Experimental Characterization of the Mechanical Properties of Concrete Based on Glass-Powder

Annually, there is an enormous amount of glass waste created worldwide, yet only a small portion of that material is recycled. Recovering waste glass (WG) in concrete demonstrates excellent progress in lowering the amount of glass. Researchers have found that adding waste glass to concrete improves its qualities; WG can be utilized as powder, fine as well as coarse aggregate. However, the question that arises is how this powder added to concrete improves, or at least maintains, the mechanical properties of the concrete despite the reduction in the cement quantity. The aim of the present paper is to investigate the behavior of concrete with the addition of glass powder. For this purpose, a control concrete and concretes were prepared with 10%, 15% and 20% of the cement content of the glass powder, based on the same concrete formulation and by varying the W/C ratio. In the hardened state, the addition of glass powder up to 20% of the cement content, generated an increase in compressive strength at 28 days; this increase is caused by the reaction between the glass powder and the lime released during the hydration of Portland cement and creates a binder called hydrated calcium silicate (S-C-H) (pozzolanic reaction). The latter plays an important role in increasing the strength of concrete, and since the fineness of the glass powder is similar to that of cement, it has a role of filling, and accelerates the pozzolanic reaction. For an addition of 20% to 30% of pozzolan, theoretically we could react all the lime produced by the hydration of Portland cement. Therefore, beyond 25% or 30% of the glass powder, the strength is affected, which has been confirmed by many researchers. Finally, it can be concluded that the use of glass powder in concrete improves its mechanical behavior compared to ordinary condition, but with a limited percentage of 20% of the cement content.