Utilization of Metakaolin as an Inhibitor of Alkali Silica Reaction in Cement Mortars Containing Chert and Silicified Limestone Aggregates

The following work aims at investigating the utilization of meta-kaolin and calcined brown smectite rich clays as inhibitors of alkali silica reaction (ASR) and improving the compressive strength in Type 1 ordinary Portland cement mortars including sand size chert or silicified limestone.   Mortars were cured and tested at 56 days age.  The compressive strength values increased to 40 MPa for the sample with 10% of Metakaolin-and 3.64% of chert content. The compressive strength values increased to 30 MPa when calcined brown clay was used instead of Meta-kaolin at the same proportion of chert.. Maximum compressive strength values of 36 Mpa and 30 Mpa were achieved when metakaolin and calcined brown clay were added to the reference mortars at a range of 5-10% and 8% respectively. Compressive strength was varied according to reactive aggregate type and percent in addition to the calcined brown clay and meta-kaolin content in the tested mortars.  Scanning electron Microscope images (SEM) have indicated the absence of cracks usually related to swelling silica gel due to the consumption of the gel through its reaction with kaolin and calcined brown clay. Keywords : chert, silicified limestone, metakaolin, alkali silica reaction