Abstract:Concrete is a very popular material in the construction industry-it is, however, susceptible to quasi-brittle failure and restricted energy absorption after yielding. The incorporation of short discrete fibers has shown great promise in addressing these shortfalls. A natural fiber such as sisal is renewable, cheap, and easily available. It has also exhibited good tensile strength and can significantly improve the performance of concrete. In this study, the physical and mechanical properties of sisal fiber-reinforced concrete were reported. Sisal fibers were added in the mix at percentages of 0.5%, 1.0%, 1.5%, and 2.0% by weight of cement. Physical properties measured are workability, water absorption, and density while mechanical properties reported are compression strength, split tensile strength, and static modulus of elasticity. The computed modulus of elasticity of sisal fiber-reinforced concrete was compared with predicted values in some common design codes. From the study, it was concluded that sisal fiber can enhance the split tensile strength and Young's modulus of concrete but cannot improve its workability, water absorption, and compressive strength.

Introduction: Fiber reinforced concrete is becoming popular in improving the quasi-brittle failure of concrete. Natural fibers such as sisal holds great promise in this regard. It has amazing tensile strength and is renewable. This paper presents the result of an investigation carried out on the effect of sisal fiber on the compressive strength, Split tensile strength, failure mode and Poisson ratio of Sisal Fiber-Reinforced Concrete (SFRC). Methods: A mix proportion of 1:1.92:3.68 and w/c ratio of 0.47 for a target compressive strength of 35 MPa was used. Sisal fiber was added at percentages of 0.5%, 1.0%, 1.5%, and 2.0% by weight of cement. The effect of specimen shape on the compressive strength of sisal fiber-reinforced concrete (SFRC) was reported. The compressive strength of cube (150mm X 150mm) and cylinder (150mm diameter and 300mm height) specimen was determined at 7 and 28 days, while Split tensile strength and Poisson ratio were obtained using cylindrical specimen (150mm diameter and 300mm height). Results and Conclusion: The result shows that the addition of sisal fiber slightly reduces the compressive strength of concrete, increases its split tensile strength up to 47.167% of the control specimen, arrests crack propagation and reduces its Poisson ratio. The correlation between the compressive strength of cylindrical and cube specimen was established with a ratio ranging between 0.82 - 0.73. The difference in the compressive strength was found to increase with rise in the percentages of sisal fiber. Based on the ratio and mechanical properties, 1.0% sisal fiber content was recommended as the optimum for reinforcing concrete.

Background: Concrete production around the globe is in billions of tons. Consequently, million metric tons of carbon dioxide are produced annually due to the cement consumption and production which, in turn, cause environmental menace. Objective: This research work examines the use of Bamboo Leaf Ash (BLA) as supplementary cementitious materials. Methods: The physical, mechanical, and durability properties were studied by partial substitution of cement with BLA at 0, 5, 10, 15, and 20% sequentially. Concrete cubes were cast and cured at 7, 28, 56, and 90 days. Beams were cast and cured at 28 days. A total number of five mixes were investigated, four out of the mix were dedicated to examining the impacts of BLA on the characteristics of concrete. Results: Soundness, consistency, initial and final setting time of cement paste values were lower than bamboo blended paste values at 5%, 10%, 15%, and 20% percentage replacement, respectively. The split tensile, compressive, and flexural strength values of conventional concrete were lower than bamboo leaf ash concrete accordingly. Water absorption, permeable voids, sorptivity, and bulk dry density of conventional concrete were higher than bamboo leaf ash concrete at all level of replacements. Conclusion: According to the analysis and experimental results obtained, BLA improved split tensile, compressive, and flexural strength benchmark at 10% as the optimum level of replacement. BLA reduced setting time, consistency, compacting factor, slump, water absorption, permeable voids, sorptivity, and density. To this end, BLA can be considered as a good pozzolanic material which can save the cost of construction, and improved concrete properties.

This study compares the effect of treated pineapple leaves fibres (T-PALF) with sodium hydroxide solution and untreated fibres (N-PALF) on the compressive and flexural strength of earth bricks stabilized with 3% and 5% cement. The fibre content ranged from 0% to 5% in steps of 1% by weight. The compressive strength tests were made at 7, 14, 21 and 28 days of curing; the flexural strength test were conducted at 28th day only. The results show that the T-PALF had a higher compressive strength when comparing to the N-PALF. The highest compressive strength of the bricks was obtained at 28 days of curing. The compressive strength at 28 days of stabilized brick at 3% and 5% of cement reinforced with T-PALF were 4.01 and 4.81 MPa, respectively, while the one reinforced with N-PALF was 3.19 and 4.63 MPa, respectively. The results further show that the highest flexural strength of both stabilized bricks at 3% and 5% of cement reinforced with T-PALF and N-PALF was obtained with the bricks stabilized with 5% of cement reinforced with T-PALF. This results show that bricks stabilized with 5% cement and reinforced with 3% of treated fibres content are good for construction of load bearing walls. It was observed; a significant improvement of the reinforced blocks under flexure than under compression.

Background: Concrete is a common material used in the construction of marine structures, such as bridges, water treatment plants, jetties, etc. The use of concrete in these environment exposes it to attack from chemicals like sulphates, chlorides and alkaline, thereby causing it to deteriorate, and unable to perform satisfactorily within its service life. Hence, the need to investigate the durability properties of concrete has become necessary especially when admixtures are used to modify some of its properties. Objective: This research work investigates the effect of Cassava Starch (CS) on the durability characteristics of concrete. Methods: The durability properties investigated in this work are water absorption, sorptivity, resistance to sulphates, sodium hydroxides and chloride penetration. The specimens were prepared by adding CS by weight of cement at 0.4, 0.8, 1.2, 1.6 and 2.0% respectively. The concrete specimens were cured for 28 days, tested for compressive strength before ponding in ionic solutions of sodium hydroxide, sulphuric acid and sodium chloride. Six (6) concrete mixes were prepared, five of which were used to evaluate the effect of CS on the durability characteristics of concrete. Results: The slump values reduced with the increasing dosage of CS due to the viscous nature of the CS paste. Generally, the addition of CS in concrete tends to improve the resistance of concrete to sulphate and chloride attack due to the ability of the muddy-like starch gel to block the pore spaces of hardened concrete, hence, reduces the rate at which water and other aggressive chemicals penetrate the concrete. In addition, the retarding ability of CS impedes the formation of mono-sulphate aluminates during cement hydration, thereby making the concrete less susceptible to sulphate attack. Conclusion: The addition of CS to concrete by weight of cement generally improved the durability characteristics of concrete, while the relative performances of the concrete mixes showed that CS 2.0 gave a better resistance to chloride penetration and sulphate attack.