Autogenous and drying shrinkage of sodium carbonate activated slag altered by limestone powder incorporation

This paper aims to study the shrinkage mechanism of sodium carbonate activated slag containing limestone powder (LP). The workability, pore structure, reaction kinetics and strength development were characterized. The results show that the autogenous shrinkage increases when the dosage of LP is low (≤30 vol%) primarily because of the intensified and accelerated reaction, but decreases when further increasing the LP content due to the dilution effect caused by the reduced binder content. A high amount of limestone powder incorporation slightly increases the pore volume in the range of mesopore and macropore, while its effect on the autogenous shrinkage is not prominent. However, the drying shrinkage of the samples is significantly increased with the increase of LP, caused by the more free water as indicated by the mass loss of the samples. In addition, the decomposition of gaylussite and natron also contributes to the enlarged drying shrinkage.