ISSN 2319-5347, ISI Impact Factor: 0.763

VOLUME 04  NO. 03 JANUARY 2015:

Title:      Assessment of compressive strength of concrete based on combination of different sizes of aggregate
Authors:B. Ahmed, M. Rahman
Abstract:  Concrete, one of the most important materials is used in construction like building construction and also in road pavement construction etc.The main objectives of this study is to investigate the variation of compressive strength due to the effect of size of aggregate locally available aggregates as well as to find out the mix ratio at which higher strength is to be obtained. The combination of different size of aggregates at which higher strength is to be obtained is also investigated. Effects of size distribution of both fine and coarse aggregate on compressive strength were analyzed in this study. Six different sizes of coarse aggregates were used while developing a mix design. The sizes of coarse aggregate were 19 mm, 12.5 mm, 9.5 mm, 4.75 mm, 2.36 mm and 1.18 mm. Mixtures of local sand and Sylhet sand (1:1) and with fineness modulus of 1.93 was used as fine aggregate. Ordinary Portland cement was used as binding material. Different trials of mixing of coarse aggregate were made (12.5 mm and 9.5 mm; 9.5 mm and 4.75 mm; 19 mm, 12.5 mm, 9.5 mm and 4.75 mm; 12.5 mm, 4.75 mm, 2.36 mm and 1.18 mm) to investigate the influence of size of aggregate on compressive strength of concrete. The concrete mixing was prepared by taking the four proportions of cement, sand and aggregate are 1:1.5:3; 1:1.25:2.5; 1:1:2 & 1:0.75:1.5. The water-cement ratio was fixed as 0.45. The gradation of both coarse and fine aggregate, unit weight of coarse aggregate, water absorption of coarse aggregate and slump test for concrete were conducted in the laboratory. Standard cylinder sizes were prepared for testing in universal testing machine. From the investigation it is observed that the compressive strength varies from 24.34 to 26.14 MPa for aggregate combination C (19 mm, 12.5 mm, 9.5 mm, 4.75 mm) at mix ratios 1 (1:1.5:3), 2 (1:1.25:2.5), 3 (1:1:2) after 7 days curing period but only in mix ratio 4 (1:0.75:1.5) the maximum strength obtained 32.38 MPa for Combination A (12.5 mm & 9.5 mm). For 14 days curing period, the compressive strength varies from 27.17 to 28.19 MPa for aggregate combination C at mix ratios 1, 2, 3 but only in mix ratio 4 the maximum strength obtained 33.96 MPa for Combination A. Similarly, the compressive strength varies from 36 to 36.34 MPa for aggregate combination C at mix ratios 1, 2, 3 after 28 days curing period but only in mix ratio 4 the maximum strength obtained 45.17 MPa for Combination A.
Keywords:  Aggregate, Concrete, Compressive Strength and Mix Ratio.

pages               148-152

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