Waste latex paint constitutes 12% of the total hazardous waste collected in Ontario, Canada. Currently only 10 to 30% of this waste is being collected. With increasingly more stringent environmental regulations on volatile organic compounds (VOCs), more latex-based paints will be produced compared to solvent- and oil-based alkyds. This will result in more waste latex paint being generated annually in Ontario and across North America. It costs municipalities between $0.90 and $1.40 CAD per litre to dispose of such waste. This study aims at investigating the benefits of recycling waste latex paint in concrete with a special focus on concrete sidewalks. Waste latex paint was used in concrete mixtures both as a partial replacement for virgin latex and for mixing water. It is shown that concrete mixtures incorporating waste latex paint have improved workability, higher flexural strength, lower chloride ion penetrability, better resistance to deicing salt surface scaling and could be more economic because they require less water-reducing and air-entraining admixtures. The annual urban concrete sidewalk construction could use the yearly production of waste latex paint while producing sidewalks with enhanced properties and durability.

The paper consists of an overview of the development of techniques for recycling concrete. Demolition, processing and the recycling of the resulting materials are often analyzed separately. "High quality" recycling of concrete waste does not always correspond to production/use of the product with the highest value, but rather the most feasible product in a specific project or region. It is by analyzing the whole disposal/supply-chain, including the substituted material, that the best effects of recycling can be achieved. Overviews of methods for environmental evaluations as well as economic considerations are presented. Integrated demolition waste management in Kosovo and an analysis of the potential market in Hong Kong are presented as examples of the worldwide market for recycled materials. Issues regarding the handling of polluted materials will be discussed from a practical point of view. Moreover, some aspects to soncsider regarding future demolition when producing new concrete products are presented.0

This study investigated the reactivity of concrete containing recycled concrete aggregates (RCA) that had shown distress due to alkali silica reaction (ASR). The investigation evaluated several mitigation techniques to control ASR in concrete containing potentially reactive RCA. Mitigation work was done with three different aggregate types; an igneous fine-grained quartzite aggregate locally called blue rock, a non-reactive limestone, and RCA containing blue rock aggregate. These aggregates were used to investigate various mitigation techniques to prevent ASR from occurring in concrete containing RCA. The mitigation strategies include the use of class F fly ash, ground granulated blast furnace slag (GGBFS), lithium nitrate, silica fume blended cement and low alkali cement. These materials were incorporated into concrete mixes by cement substitution and direct application. These mitigation strategies showed potential in controlling ASR distress in RCA concrete. Mortar bars and concrete prisms were used to investigate the mitigation strategies by following standard and modified versions of ASTM C 1260 and ASTM C 1293 specifications to evaluate expansion caused by ASR. The modified versions of ASTM C 1260 were found effective in evaluating potential ASR expansion using conventional aggregates.

This publication contains 11 papers which promote and encourage the use of recycled concrete and other materials in concrete construction, taken from presentations at the 2003 ACI Spring Convention in Vancouver, Canada. Specific subject areas include the global perspective, challenges and opportunities of concrete recycling, the barriers to recycling concrete in highway construction, and current practices in the European Union, Japan, and USA. This publication also contains research papers on the use of recycled glass as aggregates for architectural concrete, recycled scrap tire rubber, flowable slurry containing wood ash, recycled latex paint as an admixture, crushed stone dust in production of self-consolidating concrete, a new binder using thermally treated spent pot liners from aluminum smelters, and the durability of concrete containing recycled concrete as aggregates that had shown distress due to alkali-silica reaction. Note: The individual papers are also available as .pdf downloads.. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP219

With population growth and urbanization, the space available for installation of civil infrastructure is rapidly decreasing. There is need for a more efficient use of underground space, which involves the construction of tunnels and other underground structures. Due to space constraints, many underground infrastructure projects in the future will be located in rock/soil with time-dependent behavior and/or under high overburden pressure. A deformable supporting system that can serve as a buffer layer for protecting tunnel linings and buried structures from time-dependant deformations of the excavated rock/soil will therefore be needed. This study investigates the possible use of cement mortars containing crumb tire rubber to develop a flexible interface material for such applications. The effects of the water/cement ratio (w/c) ratio, rubber content and particle size on the mechanical properties of the mortars were studied using uni-axial and tri-axial compression tests. A statistical factorial experimental was designed to obtain response surfaces for the parameters under study. The findings of this research suggest that cement mortars containing ground tire rubber have superior ductility and may be used to accommodate deformations around tunnel linings, pipelines, and other buried infrastructure.