In developing countries like Ethiopia where concrete is widely used there is a steadily increasing the cost of concrete. This made construction work very expensive, due to less availability of concrete ingredients. In recent years, the use of natural fibers is become increasingly common in the civil engineering sector, as a part of energy-efficient and sustainable trends. Several researches demonstrated good properties of sheep wool fibres which a basis for compressive strength, tensile strength and improve environmental issue. The paper was focus on investigation on effects of sheep wool usage as a concrete composite material in C-25 concrete. The investigation is very important because, at present, the knowledge and the application of sheep wool fibers in this sector are relatively limited in our country. So an attempt has been made to achieve improved strength results using sheep wool fiber in conventional concrete. Experiments were conducted on concrete cubes and beam of various percentages of sheep wool fiber such as 0, 0.5, 1, 1.5 and 2% by weight of cement were tested for their workability, compressive strength and flexural tensile strength. The sheep wool were collected from different sources and dipped into salt water for 2 days to make hair surface rough. The wool has been sun dried. The mix ratio for C-25 concrete specimen was done in accordance with ASTM 595 and ACI 544.1R-96. From the study workability of the mix was reduced as percentage of sheep increase. The optimum amount of sheep wool fiber to produce concrete was 1.5%. Using 1.5% of fiber increase concrete compressive strength, flexural strength and split tensile strength property. It can be concluded that using sheep wool fibered concrete were preferable particularly to improve flexural strength.

The research has shown that use of tire rubber as coarse aggregate in Reutilization of waste tire material can help reduce the environmental pollution, generated each year in Oman‘s landfills, where tire waste is often improperly or illegally disposed of. The number of vehicles over the decade has increased considerably, and the need to identify feasible solutions to minimize tire waste is needed. The aim of this project is to identify the optimal use of waste tire rubber as coarse aggregate by partial replacement of 10%, 15%, and 20% with micro silica in the concrete. The objective of this research study is to determine and evaluate the fresh and hardened properties of the concrete. The micro silica replaced the cement by 10%, 20% in the first experiment to determine if micro silica improved the strength in the concrete. Additionally, in the second experiment, the tire rubber was treated in NaOH solution to determine the bonding improvement between the rubber and cement, while using the same replacement ratio. The mix design was developed for C35 strength for both experiments. Using 150X150X150mm cube moulds a total of 28 cubes were casted and cured for 28 days under normal conditions. The mix proportion used is 1: 1.73: 2.2 with water cement ratio of 0.47. The objective of this research is to determine the fresh and hardened properties of concrete under the influence of rubber and mineral admixtures. The results of the experiments showed a reduction in compressive strength as tire rubber content increased when compared to control mix. However, the tire rubber treated in NaOH solution yielded slightly better compressive strength results overall.

The aim of this project was to find out the strength of the soil samples with different height to diameter ratio. To compare the similar properties of different samples identical soil samples must be required. To reach up to this goal reconstituted samples were used to find the strength of them. Unconfined compression test were performed on the reconstituted soil specimen to investigate the variation of strength with the variation of specimen height to diameter ratio (H/D).The undrained shear strength of clays is commonly determined from an unconfined compression test which is necessary for the determination of the bearing capacity. It can be performed on both undisturbed and remolded specimen. In order to assure and predict the longibility and settlements of the structure due to load it is very important. H/D ratio of between 2 and 3 is generally recommended by accepted scientific and technical authorities. Nevertheless, published reports on the effect of specimen shape on soil strength are scarce. The value of test decreases significantly with increasing H/D ratio. It is less steep when the ratio is between 1.25 and 2.50. The soil samples used for this project are collected from four different locations in Dhaka. The test was performed on undisturbed soil specimen. In addition few more tests are done to know the index properties of soil. The range of variation of the ratios was 1.0 to 2.5 in this project. It was seen that the strength of soil samples was almost same for the range of ratio 1.75 to 2.5.