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Mechanical Properties of Foundation Concrete Exposed to a Swampy Area for a Prolonged Period
Nsahlai Leonard Nyuykongi,
Yamb Bell Emmanuel,
Ndigui Bilong,
Blaise Ngwem Bayiha,
Mbuh Moses Kuma
Issue:
Volume 6, Issue 5, October 2021
Pages:
126-134
Received:
30 November 2020
Accepted:
15 June 2021
Published:
15 October 2021
Abstract: A total of 24 concrete samples of nominal dimensions 300mm x 150mm x 100mm each were produced for laboratory testing using six cement dosages of 150 Kg/m3, 200 Kg/m3, 250 Kg/m3, 300 Kg/m3, 350, and 400 Kg/m3. Samples were buried at a swampy area with a moisture content of 67.38% for 56days, 84days, 112days and 196days. For concrete dosed at 400 Kg/m3, compressive strengths of 20.8MPa, 19MPa, 16.5MPa, and 12.7MPa were recorded for 56days, 84days, 112days, and 196days, respectively. The modulus of elasticity for the concrete dosed at 400 Kg/m3 is 29741.38 MPa, and the Poisson ratio is 0.177. The bulk modulus for concrete dosed at 400 Kg/m3 was found to be 15346.43MPa and the shear modulus was 12634.4 MPa. Concrete dosed at 150Kg/m3 recorded a Von Mises stress of 15.407MPa, while concrete dosed at 400 Kg/m3 recorded a higher von Mises stress of 21.984 MPa. The Von Mises stresses were far greater than most of the average uni-axial failure stresses. The maximum distortion energy for concrete dosed at 150 Kg/m3 is 9.028 KJ/m3, while that dosed at 400 Kg/m3 has a distortion energy of 6.067 KJ/m3. Other mechanical properties such as the strains, principal stresses, and failure angles were also assessed. The general trend of the analyses revealed that prolonged exposure of concrete to a humid environment has an adverse effect on the engineering performance of concrete.
Abstract: A total of 24 concrete samples of nominal dimensions 300mm x 150mm x 100mm each were produced for laboratory testing using six cement dosages of 150 Kg/m3, 200 Kg/m3, 250 Kg/m3, 300 Kg/m3, 350, and 400 Kg/m3. Samples were buried at a swampy area with a moisture content of 67.38% for 56days, 84days, 112days and 196days. For concrete dosed at 400 Kg/...
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Investigation of the Effects of Rice Husk and Rice Straw on the Properties of Lightweight Fibrecrete Blocks
Abaza Leo,
Kyakula Michael
Issue:
Volume 6, Issue 5, October 2021
Pages:
135-143
Received:
3 September 2021
Accepted:
8 October 2021
Published:
28 October 2021
Abstract: Uganda’s progress towards achieving sustainable growth is curtailed by poor and limited infrastructure, over 60% of the urban population live in slums with poor quality housing and hygiene, 44% of the households sleep in one room, the situation is more critical in Kampala where about 70% sleep in one room. About 67% of Ugandans live in dwellings with brick walls while 28% live in dwellings of mud walls reinforced with timber poles. Over 90% of framed structure in Uganda are built from reinforced concrete structures with bricks or block infill walls that are heavy thus influencing the type and size of structural members hence its cost. This research focused on use of Rice Husks (RH) and Rice Straws (RS) in lightweight fibrecrete blocks for benefit of their reduced weight, reducing environmental pollution, low processing energy, and availability at modest cost. In this research, the fibres were alkali-treated using sodium hydroxide solution prepared by dissolving 15g of sodium hydroxide pellets in 1 liter of water heated at 100°C for 60 minutes. This was aimed at increasing surface roughness, expose cellulose to fibre surface, improve fibre/matrix adhesion, eliminate weak boundary layers and remove superficial lignin layer. The alkali treated fibres were used to prepare one hundred twenty one (121) fibrecrete blocks of RH and RS with varying proportions of 0%, 10%, 20%, 30%, 40%, and 50% fibre and tested for their density, compressive strength, water absorption, thermal conductivity, fire resistances and microstructure. The densities of lightweight fibrecrete blocks ranged between 1947-1485kg/m3 with a reduction of 7.9 - 30.5% compared to aggregate blocks of 2138kg/m3 density. Compressive strength of the blocks varied between 1.53 - 5.36 N/mm2 and 1.28 - 3.48 N/mm2 for RH and RS blocks respectively with control block having compressive strength of 7.2N/mm2 at 28 days. Compressive strength loss in the lightweight fibrecrete blocks tested for fire resistance ranged between 10.7- 34.3% and 6.8-73.7% for RH and RS-blocks respectively while the water absorption ranged between 5.8-7.8% for RH and 6.4-11.3% for RS blocks and 3.6% for aggregate blocks. Thermal conductivity was improved by 13.4-64.8%. The researcher concluded that, RH-40 and RS-20 blocks have the most appropriate proportions for lightweight fibrecrete blocks. This would reduce Environmental degradation, utilize agricultural waste, increase the income of the farmers, reduce construction cost due to reduced density of fibrecrete blocks, and increase thermal insulation hence thermal comfort of the occupants.
