Comparative Analysis of Sands for Concrete Making: Case Study of River Sand, White Sand and Crushed Sand in Kinshasa, DR Congo

Abstract Background: Urbanization is one of the keys to development. Population growth and rural exodus are putting pressure on demand for social housing. The city of Kinshasa, being a megalopolis, faces this strong demand in the construction sector. Unfortunately, several problems arise, notably non-compliance with standards, haphazard construction and limited knowledge of the properties of the materials available. Methods: With the aim of making a contribution to the choice of materials, this work is based on the physical properties of sands including Congo River sand, white sand and crushed sand and their impacts on the compressive strength of the concretes made using these sands. To do this, we sampled 70kg of each type of sand that we used in the laboratory for the physical identification tests of the sands, then we made the concretes to finally move on to the mechanical tests. Results: The compressive strength of concrete made from river sand recorded a value of 23.3 N/mm2 at 7 days, then increased to 26.2 N/mm2 at 14 days, finally reaching 29.7 N/mm2 at 28 days. For white sand, the variation in the compressive strength of concrete is very small, it goes from 21 N/mm2 at 7 days, to 21.3 N/mm2 at 14 days, then to 21.5 N/mm2 at 28 days. Finally, the variation in the breaking stress of concrete made from crushed sand is 15.5 N/mm2 at 7 days, 16.05 N/mm2 at 14 days, and 18.05 N/mm2 at 28 days. Conclusion: Congo River sand has the best physical properties. Concrete made from this sand has the best compressive strength. It therefore becomes the best type of sand to use for making concrete. Crushed sand presents poor performance due to its physical properties and requires reinforcement techniques to use it in the manufacture of concrete.