Enhanced conductivity measurement techniques for evaluation of metakaolin pozzolanic activity
- Pathum Thani, Thailand : Asian Institute of Technology, 2010
- 54 leaves : ill.
- Thesis ; no. ST-10-03 .
- Asian Institute of Technology. Thesis ; no. ST-10-03 .
A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Structural Engineering, School of Engineering and Technology
Thesis (M.Eng.) - Asian Institute of Technology, 2010
This study aims to propose a rapid technique of evaluation of pozzolanic activity of metakaolin using Calcium hydroxide solution as a suspension. Different testing temperature range is used to find optimum temperature. The temperature range is selected from 40°C to 80°C. Fly-ash and sand is also tested for comparison. OPC solution was also used as the suspension to compare with calcium hydroxide suspension. Inert material (River sand) is used as a base for finding out rate of change of electrical conductivity in the suspension. 1.0 grams of metakaolin was tested in 200mL of calcium hydroxide solution. The electrical conductivity was then measured at time interval of 5 minutes and recorded in the computer for analysis. Strength activity index of the metakaolin was also done by finding out compressive strength of metakaolin for 7, 28, 56 days at varying metakaolin cement replacement. The compressive strength was found out using constant water binder ratio of 0.48. The compressive strength of the metakaolin mortar was optimum at 20% metakaolin cement replacement. The pozzolan is considered reactive as the differences between initial measured conductivity and stabilized electrical conductivity is considerably high. After studying effect of different suspension temperature, temperature of 80C is recommended as optimum temperature for evaluation of pozzolanic activity of metakaolin. The results from the electrical conductivity method was compared with the strength activity index results tested according to ASTM C 311 and it was found out that both results showed resemble each other. Linear relationships were obtained between the electrical conductivity results (corrected reduction in normalized electrical conductivity) and strength activity index results. So, it can be concluded that corrected reduction in normalized electrical conductivity can be used to predict strength activity index of metakaolin by linear regression technique. This technique is rapid and economical way to determine pozzolanic activity of metakaolin.