Composite materials with primary lead slag content: Application in gamma radiation shielding and waste encapsulation fields

Abstract

This paper presents a study on the valorization of primary lead slag as substituent of aggregate in concrete for gamma radiation shielding and as a component of cementitious binders with application in low level radioactive solid waste encapsulation. The first part of the paper outlines the impact of primary lead slag on the compressive strength and gamma radiation shielding properties of concrete. The presence of the primary lead slag as aggregate substituent in concrete, along with steel shot and barite, enhances the density and shielding efficiency against gamma radiation for Ir192, Cs137, Co60 radioactive elements with average gamma energies of 0.37 MeV, 0.662 MeV and 1.25 MeV. The results showed that even the presence of primary lead slag led to a decrease in compressive strength and all the tested concretes exhibited compressive strengths higher than 50 MPa. The utilization of primary lead slag could be recommended as aggregate in heavyweight concrete. The second part of the paper focuses on the experimental investigation of the physic-mechanical properties and low level radioactive solid waste encapsulation capacity of grout based on binders with primary lead slag content. Two binders (30% and 50% lead slag content) were used in cementitious grouts with different binder:sand ratio (1:1, 1:1.5 and 1:2), two types of sand (river sand or crushed concrete sand), different grain size distribution of sand and water/binder ratio of 0.3. It was observed that the grouts exhibit compressive strengths higher than 30 MPa, regardless of the binder:sand ratio. The increase in the binder:sand ratio influenced negatively the flow ability and positively the drying shrinkage. The low level radioactive solid waste encapsulation capacity of studied grout was lower than that of the reference grout with CRT glass waste.