New Concrete Technology Negates Traditional Concrete Placement in Sudan

Abstract

Self-consolidating concrete, also known as self-compacting concrete (SCC), is an innovative concrete that does not require vibration for placing and compaction. The mixture qualification process of Self Compacting Concrete consists from a small, well controlled laboratory batches are tested, second, the closest mixture/s is tested in production, which includes the use of batch mixing, and placing equipment, and finally a quality assurance/control plan for the fresh and hardened properties is developed. However, this paper presents a full research addressed only a small, well controlled laboratory batches and the laboratory testing phase of the mixture qualification process.

For the purpose of study, a small, well controlled laboratory batches are tested using available locally aggregates in Sudan. Therefore, Slumpflow, V-funnel, L-box shape, J-ring, and Sieve stability tests of concrete mixtures were used to determine the flowability, passing ability and segregation resistance of SCC mixtures. The produced self compacting concrete is successfully confirmed the fresh properties of SCC with Slumpflow in range of 650 to 850 mm with high viscosity and excellent segregation resistance. The hardened properties of concrete were also considered and tested. The strength of SCC was found to be same or higher than that of normally vibrated concrete with the same constituent materials. SCC has relatively higher dynamic modulus of elasticity ranged between 38 to 42 GPa, in comparison to normally vibrated concrete for the same strength range of 50 to 60 MPa. Whereas the Spilt Tensile and Flexural strength of SCC are of 2.5 MPa and 10 MPa respectively.

The major difficulty which was faced in development of SCC was on account of contradictory factors that the concrete should be fully flowable but without bleeding or segregation. It is required that the cement mortar of the SCC should have higher viscosity to ensure flowability while maintaining non-sedimentation of aggregates and that was achieved by using high content of powder (fine materials less than 0.15 mm includes cementitious materials).

Achievement of durable concrete structures independent of the quality of construction work by using Self Compacting Concrete (SCC) has been proposed to solve the problem of the durability of concrete structures due to the gradual reduction of adequate compaction and skilled workers and for complex shape for the prestressed and precast industries in Sudan. The features of high benefit of fluidity and self consolidation will result in a variety of potential benefits for the end-user. Other benefits of the application of this new concrete technology require effort to be achieved. Moreover, areas such as quality control, mixture development, and logistics may need modification or expand resources when develop self-compacting concrete in Sudan.

Keywords: Self Compacting Concrete (SCC), Sudan, Flowability, Passing ability, Segregation Resistance Slumpflow, V-funnel, L-box shape, J-ring, and Sieve stability, Powder content