Early age hardening of concrete with heavy aggregate in gamma radiation source – Impact on the modulus of elasticity and microstructural features

Abstract

The effects of gamma irradiation on concrete properties during early hardening were studied towards radioactive waste storage or accelerated processing at precast plants. Concrete mixtures containing different mineral aggregates (baryte, magnetite, amphibolite) were investigated. During initial 16 hours of hardening the mixes were irradiated using 60Co gamma source at the rate of 3.5 kGy/h. The mechanical properties and microstructural features of irradiated early-age concrete were tested: the secant elastic modulus, the compressive strength, the porosity and pore size distribution. XRD and SEM analysis were also performed. The results indicate both the stiffening and pore refinement in concrete due to early gamma irradiation. Effects of early irradiation on microstructural features of cement matrix were found in the subsurface layer up to the depth of 2 mm. The influence of different mineral aggregates in concrete on the radiation-induced changes of early age properties is discussed.