Influence of Addition of Polycarboxylate-Based Superplasticizer on Properties of High Performance Concrete

Nowadays, polycarboxylate-based (PCA) superplasticizer (SP) has become the basic ingredient to prepare high-performance concrete (HPC). PCA SP with carboxylic sulfonic groups and long poly (ethylene oxide) side chain was prepared. The behaviors and economies of PCA SP-blended concrete were investigated. Inclusion of PCA SP improves the initial fluidity and fluidity preservation of concrete. Utilizing PCA SP increased the air content and bleeding water rate and prolonged the setting times of concrete, which have a negative effect on the early-age properties of concrete. At the early curing age (7 days), concrete mixtures with 0.20% and 0.24% PCA SP have the slightly lower mechanical properties and higher water porosity than control concrete. Beyond a certain amount of PCA SP (0.24%), a large reduction in the mechanical properties and a rapid increase in the water porosity can be found in concrete. The introduction of PCA SP to concrete lowers the resistance of concrete against chloride ion penetration and increases the total material costs. The prolonged curing period is an effective method to improve the long-term properties of PCA SP series concrete. Based on the consideration from the early-age properties and the economies of concrete, at the given fluidity, an optimum amount of PCA SP must be chosen in the production of concrete.