obtained. The models make it possible to quantitatively evaluate the effect on the indicated properties of concrete of water and ash-cement ratios, the content and ratio of PFM components, as well as design the compositions of cement-ash concrete with desired properties. The studies, the results of which are presented in the article, showed the possibility, with the help of PFM additives, to significantly improve the properties of cement-ash concrete, which are important when using them for floors of industrial enterprises and, in particular, reduce ultimate shrinkage deformations by 30–50 %, reduce by 1.5–3 times their abrasion and up to 20 % increase resistance to shock.