РОЛЬ ТРИНАТРІЙФОСФАТУ В ЗАПОБІГАННІ КОРОЗІЇ СТАЛЕВОЇ АРМАТУРИ В ШЛАКОЛУЖНОМУ БЕТОНІ

Abstract

The paper is devoted to corrosion of steel reinforcement in alkali-activated slag cement (further, AASC) concrete, based on soluble sodium silicates, obtained from high consistency mixes. Trisodium phosphate Na3PO4∙12H2O (further, TSP) as
a basis of complex multifunctional additives (further, CA’s) was proposed for enhancement of AASC fine concrete crack resistance,that ensures prevention of steel reinforcement corrosion. Such CA’s provide shrinkage mitigation in AASC fine concrete during early age structure formation as well as during further increasing of fracture toughness. The soluble sodium
silicates were presented by sodium metasilicate (silica modulus 1.0, dry state) and by sodium water glass (silica modulus 2.9, density 1400 kg/m3 ). Modification of AASC fine concrete, based on sodium metasilicate, by CA composition «TSP - ordinary portland cement clinker - sodium lignosulphonate - sodium gluconate» provides enhancement of crack resistance starting
from early age structure formation while ensuring restriction of shrinkage from 0.984 (the reference) down to 0.713 mm/m after 80 d. The mentioned effect is explained both by reduction of water and by higher crystallinity of hydrates in presence on this CA. In turn,  A’s presented by compositions «TSP - glycerol» and
«TSP - glycerol - polyacrylamide» ensures enhancement of AASC fine concrete fracture toughness during late structure formation with increasing ratio of tensile strength in bending to compressive strength up to 37 - 49 % compared to the reference one when the sodium water glass is used. Specified effects of the CA’s are caused by increasing depressiveness of gel-like hydrated products, providing redistribution of stresses in artificial stone and thereby advanced fracture toughness under load.