USE OF RECYCLED GLASS IN CONCRETE PRODUCTION

Worldwide, rapid population growth causes an increasing production of solid waste, and sustainable waste management solutions are required to deal with this. Waste glass is a significant component of the solid waste stream, and most of the recycled glass cullet is used for new glassware. However, waste containers with mixed types of glass, such as windows, ovenware, and crystal, which have higher melting points and are of different colors, cannot be used for new glassware. Hence, the contaminated load is sent to landfill. As landfill capacity is limited, it is critical to consider using this waste material for other applications. While the effects of the substitution of fine or coarse aggregates have been extensively researched, information on the effects of partial replacement of coarse aggregates and total replacement of fine aggregate with glass cullet is scarce. This paper reports on continuing research at La Trobe University on using recycled aggregates in the production of concrete. The effects of partial or total replacement of coarse crushed rock aggregates with recycled glass aggregates on the strength and durability of concrete were investigated. It was found that concrete mixes produced with recycled glass exhibited lower performance than the mixes produced with crushed rock aggregates. However, the production costs were lower and the appearance of concrete was improved, making it applicable for finishing products, noise barriers and light-trafficked footpaths.

Correlation relationships between mechanical parameters of Bulgarian crushed-rock aggregates utilized in railway construction

Crushed-rock aggregates from 11 railway ballast-producing quarries in Bulgaria have been investigated. The test materials consist of igneous and sedimentary rocks of different ages: basaltic andesite, trachyte, diabase, andesitic tuff, quartz-cemented sandstone, dolomite and five varieties of limestone. The standard laboratory tests (Los Angeles, micro-Deval and point load) and in-situ test (Schmidt hammer) were carried out for determination of the following mechanical properties of aggregates: resistance to fragmentation; wear resistance; strength; and rock hardness. Results show that Los Angeles coefficient (LA) values range from 11.9% to 28.4%. The micro-Deval coefficient (MDE) varies between 3.7% and 22.4%. The point load strength index (IS(50)) is between 4.0 MPa and 8.8 MPa. The Schmidt hammer rebound value (SHV) ranges from 34.4 to 60.2. The possibility of predicting the Los Angeles and micro-Deval coefficients from the Schmidt hammer rebound value and the point load strength index was studied. Regression analysis shows a strong correlation between Los Angeles coefficient and point load strength index (coefficient of determination R2=0.93), a good correlation between the Los Angeles coefficient and the Schmidt hammer rebound value (R2=0.62) and moderate correlation between the micro-Deval coefficient and the Schmidt hammer rebound value (R2=0.51).