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2007 research outputs found
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Design of Controlled Pre-Split Blasting in a Hydroelectric Construction Project
No full textGeologic conditions and design requirements around upstream Nachtigal Falls, in Cameroon, for the hydroelectric construction project on the Sanaga River dictated close control of blasting procedures with very precise geometry to obtain safe and economical excavation lines. Various techniques of pre-split blasting were used in the initial stage of all major excavations. Hole diameters for pre-splitting were 89 mm, and hole spacing ranged from 0.8 to 1m. Explosive charges varied from 1 to 7 kg per hole, and the detonating cord linear charge ranged from 12 to 60g. The contour blasting technique is aimed at controlling overbreak and improving remaining slope stability. Over-break or over-excavation needs to be controlled since its occurrence compromises the operations in terms of safety (instability in the remaining slope; loosening rocks that increase the risk for operational people; an irregular free face for subsequent blasting); and costs (need for reinforcement of the remaining rock structure through costly sustainment systems; increase in concrete volumes in civil works). This paper discusses in detail the design and field implementation of pre-split blasts successfully carried out to achieve clean vertical walls in moderately dipping, though complexly sheared and jointed gneiss. Based on the results of the experiments, we were able to design a pre-splitting pattern both experimentally and in a very cost-effective manner. It is felt that the methods developed on this project could have useful applications on other major construction projects. Doi: 10.28991/CEJ-2023-09-03-05 Full Text: PD
Characterization of Groundwater Quality and Human Health Risk Assessment
No full textThe study aimed to appraise groundwater quality in the Mekong Delta using a groundwater quality index (GWQI) and estimate human health risks associated with groundwater consumption. Groundwater samples were collected at sixty wells distributed in An Giang, Kien Giang, Hau Giang and Dong Thap provinces. Twelve water quality parameters were measured, including pH, total dissolved solids (TDS), hardness, coliform, nitrate (NO3ˉ), nitrite (NO2ˉ), ammonium (NH4+), sulfate (SO42-), iron (Fe), manganese (Mn), arsenic (As) and cadmium (Cd). The results were compared with the national regulation on groundwater quality. The findings of this study indicated that groundwater in the Mekong Delta was contaminated with microorganisms and some heavy metals (Fe, Mn, and As). This was related to anthropogenic activities, such as improperly treated domestic wastewater and agricultural and industrial wastes. Based on the results of GWQI, 30% of the total groundwater samples in the Mekong Delta were classified as very good for drinking purposes. However, over 26% of all samples were unsuitable for drinking. In terms of risk assessment, children were rather susceptible to cancer risks and adverse health effects through drinking As-contaminated groundwater than adults. The cancer risks of consuming As-contaminated groundwater for children and adults were up to 4.28í—10-3that is higher than the acceptable risk. The highest aggregate hazard quotient of heavy metal-contaminated groundwater for children and adults was 9.54, which means that they could suffer adverse health effects. Groundwater is an indispensable source of freshwater in the Mekong Delta; thus, home water treatments are recommended to protect public health, and an in-depth groundwater quality and health risk assessment should be conducted. Doi: 10.28991/CEJ-2023-09-03-09 Full Text: PD
Punching Capacity of UHPC Post Tensioned Flat Slabs with and Without Shear Reinforcement: An Experimental Study
No full textPunching capacity is one of the main items in the design of both pre-stressed and non-pre-stressed flat slabs. All international design codes include provisions to prevent this type of failure. Unfortunately, there is no code provision for UHPC yet, and hence, the aim of this research is to experimentally investigate the impact of column dimensions and punching reinforcement on the punching capacity of post-tensioned slabs and compare the results with the international design codes' provisions to evaluate its validity. The test program included five slabs with a compressive strength of 120 MPa: one as a control sample, two to study the effect of column size, and the last two to study the effect of punching reinforcement. Comparing the results with the design codes showed that ACI-318 is more accurate with an average deviation of about 5%, while EC2 is more conservative with an average deviation of about 20%. Besides that, punching reinforcement reduces the size of the punching wedge by increasing the crack angle to 28° instead of 22° for slabs without punching reinforcement. Also, the results assure that both ductility and stiffness are enhanced with the increased column dimensions and punching reinforcement ratio. Doi: 10.28991/CEJ-2023-09-03-06 Full Text: PD
Four-Face Heated Uniaxial Reinforced Concrete Columns Interaction Charts
