Modified high strength lightweight-aggregate concrete based on expanded clay: composition, structure, properties

Abstract

The study is devoted to the development of increased strength lightweight concrete based on Portland cement modified with a complex organo-siliceous additive containing a polycarboxylate superplasticizer and an active fine-ground siliceous component. The effect of this complex additive on the physical and chemical characteristics of the hydration and structure formation processes was investigated and it was shown that the high kinetics of the strength gain is provided by directional formation of low-basic calcium hydrosilicates, hydrogranates and plazolite, which are crystallo chemically similar to each other, and provide a dense and strength cement stone matrix. Modification by a complex additive makes possible to obtain concrete mixes with S4 consistency while a portland cement consumption per 1m3 of not more than 330 kg, with a compressive strength of  55 MPa, watertightness up to W8, frost resistance up to F400, corrosion resistance coefficients Kc in the magnesium sulfate, sodium and ammonium solutions by 10 to 24%. The introduction of a complex additive also helps to reduce the relative shrinkage by 16 ... 19% compared to the control composition, which has a positive effect on the durability of the resulting concrete.