Influence of Mixture Condition and Moisture on Tensile Strain Capacity of Concrete

Sontaya Tongaroonsri and Somnuk Tangtermsirikul*

ABSTRACT: The effect of water to binder (w/b) ratio, paste content, type of cement, content of mineral admixtures, aggregate maximum size (G_max), sand content, and presence of moisture on the tensile strain capacity, or cracking strain, of concrete were investigated using flexural test method. The investigation showed that the effect of cement type, paste content and sand content in the tested ranges was not significant. The cracking strain decreased with the increase of the w/b ratio, and replacement ratio of fly ash and limestone powder. For ground granulated blast-furnace slag (GGBS), specimens containing 30% and 50% GGBS showed a higher cracking strain than that without GGBS, but at 70% GGBS, the cracking strain decreased. The cracking strain of concrete with a high w/b ratio (w/b=0.55) was the highest when G_max was 19 mm. However, when the w/b ratio was 0.30, there was a tendency that the cracking strain was the highest when G_max was 10 mm. The cracking strain increased whereas the flexural strength and splitting tensile strength reduced when concrete was oven-dried.

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School of Civil Engineering and Technology, Sirindhorn International Institute of Technology, Thammasat University, Patumthani 12121, Thailand.

* Corresponding author, E-mail: somnuk@siit.tu.ac.th

Received 20 Dec 2006, Accepted 5 Oct 2007