Mechanism for reduction in compressive properties of cementitious materials in relation to internal crack patterns due to ASR and DEF expansion

Abstract

This study discusses the mechanism for the changes in the compressive properties of internally cracked concrete due to expansion phenomena. The internal crack patterns due to alkali-silica reaction (ASR) and delayed ettringite formation (DEF) are reproduced using the model concrete with artificial cementitious aggregate. The compressive behaviors are clarified using a uniaxial compressive test with digital image correlation. As a result, in terms of ASR, the trends for reduced mechanical properties in model concrete differ from the expansion phenomena under stress-free condition and the anisotropy of change in mechanical properties due to the aggregate crack orientation changes is observed. For DEF, the reduction in mechanical properties is independent of thickness of a debonding crack. Consequently, the mechanism for reduction in compressive strength and elastic modulus by the aggregate cracking and gap formation due to ASR and DEF based on the compressive stress transfer path at the cross-sectional area was proposed.