Soils containing significant levels of silt or clay generally exhibit unacceptable engineering properties (i.e. low strength, high compressibility and high level of volumetric changes) when exposed to variation in moisture content. Chemical stabilizers such as cement and lime which are currently practiced, are often high-priced and unhygienic in terms of environmental sustainability. The prevailing study intended to explore the potential of the local Rice Husk Ash (RHA) which is an agricultural waste, with lime as a soil stabilizer. This experimental study was conducted on clayey soil with high plasticity. Different mixture proportions of RHA (i.e. 5%, 10%, 20% and 30%) and lime (i.e. 10% and 20%) were used to treat the parent soil. Observations were made for variations in index (i.e. liquid limit, plastic limit, sieve analysis, etc.) and mechanical properties (i.e. compressibility, permeability and shear strength) of treated soils soon and 28 days after mixing. It was found that 10% of RHA and 20% of lime by dry soil weight as the optimum dosage for the treatment. This optimum dosage increases the unconfined compressive strength and internal friction angle by 54.05% and 60.48%, respectively and reduces plasticity index by 56.67% at 28 days after mixing. It could be identified that RHA and lime mixture was capable of improving index and mechanical properties of soil, positively.

Limited studies have gathered information on structural health monitoring (SHM) of underwater structures, and most of those studies are outdated. The existing methods evaluated structural distresses separately, without accounting for the correlation between the distresses. This study developed a SHM tool which accounts for the reciprocal relationships and priority weights of different structural distresses, and assessed underwater structures using the developed structural health monitoring tool. A new rating method was developed using fuzzy analytic hierarchy process (FAHP) which incorporates visual inspections of surface distresses, nondestructive tests (NDTs), crack details, hydraulic conditions, and casual characteristics of the underwater structures. The SHM tool was applied to 12 underwater structures, including bridges, dams, canals, water tanks and quay walls. The results of NDTs such as rebound hammer tests and ultrasonic pulse velocity tests, crack surveys, and visual observations on underwater concrete structures are employed in the SHM tool and the structures were rated using priority weights allocated to different attributes. The SHM tool developed in this study supports enhanced efficiency and effectiveness of structural health monitoring of underwater structures and proposes a numerical framework which can be employed to rate and compare the structural health of different underwater concrete structures.

Green building rating systems are developed to promote sustainability. Existing rating systems use both numerical and linguistic descriptors. In addition, existing rating systems do not directly identify the priority or interrelation between different parameters. The objectives of this study are to develop a priority weights-based green building rating model with numerical descriptors and to propose a remediation plan for existing buildings to obtain green certification under the developed rating model. In this paper, the analytical hierarchy process is used to develop a green building rating system. Based on the opinions of 100 experts, the priority weights of parameters were determined. The numerical thresholds of point allocation, equations, and priority weights of the proposed rating model supports a definitive classification on green building performance. For buildings with poor green performance, a remediation plan is proposed that can be adopted to upgrade and obtain green certification for buildings under the developed rating model.

Steel slag is a melted by-product that mainly consists of calcium carbonate and metal oxides generated in the process of steel manufacturing. The main objectives of this study are to evaluate the effectiveness of steel slags as fine and coarse aggregates in concrete and to determine the optimum quantity of steel slag as fine and coarse aggregates to enhance the strength of concrete. Concrete cubes were cast by mixing steel slag as replacement (i.e. 0%, 10%, 25%, 50%, 75% and 100%) for fine and coarse aggregate, separately. Abrasion test, sieve analysis, water absorption and specific gravity test were conducted to determine the properties of raw materials. Unit weight, workability, compressive strength, splitting tensile strength and the possibility of corrosion were experimentally evaluated to determine the effectiveness of steel slag. It is found that 75% steel slag mixed concrete indicates improvements in compressive strength, splitting tensile strength and unit weight, respectively. Further, it was noted that steel slag aggregates were not corroded after conducting the Accelerated Corrosion Test Method (ACTM). Therefore, the use of steel slag as fine and coarse aggregates for concrete would improve the mechanical properties of concrete and reduce the adverse environmental impact.

Demand for energy-efficient, economical and healthy construction materials has increased recently due to factors such as global warming and related diseases. Therefore, the need for construction materials such as clay bricks which has good thermal insulating property has increased. This study aims to investigate the possibility of using banana fibres and lime to improve the thermal and structural properties of unburnt clay bricks. Engineering properties of the bricks such as compressive strength, thermal properties, water absorption, the initial rate of suction, and bulk density were tested to observe variations. Materials were selected considering properties such as withstanding high temperatures, higher fibre content, coefficient of thermal conductivity, availability, and durability. An increment of 35.19% was observed in the compressive strength for 4% mixed unburnt clay bricks. The amount of maximum reduction of indoor temperature is 4.2°C. Therefore, the use of banana fibre and lime mixed with unburnt clay brick would be improved both structural properties and thermal characteristics of masonry walls, effectively.