Abstract: Uganda’s progress towards achieving sustainable growth is curtailed by poor and limited infrastructure, over 60% of the urban population live in slums with poor quality housing and hygiene, 44% of the households sleep in one room, the situation is more critical in Kampala where about 70% sleep in one room. About 67% of Ugandans live in dwellings wi...
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Performance Efficiency of Common Reed, Sand and Gravel for Greywater Treatment in a Constructed Wetland in Akure, Nigeria
Alao Femi,
Alatise Micheal Olanrewaju,
Olanrewaju Olawale
Issue:
Volume 6, Issue 5, October 2021
Pages:
144-148
Received:
28 March 2021
Accepted:
10 May 2021
Published:
30 October 2021
Abstract: The release of greywater lacking any treatments into drainage channels, land surfaces and normal water bodies will lead to environmental deprivation and health risks. In this study, common reed combined with natural materials of sand and gravel was used in a system of constructed wetland for the treatment of greywater in Akure, Nigeria. Raw greywater (RGW) was collected from Jadesola Hostel, Federal University of Technology, Akure, and pretreated using a combination of gravel with fine sand, arranged accordingly. The filtered water was subsequently released to a plastic constructed wetland (CW) consisting of similar combination of layers of gravel and sand with common reed planted on it to achieve complete treatment. The RGW, filtered greywater (FGW) and treated greywater (TGW) were analyzed for biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solid (TSS), total nitrogen (TN) and fecal coliforms (FC). Results showed reductions in BOD, COD, TSS, TN and FC by 80.20%, 78.35%, 56.07%, 45.93% and 74.71%, respectively, for FGW and by 90.92%, 91.46%, 93.46%, 53.66% and 82.10%, respectively, for TGW. Therefore, it was concluded that the combination of common reed, sand and gravels in constructed wetland offers an effective means of accomplishing physical and biological treatment of greywater, especially for reuse in irrigation. Hence, it was recommended that acceptance of the combined system will help farmers in ensuring sufficient treatment of greywater and satisfies the standard requirements for wastewater reuse and application in both field crop irrigation and other outdoor needs.
Abstract: The release of greywater lacking any treatments into drainage channels, land surfaces and normal water bodies will lead to environmental deprivation and health risks. In this study, common reed combined with natural materials of sand and gravel was used in a system of constructed wetland for the treatment of greywater in Akure, Nigeria. Raw greywat...
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Assessment of Drainage Structure by Using ArcGIS Software: The Case of Bale Robe Town, Ethiopia
Gutema Wakjira,
Garuma Negasa
Issue:
Volume 6, Issue 5, October 2021
Pages:
149-160
Received:
26 August 2021
Accepted:
12 October 2021
Published:
30 October 2021
Abstract: An increase in the frequency of extreme weather events such as heavy storms and floods has been reported in various parts of the world. Ethiopian cities at large, are troubled with storm water leading into floods especially during the rainy season due to inadequate installation of desired infrastructure. In the Robe town since the construction of impermeable surface like roads, sidewalks, buildings and others are highly increasing. They are reducing natural permeable surface that can infiltrate water into the ground. Those impermeable surface are create flooding and more storm water runoff in this town. In this town water flows through road especially during heavy rain are resulted in negative impacts on road pavement performance and on the overall situation of the town’s basic infrastructures. The objective of this research was to assess drainage structure in Bale Robe town by using ArcGIS software. The specific objectives of this study were; determining general characteristic of EDS, computing slope and capacity of EDS, identifying highly affected road segment due to improper drainage and recommending appropriate counter measure for identified defects. Majority of the data for the study were obtained from the field survey using surveying equipment and field observation, and some data were collected from concerned sectors. The population contains all existing drainage structures except earthen drainage structure. As a result of the study EDS have different types, and base widths, the capacity of some drainage structure are less than the required capacity while some of them are greater than the required capacity. There were both opened and closed drainage structures with slope of EDS between 0.1 percent and 1.96 percent. The terrain category of the town is flat and rolling. Generally, the EDS in the town has different general characteristics, capacities and different defects. The identified defects were due to different factors; like poor design, poor environmental assessment, and lack of maintenance were the main causes of street flood in the study area. In this town the following measurements should be taken to solve the identified defects, properly cleaning of drainage structure before and after rain, cover open drainage structure, improve the longitudinal gradient of drainage structure and improve the capacity EDS based on the ERA standard and causes of the defects.
Abstract: An increase in the frequency of extreme weather events such as heavy storms and floods has been reported in various parts of the world. Ethiopian cities at large, are troubled with storm water leading into floods especially during the rainy season due to inadequate installation of desired infrastructure. In the Robe town since the construction of im...
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