The construction industry relies heavily on concrete as a building material. The coarse aggregate makes up a substantial portion of the volume of concrete. However, the continued exploitation of granite rock for coarse aggregate results in an increase in the future generations’ demand for natural resources. In this investigation, coconut shell was used in the place of conventional aggregate to produce coconut shell lightweight concrete. Class F fly ash was used as a partial substitute for cement to reduce the high cement content of lightweight concrete. The impact of steel fiber addition on the compressive strength and flexural features of sustainable concrete was investigated. A 10% weight replacement of class F fly ash was used in the place of cement. Steel fiber was added at 0.25, 0.5, 0.75, and 1.0% of the concrete volume. The results revealed that the addition of steel fibers enhanced the compressive strength by up to 39%. The addition of steel fiber to reinforced coconut shell concrete beams increased the ultimate moment capacity by 5–14%. Flexural toughness was increased by up to 45%. The span/deflection ratio of all fiber-reinforced coconut shell concrete beams met the IS456 and BS 8110 requirements. Branson’s and the finite element models developed in this study agreed well with the experimental results. As a result, coconut shell concrete with steel fiber could be considered as a viable and environmentally-friendly construction material.

This study investigated the effect of adding fly ash on the mechanical and durability characteristics of coconut shell (CS) concrete. Two different mixes were developed, one with CS and the other with conventional aggregate and CS as coarse aggregate. Cement was replaced with Class F fly ash in terms of weight at 0, 10, 20, and 30% in both mixes. Test result showed that the CS concrete with 10% fly ash replacement level exhibited the highest compressive and tensile strength. The addition of fly ash decreased the porosity of CS concrete due to its fineness and increased hydration products in the matrix at later ages. Additionally, it also improved the weak aggregate interfacial transition zone of CS lightweight concrete. Thus, the fly ash addition in CS concrete showed lower values of water absorption, permeable voids, sorptivity, and chloride permeability. Furthermore, the increasing content of fly ash addition improved the durability characteristics of CS concrete considerably.

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The improvised construction techniques and utilization of industrial wastes in manufacturing concrete play a major role in sustainability. The artificially manufactured aggregates are gaining importance in the present era. The use of fibers as secondary reinforcement is greatly pronounced. Sintered fly ash aggregate concrete and normal aggregate concrete with and without basalt fiber with 28 days compressive strength of 30 Mpa were cast and tested. The stress–strain curve of the lightweight concrete has a lower modulus of elasticity when compared with the normal aggregate concrete. A simple linear relationship has been developed between the mechanical properties using regression analysis. The water absorption and void ratio had a direct relationship with the sorptivity and ponding of concrete. The strength and durability aspects of the lightweight aggregate concrete had better agreement with the requirements of the structural lightweight concrete. Strict adherence to codal provisions with respect to strength and durability can be made for improvised behavior.