Title: Effect of Internal Curing as Mitigation to Minimize Alkali- Silica Reaction Damage
Author(s): Mengesha A. Beyene, Jose F. Munoz, Richard C. Meininger, and Carmelo Di Bella
Publication: Materials Journal
Appears on pages(s): 417-428
Keywords: alkali-silica reaction (ASR); capillary porosity; fluorescence microscopy; image analysis; internal curing (IC); lightweight aggregate (LWA); quantitative paste characterization; SEM-EDS; surface resistivity
Internal curing can reduce alkali-silica reaction (ASR) damage in concrete. Alkali reactions with chert in natural sand caused
damaging ASR in plain concrete. However, ASR damage was minimal in companion internally cured (IC) concrete in which a portion of the sand was replaced with pre-wetted lightweight
aggregate (LWA). IC improved paste quality through a quantitative reduction in paste porosity and unhydrated cement. This was assessed using quantitative paste characterization including image analysis of backscattered electron (BSE) images, quantitative fluorescent intensity assessment, resistivity measurements, and qualitative analyses using SEM-EDS and polarized light microscopy. In concretes with the same water-cement ratio (w/c), IC concrete has denser paste microstructure from increased hydration due to additional water from pre-wetted LWA. Less permeable paste reduced fluid ingress, ASR reaction, and crack propagation. This demonstrates the potential of internal curing as a mitigation tool in reducing damage from ASR when high cement content and potentially reactive aggregates are used.