The Department of Civil Engineering of The University of Asia Pacific (UAP) has taken an initiative for the sustainable development of concrete technology in Bangladesh. The department has planned to complete this study in four parts, such as Part 1, Part 2, Part 3 and Part 4 by a two-year period. Part 2 was carried out in Fall 2005, which covered the following investigations:  

1.      Quality of Various Cement Brands in Bangladesh – Part 1

The demand for cement in Bangladesh is increasing rapidly. In the meantime, to meet the demand of cement in the local market, more than sixty cement companies were established.  Among the most commonly used cement brands, eleven cement brands were investigated. Normal consistency, initial setting time, final setting time, fineness (#100 and #200 sieves), bleeding, and compressive strength for 3, 7, 14, and 28 days were tested as per ASTM. Some cement show low compressive strength, high amount of bleeding, and long setting time. To avoid the problems, related to the poor quality of cements in the market, it is necessary to evaluate the quality of cement before use in construction.     

2.      Investigation on Concrete Made with Brick Aggregates: The Effect of Dusts and Pre-Coated Aggregates

Dust mixed sand is commonly used in construction works in Bangladesh. Therefore, a study on the effect of dust on the compressive strength of concrete was carried out. Dusts passing through No. 100 sieve, retained on No. 200 sieve, and passing through No. 200 sieve were investigated separately. The inclusion of dust in sand or aggregate reduces the workability and strength of concrete. This study was carried out with 10% dust in sand.     

Cylinder strength of concrete made with cement paste coated brick aggregates was also investigated at 7, 14, and 28 days. The W/Cs of cement paste coat was 0.35, and concrete was 0.55. Pre-heated brick chips (40oC) were also included in the investigation. Compared with the normal aggregates, a 10-20% increase in compressive strength was found for cement paste coated and pre-heated brick aggregates. 

3.      Mechanical Properties of Concrete made with Brick and Stone Aggregates

In design codes, like ACI, PCI., etc., empirical relationships are generally found for concrete made with stone aggregates. But, in Bangladesh, brick aggregates are widely used. Therefore, modifications of these equations are necessary for brick aggregates. With this objective, an investigation on the mechanical properties of concrete made with brick and stone aggregates was carried out. It was found that for a high W/C ratio (=0.55), the strength of concrete made with brick aggregate is higher than the same made with stone aggregate. Empirical relationship between compressive strength and Young’s modulus of concrete made with brick aggregate was developed.