QUALITY ASSESSMENT OF REPRESENTATIVE CEMENT BRANDS OF BANGLADESH

Abstract

The increased demand of Bangladeshi cement in construction industry has gained attention of researchers, engineers and practitioners to understand the quality of cements. A number of industries produce cement not only to meet the local demand but also export cement abroad. The research aims to investigate the physical qualities of cements of different brands of Bangladesh using experimental investigations. The physical properties of cement include normal consistency, initial and final setting time, compressive strength of cement mortars, compressive strength of cylindrical concrete, density, specific gravity and fineness of cement. Standard tests were performed on cements manufactured by ten different industries of Bangladesh. A total 300 tests samples on CEM II/B-M type representative cement samples were prepared to conduct tests on those physical parameters as per ASTM specifications. The experimental results obtained from this study were also analyzed to investigate the statistical parameters. The results are compared with the ASTM guideline values and previous available study. In addition, correlations are also developed to find relationships between compressive strength of concrete and their age of curing. The influence of initial and final setting times on concrete strength are also investigated. The experimental result shows that almost all the samples meet the ASTM requirement that ultimately proves the good quality of Bangladeshi Cements. Moreover, the results are compared with an existing study for some cases. The comparison reveals that the quality of Bangladeshi cements has improved in last decade quite significantly in terms of mechanical strength of concrete. The relationship between mortar strength and concrete strength from the same batch of cement are also investigated. vi In addition, Regression analyses are conducted using the tested results. The regression relationships among 28-days compressive strength of cement mortar and 3-days and 7- days compressive strength of cement mortar, the following relationships are obtained as follow f′ c −28D = 2.10 ∗ f′ c −3D and f′c −28D = 1.49 ∗ f′ c −7D respectively. The coefficients of determination of the relationships, R2 are 0.956 and 0.952 respectively. The regression relationships among 28-days compressive strength of cement cylindrical concrete specimens and 7-days and 14-days compressive strength of cylindrical concrete specimens are obtained as follow f′c −28D = 2.12 ∗ f′c −7D and f′c −28D = 1.71 ∗ f′c −14D respectively. The coefficients of determination of the relationships, R2 are 0.99 and 0.976 respectively. The results obtained from this study is expected to provide clear understanding on the physical properties of Bangladeshi cement qualities and their applicability as ingredient of concrete.