Recycled Glass Powder Produced by Steel and Ceramic Milling as a Supplement to Portland Cement for More Sustainable Concrete

This study demonstrates the successful use of eco-friendly recycled glass powders (RGPs) in mortar and concrete as pozzolanic substitute for portland cement. As part of the evaluation, two RGPs were produced by steel and ceramic ball mills, namely, RGP (SB) and RGP (CB), respectively. Also included in the experiment as a reference was a commercial ceramic ball-milled RGP. All three evaluated RGPs were found to be reactive pozzolans based on a series of reactivity test results, including a strength activity index of greater than 80 % on all ages of 7, 28, and 56 days in mortar and concrete. Multiple indicators, such as higher generated heat in pozzolanic reactivity testing by isothermal calorimetry and portlandite consumption, indicated ceramic milling could produce a more reactive glass pozzolan, perhaps from the alumina residue from ceramics milling media. However, the higher reactivity of RGP (CB) did not lead to a greater compressive strength when used in concrete. Furthermore, a color difference was not detected between RGP (SB) and RGP (CB) concrete specimens. This study shows that both steel and ceramic media are viable for RGP production based on pozzolanic reactivity, strength, electrical resistivity, and concrete color. Other factors, such as productivity and cost, should be considered when choosing the proper production method for RGP at the industrial scale.