Title:
Alkali-Silica Reactivity of Belitic Calcium Sulfoaluminate (BCSA) Cement Concrete
Author(s):
Tayyab Adnan
Publication:
Web Session
Volume:
Issue:
Appears on pages(s):
Keywords:
DOI:
Date:
10/23/2022
Abstract:
Belitic calcium sulfoaluminate (BCSA) cement is an alternative cement known for its rapid strength development and volume stability. This has long supported its use for accelerated pavement and bridge deck repair. More recently, researchers have investigated its use in structural concrete, where its low embodied energy and CO2 emissions contribute toward infrastructure decarbonization. However, insufficient knowledge on its fundamental material properties limits practical adoption. Specifically, more information is needed on the long-term durability of BCSA composites. To that end, this research studies alkali-silica reaction (ASR) in BCSA concrete. ASR is a deleterious reaction between alkaline cements and certain reactive aggregates that causes premature degradation and failure of concrete structures. Some researchers suggest BCSA cement is immune to ASR, but these claims have not been validated and the mechanisms of mitigation are not well understood. In this study, we evaluate the alkali-silica reactivity of BCSA concretes made with non-reactive limestone and Spratt siliceous limestone aggregates using accelerated and long-term expansion tests. Expansion results are similar between BCSA concrete with non-reactive and reactive aggregates, suggesting ASR did not occur. However, petrographic analysis with scanning electron microscopy and energy dispersive spectroscopy reveal abundant gel-filled through-aggregate cracking and significant mobility of iconic species between the aggregate and paste phases. These are all clear indicators of ASR. Although Spratt limestone is an extreme case, these results suggest ASR can occur in BCSA concrete under certain conditions but may not be evident from standard expansion tests.