Effects of Sesame Straw Ash as a Substitute for Cement on Strength Characteristics of Concrete

Concrete is broadly used as a building material across the globe, and its use is raising the need of cement in the construction industries. High price of cement and environmental debasement are the driving problems forcing the researchers to come up with alternative materials from large volumes of agricultural wastes as a partial replacement for cement. This study aims at recycling agricultural waste ash (i.e.  Sesame straw ash) as a substitute for cement in the production of sustainable and environmentally friendly greener concrete. Preliminary tests on constituent materials were conducted in order to find out their physical properties. Influences of sesame straw ash (SSA) on cement paste were looked into for addition of 0, 5, 10, 15, 20 and 25 % by weight of cement. The Compressive and flexural strengths as well as the slump of concrete made with different portions of SSA (i.e. 0 – 25 %) were investigated. A 100 mm cubes and 100 mm X 100 mm X 450 mm beams of SSA-concrete were tested for compressive and flexural strengths at 3, 7, 28, 56 and 90 days of curing in line with procedure outlined in BS 1881-116: (1983) and BS 1881-118: (1983) respectively. The outcomes of the workability test show that as the portion of SSA increases the workability a fresh concrete decreases, but consistency, setting times, and soundness of SSA-cement paste increase as the portion of SSA increases. However, the strengths of SSA-concrete increase as the duration of curing increases, and decrease as the portion of SSA increases. It was detected that the strength of concrete produced with 10 % SSA content was beyond the designed strength of 20 N/mm2 at 28 days of curing. In addition, the densities of SSA-concrete samples fall within the limits of 2200 kg/m3 to 2600 kg/m3. Finally, it was concluded that the maximum amount of SSA to be used should not exceed 10 % replacement in concrete production

Effects of Load Ratio Variation on the Safety of Timber Concrete Composite Floor

This paper presents the structural reliability appraisal of timber concrete composite floor designed in line with Eurocode 5 (2004) and Eurocode 2, (2004). Limit state expressions for timber concrete composite floor subdued to tension, bending, tension and bending, shear and compression were generated and their entailed reliability degrees were assessed. The basic variables associated with the design are considered to be random variables with their properties espoused from the previous studies. Reliability analysis was performed using reliability mothed i.e. first order reliability method (FORM) owing to assess the safety levels of the composite floor structural elements by considering six different modes of failure. The analysis comprised of different selected species of softwood, hard wood and glue laminated timber whose strength class were obtained from BS EN 338, 2008 and concrete of strength class C30 from Eurocode 2. The results obtained disclosed that safety indices decrease as the load ratio steps up that led to cut down of the strength. It was detected that timber with strength classes D70, D50 and C50 are safe against all different failure modes looked at except C50 and D50 against shear failure at load ratio of 1, 1.5 and 2. It was conclude timber of strength classes D70, D50 and C50 would reliable for the construction of composite floor i.e. timber-concrete floor