No full textThis paper presents an analytical method for generating the interaction diagrams of uniaxially reinforced concrete (RC) columns that are subjected to four-face heating. Twenty-one (21) specimens obtained from previous case studies that were subjected to four-face heating (with different fire test times ranging from 63 to 356 fire minutes) are used to validate the proposed uniaxial interaction charts. The results obtained from the case studies and from the proposed charts are also compared with the finite element software (FIN EC). The 500°C isotherm as well as the zone method are used in the computer software program to find the required load capacities. The proposed method's values fall within the range of values obtained from laboratory tests and computer software, which suggests its validity. Also, the zone method in FIN-EC software is reliable for evaluating load-bearing capacity, while the 500°C method is useful in situations with shorter fire times. The results obtained provide a valuable tool for designing and evaluating structures that may be exposed to fire. Nonetheless, the study is restricted by its concentration on a particular type of column under four-face heating, which may reduce its relevance to other types of structures and heating situations. Doi: 10.28991/CEJ-2023-09-07-01 Full Text: PD
Reducing the Highway Networks Energy Bills using Renewable Energy System
No full textJordan has significant renewable energy potential due to its remarkable geographical location and climate conditions. This potential elevates engaging several innovative renewable alternatives in energy development, which may efficiently minimize the excessive import of traditional energy sources. The objective of this research is to study the potential of utilizing clean and affordable solar energy along roadways such as Jordan's Desert Highway-15 to be in line with the United Nations Sustainable Development Goals (UN-SDG's) by installing selected solar panels that possess adequate friction and the ability to allow solar radiation to reach the solar cells, in addition to allowing the load to be bypassed around the cells. The shoulder of the highway, with a length of 315 km and a width of 3.0 meters, has been exploited in order to supply the neighboring areas with energy for those roads, particularly those paved roads, which are poorly lit at night. Furthermore, this study provides direction and guidance concerning the structural performance of non-traditional pavement materials, which are a form of subgrade or pavement reinforcement. The performance of a prototype board on a variety of structural bases has also been evaluated. Overall, this paper found that it is possible to design a solar road panel to withstand traffic loading and that the concrete structural base allows for a significant improvement of the analyzed prototype design, especially in countries with limited energy sources and dependent on imports such as Jordan. Doi: 10.28991/CEJ-2023-09-11-019 Full Text: PD
Optimizing the Flexural Behavior of Bamboo Reinforced Concrete Beams Containing Cassava Peel Ash using Response Surface Methodology
No full textThe growing concern to reduce global warming has necessitated the use of more eco-friendly materials in construction. The study is focused on the utilization of cassava peel ash as supplementary cementitious material and bamboo as reinforcement in concrete beams. The response surface methodology approach was explored to determine the effect of simultaneously varying the cassava peel ash content, bamboo size, beam length, and beam depth on the flexural strength and strain of beams. An analysis of variance was carried out on experimentally obtained results to determine the accuracy of the obtained models and the contributions made by the linear interaction and quadratic terms on flexural strength and flexural strain. The coefficient of determination obtained for RSM models showed a good correlation between all predicted and experimentally obtained results. The optimum conditions obtained for bamboo-reinforced concrete containing cassava peel ash were 3% cassava peel ash, 16 mm bamboo diameter, 500 mm beam length, and 150 mm beam depth. The predicted flexural strengths were 11.85, 14.34, and 14.95 N/mm2 and flexural strains of 0.64, 0.67, and 0.91 for 28 days, 56 days, and 90 days, respectively. To validate the model prediction, a laboratory experiment was conducted using the optimum mix design proportion. From the results obtained, it was observed that the experimental results were close to those predicted by the models. These models can be efficiently used for simulating the flexural behavior of bamboo-reinforced concrete beams. Doi: 10.28991/CEJ-2023-09-08-011 Full Text: PD
Impact of Prior Knowledge about Autonomous Vehicles on the Public Attitude
No full textIt is anticipated that AVs will offer multiple benefits, such as an improvement in the level of mobility, increasing the level of comfort, and reducing the number of traffic accidents. However, the public attitude is the main determinant factor that will face the deployment of AVs and in turn affect their implications. Over the last few years, there was a debate on the impact of the level of knowledge about AVs on public attitudes. While some studies show that people with higher levels of knowledge about AVs are the most optimistic, some other studies show that the public attitude moves in the negative with an increase in the level of knowledge. Thus, this study focuses exclusively on quantifying and understanding the impact of the level of knowledge and the public attitude in the US. A questionnaire survey was designed and conducted between June and November, 2022. A total of 5778 complete responses were received from all over the US and the analysis was conducted to estimate the public attitude and level of knowledge by region. The results show that there is a negative shift in public attitude with the increase in the level of knowledge about AVs. In addition, the results show that 1% increase in the level of knowledge about AVs is associated with 0.65%, 0.68%, and 2466 (USD) $ decrease in the level of interest, trust, and willingness to pay for AV and 0.56% increase in the level of concern about traveling in AVs. Moreover, the results are discussed in light of both the diffusion of innovation theory and the Gartner Hype curve. Doi: 10.28991/CEJ-2023-09-04-017 Full Text: PD
