Reduction in alkali-silica expansion due to steel microfibers

The alkali-silica reaction (ASR) produces an expansive gel that may cause c racking and displacement in concrete structures. Steel microfibers ranging from 1% to 7% by volume of cement mortar were incorporated to reduce the ex pansion and cracking. All specimens contained 5% of opal by weight of fine aggregates. The samples were cast and tested according to ASTM C-1260. A co nsiderable reduction in expansion was observed for all steel microfiber-rei nforced mortar specimens compared to the control specimens without fibers. The higher the fiber volume fraction, the lower the expansion. At constant fiber volume fraction, the expansion was further reduced when the curing ti me was extended from 1 day to 7 days due to an increase in the fiber-matrix interfacial bond strength. (C) 2001 Elsevier Science Ltd. All rights reser ved.