Concrete crack is one of the main problems observed in concrete technology due to drying shrinkage. Incorporating fibers in concrete production is one of the mechanisms implemented to mitigate cracks. Nowadays, investigators concentrate on different techniques to replace human‐made fiber with existing natural fibers for fiber‐reinforced composite material. Utilization of natural fiber has an initiation for the development of eco‐friendly materials by reducing damages caused by human‐made materials and saving nonrenewable resources. Natural fibers are readily and abundantly available, sustainable, and biodegradable, with low cost and low density, and have superior specific properties. Nevertheless, there are some limitations of natural fiber compared to human‐made fiber. Consequently, significant energy was applied to alter natural fiber’s surface and morphology using physical, chemical, and biological treatment techniques to overcome the limitation. The primary intention of surface treatment is to modify the bond between the fiber surface and the polymer matrix. However, based on this literature review, there were no specific treatment techniques to be followed to select the best one from the others as criteria. It should include all parameters to consider starting from the stage from the cradle to the grave, cost of chemicals, transportation, and labors, including energy consumption and effluent energy. Additionally, their environmental effect also investigated in detail to compare each other.

This study primarily emphasizes the effect of alkaline treatment on the surface morphology, and the physical properties of extracted bamboo fibers were investigated in detail. The bamboo fibers were extracted from raw bamboo culms using a mechanical extraction process followed by roller-milling techniques. The physical properties of the extracted bamboo fibers and their chemical composition were examined based on standard requirements. The extracted and sun-dried bamboo fibers were subjected to surface modifications by treating them with a 5 wt.% NaOH solution. The process involved soaking the extracted bamboo fibers for 1 day at ambient temperature; subsequently, the alkali-treated fibers were washed with distilled water several times to remove alkali content from the fiber surface until it became neutral. Finally, the fibers were dried under the sun for a week. The alkali-treated and untreated extracted bamboo fibers underwent characterization using Fourier transform infrared spectroscopy (FTIR), Thermogravimetric analysis (TGA), X-Ray diffraction (XRD) analysis, and Scanning electron microscopy (SEM). The investigation revealed an improvement in the surface morphology of the alkali-treated extracted bamboo fibers, with a significant reduction in surface roughness, as illustrated by SEM. Test results from FTIR, XRD, and TGA indicated that the alkali-treated fibers had removed lignin and hemicellulose from their surface. This study strongly suggests that bamboo fibers prepared using these techniques could be utilized as reinforcing material in composite production.

This research explores the use of treated hybrid natural fibers—wheat straw and bamboo—as reinforcements in concrete for pavement applications. Motivated by environmental and economic benefits, the study investigates how these fibers can enhance the mechanical and durability properties of concrete. Wheat straw fibers, abundant in Ethiopia due to extensive wheat farming, help control micro-cracks and increase the tensile strength of concrete, while bamboo fibers, also locally available, reduce macro-crack propagation and improve concrete toughness. To prepare these fibers, wheat straw was cut to 25 mm in length and bamboo fibers were treated with a 5% sodium hydroxide solution before being cut into lengths of 30, 45, and 60 mm. A concrete mix targeting a cube compressive strength of 30 MPa incorporated 0.1% wheat straw fibers, with varying bamboo fiber contents (0.5%, 1%, and 1.5%) by weight of cement. The results indicate that the uniquely treated hybrid natural fiber-reinforced concrete mix exhibits noticeable enhancements in mechanical properties, with approximate increases of 4.16%, 8.80%, and 8.93% at 7, 28, and 56 days, respectively. Furthermore, the split tensile strength, flexural strength, and durability properties of the concrete were significantly improved by the proposed fiber concentration and length compared to the control concrete mix design. This treatment also shifted the failure mode of the concrete from brittle to ductile and enhanced its energy absorption capacity up to 7.88% higher than that of the control concrete. Based on the AASHTO 1993 pavement design guidelines, this fiber-reinforced concrete reduces pavement thickness by 11% compared to the control concrete while improving post-cracking behavior. This hybrid natural fiber-reinforced concrete presents a promising, sustainable, and eco-friendly alternative for rigid pavement construction.