Impact of the Skill Shortage on the Construction Supply Chain Performance in Australia
No full textThe purpose of this paper is to investigate how the skill shortage impacts the performance of the construction supply chain in Australia. The study has adopted a quantitative research method. The quantitative data were collected by conducting a survey of employees who work in construction companies in Australia. A regression analysis was used to analyze the data from 113 respondents. The findings of the study reveal that the construction sector in Australia has high labour costs, but workers are still thinking they are not getting paid enough and cannot invest more in themselves to improve their skills. There is a lack of academic and vocational training programs offered to them. Insufficient recruitment and incentive policies are also main barriers to attract talents to the construction industry in Australia. The situation became more serious during the COVID-19 period due to the lockdowns, lack of skilled migrants, and Government working visa policies. The study implies that firms should have a deeper understanding of the reasons for the skill shortage. Firms also need to devise strategies for hiring the right talent. Further, it was found that quality talent can come from the local or foreign markets. More effective selection criteria should be designed so that the best-fit approach can be implemented. Doi: 10.28991/CEJ-2023-09-02-08 Full Text: PD
Behavior of Centrifuged GFRP Poles Under Lateral Deflection
No full textCentrifugal-manufactured GFRP pipes are widely used today as lighting and low-power transmission poles due to their lightweight, high electrical insulation, low cost, and corrosion resistance. Despite these advantages, GFRP poles suffer high deflection problems due to their low elastic and shear moduli values. In order to overcome this disadvantage, three techniques were suggested to control the lateral deflection of the GFRP poles: an extended internal steel stub, external steel angles, and internal steel bracing bars. The main objective of this study is to determine the optimum strengthening technique to improve the serviceability of GFRP poles in terms of lateral deflection according to ASTM D4923. An experimental research program containing five full-scale GFRP poles was carried out to determine the optimum strengthening technique and the effect of connectors opening near the base and compare it to previous research. The results indicated that flexural stiffness was increased by 44%, 66%, and 38% for the extended stub, steel angles, and bracing bars, respectively. Besides that, the reduction in flexural stiffness due to connector opening was about 8%. The measured deflections showed good matching with simplified mathematical calculations, and the division was about ±10%. The external steel angle technique showed the best efficiency in Stiffness behavior. Doi: 10.28991/CEJ-2023-09-06-07 Full Text: PD
Subsurface Analysis Using Microtremor and Resistivity to Determine Soil Vulnerability and Discovery of New Local Fault
No full textMicrotremor and geoelectrical resistivity surveys have been conducted in areas where the April 10, 2021, earthquake of 6.1 Mw caused the most damage. Wirotaman Village, Malang Regency, was one of the regions with the most extensive damage. This study aims to investigate the seismic vulnerability and subsurface conditions that result in severe damage at the research location. This study's Horizontal to Vertical Spectral Ratio Analysis (HVSR) curve was derived from the recorded microtremor signal in the frequency domain. The frequency parameter and amplification factor obtained from the curve are used to determine the seismic vulnerability index. In addition, a geoelectrical resistivity study with a dipole-dipole configuration was conducted at the site with the most extensive damage. The results of this study show the correlation between the results of the HVSR curve analysis and geoelectrical resistivity in determining the seismic vulnerability of an area. The results indicated that the high seismic vulnerability index value ranged from Kg= 12.0 to 18.0, with the most severe damage concentrated in the Southwest at SA 05 and SA 06. Based on the results of the geoelectrical survey, information was obtained that several points of damage to buildings at SA 05 (red circle) were on the same line, where this condition was associated with the possibility of new faults at that location. This microtremor and geoelectric resistivity investigation reveals thick sedimentary deposits with a high seismic vulnerability index and low resistivity. This study's findings can be utilized as a guide for micro zonation studies in research areas. This research contributes to the surrounding community in the form of disaster mitigation, where construction must avoid local fault positions that have been found to reduce the level of damage when natural geological disasters occur. Doi: 10.28991/CEJ-2023-09-09-014 Full Text: PD