Upon the completion of national road projects, their cost and time deviations are often reported. These deviations from the projected values are a result of complications in the time and cost management of such projects. Controlling the cost and time overrun of projects is important for successful implementation and efficient project management. However, few studies have attempted to measure the project cost and time management efficiency in civil engineering. Thus, this issue requires further investigation. In this study, large road projects that had poor cost and time management were selected. The chosen projects were configured as Decision Making Units (DMUs) in a Data Envelopment Analysis (DEA). DEA is a non-parametric modern mathematical tool for measuring relative managerial performance and determining efficient DMUs. A list containing the causes of cost and time deviations and the percentage deviation for each DMU was prepared. The cost and time management efficiency of the DMUs was calculated using DEA, and the resulting values were ordered according to importance. It is believed that this process will contribute to better cost and time management.
Read moreThe successful application of extrusion-based 3D-printed geopolymer mortars largely depends on precursor chemistry, activator composition, mixture proportions, and fresh-state behavior, which is highly sensitive to time-dependent structural build-up. This review examines the relationships among mix design, geopolymerization chemistry, rheological properties, and printability requirements for 3D-printed geopolymer mortars. Particular emphasis is placed on the effects of precursor type, alkaline activator characteristics, liquid-to-solid ratio, additives, and fibers on flowability, yield stress, viscosity, extrudability, buildability, shape retention, and interlayer bonding. The review further discusses how geopolymerization kinetics influence the evolution of fresh-state properties, the printable time window, and the transition from extrusion to structural stability. In addition, early-age performance is evaluated in terms of setting behavior, green strength development, and layer-interface integrity. Current challenges, including the lack of standardized test methods, limited comparability among published studies, and the complex coupling between material design and process parameters, are also highlighted. Finally, the review identifies key research gaps and proposes future directions for developing robust, printable, and sustainable geopolymer mortar systems for additive manufacturing in construction.
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