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Roller-compacted concrete (RCC): is defined as that concrete of no-slump consistency in its unhardened state that is transported, placed, and compacted by roller compaction. RCC has traditionally been used for carrying heavy loads in low speed are…
Roller-compacted concrete (RCC): is defined as that concrete of no-slump consistency in its unhardened state that is transported, placed, and compacted by roller compaction. RCC has traditionally been used for carrying heavy loads in low speed areas. However, it has been used recently in commercial areas and highways. Steel fiber reinforced roller compacted concrete (SFR-RCC) is RCC mixture with an added amount of steel fiber (SF) to improve the compressive and flexural strength and to increase the inherent ability to control cracking.
The purpose of this research is to study the effect of using steel fiber reinforcement on the properties of RCC in which cementitious materials (CMs) was partially replaced with cement kiln dust (CKD), in airports pavement. In this study, the (SFR-RCC) mixes were prepared using different contents of SF, (30, 50, 70, 90 kg/m3) of concrete. An amounts of (5%, and 10%) of cementitious materials (CMs) weight were partially replaced by cement kiln dust. Preparing SFR-RCC specimens was done by mixing all materials, next compacting the mixes in the laboratory using a locally made manually controlled roller device. Compressive, and flexural strength tests were done using cubes and prisms obtained by sawing SFR-RCC specimens. Ultrasonic pulse velocity (UPV) and bulk density tests were also conducted. The test results of plain samples (with no SF) at 28-days age showed that the partial replacement of (5%) of CMs by CKD was better than the (10%) replacement, concerning compressive strength, flexural strength and the bulk density. The results showed that the RCC specimens with 5% replacement of CMs by CKD possessed at 28 days age, a 2.37 ton/m3 bulk density, and a compressive, flexural strengths of 31, 7.6 MPa respectively while the UPV was equal to 4.33 km/sec. It was shown that the compressive strength of the RCC specimens with 5% replacement of CMs by CKD, increased by (19, 25, 32, and 42%) when the concrete was reinforced with SF with contents of (30, 50,70, and 90 Kg/m3 SFR), respectively compared with results of plain concrete with the same CKD replacement. The corresponding increases in the flexural strength were (15, 34, 37,and 40%) respectively. Furthermore the specimens with 10% replacement of CMs by CKD had an increase in the compressive strength by (14, 22, 26, and 41%) when the concrete was reinforced with (30, 50,70, and 90 Kg/m3 SFR) respectively. The corresponding increases in flexural strength were (4, 23, 36, and 40%) respectively. Regarding the consistency of the concrete, there is a decrease in its workability with the increase in the addition of SF. The results of (UVP) test had shown that the RCC specimens possessed good concrete quality especially for the fiber reinforced mixes. The research had shown the feasibility of using steel fibers as a reinforcement for RCC in which CKD was used as a substitution for 5 to 10 % of CMs.This will enhance the properties of RCC and decrease the negative impacts of CKD on the environment.
