M. Z. Hossain

SOME ASPECTS OF PHYSICAL AND MECHANICAL PROPERTIES OF SAWDUST CONCRETE

This paper presents experimental results on some physical and mechanical properties of concrete containing sawdust. Concrete specimens having various cement to sawdust ratios of 1:1, 1:2 and 1:3 by volume were made and tested for workability, density, water absorption, strength and modulus of elasticity at different curing periods of 7, 14 and 28 days. It has been found that with the increase in the amount of sawdust, the workability and density of concrete decreased; the water absorption capacity of concrete, however, increased with the increase in volume. Although the strength of sawdust concrete increased with curing period, the strength and the corresponding modulus of elasticity decreased with the increasing amount of sawdust in the mix. The results obtained and the observation made in the short-term investigation suggests that sawdust concrete can suitably be used as a building material in construction.

Waste Shell Husks Concrete: Durability, Permeability and Mechanical Properties

Shell husk is annually produced as a byproduct of shell production in Japan. According to Japanese Ministry of Forestry, Fisheries and Agriculture, the amount of the abandoned shell husk is about 151,000 tons per year. This huge amount of abandoned shell husk is not only thrown away without any commercial return but also causing pollution and environmental problems. To mitigate the pollution and environmental problems, possible utilization of abandoned shell husk is thoroughly observed in concrete construction. Overall response of the mechanical properties of concrete specimens containing different percentage of abandoned shell husk aggregates such as 0, 10%, 0, 30%, 40% and 50% in the ratio of mass is demonstrated. Results of engineering properties such as compressive strength,Young’s modulus, tensile strength, unit weight, water absorption capacity and coefficient of hydraulic conductivity are depicted. It is observed that the use of shell husk in concrete improves strength and durability performance of concrete treated in aggressive sea environments.

Effect of Reinforcement on Flexural Properties of Brittle Composites

The flexural properties in terms of ductility of laminated brittle composites have been studied experimentally in the laboratory. Test specimens consisting of variable layers of mesh were prepared and tested under third point loadings. It was observed that the brittle matrix altered it properties and behaved as the ductile matrix even with small amount of ductile materials. The causes of the change in the properties have been clarified by analyzing the experiment data. The experimental results were verified by the theoretical formulation. The formulation showed that the flexural modulus of the entire section of brittle composites obtained by section analysis is equal to the modulus of ductile layers plus a factor of the difference of modulus of ductile and brittle layers. This factor is third order of ductile layer causing flexural properties in brittle composite even with 10% of ductile materials.