Behaviour of reinforced concrete affected by damage due to combined alkali silica reaction and delayed ettringite formation

Abstract

Alkali silica reaction (ASR) and delayed ettringite formation (DEF) are harmful swelling pathologies in concrete that have been observed in many reinforced concrete structures worldwide. It is particularly important to understand how expansion and damage due to combination of the two pathologies affect the durability of reinforced concrete. On the other hand, non-destructive testing (NDT) methods have been used in detection and monitoring of swelling pathologies in concrete with an advantage of using the same specimens for several measurements hence reducing error between measurements. In this context, this research aims to understand the combined ASR and DEF damage effect in reinforced concrete by using NDT methods. For this purpose, cylindrical plain and reinforced concrete specimens with diameter 160 mm, and height 320 mm were poured. The reinforcement ratios were 1 and 0.6% in longitudinal and transverse direction respectively. After casting, specimens were cured in autogenous conditions at 20⁰C for 28 days then after stored in tanks at 38⁰C while fully immersed in water for monitoring. The specimens’ expansions in longitudinal and radial directions were measured by length comparators. The damage was monitored by NDT methods of linear and non-linear vibration and cracking observations. The important results, discussions and conclusions obtained in this research campaign are detailed in the main content of this paper. These discussions are vital towards development of combined ASR and DEF research and modeling on reinforced concrete.