The effect of admixtures on hydration kinetics, shrinkage, and strength of HPC

Abstract

Abstract The paper investigates the impact of admixtures on the properties of high-performance concrete (HPC). A series of test were conducted to evaluate the influence of the studied additives and their combinations on drying and autogenous shrinkage, thermal kinetics and strength of cement pastes, mortars and concretes. It is shown, that replacing part of the cement with silica fume has no significant impact on drying shrinkage. The study demonstrates that polycarboxylate-based superplasticizer and shrinkage reducing admixture (SRA) containing neopentyl glycol enhance fresh concrete workability, produce hardened concrete with high strength and durability, and reduce early-age shrinkage in HPC by up to 3 times. The findings reveal that the use of SRA admixture provides a stable effect only at a dosage above 1 wt.% in HPC, where the amount of binder significantly affects drying shrinkage. Results indicate, that combined action of 1.5% of SRA and 0.6 kg/m3 of polypropylene microfibers allows to obtain 40% lower drying shrinkage compared to non-modified HPC.