This specific study investigates the chemical and morphological properties of naturally treated wheat straw fiber growing around in Jimma zone. The chemical composition properties including cellulose 45.43%, hemicellulose 36.50%, and lignin 21.61% were determined. The physical properties of naturally treated wheat straw fibers, such as bulk density, particle density, moisture content, and ash content, are 0.037 g/cm³, 0.194 g/cm³, 10.04%, and 1.44%, respectively. The chemical functional group of naturally treated wheat straw fiber was established by Fourier transform infrared spectroscopy (FTIR), crystallinity index is calculated by X-ray powder diffraction (×RD) analysis, and the thermogravimetric analysis (TGA) result ensures that the naturally treated wheat straw has thermally withstood up to 314.35°C. A fiber’s surface morphology shows the presence of shallow pores, which increase the surface roughness of the fiber; this contributes to increased contact surface area, which ensures better fiber-matrix adherence in composite fabrication. We conclude that naturally treated wheat straw fiber has a significant value in fiber reinforced concrete technology as reinforcement materials in concrete composites formation by incorporating optimum percentage to reduce the limitation of concrete and to enhance the mechanical properties of concrete.

The utilization of fly ash (FA) and powdered granulated steel slag (PGSS) as additives in soil stabilization plays a crucial role in environmental, economic, and weak soil property improving advantages. In this study, the combined effect of FA and PGSS in improving expansive subgrade soil was investigated. The materials used for this study were expansive soils, FA, and PGSS. The study has applied an experimental research method. For this investigation, the index properties, Free Swell Index (FSI), unconfined compressive strength (UCS), optimum moisture content (OMC), California bearing ratio (CBR), and scanning electron microscope (SEM) tests were done for treated and untreated expansive soils. The findings indicated that as the mixture of FA (0 to 12.5 at 5 increment) and PGSS (0 to 25 at 5 at 2.5 increment) is added to the untreated expansive soils, the index properties, FSI, and OMC of the soils were significantly declined. The CBR values of expansive soils containing 20 FA and 10 PGSS mixture were 13.8 and 16.21, respectively, which improved the quality of the soils by 85.43 and 84.82, respectively. While the untreated expansive soils have a UCS value of 0.34kg/cm², the treated soil comprising 20 FA and 10 PGSS mixture has a UCS value of 13.42kg/cm², indicating that the soil strength is enhanced by 97.47. The results of the studies demonstrate that adding FA and PGSS to expansive soil improves its stability and strength. The study concluded that disposals such as FA and PGSS might be effectively used in enhancing the characteristics of construction materials and used for the construction.

Expansive soil refers to a particular type of soils – almost clayey soils in property - that expand as they absorb water and shrink when they dry out. The process of swelling generates pressures that can cause lifting, or heaving of structures whilst shrinkage process can cause differential settlement on civil structure. A large number of buildings and roads are placed on such type of soil and exposed to the danger from this swelling and shrinkage processes. In order to avoid the previous mentioned risk from the expansive soil, a technique of soil stabilization should be made for this type of soil to enhance some of its properties. In this study, the experimental investigations have been made to study the suitability of natural gravel from jiren quarry site to improve properties of expansive soil. The important parameters to be determine the geo-technical properties such as Specific gravity, Liquid limit, Plastic limit, Plasticity index, dry density and California Bearing (CBR) ratio values. According to ERA 2002 this type of soils is poor for subgrade for road construction. In order to realize the desired objective, a purposive sampling technique which is non –probability method was adopted in order to collect disturbed soil samples at depth of 1.5m and natural gravel from jiren quarry site used for the preparation of different laboratory tests. The laboratory work involved sieve analysis along with consistence test to classify the soil sample. The preliminary investigation of the soil shows that it belongs to A-7-5 class of soil in AASHTO and CH in USCS soil classification system. Soils under this class are generally of poor for subgrade road construction. Atterberg limits, compaction and CBR tests were used to evaluate properties of stabilized soil. The soil was stabilized with natural gravel in stepped concentration of 5%, 10%, 15%, 20% and 25% by dry weight of the soil. Analysis of the results shows the addition of natural gravel improve the geotechnical properties of the expansive black cotton soil. The addition of natural gravel reduces plasticity index, swelling and OMC with an increase in MDD and CBR with all increased natural gravel contents. The addition of 20% and 25% of natural gravel established an increased CBR value by 670% and 958% respectively, indicating the subgrade class falling under S4 and S5 respectively. From this study it was found out that natural gravel stabilized with soil do meet the minimum requirement of ERA pavement manual specification for use as a sub-grade material in road construction.