Utilization of ground waste glass cullet in the industrial production of precast concrete elements

In the study, a field trial was carried out to evaluate the applicability of ground waste glass cullet as a binder component, in the industrial production of precast concrete elements. The influence of glass cullet addition on the properties of fresh and hardened concretes was compared to siliceous fly ash. Moreover, the effects of a partial substitution of the natural aggregate with recycled concrete and expanded clay aggregate were determined. The compressive strength of concretes, in which 25% of cement was substituted with ground waste glass cullet, was even 20% higher compared to elements with an analogous addition of siliceous fly ash. Over 56 days, no drops in strength related to the harmful effects of the alkali-silica reaction were observed. Replacing half of the natural aggregate with graded recycled concrete aggregate, allowed to lower the thermal conductivity of the walls by approx. 10%, with no negative impact on the compressive strength of precast elements. However, a decrease in the consistency of fresh mix was observed after 30 minutes. Replacing the 2÷8 mm gravel with the same fraction of expanded clay resulted in an approx. 18% decrease in thermal conductivity, while maintaining satisfactory mechanical properties. It was concluded that ground waste glass cullet can be successfully used as a fly ash replacement in the production of precast concrete elements.