Because of the recent progress in materials properties, specifically high-strength concrete, further research is needed to evaluate its suitability, understanding, and performance in the modern-day world. This research aims to enhance the performance of ultra-high-strength geopolymer concrete (UHS-GPC) by adding nano-silica (NS) and polypropylene fibers (PPFs). Three 1%, 2%, and 3% different amounts of PPFs and three NS 5%, 10%, and 15% were utilized in the samples. Various performance parameters of UHS-GPC were evaluated, such as fresh property, compressive strength, modulus of elasticity split tensile, flexural and bonding strength, drying shrinkage, load-displacement test, fracture performance, and elevated temperature. The test outcomes showed that by raising the percentage of PPFs and NS to the allowable limit, the performance of UHS-GPC can be improved significantly. The most improved performance of UHS-GPC was obtained at 2% polypropylene fibers and 10% nano-silica, as the compressive, splitting tensile, flexural. Bond strength was improved by 17.07%, 47.1%, 36.52, and 37.58%, and the modulus of elasticity increased by 31.4% at 56 days. The study showed that the sample with 2% PPFs and 10% NS had excellent performance in the load-displacement test, drying shrinkage, fracture behavior, and elevated temperature. At 750°C elevated temperature, the samples’ strength was reduced drastically, but at 250°C, the modified samples showed good resistance to heat by retaining their compressive strength to some degree. The present work showed the suitability of PPFs and NS to develop ultra-high-strength geopolymer concrete, which can be used as a possible alternate material for Portland cement-based concrete.
The construction sector is garnering increasing concern as an industry that generates significant pollution while suffering from a lack of adequate environmental performance evaluations. The purpose of this study is to evaluate the environmental performance of construction sector industries using the ISO 14031 standard in three dimensions: planning, using data and information, and reviewing and improving environmental performance evaluations. Using a descriptive and correlational approach, this study described and analyzed the level of implementation using a 7-point Likert scale questionnaire distributed to 1000 organizations in Saudi Arabia. The questionnaires were completed between May and December of 2018 and the results were measured against similar studies. The mean positive percentage responses were 31.36 and expressed the implementation levels of the three dimensions of environmental performance. The corresponding values for the three dimensions' items were 33.36, 29.83, and 30.95 respectively. The minimum Kendall correlation coefficients for each item in a dimension were 0.79, 0.79, and 0.83, respectively. The maximum correlation values between an item and a dimension to which the item did not belong were 0.25. This study answers a fundamental question regarding the implementation level values of environmental performance in construction organizations based on the ISO 14031 standard model and analyzes the pairwise correlation among the descriptor variables of the model. Further studies are needed to investigate the model structure using the principle component, factor analysis, and cluster analysis.
Reprocessing solid waste materials is a low-cost method of preserving the environment, conserving natural resources, and reducing raw material consumption. Developing ultra-high-performance concrete materials requires an immense quantity of natural raw materials. The current study seeks to tackle this issue by evaluating the effect of various discarded materials, waste glass (GW), marble waste (MW), and waste rubber powder (WRP) as a partial replacement of fine aggregates on the engineering properties of sustainable ultra-high-performance fiber-reinforced geopolymer concrete (UHPGPC). Ten different mixtures were developed as a partial substitute for fine aggregate, each containing 2% double-hooked end steel fibers, 5%, 10%, and 15% GW, MW, and WRP. The present study assessed the fresh, mechanical, and durability properties of UHPGPC. In addition, to evaluate concrete development at the microscopic level due to the addition of GW, MW, and WRP. Spectra of X-ray diffraction (XRD), thermogravimetric analysis (TGA), and mercury intrusion (MIP) tests were conducted. The test results were compared to current trends and procedures identified in the literature. According to the study, adding 15% marble waste and 15% waste rubber powder reduced ultra-high-performance geopolymer concrete’s strength, durability, and microstructure properties. Even so, adding glass waste improved the properties, as the sample with 15% GW had the highest compressive strength of 179 MPa after 90 days. Furthermore, incorporating glass waste into the UHPGPC resulted in a good reaction between the geopolymerization gel and the waste glass particles, enhancing strength properties and a packed microstructure. The inclusion of glass waste in the mix resulted in the control of crystal-shaped humps of quartz and calcite, according to XRD spectra. During the TGA analysis, the UHPGPC with 15% glass waste had the minimum weight loss (5.64%) compared to other modified samples.
Decision-making and subjective evaluation are two important aspects that characterizes the involvement of an organization in tender process. Moreover, selection of the right project to bid for is a principal feature of business success. The study aims to investigate the behavioral differences of Saudi construction contractors toward internal and external factors based on the process of modelling the bidding decisions. A quantitative research design is used to investigate the behavioral differences of 97 contractors recruited from construction industry of Saudi Arabia. A questionnaire was distributed among the respondents that would help in identifying the significant level of factors affecting the bid or no bid decision. The impact of internal and external factors on the bidding decisions was evaluated using one-way ANOVA analysis. The results have shown a significant and positive effect of internal and external factors on the bid or no bid decision; including job start time, work capital requirement, availability of qualified human resources, bidding methods, bidding document price, project supervision procedure and etc. The study has helped in establishing a better understanding toward the behavioral differences of contractors with respect to the bidding decisions.
PurposeThe purpose of this research is to identify the constraints and restrictions and their impact on the construction projects in Saudi Arabia from three key participants' perspectives for the planning stage.Design/methodology/approachUsing a descriptive-analytical approach, this research described and analyzed the frequency and severity of failure factors in construction projects in the planning stage using a five-Likert scale questionnaire in Saudi Arabia construction between 2019 and 2020. A total of 100 experts from contractors, consultants and owners were included in the study.FindingsThe findings have shown that time dispute was the major factor affecting the projects to be failed. Similarly, cost overrun and total abandonment have an impact on project failures. The findings have indicated that government officials were involved in delaying the projects while contractors also failed in the project deliveries.Research limitations/implicationsFurther research is needed to investigate the relationship between failure characteristics and project success measures in the same stage, in addition to, factors of failure for construction projects' life-cycle stages.Originality/valueThe findings have indicated that government officials were involved in delaying the projects while contractors also failed in the project deliveries.
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