EFFECT OF HIGHLY REACTIVE RICE HUSK ASH ON DURABILITY OF CONCRETE AND MORTAR

The performance of a highly reactive rice husk ash (RHA) as a supplementary cementing material for producing high strength and high durability concrete is reported in this paper. The effects of the specific surface area of RHA, RHA content, and water-cementitious ratio on the compressive strength of mortar are investigated. Some basic properties of the RHA mortar such as acid resistance, abrasion resistance, and alkali-silica expansion are also examined. Furthermore, the properties of the RHA concrete such as freezing and thawing resistance and compressive strength are tested. The pore size distribution and quantitative analysis of calcium hydroxide in the hardened RHA mortar and paste are used in evaluating the pozzolanic reactivity of the RHA. The compressive strengths of the mortar and concrete are significantly improved by the RHA addition, and are higher than those of the control mortar and concrete. Unlike other pozzolanic materials, the concrete incorporating the RHA shows excellent strength development at early-age even without steam-cure. The acid resistance of the mortar is remarkably improved by the RHA addition. The abrasive coefficient loss of the mortar with RHA is marginally smaller than the control mortar. With increasing RHA content of the mortar, the expansion of the mortar due to alkali-silica reaction is decreased. The pore size distribution of the RHA mortar shows a tendency of shifting towards the smaller range of pores compared to the control mortar. After 240 testing cycles, the effect of the RHA addition on the resistance to freezing and thawing cycling of air-entrained concrete is negligible. The calcium hydroxide contents of the mortar and the paste are decreased with the addition of RHA. Moreover, the RHA pastes show calcium hydroxide content lower than the silica fume pastes at early-ages.

Language

  • English

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 205-222

Subject/Index Terms

Filing Info

  • Accession Number: 00793939
  • Record Type: Publication
  • Report/Paper Numbers: SP 192-13
  • Files: TRIS
  • Created Date: Jun 28 2000 12:00AM