The suitability of burnt and crushed cow bones (BCCB) as partial replacement for fine aggregate in concrete was studied. The percentages of replacements of fine aggregates of 0, 10, 20, 30, 40 and 50%, respectively of BCCB were tested considering 1: 2: 4 and 1: 1 1 / 2 :3 concrete mix ratios. The cow bones were burnt for 50 minutes up to 92 o C before being crushed. Ninety-six (96) concrete cubes of 1: 2: 4 mix ratio and ninety-six (96) concrete cubes of 1 : Â : 3 mix ratio measuring 150x150x150mm were tested for the compressive strength at 7, 14, 21 and 28 days respectively. The research revealed that the BCCB acted as a retarder in the concrete. Water-cement ratio increased with the increase in the percentage of the BCCB. The mixes of 1:2:4 and 1: :3 at 28 days curing yielded average compressive strengths in N/mm 2 ranging from 16.49 - 24.29 and 18.71 - 29.73, respectively. For the mix ratios of 1:2:4 and 1: : 3 at 28 days curing age, Â it was observed that increase in the BCCB content beyond 40 and 50%, respectively resulted to the reduction of the average compressive strength below recommended minimum strength for use of concrete in structural works. http://dx.doi.org/10.4314/njt.v36i3.4

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Suitability of burnt and crushed cow bones as partial replacement for fine aggregate in concrete

Abstract Cement production is held responsible of polluting the atmosphere with carbon dioxide (CO 2 ). The researchers have shown that manufacturing of one ton of cement releases about half ton of carbon dioxide into the atmosphere. So, there is a need to produce alternative cement instead of ordinary Portland cement (OPC). Waste materials such as sugarcane bagasse are difficult to dispose which result in environmental hazard. This study investigates the use of sugarcane wastes in concrete, where two forms of sugarcane wastes were used in this study. The first form was using the sugarcane bagasse ash as partial replacement of cement in both mortar and concrete mixes, where, in mortar, the used ratios were 5, 10, and 20% of the total weight of cement. But in concrete, the used ratios were 5, 7.5, and 10%. The samples were tested in compression and split tension. The results showed that the optimum ratio of using sugarcane bagasse ash as a partial replacement of cement was 5%. Similar results were obtained in both mortar and concrete sample. For the bagasse fibers, adding the fibers to the concrete mixture led to the reduction of compressive strength. But on the other hand, the addition of bagasse fibers reduced the crack width formed in the slab. 

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The use of sugarcane wastes in concrete

Sugar cane juice (SCJ) was investigated as a retarding agent in concrete production. Slump values and compressive strength of concrete with partial replacement of water by sugar cane juice was also investigated. The concrete cubes were prepared by replacing water with SCJ in the following proportions 0, 3, 5, 10 and 15%. The cubes were cured, tested and the physical  properties of interest in this study were determined. Results show that the final setting time of concrete was delayed with increase in content of the SCJ in the concrete mix. At 0% SCJ, final setting time was 3½ hours, while final setting time at 15% SCJ was 6 hours, reflecting additional 2½ hours setting  time. The compressive strength of the (water:SCJ) concrete decreased with increase in the content of SCJ in the concrete mix, up till 10% SCJ content. Keywords: sugar cane juice, setting time, slump values,  compressive strength

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Sugar cane juice as a retarding admixture in concrete production

The characteristics of concrete are influenced by the ratio of water to cementitious materials (w/c) used in the mixture. An increase in paste quality will yield higher compressive and flexural strength, lower permeability, increased resistance to weathering, improve the bond between concrete and reinforcement, reduced volume change from drying and wetting, and reduced shrinkage cracking tendencies. Admixtures are used to improve the properties of concrete or mortar. The current study investigates the effect of Sisal Juice Extract (SJE) as an admixture on concrete durability. SJE contains unrefined minerals which can be used as organic retarders to increase the rate of strength development at an early age. A total of 84 concrete cubes were produced in 7 sets of 12 samples each. One set was the control mix which had zero SJE content. The remaining sets had varying dosages of SJ namely 5%, 10%, 15%, 20%, 25%, and 30%. Twelve beam specimens were also cast and subjected to the three-point flexural test. To establish the effect on strength of concrete, compressive strength was tested at 7, 14, 28, and 56 days while flexural strength was tested at 28 days. The highest compressive strength was achieved at 5% dosage beyond which a decrease in strength occurred for all the higher dosages.

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The Effect of Sisal Juice Extract Admixture on Compressive and Flexural Strength of Cement Concrete

Improvement of mechanical and physical properties of normal concrete using mulberry extract as an admixture

The effect of sugar cane juice, (SCJ) on slump values, setting time and compressive strength of concrete cubes was investigated. A total of 32 concrete cubes of size 150x150x150mm with a mix ratio of 1:2:4 were cast with different percentages of unfermented sugar cane juice replacing some proportion of water in the concrete mix. Water/Sugar Cane Juice/cement ratio was held constant at 0.45. The concrete cubes were prepared by replacing water with SCJ in the following proportions 0, 25, 50 and 100%. The cubes were cured, tested and the physical properties of interest in this study were determined. The slump values of the concrete decreased from 40mm at 100: 0 (water:SCJ) to 18mm at 50:50 (water:SCJ) and to 0mm (collapse) at (0:100) (water :SCJ). The final setting time of concrete increased with increase in proportion of SCJ. The highest final setting time of 42 hours (considered excessive), occurred at 75:25 (water:SCJ) proportion. The compressive strength of the (water:SCJ) concrete decreased as the percentage of SCJ increased up to 25% SCJ. Thereafter, an increase in compressive strength was noticed up till 100% SCJ, with a maximum strength of 13.08N/mm 2 occurring at 100% SCJ at 28 days. The early strength reduction is due to quick-setting of the concrete, at 25% SCJ, retardation commences and the strength of concrete increases. The study has been carried out at 0, 25, 50 and 100% replacement by weight of potable water with SCJ. A comparative study has been done between concrete made with potable water and those made with water/sugar cane juice. http://dx.doi.org/10.4314/njt.v34i2.6

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N Nwaiwu

Papers

Effect of sugar cane juice on slump values, setting times and strength of concrete