Rubberized Portland Cement Concrete

The use of recycled tire rubber in a portland cement concrete (PCC) mixture is investigated as a possible alternative for nonconventional PCC mixtures. This study is focused on the determination of the practicality of producing such mixes and evaluating their engineering properties. An experimental program was developed to use two types of tire rubber (fine crumb rubber and coarse tire chips) in PCC mixtures. A control PCC mix is designed using American Concrete Institute mix design methods, and three groups of rubberized PCC mixes were developed by partially replacing the aggregate with rubber. Eight tire rubber contents were used in each group. Mixes were tested in compressive and flexural strength in accordance to ASTM standards. Results show that rubberized PCC mixes can be made and are workable to a certain degree with the tire rubber content being as much as 57% of the total aggregate volume. However, strength results show that large reductions in strength would prohibit the use of such a high rubber content. It is suggested that rubber contents should not exceed 20% of the total aggregate volume. A characteristic function that quantifies the reduction in strength for rubberized concrete mixes was developed that could be useful for mix design purposes. Rubberized concrete mixes may be suitable for nonstructural purposes such as lightweight concrete walls, building facades, and architectural units. They could also be used as cement aggregate bases under flexible pavements. Fire hazards are of major concern and need to be thoroughly investigated before recommendations for practical implementation are drawn.