Abstract Manager

Several studies have has been conducted elsewhere to evaluate the suitability of recylced glass powder as a supplementary cementitious material (SCM) in portland cement concrete (PCC) mixes. However, an environmental scan by Manitoba Transportation and Infrastructure (MTI) noted a limited use of recylced glass powder in Canada. Manitoba Liquor and Lotteries Corporation reached MTI to look into the potential use of this material in concrete mixes in Manitoba. A laboratory testing program was undertaken in 2023-2024 with some financial support from Manitoba Environment and Climate Change. The testing and analysis program included coarse aggregate from four sources, two types of portland cements and five different combinations of glass powder (0 to 20%) and fly ash (20 to 0%) for each cement and aggregate type. This resulted in specimen preparation and testing of forty (40) concrete mixes.

The test results and analysis indicated that recycled glass powder has no beneficial impact on the compressive strength, modulus of rupture (flexural strength) and modulus of elasticity of concrete containing GU cement. The trends of the durability property of concrete containing GU cement were inconsistent between ages of concrete at the time of testing and among varied glass powder contents in the concrete mixes. For the concrete containing GUL cement, 5% glass powder (and 15% fly ash) has shown to provide some beneficial effects as compared to the concrete with no glass powder and 20% fly ash content (reference fly ash content). A gradual decrease in concrete quality was noted with further increase in glass powder (decrease in fly ash) contents in concrete mixes containing GUL cement. The quality of concrete mixes containing GUL cement were shown to be inferior to the concrete mixes having GU cement. This confirms the findings in previous study and some field observation by MTI that properties of PCC containing GU and GUL cements are not equivalent. In the PCC mix design, 25-30 kg (per cubic meter of concrete) additional GUL cement was required to achieve closely equivalent properties of PCC mix containing GU cement. These findings raise question about the environmental benefit of GUL cement and suitability of recycled glass pozzolan as a SCM.

The objective of this paper is to present the details of the above specified testing, analyses and findings. The presented information may help agencies and interested individuals in assessing the suitability of the recycled glass powder as a SCM and benefit of GUL cement.