Drying Shrinkage and Prediction Model of Alkali-Slag Concrete

Abstract

Green high performance alkali-slag concrete(ASC) was prepared by adding Na2SiO3 and NaOH complex activator in slag. Physical, mechanical and drying shrinkage performance of ASC were studied by workability, strength and drying shrinkage tests. The results show that slump of ASC exceeds 160mm, fluidity and workability is excellent. 28d compressive strength and flexural trength of ASC are 90MPa and 8.36MPa, 7d strength are 83.7MPa and 7.47MPa, which belongs to high–early strenth. drying shrinkage of ASC are ratherish bigger than portland concrete(PC) anytime, but correspond to PC at later period from 28d, anyhow ASC belonged to low deformation concrete but with ratherish bigger early deformation, therefore early keep should be reinforced. drying shrinkage of ASC increase with dosage of slag anytime, but don’t increase with ratio of activator solution to slag linearly. And a suited logarithm prediction model of ASC was established, which can predict the drying shrinkage of ASC.

Autogenous and drying shrinkage of alkali‐activated slag mortars

“…The water‐insoluble reducing agent can fill in the meniscus, decrease the interfacial contact tension, and finally reduce the capillary pressure . For ordinary Portland cement, the reduction effect of SRA is lower than alcohol glycol ethers, but the effectiveness seems to be opposite here for the AAS systems.…”

“…In summary, there are three widely used models for drying shrinkage of portland cement based materials and alkali‐activated binder as follows:where ε s ( t ) is the drying shrinkage strain after ages t (microstrain); a , b is the constant related to concrete mix proportion. This logarithmic equation was established and has been applied to predict the drying shrinkage of alkali‐slag concrete …”