Concreting methods that produce low carbon

Abstract

A new types of concretes have been produced recently which is completely dissimilar from the conventional concrete in the method of mixing, handling, pouring, consolidation, behaviours, cost …….etc., Such as two-stage concrete (TSC) and Rock-Filled Concrete (RFC). Two-stage (Pre-placed Aggregate) concrete (TSC) unlike normal concrete (NC), it is made by first placing the coarse aggregate in the formwork and then injecting a grout consisted of sand, cement and water to fill the voids between the aggregate particles. The main benefits of the method are widely appreciated as Low heats of hydration, high compressive strengths and density, economic savings, practically no mass shrinkage, low coefficient of thermal expansion, excellent bond to existing structures. A new type of concrete named rock-filled-concrete (RFC), which was based on the technology of self-compacting concrete (SCC), has already been employed in hydraulic engineering structures. The construction technology of RFC mainly consists of two processes: filling the working space with large scale rock mass and pouring the SCC into the pre-packed rock body. Less cement in the composite, which results in less heat of hydration, makes the temperature control of RFC much easier, and this new construction method leads to fast construction speed, high concrete quality and low cost. This paper presents two special types of concrete; two-stage concrete and rock filled concrete and presents the advantages and special requirements for each of the two special types of concrete and their uses.