Properties of cement pastes and mortars containing recycled green glass powder

Abstract

This work deals with the characterization of the properties of mortars and cement pastes made with powdered soda lime waste glass. Different rates of cement replacement by weight are used: 0%, 10%, 25%, 35% and 60%. Both fresh and hardened properties are assessed. The influence of glass powder on the workability of mortar is determined using flow table tests. Chemical shrinkage and hydration heat of early age blended cement paste are evaluated using gravimetric methods and isothermal calorimetric respectively. The dynamic Young’s and shear moduli of mortar are evaluated using nondestructive methods. Mechanical performances of mortars are measured using flexural and compressive strength tests. Pore structures of different mortars are investigated with mercury intrusion and water porosity tests.Results from this investigation indicate that the amount of cement replacement by glass powder plays a critical role in determining mortar characteristics. Chemical shrinkage and heat assessment show that high glass powder replacement of cement paste increases the hydration reaction rate. Compressive strength and dynamic Young’s and shear moduli values decrease with increasing glass powder content especially for mortar made with 60% glass powder.Mortar made with 60% glass powder has bigger pores due to the dilution effect, i.e., the reduction in the amount of hydration product at 7 days hydration. Significant compressive strength is gained between 7 and 90 days for mortar with glass powder, especially with 60% replacement showing pozzolanic reaction taking place during this period. The pozzolanic reaction that occurs between glass powder and calcium hydroxide (Ca(OH)2) to form more calcium silicate hydrate gel (C-S-H) leads to the refinement of pores and the reduction of porosity.