High-Performance Concrete Incorporating Rice Husk Ash as a Supplementary Cementing Material

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Title: High-Performance Concrete Incorporating Rice Husk Ash as a Supplementary Cementing Material

Author(s): Min-Hong Zhang and V. Mohan Malhotra

Publication: Materials Journal

Volume: 93

Issue: 6

Appears on pages(s): 629-636

Keywords: durability; high-performance concretes; portland cements; pozzolans; rice husk ash; silica fume.

Date: 11/1/1996

Abstract:
This paper presents results on the physical and chemical properties of rice husk ash (RHA), and deals with the properties of fresh and hardened concrete incorporating the same ash. The properties of fresh concrete investigated included workability, bleeding, setting time, and autogenous temperature rise, and those of the hardened concrete included compressive, splitting tensile, and fexural strengths, modulus of elasticity, drying shrinkage, resistance to chloride ion penetration, resistance to freezing and thawing cycling, and salt-scaling resistance. In addition to the effects of the percentage of RHA and the water-cementitious materials ratio on the properties investigated, the properties of the RHA concrete were also compared with those of the control portland cement concrete and silica fume concrete. The test results indicate that the RHA is highly pozzolanic and can be used as a supplementary cementing material to produce high-performance concrete. Although it requires a higher dosage of the superplasticizer and the air-entraining admixture compared with those of the control concrete and the silica fume concrete, the RHA concrete can be produced with satisfactory slump, air content, and setting time. In general the RHA concrete had higher compressive strengths at various ages up to 730 days compared with that of the control concrete, but a lower value than that of the silica fume concrete. The flexural and the splitting tensile strengths, modulus of elasticity, and drying shrinkage of the control concrete and the concrete incorporating RHA or silica fume were comparable. The RHA concrete had excellent resistance to chloride ion penetration, and the charge passed in coulombs was below 1000 both at 28 and 91 days. The RHA concrete also showed excellent performance under freezing and thawing conditions, and its resistance to deicing salt scaling was similar to that of the control concrete and marginally better than that of the silica fume concrete.