Habibur Rahman Sobuz

The chemical modification of tropical wood polymer composites

Wood polymer composites were manufactured from several types of tropical wood species by impregnating the woods with acrylonitrile monomer solution. The physical and mechanical properties of wood polymer composites were then investigated in this study. The vacuum-pressure method was employed to impregnate wood samples with monomer and in situ polymerization. Acrylonitrile reacted and incorporated with wood, which was confirmed through Fourier transform infrared spectroscopy and scanning electron microscopy test analysis. The mechanical properties of wood samples in terms of modulus of elasticity and compressive modulus were found to be improved on acrylonitrile treatment. Besides, the fabricated wood polymer composite samples had lower water absorption and higher surface hardness (Shore D) value as compared to their corresponding raw one. For wood polymer composites, a significant improvement was found in physical and mechanical properties compared to the raw woods.

Characterization of Rice Husk Carbon Produced through Simple Technology

Textile wastewater contains different colors which are harmful to the environment. Activated carbon can be used for the decolorization of textile wastewater. Most of the textile plants in Bangladesh do not use the activated carbon due to its expensive cost and still it is classified as imported item. Low-cost activated carbon produced from locally available materials can solve this problem. This paper describes the color removal of textile wastewater by adsorption process using activated carbon derived from rice husk in a low-cost method. Thermal activation system was applied for the preparation of carbon. The maximum adsorption of color was found at an optimum temperature of 400C with the retention time of 60 minutes. Thus this study demonstrated encouraging performance of activated carbon produced from rice husk compared to the industrial grade activated carbon for decolorization of textile wastewater in the analysis.

Thermal and decay-resistance properties of tropical wood–plastic composites

This investigation concerns about the thermal and decay resistance properties of tropical wood polymer composites. Wood polymer composites were prepared from several types of tropical wood species by impregnating the woods with ethyl methacrylate that was combined with a cross-linker, hexamethylene diisocyanate. Thermal properties of wood polymer composites in terms of thermogravimetric analysis and differential scanning calorimetry were evaluated, and an improvement in thermal stability was found on ethyl methacrylate and ethyl methacrylate–hexamethylene diisocyanate treatment. A significant improvement in decay resistance was also identified in wood polymer composites that were treated with ethyl methacrylate, and also, with ethyl methacrylate–hexamethylene diisocyanate. The improvement in properties was observed as more potential with ethyl methacrylate–hexamethylene diisocyanate combination rather than ethyl methacrylate.

Structural Lightweight Concrete Production by Using Oil Palm Shell

Conventional building materials are widely used in a developing country like Malaysia. This type of material is costly. Oil palm shell (OPS) is a type of farming solid waste in the tropical region. This paper aims to investigate strength characteristics and cost analysis of concrete produced using the gradation of OPS 0–50% on conventional coarse aggregate with the mix proportions 1 : 1.65 : 2.45, 1 : 2.5 : 3.3, and 1 : 3.3 : 4.2 by the weight of ordinary Portland cement, river sand, crushed stone, and OPS as a substitution for coarse aggregate. The corresponding w/c ratios were used: 0.45, 0.6, and 0.75, respectively, for the defined mix proportions. Test results indicate that compressive strength of concrete decreased as the percentage of the OPS increased in each mix ratio. Other properties of OPS concrete, namely, modulus of rupture, modulus of elasticity, splitting tensile strength, and density, were also determined and compared to the corresponding properties of conventional concrete. Economic analysis also indicates possible cost reduction of up to 15% due to the use of OPS as coarse aggregate. Finally, it is concluded that the use of OPS has great potential in the production of structural lightweight concrete.

The effect of curing time on compressive strength of composite cement concrete

The effect of curing condition of five different composition of Portland composite cement (PCC) and ordinary Portland cement (OPC) were investigated in this study. Compressive strength development of five different concrete types has been investigated in terms of cement content and curing duration. From the experimental observation, it is found that the early age strength of concrete made with PCC is lower than that of concrete made with OPC due to the presence of fly ash in PCC which is responsible for the pozzolanic reaction. The continued pozzolanic activity of fly ash contributes to increase strength gain at later ages at continued curing condition. It is also found that drying ambient conditions reduction of the strength potential of concrete made with PCC because the secondary (pozzolanic) reaction fails to contribute to the development of strength.

Deflection and cracking behavior of RC beams externally reinforced with carbon fiber laminates

This article presents the results and discussions of experimental and analytical work on CFRP-strengthened RC beams investigating the cracking and deflection performance. The aim of this study is to evaluate the time-dependent behavior by different degrees of strengthening scheme and two types of sustained loads. Eight RC beams were cast and tested under sustained loads for cracked and uncracked section. An analytical method based on EMM is developed to predict the time-dependent behavior of CFRP externally bonded RC beams. A simplified tension stiffening model for calculating the time-dependent deflection is modified for CFRP-reinforced concrete beams.