Characteristics of self-consolidating concrete with RAP and SCM

Self-consolidating concrete (SCC) is used nowadays in many of concrete construction projects. It has superior characteristics such as a low yield and considerable viscosity. In addition, it does not segregate. These characteristics make it very attractive to contractors. Also, SCC is used when there is no access to vibrators or when it is difficult to vibrate to consolidate the concrete in the event of having heavy and complex reinforcements. The SCC can consolidate itself under the effect of its self-weight without the need for mechanical compaction. The aggregates are used as fillers in the concrete mixture to provide the needed volume and it is also a cheap material, but it is not renewable material. Therefore, the use of waste materials such as recycled asphalt pavement (RAP) to replace a percent of the conventional aggregates can result in a more cost-effective and sustainable concrete. The objective of this study is to investigate the fresh and hardened properties of more sustainable SCC that contains both supplementary cementitious material (SCM) and RAP. A conventional control Portland cement concrete (PCC) SCC mixture with targeted properties was developed and its properties were altered later to produce the remaining RAP concrete mixtures. The concrete mixtures had similar properties to the control concrete mixtures, but up to 40% coarse aggregates was replaced by RAP. It is possible to prepare concrete mixtures containing both SCM and RAP as slump flow values of mixtures were above the minimum limits of SCC. It was found that the compressive and tensile strength of concrete decreases as the RAP content increases. Adding fly ash seems to result in lower strength than that when slag is added. Increasing RAP content may increase the amount of free shrinkage. Adding RAP may reduce the beam load carrying capacity. Increasing RAP content may make reinforced concrete beams stiffer.