The use of Supplementary Cementitious Materials (SCMs) or industrial wastes as a partial replacement for cement in the production of concrete is an urgent need in the construction industry due to cement's growing environmental challenges and rising cost. In respect of this, we conducted research work on proportioning binary concrete mixes. Fly ash (FA) replaced 10 %, 20 %, and 30 % of the cement, while silica fume (SF) replaced 5 %, 10 %, and 15 % of the cement. A control concrete mix was also developed with 100 % cement and no SCM. The results showed no increase in compressive strength for FA concrete compared to control at the early age of 3–28 days, but a maximum increase in compressive strength of 4 % was discovered at a later age of 56 days for concrete with 20 % FA. For 5 % SF concrete, a considerable strength increase of 15 % was seen at the early age of 3 days. Like with FA concrete, 2 % improvement in strength was recorded at the later age of 56 days for 10 % SF concrete. This study further focused on the concrete's temporal evolution of compressive strength by developing a strength evolution model (SEM) using nonlinear regression analysis at a 95 % confidence level. Pearson correlation coefficient was used to determine the correlation between the model values and the experimental results. For comparison, the fib Model Code 2010 was applied to the experimental data, and a good agreement was observed among the proposed model, the fib Model values, and the experimental results. The proposed model can be expanded to address further regression-related problems. Finally, environmental life cycle assessment revealed that utilizing 10 %, 20 %, and 30 % of FA lowered Global Warming Potential (GWP) by 9 %, 19 %, and 29 %, respectively. Likewise, using 5 %, 10 %, and 15 % of SF reduced the GWP by 5 %, 9 %, and 14 %.

Cement-based composites, as primary construction materials, have undergone significant advancements over the years, yet researchers still face challenges in terms of their durability and impact on the environment. The goal of this research is to develop environmentally friendly cementitious composites blended with sugarcane bagasse ash (SCBA) and reinforce them with multi-walled carbon nanotubes and polypropylene (PP) fibers. Because of the high cost associated with carbon nanotubes (CNTs) and PP fibers, as well as CO₂ emission, which affect the economic and environmental aspects of this field, an agricultural waste such as SCBA was introduced in the current study that is both economically and environmentally viable. For this purpose, five mixes were designed by varying the CNTs content whilst keeping the PP fibers and SCBA contents constant at 1.5% and 15% by weight of the binder (ordinary Portland cement + SCBA), respectively. The developed blends were tested for various mechanical and durability properties, i.e., compressive strength, flexural strength, impact strength, water absorption, and ultrasonic pulse velocity. Moreover, the microstructures of the newly developed low-carbon SCBA-based composites reinforced with PP fibers and CNTs were studied through scanning electron microscopy and energy dispersive spectroscopy. The results showed that the developed blends incorporating 15% SCBA, 1.5% PP fibers, and 0.08% CNTs, by weight of the binder, demonstrated the compressive, flexural, and impact strengths as 15.30 MPa, 0.98 MPa, and 0.11 MPa, respectively. The investigated blends proved to be cost-effective and environmentally beneficial, rendering them suitable for utilization in general construction and maintenance works.

River barrages ensure water availability for enhanced irrigation and human consumption. Of course, effective and sustainable management of existing barrages requires controlling riverbed erosion through appropriately designed stilling basins with their appurtenances. The present study assesses the stilling basin performance of the Taunsa Barrage, a vital water resources infrastructure built in 1958 in Punjab, Pakistan, and rehabilitated between 2004 and 2008 through the construction of a subsidiary weir (SW) downstream of the main weir. A physical modeling approach was employed, consisting of two distinct phases of laboratory experiments. Phase 1 replicated the Taunsa Barrage before rehabilitation, assessing the need for SW construction under different discharge rates and downstream bed elevations. Phase 2 reproduced the post-rehabilitation conditions, including varying discharge values, heights and positions of the SW, to evaluate the stilling basin design concerning the ability to dissipate flow energy. The results demonstrated (i) inadequate tailwater levels and oscillating hydraulic jump formation under increased discharges in pre-rehabilitation conditions (highlighting the poor performance of the original Taunsa Barrage stilling basin and the need for an SW to address these hydraulic deficiencies), and (ii) that the SW, under the design conditions, achieved optimal head loss for discharge values near the design discharge. However, the head loss efficiency was highly sensitive to variations in the distance and height of the SW due to hydraulic jump pulsations. Moreover, the head loss efficiency rapidly degraded for discharges greater than the design discharge. These findings indicate that the Taunsa barrage stilling basin may lack the capacity to accommodate higher discharges resulting from the interplay between climate change and land use alterations within the upstream Indus River basin. Future research should focus on developing a design that enhances energy dissipation robustness, reducing susceptibility to potential discharge increases.