EFFECT OF SILICA FUME AND RICE HUSK ASH ON ALKALI-SILICA REACTION

The alkali-silica reaction (ASR), which occurs between the alkaline hydroxides in cement paste and reactive minerals in the aggregate, produces an expansive gel that may cause cracking and displacement in concrete structures. Currently, pozzolanic materials are used to prevent or minimize this cracking. An experimental program was undertaken to study the effect of different levels of cement replacement by silica fume (SF) or rice husk ash (RHA) on the expansion of mortar bars containing two types of reactive aggregates. The morphology and composition of the ASR gel were determined using scanning electron microscopy and energy-dispersive x-ray. The results indicate that it is possible to significantly reduce the mortar bar expansion for both types of aggregate using either SF or RHA. As predicted by double-layer models, the expansion of the mortar bars was highly correlated to the gel composition. The experimental results were also analyzed using the Kruskal-Wallis nonparametric method to validate the effect of these pozzolanic replacements on ASR gel composition.

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  • English

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  • Accession Number: 00797239
  • Record Type: Publication
  • Contract Numbers: 804-4-27-95
  • Files: TRIS
  • Created Date: Aug 23 2000 12:00AM