Prediction of later-age compressive strength of normal concrete based on the accelerated strength of concrete cured with microwave energy

Abstract

Microwave energy can accelerate the hydration of cement, resulting in rapid strength development of concrete in an early period. In this paper, prediction of later-age compressive strength of normal concrete, made with rapid-hardening and ordinary Portland cement, based on the accelerated strength of concrete cured with microwave energy was investigated. To accelerate curing properly, the optimal microwave curing process for concrete was first determined and then was applied to concrete. The possible early ages for the strength prediction were found to be at 3.5 and 5.5 h for concrete made with rapid-hardening and ordinary Portland cement, respectively. For each cement type, a formula for the strength prediction was derived from the relationship between accelerated early-age strength of concrete cured with microwave energy and later-age strength of normally cured concrete. Predictions of strength at 7 days for concrete made with rapid-hardening Portland cement and 28 days of concrete made with ordinary Portland cement were within 15% agreement with actual test results.