A developing country like Bangladesh is establishing many power plants where coal is being used as a primary fuel. The generation of coal waste is increasing with the mining of coal, which may cause an adverse environmental effect. So, it is required to be managed in a proper manner, such as reuse and recycle the coal waste. The objective of this study is to investigate the significance of coal waste used as a road subgrade. Due to the lack of some physical and strength properties, the waste cannot be used directly as a subgrade. So, the investigation was done to stabilize the fresh coal waste with different percentages of fly ash such as 0%, 10%, 12% and 15% to justify the suitability of its intended use. It is found that with the increasing percentages of fly ashes, the plasticity index reduces significantly. With the addition of fly ash, the dry density increases, while the optimum moisture content decreases significantly. After analyzing the test result, it is found that coal waste with 15% fly ash having unconfined compressive strength and CBR value is 17.79 psi and 23.12% respectively which is sufficiently significant for use as road subgrade.

Proper disposal of plastics and its derivatives is one of the biggest challenges all over the globe. Due to the improper management of plastic product environment is being polluted. Plastic waste generation and plastic waste-based pollution in Bangladesh is leaping at a high pace. Among numerous ways of disposal of waste plastics, one can be using it in flexible pavement construction. According to the Bangladesh Waste Database 2014, Dhaka city alone produces 25.44% (5,925.51 tons/ day) of waste, of which 8.45% is plastic. In the construction of bituminous pavement, plastics, as well as construction debris, are being used in the form of aggregate and filler materials popularly. This study focusses on the improvement of properties of bitumen by blending it with LDPE (Low-density polyethylene) and PP (Polypropylene) at a different proportion. Three cases were considered in the study for plastic waste addition, Case-01:-only LDPE; Case-02:-LDPE: PP=3:1; Case-03:-LDPE: PP=1:1. For each case, 3%, 6%, 9%, 12%, and 15% of plastic waste was mixed with bitumen. It was found that the penetration value and ductility decrease with the increasing proportion of plastic waste in bitumen, whereas the softening point increases for every case. Loss on heating, flash & fire point also been improved with the plastic addition. The performance of Case-03 (LDPE: PP=1:1) is better than others. Minimum penetration value, 11 and maximum softening point, 90°C, is found for this case, which indicates a 90% improvement compared to virgin bitumen. Due to the addition of plastic waste, the ductility always gets affected. But overall, a significant improvement in the properties of bitumen is noticeable.

Compressed cement-soil block is used as low cost building material. In the south-western region of Bangladesh, there is availability of organic soil which is in the formation of overlying layer. Moreover, sandy materials do not occur and are not found easily in Bangladesh. The scarcity of sandy materials has led to the increase of the retail price and subsequently to higher production cost. So organic soil materials have been used as filler directly to produce cement-soil block. In this study, the compressive and flexural strengths of cement-soil block of density 1448kg/m³ to 1611kg/m³ with specified ratio of cement content were investigated using prism specimens. The observed elapsed periods were 1, 3, 7, 14, 28, 56 and 112 days with the variation of organic contents of 2%, 5%, 10%, 20% and 40%. Preferable results on the 28th day indicated that the compressive strength and the flexural strength of cement-soil block with 20% organic content increased by 125% and 102% respectively. Moreover, the influence of density on the strength properties of cement-soil block was found to be higher than the age of the specimen.