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Date palm fiber (DPF) is one of the abundant solid waste materials in the agriculture sector in Saudi Arabia, and it is gaining great attraction due to its advantages compared to synthetic and other natural fibers. For proper utilization of DPF in cementitious composites, its performance under high temperatures needs to be understood. This is because DPF is a cellulose-based agricultural fiber material and is expected to degrade when subjected to high temperatures. This will cause a significant loss in strength and structural integrity of the composites. The use of Pozzolanic materials has been reported to reduce the loss in mechanical properties of cementitious composites under high temperatures. With powdered activated carbon (PAC) being a low-cost material compared to other Pozzolanic materials, this study utilized PAC as an additive to the DPF-reinforced concrete to mitigate its loss in mechanical strength when exposed to elevated temperature. The experiment was designed using response surface methodology (RSM), which was used to construct mathematical models for estimating the strengths of the concrete exposed to high temperatures. The DPF was added at proportions of 1%, 2%, and 3% by weight of cement. Similarly, the PAC was added at 1%, 2%, and 3% by weight of cement to the concrete. The concrete was subjected to elevated temperatures of 300 °C, 600 °C, and 900 °C for a 2 h exposure period. The degradation of the concrete in terms of mass loss and the compressive strength of the concrete after heating were measured. DPF in the concrete led to an escalation in weight loss and reduction in strength, which was more pronounced at a temperature of 600 °C and above. The addition of PAC resulted in an enhancement in the strengths of the concrete containing up to 2% DPF at 300 °C, while at 600 °C the improvement was minimal. The models developed for predicting the mass loss and strengths of the DPF-reinforced concrete under high temperatures were statistically significant with a high correlation degree. Based on the optimization results, DPF-reinforced concrete produced with 1% DPF, and 2.27% PAC as additives and subjected to a temperature of 300 °C for 2 h yielded the lowest mass loss of 2.05%, highest residual compressive strength and relative strength of 45.85 MPa and 106.7% respectively.

The use of natural fibers in cementitious composites continue gaining acceptability and applicability due to the shortcomings and disadvantages of synthetic fiber; this is because natural fibers have advantages of sustainability, eco-friendliness, and economy. Biodegradable natural fibers, being low density and lightweight, with typical values of strength-to-weight ratio, aspect ratio, elastic modulus, and strength, may be competitive for substituting synthetic fibers such as glass and carbon. Indeed, natural fibers are mostly non-irritating for the skin and typically pose no troubles or issues for breathing, which is not the case with many synthetic fibers. Date palm fiber (DPF) is a natural fiber obtained as waste material from a date palm tree. In many countries, with large date production, DPF is easily available as a process by-product, with a low processing cost. Being sustainable and environmentally friendly, DPF is continuously gaining acceptability as fiber material in different composites such as concrete, mortar, gypsum composites, clay composites, and bricks. Based on the most available literature reviewed, DPF reinforced composites have been found to be a good insulation material, with higher thermal properties, thereby reducing energy consumption which consequently saves the running and maintenance cost of the building. DPF reinforced composites were reported to have higher energy absorption capacity, ductility, and bending resistance, leading to delaying crack propagation and preventing catastrophic failures of structures such as beams and slabs. Additionally, due to its lower density, DPF reinforced composites have the advantage for usage in areas prone to seismic effects, and when used for buildings, the overall weight of the building is expected to reduce hence reduction in foundation cost. The major setback of using DPF in composites is the reduction in the compressive strength of the composites and the durability performance of the composites. Therefore, for effective usage of DPF in composites to derive the maximum benefits, there is a need to devise a method of mitigating its negative effects on the compressive strength and durability performance of the Composites; this is a future study that needs to be explored for better performance of DPF in cementitious and other materials composites.