International Concrete Abstracts Portal

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

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 use of mineral admixtures as addition to or replacement of portland cement has been attracting a great amount of interest in recent years. Using suitable quantities of those minerals not only improves some properties of fresh and dry concrete, but also reduces portland cement demand and helps solve several environmental problems. Aluminium production in various parts of the world generates a considerable amount of waste which contains leachable cyanides and fluorides that cause a serious environmental problem. This paper presents a study of the effect of substituting a percentage of cement by a glass flit in mortar and in concrete. The term glass frit refers to spent pot liners resulting from the aluminium production process, that have undergone various treatments and have been ground to the fineness of a cement. The various results obtained in different tests conducted on mortar and concrete showed that glass frit has a remarkable reactivity potential and an interesting rheological behaviour. Replacing a percentage of cement by glass frit improves workability and strengths of mortar and concrete. For a given slump, concrete containing 25% of glass frit requires 50% less water reducer than that of control concrete. The compressive strengths developed in mortar or in concrete are very similar or even greater than those made with portand cement only or those incorporating blast furnace slag with equivalent cement replacement rate.

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.

Crushed limestone dust is a waste material from the production of concrete aggregate by crushing quarried limestone rocks. The dust is usually less tan 1% of the aggregate production. Although it is coarser than common cementing materials such as as Portland cement, coal fly ash and ground blast furnace slag, it is fine enough to cause many problems during materials handling and disposal. Laboratory results have indicated that crushed limestone dust can be used to produce self-consolidating concrete (SCC) with properties similar to those of SCC containing coal fly ash. . Due to the differences in morphologies and particle size distribution, the mix design has to be modified when crushed stone dust instead of fly ash or ground blast furnace slag is used. Fresh SCC mixtures containing limestone dust loses its flowability and sets faster than the mixtures containing fly ash due to the acceleration of the hydration of Portland cement by the limestone powder. SCC containing limestone dust exhibited strengths similar to that containing fly ash during the first seven days, but the former exhibited lower strength than the latter at 28 and 90 days due to the contributions from the pozzolanic reactions between coal fly ash and lime released from the hydration of Portland cement. The former also have lower autogenous and drying shrinkages than the latter.