Abstract:
Self-Compacting Concrete (SCC) has revolutionized construction industry and is being used extensively throughout the world. This study was made to compare the role of river gravel and crushed stone aggregates in Self-compacting concrete (SCC) systems while simultaneously evaluating the feasibility of using local Marble Powder (MP) and Limestone Quarry Dust (LSQD) systems as partial replacement of cement in self-compacting paste and self-compacting concrete (SCC) with a view to manufacture SCC in Pakistan. Limestone Quarry Dust (LSQD) and Marble Powder (MP) were used as secondary raw materials (SRMs) up to 30% replacement of cement in both SCP and SCC systems. The grading and content of both types of coarse aggregates was kept constant. The results indicate that the river gravel and crushed stone aggregates along with secondary raw materials used in this research affect the properties of self-compacting cementitious system (SCCS) in both fresh and hardened state. It was observed that these coarse aggregates and SRMs affect the water demand, super plasticizer demand, flow and strength behaviour of SCCS. At higher replacement levels (more than 10%), SCP systems based on Limestone Quarry Dust (LSQD) had higher water demand as compared to marble powder (MP) based systems and also higher superplasticizer demand for the target flow. In self-compacting concrete formulations, river gravels gave better flowabiltiy indices than crushed stone aggregates while crushed stone aggregates gave better strength results for the tested similar formulations. At 10% replacement of cement by LSQD and MP, the optimum results both in terms of flowability and strength were obtained in all the investigated self-compacting cementitious systems. MP based formulations gave better strengths as compared to LSQD based ones at the same replacement level in Self compacting paste and concrete systems. Self-compacting concrete samples were cast, cured and tested as per EN 196 (4x4x16 cm3 prisms) and BS EN 12390-1 (4”x4”x4” cubes) with both standards giving comparable results. It is suggested that SCCS samples based on EN 196 should be used for economy and efficiency. After the analysis of results, it can also be stated that river gravel, crushed stone aggregates and both secondary raw materials can be successfully used in making self-compacting concrete systems in Pakistan and pumping may also be used for placements by slight readjustment of SCC formulations.
