Non-steady-state Chloride Migration of Self-compacting Concrete under Early-stage Accelerated-microwave Curing at Low Pressure Condition

Abstract

This research studied the diffusion of chloride ions in self-compacting concrete mixed with recycled concrete aggregate (RCA) as coarse aggregate. The concrete mixing proportions were as follows: water-to-cement ratios (w/c) of 0.35, 0.45, and 0.65, and the amounts of hydraulic cement were 350, 400, and 450 kg/m³. The superplasticizer dosage calculated per unit weight of cement content equals 0.60 %wt. The test investigated the chloride-ion diffusion coefficient (CDC) according to the NT BUILD 492 standard (Non-Steady State Chloride Migration) of concrete at the curing age of 28 days. The comparison was made with concrete mixed with coarse ground limestone aggregates with a nominal maximum size of 25.0 mm (control concrete). Results found that the CDC of concrete mixed with RCA showed an increasing tendency with increasing w/c compared to the control concrete but decreased significantly with increasing cement content.