Effect of wheat straw ash as cementitious material on the mechanical characteristics and embodied carbon of concrete reinforced with coir fiber.

The use of supplementary cementitious materials has been widely accepted due to increasing global carbon emissions resulting from demand and the consequent production of Portland cement. Moreover, researchers are also working on complementing the strength deficiencies of concrete; fiber reinforcement is one of those techniques. This study aims to assess the influence of recycling wheat straw ash (WSA) as cement replacement material and coir/coconut fibers (CF) as reinforcement ingredients together on the mechanical properties, permeability and embodied carbon of concrete. A total of 255 concrete samples were prepared with 1:1.5:3 mix proportions at 0.52 water-cement ratio and these all-concrete specimens were cured for 28 days. It was revealed that the addition of 10 % WSA and 2 % CF in concrete were recorded the compressive, splitting tensile and flexural strengths by 33 MPa, 3.55 MPa and 5.16 MPa which is greater than control mix concrete at 28 days respectively. Moreover, it was also observed that the permeability of concrete incorporating 4 % of coir fiber and 20 % of WSA was reduced by 63.40 % than that of the control mix after 28 days which can prevent the propagation of major and minor cracks. In addition, the embodied carbon of concrete is getting reduced when the replacement level of cement with WSA along with CF increases in concrete. Furthermore, based on the results obtained, the optimum amount of WSA was suggested to be 10 % and that of coir fiber reinforcement was suggested to be 2 % for improved results.

Numerical modelling on geotechnical features of soil mixture using recycled tire crumb to strengthen the seismic isolation in building.

In this research, the performance pertaining to tire crumb obtained from scrap tire processing plants is discussed. These tire crumbs are blended with soil at a 30% ratio. When subjected to seismic load, the performance of the 30% tire crumb combination is superior to the 0% tire crumb combination. The investigation is classified into two phases. Phase 1 of the study involves conducting an experimental investigation by applying cyclic loads to a model footing that was resting on the soil with and without tire crumbs. This study reveals that a 30% tire crumb combination achieves optimum energy absorption and minimal footing stiffness, which is a crucial component needed for base isolation. Additionally, using the PLAXIS 2D software package, finite element analysis was carried out during the second phase of the study. For this study, a three-story residential building close to the border between India and Nepal is used. Three different disastrous seismic excitations are applied to the building. From this analytical analysis, it is reported that a 60-70% reduction in acceleration is attained for 30% tire crumb combination with soil. Therefore, from the two phases, it is evaluated that the inclusion of tire crumbs with soil is an excellent seismic base isolation material.

Maintenance of crack with infilling polymer modified mortar for shear deficient of reinforced concrete beam.

Being a developing country, Pakistan needs sustainable and cost-effective strengthening/ retrofitting solution to be adopted/ practiced in the construction industry. The research reported in this paper was aimed to study the effectiveness of PMM, an indigenous product, for repairing reinforced concrete beams, resulting more effective and cost benefiting repair and strengthening for restoration of pre-cracked RC structures. This article presents the research results of experimental investigation conducted for repairing of cracks in shear deficient reinforced concrete (RC) beams with locally available novel material polymer modified mortar (PMM). A total of 6 beams; divided in three groups i.e. short beams, medium beams and deep beams with varying depths and same mix design were tested to four point loading under monotonic loading conditions until failure loads. Afterwards, these beams were repaired with PMM and cured with water for 72 h for retesting until failure. Load at first crack and at failure, crack pattern and deflections were recorded for all specimens during testing. Results from the experimental investigation indicate that load carrying capacity of the repaired beams was significantly restored in comparison to the control specimens. However, repaired specimens of medium group showed more improvement in load carrying capacity as compared with those of repaired specimens of short and deep group. The specimens of medium group restored up to 90% of their original load carrying capacity. The ductility is improved significantly for all shear critical repaired RC beams up to opening of cracks. Sudden brittle failure was observed after opening of repaired cracks. The contribution of PMM to load carrying capacity was found more significant for medium beams as compared to short and deep beams. The results of this study indicated that application of polymer modified mortar is effective technique for repairing of cracks in shear deficient RC beams.

Development of alkali activated paver blocks for medium traffic conditions using industrial wastes and prediction of compressive strength using random forest algorithm.

Geopolymer is an environment friendly construction material that could be synthesized using either the natural source or the industrial byproducts such as flyash and GGBS. The characteristics of the Geopolymer rely on the proportion of the flyash and GGBS and the concentration of the activator solution used. In this research work, the effect of partial replacement of flyash with GGBS in proportions such as 0, 10, 20, 30 and 40% is investigated. Also Molarity of NaOH are tested from 8 to 14 M and both the parameters are optimized. In this optimized Geopolymer concrete, the utilization of iron slag as a partial substitute for river sand in various proportions such as 10, 15, 20, 25, 30 35, 40 and 45% are investigated. The optimized Geopolymer concrete with iron slag is investigated for its performance as a paver block with incorporation of banana fiber in proportions such as 0, 0.5, 1 and 1.5 and is compared with conventional cement concrete paver block. The results show that there is a significant enhancement in the properties of Geopolymer concrete with the different levels of optimization and the utilization of natural banana fiber. The developed sustainable paver block was found to with stand medium traffic conditions as per IS 15658:2006. Further this study employed random forest (RF) algorithm for the prediction of compressive strength of geopolymer concrete specimens for the variable parameters such as molarity of alkaline solution, Flyash/GGBS ratio and partial replacement of river sand with iron slag. The performance evaluation parameters represented high accuracy of developed RF model. This research work unleashes a heft potential of Geopolymer concrete to develop economical eco-friendly sustainable paver blocks to the society through mitigation of environmental strain on the ecosystem.

Effects of blended-cement paste chemical composition changes on some strength gains of blended-mortars.

Effects of chemical compositions changes of blended-cement pastes (BCPCCC) on some strength gains of blended cement mortars (BCMSG) were monitored in order to gain a better understanding for developments of hydration and strength of blended cements. Blended cements (BC) were prepared by blending of 5% gypsum and 6%, 20%, 21%, and 35% marble powder (MP) or 6%, 20%, 21%, and 35% brick powder (BP) for CEMI42.5N cement clinker and grinding these portions in ball mill at 30 (min). Pastes and mortars, containing the MP-BC and the BP-BC and the reference cement (RC) and tap water and standard mortar sand, were also mixed and they were cured within water until testing. Experiments included chemical compositions of pastes and compressive strengths (CS) and flexural strengths (FS) of mortars were determined at 7th-day, 28th-day, and 90th-day according to TS EN 196-2 and TS EN 196-1 present standards. Experimental results indicated that ups and downs of silica oxide (SiO2), sodium oxide (Na2O), and alkali at MP-BCPCC and continuously rising movement of silica oxide (SiO2) at BP-BCPCC positively influenced CS and FS of blended cement mortars (BCM) in comparison with reference mortars (RM) at whole cure days as MP up to 6% or BP up to 35% was blended for cement.