Complementary Effect of Heat Treatment and Steel Fibers on Mechanical and Microstructural Properties of High-Performance Concrete

摘要

Concrete heat treatment is commonly used to speed up early gaining rate in mechanical strengths. How- ever, adding some other ingredients can help to improve this desired effect. The aim of this study was to investi- gate the value-added use of steel fibers in combination with heat curing on some mechanical and microstructural prop- erties (compressive strength, modulus of elasticity, modulus of rupture, splitting tensile strength, direct tensile strength, X-ray diffraction and fracture surface observations) of high- performance concretes. Two categories of high-performance concretes were assessed: fibrous and non-fibrous. Four vol- ume fractions of steel fibers were used: 0, 0.5, 1 and 2%. Replacements of silica fume into the concrete were 0 and 15% by weight of cement, and the reference slump was 170 ± 8mm. All concretes were subjected to heat curing and evaluated versus standard cured. The complementary effect of both steel fibers and heat curing succeeds to par- ticipate toward improvement of early mechanical properties particularly tensile strengths, increase C-S-H content and develop bonding of the cementitious matrix to steel fibers. This could be attributed to disperse ability of steel fiber scat- tering heating effects more uniformly throughout concrete section. Among diverse steel fibers content used, 2% pro- vided better dispersions effect.