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In this study an attempt is made to investigate the properties and CBR characteristics of fine sand and waste dust from construction debris. Attempts are also made to study the effect of soaking period on CBR value of waste dust from construction debris. Waste dusts passing through 600 µm sieve from construction debris and river sand are selected for investigation. Standard Test procedures specified by AASHTO are followed in this investigation. The testing includes the determination of specific gravity, sieve analysis, optimum moisture content, dry density and CBR value. Dense unit weight, specific gravity and fineness modulus of construction debris is 1273.44 Kg/m3, 2.43 and 1.36 respectively and for fine sand 1132.25 Kg/m3, 2.62 and 1.64 respectively. Un-soaked CBR value of construction debris and fine sand are 10.36% and 12.5% respectively. Soaked CBR values of construction debris and fine sand are 5.36% and 6.07% respectively. The study reveals that waste dust from construction debris is as good as fine sand for construction of sub-grade from the stand point of properties and CBR characteristics.

Faecal sludge generating from fixed-place defecation system has been an increasing concern in Bangladesh. In the city, this challenge is acute due to high population density, rapid and unplanned growth, and inadequate service provisions. Energy can be recovered from faecal sludge (FS) by converting the waste into usable heat, electricity, or fuel through pyrolization. Through Pyrolyzation biochar, biofuel, biogas can be obtained. Biochar can be produced by heating FS at high temperature. The burned portion of the sludge is the biochar, condensed steam is the biofuel and the uncondensed part is the biogas. This study shows that FS has volatile matter ranged between 39 to 50%, which qualify the FS as fuel. The ash residue of FS is between 34 to 45%. The rest of this is moisture. From Thermo Gravimetric Analysis (TGA) it was observed that major thermal events (mass loss rate) were found approximately between 150°C and 400°C which was considered as the ideal temperature range for pyrolysis process. Significant amount of biochar but negligible amount of biogas and biofuel were obtained from the samples by the pyrolysis process. 93.3% biochar, 2.8% biofuel and 3.8% biogas (at 200°C); 91.4% biochar, 3.5% biofuel and 5.1% biogas (at 300°C); 84.6% biochar, 9.3% biofuel and 6.1% biogas (at 400°C) were obtained. The result of pyrolysis analysis shows significant potential for energy recovery from FS.

In bituminous road construction aggregate is the principal material. Aggregates constitute about 90% or even more of the total construction materials. While selecting aggregate for road construction, search has to be intensified for easily accessible, low-cost natural aggregates and investigate the suitability of indigenous aggregates. Every effort must be taken to select the most economical aggregate which should also perform satisfactorily the design criteria for the road construction conditions. A laboratory investigation was carried out to investigate the design performance of bituminous pavement using different fine aggregates. While constructing bituminous pavement a mix of coarse aggregate, fine aggregate, mineral filler, and bitumen are used. The demand for natural fine aggregate can be reduced by recycling waste tiles chips. Waste tiles, chips aggregate refer to aggregate that has been previously used in the concrete structure as a floor finish. This study easy carried out to investigate the possibility of using waste tiles, chips as a fine aggregate. Therefore, two types of fine aggregate were used to study and compare the behavior of bituminous mixes using waste tiles with that of coarse sand. The Marshall Mix design procedure specified by AASHTO standard was followed in the determination of stability, flow, density, voids in the mixes and the optimum bitumen content. The test specimens were compacted with 50 blows from the consideration of medium traffic. The test results indicated that dense graded bituminous mixes with two types of different fine aggregates satisfy the Marshall Design criteria. From the economic consideration, mixes with waste tiles, chips are comparatively more suitable when available at the construction site. Dense bituminous mix using waste tiles, chips as fine aggregate for medium traffic, is a feasible option from the standpoint of stability, stiffness, deformations and void characteristics.

Embankments play a significant role in protecting cities from many natural disasters. Erosion and landslides of embankments and natural slopes are common phenomena occurring every year in Bangladesh. It has become a great concern of protecting embankments and natural slopes from failure. In many cases, traditional methods for protecting embankments and natural slopes are not effective during their designed lives. In such a condition, bio-engineering has been adopted in many countries as an effective and environment friendly measure for the protection of slopes. The role played by vegetation in improving slope stability is now well recognized. Many research works have been done in many countries on many species of trees that are locally available and suitable for the climatic and soil conditions of that country. In this study, an attempt has been made to evaluate the performance of lebbek tree and royal poincianain protecting the Rajshahi City Protection embankment. In-situ direct shear test was performed on block samples to determine the in-situ shear strength of rooted soil and soil without root. A numerical analysis has been performed to compute the factor of safety and shear strength of slope soil with root and without root. Also the effect of different types of vegetation on slope stability is observed by numerical analysis. It has been found that the values of factor of safety vary between 1.781 and 1.926 in case of slope without root whereas the values of factor of safety vary between 1.997 and 2.173 in case of slope with root. In numerical analysis, the shear strength of soil varies between 40.311 kPa to 41.782kPa in case of slope without root whereas in case of slope with root this value varies between 50.929 kPa to 52.13 kPa. The average percentage of increase in shear strength for lebbek tree root is 14.35% whereas this value for royal poinciana is 24.29%. It has been also found thatthe factor of safety of soil slopes without vegetation, with uniform vegetation, cylindrical vegetation and semi-spherical vegetation are 1.605, 1.653, 1.654 and 1.616 respectively. From the results, it is understood that plants with cylindrical root architecture increase the most significantly slope stability. It also appears that lebbek tree and royal poinciana may be low-cost and environment friendly alternative solution for the protection of embankment in Bangladesh.