Valorization of nano-PbO as an additive to modify the properties and radiation shielding of alkali-activated slag mortar

Abstract

In this work, for the first time, the possibility of employing nano-lead oxide (nPbO) in alkali-activated slag (AAS) mortar as a modifier agent for its properties was studied. Different ratios of nPbO (0 wt%, 1 wt%, 3 wt% and 5 wt%) were added to the plain AAS mortar. The effects of these ratios on flowability, mechanical strength, water absorption, total porosity, aging resistance, gamma-ray radiation shielding, crystalline phases, thermal analysis and microstructure were investigated. The gamma-ray attenuation coefficients were determined as a function of the additive percentages of lead oxide for gamma-ray energies of 1332, 1173 and 662 keV using Co-60 and Cs-137 sources. Different techniques were used to analyze the results. The results showed higher flowability of the mixtures with introducing nPbO. The flowability increased with increasing nPbO ratio. The mechanical strength and aging resistance increased with introducing 1% and 3% nPbO, then slightly decreased with including 5% nPbO. Water absorption and total porosity decreased with introducing 1% and 3% nPbO, then slightly increased with including 5% nPbO. Introducing nPbO in the AAS system improved the radiation properties, of which the attenuation coefficients increased with including nPbO. In a word, using suitable ratios of nPbO improved the fresh, hardened, durability and radiation properties of AAS mortar and can provide it for wider applications.