Year

1999

Degree Name

Doctor of Philosophy

Department

Department of Civil, Mining and Environmental Engineering

Abstract

This study has developed limestone modified cements to be used for self-compacting and vibrated high performance concretes. The study has also placed emphasis on the development of rapid testing methods for determining quality of self-compacting concrete. In addition, a mix design method that can be applicable for different materials was proposed to ensure high durability and economic efficiency for self-compacting high performance concrete. The effect of aggregate maximum size, coarse to total aggregate ratio, water to binder ratio and paste volume on superplasticizer requirement, compressive strength and drying shrinkage of high performance concretes also were investigated in the study.

The test results showed that the use of limestone modified cements, consisting of Portland cement and milled limestone with suitable content and fineness, can result in reduced superplasticizer requirement, improved compressive strength, reduced heat of hydration and drying shrinkage as well as reduced cement content of high performance concretes. These benefits would therefore enable high-performance concrete to be produced more economically.

Rapid testing methods for determining blocking behaviour, deformability and segregation resistance of self-compacting concrete were developed. Test results showed that the proposed method and developed apparatus are useful in the rapid evaluation of quality of self-compacting concrete.

The proposed mix design method combines the criteria for aggregate blocking and liquid phase (deformability, segregation resistance and flow velocity as well as superplasticizer requirement), criteria for selection of optimum coarse to total aggregate ratio and construction criteria. The method can be used to design self-compacting concrete having high durability, economic efficiency and application for different materials. The developed criteria should also reduce the need for repeated mixing trials, the times and extent of laboratory procedures and practices.

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