Influence of steel and polypropylene fibers on cracking due to heat of hydration in mass concrete structures

摘要

Steel and polypropylene fibers result in a significant enhancement in strength, ductility, and toughness of concrete. This paper investigates experimentally and numerically the effect of these fibers on heat of hydration and early-age cracking in mass concrete structures. Experimental investigations were conducted on evolution of strength, Young's modulus, and adiabatic heat rise in fly ash concrete mixes with steel and polypropylene fibers. Concrete mixes with ordinary Portland cement, 40% fly ash replacing the cement, 40% fly ash with 0.3 and 0.5% steel fibers, and 40% fly ash with 0.3 and 0.5% propylene fibers were investigated. The evolution of compressive and tensile strength, modulus of elasticity, and adiabatic heat rise using semi-adiabatic calorimeter for all mixes was measured. The evolution of temperature at several locations in two full-scale mass concrete blocks with normal concrete and fly ash concrete was measured. A multiphysics-based finite element simulation of the two field mass concrete blocks was carried out using the software DIANA FEA BV (South Holland, Netherlands), which predicted the heat generation, temperature field, stresses developed in the blocks, and the associated cracking with good accuracy. The effect of steel and polypropylene fibers on heat, temperature, and stress generation in mass concrete blocks was investigated using the experimentally obtained parameters. The polypropylene fibers result in significant performance enhancement for early-age cracking compared with the steel fibers.