INFLUENCE OF COARSE AGGREGATE CHARACTERISTICS ON CONCRETE PROPERTIES

Abstract

A good number of infrastructure projects are implemented in Bangladesh during the last decade and many more are still in pipeline. In the financial year 2017-18 approximately 12.7 million tons of aggregate are used by the construction industries. Local sources could supply only 11% of those aggregate and rest 89% are collected from foreign sources. Due to the wide variation of aggregate sources performance of concrete become unpredictable in some cases. Therefore, in the present study influence of coarse aggregate characteristics on concrete properties are investigated in the context of Bangladesh. To evaluate the performance of aggregate and corresponding concrete, six widely used coarse aggregate sources are selected for this study. A series of laboratory test are conducted to evaluate the ACV, TFV, LAA, EI, and FI, specific gravity, water absorption and unit weight for all six aggregates. Additionally, chemical composition and petrographic properties are also explored. Keeping the gradation of aggregate constant, two type of concrete mix (w/c ratio 0.3 and 0.4) were prepared to cast concrete cylinders and beams by using six sources of coarse aggregate. Admixture is used in concrete mix to achieve similar workability for all concrete, especially for low w/c ratio concrete. Concrete properties including compressive, tensile and flexural strengths are determined. The study finds that physical properties of aggregate generally influence the properties of concrete, especially for concrete with 50 MPa compressive strength. The outcomes of the study will help the engineers to select appropriate sources of aggregate depending on concrete strength requirement.