Effect of various fiber on early- age shrinkage cracks and mechanical strength of high strength concrete

Abstract

When the concrete loses its moisture, shrinkage and volume reduction is happening and eventually cracks create and deformations in the concrete are increased. In this study, the effect of polypropylene, steel, glass, basalt and polymer fiber on compressive strength, flexural strength and shrinkage cracks (early ages) of high strength concrete mixtures were evaluated. The restrained shrinkage test was performed on concrete ring specimens with height of 150 mm, inner diameter of 30 mm and outer diameter of 40 mm according to ASTM C 1581 standard. The crack width and age of restrained shrinkage cracking were main parameters studied in this research. The results showed that, adding fiber, caused increases the compressive strength 16%, 20% and 3% at the age of 3, 7 and 28 days respectively, and also, increased flexural toughness index up to 7.7 times. steel and glass fiber provided good performance in flexural strength, but had relatively poor action in the velocity reduction and cracking time of restrained shrinkage. Also, crack in all of concrete ring specimens except polypropylene containing mixture, was developed to full depth crack. The mixture of polypropylene fiber containing showed reduction in crack width up to 62% and increasing age cracking up to 84%.

Keywords

• fiber
• high strength concrete
• crack
• early-age shrinkage
• mechanical strength