摘要: |
The use of low-level replacements of mineral admixtures in reducing expansion of mortar bars due to alkali-silica reaction (ASR) was investigated. Silica fume, powdered bottle glass, fly ash, and slag cement were examined for their potential to mitigate ASR in portland cement concrete that incorporates reactive-waste glass aggregate. All the mineral admixtures under investigation decreased ASR expansion. However, only a few were able to bring expansions below the 0.20% limit of deleterious expansion specified by ASTM C1260. The cement replacement levels effective in reducing expansions below 0.20% were 20% for silica fume, 20% for specific fly ashes, and 40% for powdered glass. The only characteristic of the fly ashes identified for reducing ASR expansion was fineness, expressed as the percent retained in the No. 325 sieve. The mix incorporating 20% silica fume was found to be the most satisfactory for a planned pavement patch application. However, a second-choice mix that uses 40% powdered glass showed excellent potential for resisting ASR but achieved only 90% of the strength required in 24 hours. |