Fresh and hardened properties of self-consolidationg concrete incorporating metakaolin

Mayo, Justin R. (2013) Fresh and hardened properties of self-consolidationg concrete incorporating metakaolin. Masters thesis, Memorial University of Newfoundland.

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Abstract

This thesis aims to study the fresh and hardened properties of self-consolidating concrete (SCC) produced with metakaolin. The first stage of the study was to identify the most favourable replacement of cement with metakaolin by varying the metakaolin content from 0 to 25% in SCC. Typical tests for SCC were conducted on the fresh and hardened properties for all mixtures. Based on these test results, the optimum metakaolin percentage was chosen and the effect of the mixture design on SCC was studied. Using the same tests as the first stage, the second stage varied the coarse-to-fine aggregate (C/F) ratio, coarse aggregate size, binder amount, and air content to optimize SCC containing metakaolin. The third stage of the program was to study the effect of metakaolin and mixture design on the shear capacity and cracking behaviour on full-scale sec beams. The results indicated that 20% metakaolin replacement gave the optimal flowability, passing ability, segregation resistance, 28- and 90- compressive strengths, Flexural Strength (FS), Splitting Tensile Strength (STS) and Modulus of Elasticity (ME). However, the addition of metakaolin, increased the viscosity of the mixture and the high range water reducer (HRWR) demand. Varying the mixture design showed, using a lower C/F ratio of 0. 7, increasing the coarse aggregate size to 20 mm, increasing the total binder content to 500 kg/m³, and using air entrainment up to 7%, all helped to improve the flowability, viscosity, and passing ability of SCC. However, when using a lower C/F ratio of 0.7, the HRWR demand increased for all mixtures, while all other design parameters reduced the HRWR demand. Examining the mechanical properties, it was seen that using either a lower C/F ratio of 0.7 or increasing the binder content to 500 kg/m³ improved the compressive strength as well as the strength development, flexural strength, splitting tensile strength and the modulus of elasticity. While, increasing the coarse aggregate size to 20 mm or increasing the air entrainment to 7% resulted in a reduction in the compressive strengths and strength development, flexural strength, splitting tensile strength and the modulus of elasticity. Using a larger C/F ratio of 1.2, was shown to decrease the normalized shear strength, while increasing the post diagonal cracking resistance in normal-strength sec beams, although, in high-strength sec beams, there was no significant variation. In addition, increasing the coarse aggregate size to 20 mm, increased the normalized shear strength and post diagonal cracking resistance in normal-strength sec beams, and showed no affect in high-strength sec beams.

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