Building Engineering

Effect of natural pozzolana, pozzolanic sand, and basalt on thermal and mechanical properties of green concrete

Moustafa Wassouf — 2024-11-08

Green concrete, also known as sustainable concrete, is a building material that aims to reduce environmental impact by using natural, recycled, or sustainable materials in its production. One way to achieve sustainability in concrete is to replace cement with pozzolanic materials, which not only reduces the carbon footprint but also improves the performance of concrete and reduces its cost. This study aims to use natural materials that can partially or completely replace cement and conventional aggregates in concrete mixes. pozzolanic gravel (GPoz) replaced coarse aggregate, basaltic sand (SBas) and pozzolanic (SPoz) replaced fine aggregate, while ground pozzolana (PN) replaced cement. This work focuses on the experimentation and simulation of concrete mixes using the four abovementioned materials. 36 cubes were cast to conduct the thermal conductivity test by direct exposure of concrete samples, where an insulated thermal chamber was designed from thermal bricks, equipped with a heat source from the bottom and an empty space for the tested sample from the top, and then the resistance test on simple pressure was conducted for the cubic samples at the age of 28 days. Pozzolanic aggregate, when used in combination with basalt sand, showed greater thermal resistance compared to conventional concrete. Even with the replacement of 50% of the cement with ground pozzolana, we notice an increase in resistance of more than 11%, but with the replacement of basalt sand with pozzolana sand, we notice an increase in thermal resistance of more than 53%. As for the mechanical properties represented by resistance on simple pressure, we notice an acceptable decrease in resistance when replacing cement with pozzolana, with the exception of mixtures containing aggregates and pozzolana sand together, where replacing 50% of the cement with pozzolana increases the resistance on simple pressure by more than 46.4%.

Appraising the potentials of reusing plastic bottles as building blocks for housing construction at Paipe village Abuja Nigeria

Mansir Dodo — 2024-11-08

Plastic bottles package a multitude of commodities consumed worldwide. Upon consumption of the commodity, the disposed plastic bottles accumulate as waste, having impacts on both the aquatic and terrestrial environment. In a bid to convert such waste to wealth, plastic bottles are creatively reused for different applications, such as pedestrian bridge boats and street furniture, amongst others. Another application of reusing plastic bottles is their serving as building blocks for housing construction. Reports and research in Nigeria confirm the proliferation of plastic bottles littering the environment, which if reused in housing construction has the potential to contribute to achieving both UN Sustainable Development Goals (SDG) 11 (making human settlements sustainable) and 12 (ensuring sustainable consumption and production). Although Nigeria is traced to being the first country in Africa to reuse plastic bottles in housing construction, not much research output exists from practitioners’ experience on the potentials of reusing plastic bottles as a sustainable construction material as practiced in countries like Vietnam, India, and the Philippines, among others. As such, this study investigates the potential factors driving the practice of reusing plastic bottles in Nigeria with a view to ascertaining the satisfaction derived from the practice for sustainable housing construction. Primary data was collected using a structured questionnaire from 41 respondents identified as having experience in using plastic bottles in construction (5 staffs of Awonto Konsult as well as 36 staffs of Brains and Hammers Construction). Data was analysed descriptively using both IBM SPSS Statistics 23 as well as MS Excel to compute the Mean Score as well as the Relative Satisfaction Index (RSI). Only 30 questionnaires were successfully retrieved and fully answered. Amongst the 10 potential factors studied driving reusing plastic bottles, results show that almost all respondents tend to be ‘satisfied’ with both ‘strength and stability’ (having a Mean Value of 4.70 and RSI of 0.94) as well as ‘durability’ (having a Mean Value of 4.50; RSI of 0.90) of buildings built with plastic bottles. These two factors recorded the highest ‘satisfaction’ ratings, leaning towards ‘very satisfied’. Regarding the factor ‘fire resistance’ of buildings built with plastic bottles (having a Mean Value of 3.40; RSI of 0.68), results reveal that 50 percent of the respondents are ‘unsure’ if it is a satisfactory factor driving reusing plastic bottles or not. The study found that the satisfaction ratings of technical and environmental factors have higher appeal to respondents compared to health and safety and also financial factors. It is recommended that Awonto Konsult and also Brains and Hammers Construction invest more in information related to the fire resistance of plastic bottles used in construction because fire outbreaks pose great threats to buildings. Equally, wider empirical research on plastic bottle wastes, if undertaken, could support the development of policies for waste management, particularly in developing countries. This research has the potential to convert waste into wealth in a bid to minimising environmental impacts of disposed plastic bottles as well as contribute to sustainable materials, particularly for rural housing. Since this study was based on a survey, experimental studies of potentials driving the reuse of plastic bottles in housing construction will reveal results that could enable more sustainable housing construction in Nigeria.

Potential risk factors affecting cost and schedule performance in the case of construction projects in Dire Dawa city administration and Harari region, Ethiopia

Yonatan Getachew Zegeye — 2024-11-08

Construction projects are inherently fragmented and complex, influenced by various risk factors that can significantly affect both costs and schedules. Identifying and prioritizing these risk factors is crucial for enhancing project management and achieving successful outcomes. This research aimed to identify the most significant risk factors affecting construction projects in terms of cost and schedule performance within the Dire Dawa City Administration and Harari Region, considering the perspectives of contractors, clients, and consultants to provide actionable insights for risk mitigation. A comprehensive literature review and pilot survey initially identified 41 risk factors, which were refined through an iterative process to select 42 factors for a detailed questionnaire survey. Additionally, semi-structured interviews were conducted to gather qualitative insights. Data analysis employed mean ratings to identify the top ten risk factors, utilizing Probability Impact (P-I) Matrix and regression techniques to assess each factor’s significance. The results highlighted six critical risk factors among the ten identified as most impactful: inflation, increases in material prices, exchange rate fluctuations, payment delays, poorly coordinated design, and material delays. The findings indicated strong positive correlation values (R = 0.800 and R = 0.840) in both models, suggesting that as one variable increases, the other tends to increase as well. These insights provide valuable guidance for project managers, emphasizing the need to focus on these critical risk factors to improve cost and schedule management, ultimately enhancing project outcomes and minimizing cost overruns in the region.