This article presents results of an experimental study involved testing of two-layer reinforced concrete beams with one-layer of periwinkle shell aggregates concrete both in tension and compression zone having cross-sections of 100 x 150 mm, the total span of 1200 mm and effective length 1100mm. Flexural reinforcement (As =2Φ8mm) and (A S 1 =2Φ8mm) and shear reinforcement (Asv =Φ6mm @ 200mm c/c). A total of twelve (12) reinforced beams were produced and grouped into; Type-RC (Beams and cubes cast completely of crushed stone aggregates concrete of 1:2:4 mix), Type-R1 (Crushed stone aggregates concrete (1:2:4 mix) with a depth of 75mm at the top layer and Periwinkle aggregate concrete (1:2:1 mix) with a depth of 75mm at the bottom layer, Type R2 (Periwinkle aggregates concrete (1:2:1 mix) with a depth of 75mm at the top layer and 75mm of crushed stone aggregate concrete (1:2:4 mix) at the bottom layer), Type R3 (Periwinkle aggregates concrete (1:2:1 mix) with a depth of 50mm at the bottom layer and 100mm of crushed stone aggregate concrete (1:2:4 mix) at the top layer. All the beam samples were tested under two-point loads. Results reveal that the two-layer beams had higher bending resistance as the control beams cast completely of crushed stone aggregate concrete. Also, the study showed that the beam Type-R1 had bending resistance of 6.62kNm and is 23.3% higher than beam Type-RC which had bending resistance of 5.08kNm while beam Type-R2 had bending resistance of 5.71kNm and is 11% higher than beam Type-RC. Beam Type-R3 had bending resistance of 6.21kNm and is 18.2% higher than beam Type-RC. The load-deflection records of all the beam samples were noted. The deflection of two-layer beams was considerably lower than control beams cast completely of crushed stone aggregates concrete. Base on the findings, it is recommended that periwinkle aggregate concrete can be used as a layer in reinforced concrete beams both in compression and tension zone, not more than 0.5H.
This paper presents the results of an investigation into the optimum depth of the lower concrete grade (LCG) at the tension region in a two-layer reinforced concrete beam. A total of nine (9) simply supported two-layer RC beams (1100 x100 x150 mm) were studied. Two 8 mm and two 6 mm diameter rods were used as reinforcement at the bottom and top of each two-layer beam, respectively. The beam samples were grouped into two: the first group comprises two-layer RC beams produced with 1:2:4 as the higher grade and 1:3:6 as the lower grade; the second group comprises two-layer RC beams cast with 1:2:4 as the higher grade and 1:4:8 as the lower grade. The depth of LCG adopted for each group is 25 mm to 100 mm at a step of 25 mm out of the total beam depth of 150 mm. The beams were subjected to two-point static loading to evaluate the load resistance and deflection. The results show that the greater the depth of the layer under compression, the stiffer the beam. The two-layer RC beam has an equal loading carrying capacity as the beam made entirely of higher grade. The depth of the layer of RC beam under tension in two-layer beams should be kept between 40 and 50% of the overall beam depth, which would be desirable structurally.
The amounts of waste glass in the Bayelsa State metropolis have been growing noticeably without being reutilized increasing the danger to public well-being because of the shortage of land area. This rising challenge of waste glass in the Bayelsa State metropolis can be improved if new dumping possibilities other than landfill can be discovered. This study is geared toward the better use of waste glass material as admixture in concrete as a means to improve the concrete compressive strength. To achieve research objectives, the broken waste glasses were obtained from aluminum fabrication workshop in Amassoma. Bayelsa state Nigeria, the glasses were then milled to a fine powder smaller than 0.075mm and burnt at a controlled temperature of 200, 400, and 6000C respectively. A total of 156 concrete cubes of 150mm x 150mm x 150mm were produced employing different contents of calcined or burnt waste glass powder as admixture. The quantity of calcined waste glass powder used as admixture was varied from 0-20% at step of 5% for three different temperatures, 2000C, 4000C and 6000C. The samples were cured for 7, 14, 21 and 28days and tested in the laboratory for compressive strength. Results obtained from the study showed that the best addition dosage of calcined waste glass powder at 2000C, 4000C and 6000C are 20%, 5% and 5%. A 20% addition of Calcined waste glass powder at 2000C exhibited about 23% increase in compressive strength than the control. Base on the findings, it is recommended that the use of calcined waste glass powder as pozzolanic material should be embraced for production of concrete and can be utilized in concrete production as admixture with 5% - 20% for 2000C 4000Cand 4000C respectively.
The amounts of waste glass in the Bayelsa State metropolis have been growing noticeably without being reutilized increasing the danger to public well-being because of the shortage of land area. This rising challenge of waste glass in the Bayelsa State metropolis can be improved if new dumping possibilities other than landfill can be discovered. This study is geared toward the better use of waste glass material as admixture in concrete as a means to improve the concrete compressive strength. To achieve research objectives, the broken waste glasses were obtained from aluminum fabrication workshop in Amassoma. Bayelsa state Nigeria, the glasses were then milled to a fine powder smaller than 0.075mm and burnt at a controlled temperature of 200, 400, and 6000C respectively. A total of 156 concrete cubes of 150mm x 150mm x 150mm were produced employing different contents of calcined or burnt waste glass powder as admixture. The quantity of calcined waste glass powder used as admixture was varied from 0-20% at step of 5% for three different temperatures, 2000C, 4000C and 6000C. The samples were cured for 7, 14, 21 and 28days and tested in the laboratory for compressive strength. Results obtained from the study showed that the best addition dosage of calcined waste glass powder at 2000C, 4000C and 6000C are 20%, 5% and 5%. A 20% addition of Calcined waste glass powder at 2000C exhibited about 23% increase in compressive strength than the control. Base on the findings, it is recommended that the use of calcined waste glass powder as pozzolanic material should be embraced for production of concrete and can be utilized in concrete production as admixture with 5% - 20% for 2000C 4000Cand 4000C respectively.
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