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This study experimentally investigated the effectiveness of the inclusion of basalt fibers in concrete to enhance the performance of the concrete components when exposed to elevated temperatures. Concrete specimens were reinforced with basalt fibers at dosages of 0.25%, 0.5%, 0.75%, and 1%, and then exposed to high temperatures of up to 600 °C. Chopped basalt fibers act as fillers and bridge the gaps and micro-cracks within concrete, resulting in the high strength and energy absorption capacity of basalt fiber-reinforced concrete. At elevated temperatures, when the surface-bound water becomes evaporated, additional stress was found to be released through the softening of basalt fibers. Moreover, at such high temperatures, basalt fibers held the aggregates and cement paste in position by gripping the macro-cracks when the hydration products of concrete began to decompose. The residual strength in fiber-reinforced concrete was thereby significantly higher than that in non-fibered concrete. However, beyond the optimum level of fiber addition, agglomeration, and the non-uniform dispersion of fibers was observed, which results in the lowered performance of the concrete.

This study investigated the effect of corroded web reinforcement on the shear behavior of reinforced concrete (RC) beams. In this study, nine shear-critical RC beams were cast and tested. Six of these beams were corroded stirrups, while the remaining three beams were uncorroded stirrups serving as control samples. An accelerated corrosion technique was employed to corrode the stirrups in the beams. After the accelerated corrosion process, the beams were tested in three-point bending over a simply supported span. The shear span-to-depth ratio was kept constant at 3 for all beam specimens. The effects of the corrosion level, the type of steel stirrups (smooth or deformed), and the stirrup diameter were considered in the tests. The corrosion damage could easily be observed in the form of rust stains and corrosion cracks, which developed parallel to the stirrups. The beams with higher corrosion levels showed a reduction in their shear capacities. This reduction was more apparent in the beams with deformed steel stirrups. The shear capacities of the test beams were analyzed using a theoretical model that considers the effects of corrosion of the stirrups. The results of the analysis showed a good correlation between the experimental and theoretical shear strengths of the beam specimens.

This research investigates the possibility of grinding and burning bivalve clam seashells to produce seashell ash powder. This ash is used to partially replace cement by 5, 10, 15 and 20% by weight. These mixes are tested and compared with a SC0 that has 0% seashell ash powder (SC0). The fresh and hardened properties of all mixes are studied through a variety of tests, including: slump, unit weight, compressive strength and splitting tensile strength. The durability of seashell concrete cubic specimens is studied by immersion in 5% NaOH(aq) and MgSO4(aq) solutions. The addition of thermally treated seashells increased the calcium hydroxide content. The results also show that the compressive strength of the 5% replacement is slightly higher than the SC0 at 28 and 90 days of age, while the tensile strength is higher than the standard for the 5% and 10% of replacement at 7 and 28 days. Furthermore, the slump test value generally increases with increasing the percentage of replacement. The highest durability against sulfate and alkaline attacks is obtained with 5% replacement of cement with seashells which reported the lowest decrease in weight and the highest compressive strength after immersion in 5% NaOH(aq) and MgSO4(aq) solutions. The 5% replacement mix is the optimum percentage of replacement. Therefore, this study recommends replacing cement with 5% seashell cement. This research investigates the possibility of grinding and burning bivalve clam seashells to produce seashell ash powder. This ash is used to partially replace cement by 5, 10, 15 and 20% by weight. These mixes are tested and compared with a SC0 that has 0% seashell ash powder (SC0). The fresh and hardened properties of all mixes are studied through a variety of tests, including: slump, unit weight, compressive strength and splitting tensile strength. The durability of seashell concrete cubic specimens is studied by immersion in 5% NaOH(aq) and MgSO4(aq) solutions. The addition of thermally treated seashells increased the calcium hydroxide content. The results also show that the compressive strength of the 5% replacement is slightly higher than the SC0 at 28 and 90 days of age, while the tensile strength is higher than the standard for the 5% and 10% of replacement at 7 and 28 days. Furthermore, the slump test value generally increases with increasing the percentage of replacement. The highest durability against sulfate and alkaline attacks is obtained with 5% replacement of cement with seashells which reported the lowest decrease in weight and the highest compressive strength after immersion in 5% NaOH(aq) and MgSO4(aq) solutions. The 5% replacement mix is the optimum percentage of replacement. Therefore, this study recommends replacing cement with 5% seashell cement.

Proficient and proper management of different types of waste materials is one of the major concerns to ensure a clean environment. The utilization of wastes in the production of concrete has attracted much attention in recent years because of the low-cost of waste materials along with saving a significant place for landfill purposes and also enhance the performance of concrete. In this study, the possibility of sheep wool fibers (SWF) and modified sheep wool fibers (MSWF) in the production of fiber-reinforced concrete was investigated by assessing the mechanical and microstructural properties. Eight concrete mixes containing 0–6% normal wool sheep fibers with a length of 70 mm were made. Further, four concrete mixes with the modified wool sheep fibers of 0–1.5% with the same length were made. The addition of both SWF and MSWF reduced the slump values of fresh concrete. The inclusion of sheep wool fibers to concrete mixes decreased the compressive strength. However, the addition of sheep wool fibers subsequently improved the tensile and flexural strength values of concrete, thereby improving the concrete ductility with higher energy absorption capacity. The microstructural characteristics of sheep wool fiber reinforced concrete were conformed to have good bonding and low voids. The findings of the study revealed that the addition of sheep wool fibers in the production of concrete is viable both technically and environmentally.

Preplaced aggregate concrete (PAC), also known as two-stage concrete (TSC), is a particular type of concrete that is produced by placing coarse aggregates in a form and voids amongst them are then injected with a flowable grout. The preplaced aggregate fiber reinforced concrete (PAFRC) is new developed concrete, with a unique mixture of coarse aggregates and short fibers that are premixed and preplaced in the formwork and injecting grout into the voids of the aggregate mass. The current study develops the concept of a new PAFRC reinforced with waste polypropylene (PP) carpet fibers and investigate its strength and transport properties. Palm oil fuel ash (POFA) was used as partial cement replacement. Six PAFRC mixes with fibers varying from 0 to 1.25% with a length of 30 mm were made by the gravity method. Another six batches with the similar fiber dosages were made, where the pumping method was used to inject the grout into the voids between the aggregates. The results showed that by adding carpet fibers, the compressive strength of PAFRC specimens reduced. However, the PAFRC specimens revealed a notable enhancement in the tensile strength values. Moreover, water absorption, sorptivity, and chloride penetration depth were reduced for POFA-based PAFRC specimens reinforced with carpet fibers. The study revealed that the carpet fibers are potential to be used in PAFRC by developing the transport and strength properties.