A Feasibility Study of Incorporating Bottom Ash in Roller Compacted Concrete Pavements

Roller compacted concrete as a pavement material has been gaining acceptance over the past years. RCC can be of particular interest in base course applications combing attractive cost with easiness of construction. RCC is a friendly pavement material to incorporate by-products of industries such as bottom coal ash. This paper presents a laboratory research of RCC mixtures with addition of bottom coal ash. This non-standardized ash was used replacing the natural fine aggregate content. RCC mixtures with cement contents of 80 kg/m3, 120 kg/m3 and 160 kg/m3 were investigated. Other mixtures incorporating various levels of bottom ash were also prepared. Flexural strength was evaluated for each mixture at 28 and 90 days. Ultrasound measurements were also performed using the indirect transmission mode to assess the relationship between pwave speed and flexural strength. The results revealed an increase in flexural strength levels at increasing levels of fine aggregate replacement by bottom ash. A decrease of the order of 15% of cement content was observed at a specified flexural strength level of 2.5 MPa. This study indicates that the addition of bottom ash in RCC mixtures might lead to lower cement contents as well as to a less demand of fine aggregates.