Peach shell (PS) used as a substitute for normal weight aggregate (NWA) in concrete was investigated. A series of mixes were prepared by 0%, 25%, 50%, 75% and 100% PS as a substitute for NWA, while other parameters were set as constant. Results showed that 100% alternative NWA with PS, compressive strength, splitting tensile strength, flexural strength, modulus of elasticity reduced by 44.0%, 34.5%, 46.5% and 43.4%, respectively, and 24-h water absorption and porosity were 10.2% and 17.4%, respectively. However, its oven-dry density was 25% lighter than the control mix. Creep results showed that the creep strain of concrete and the concentrations of K⁺, Ca²⁺, Na⁺, Mg²⁺ and Sr²⁺ in the concrete solution increased significantly with the increase of PS content, and the creep strain of P0, P25, P50, P75 and P100 mixes at 570 h were 1.82 × 10⁻⁴, 6.96 × 10⁻⁴, 9.09 × 10⁻⁴, 11.21 × 10⁻⁴ and 15.12 × 10⁻⁴, respectively. After creep test, the compressive strength of all mixes increased. The results show that PS can be utilised to produce lightweight aggregate concrete, and the maximum replacement of NWA with PS beyond 50% is not recommended.

In this study, the mechanical and creep properties of the apricot shell (AS) as a replacement for the coarse aggregate were investigated. The alternative volume ratio of the coarse aggregate was set as 0%, 25%, 50%, 75% and 100%, respectively. The results showed that the coarse aggregate was completely replaced by the AS, the compressive strength, splitting tensile and flexural strength, and modulus of elasticity of apricot shell concrete (ASC) were 26.1 MPa, 1.85 MPa, 3.18 MPa, and 9.3 GPa, respectively, and decreased by 32.6%, 30.7%, 24.8%, and 34.5% compared to the concrete without AS, respectively. However, the oven dry density of AS 100 mixture was 1,762 kg/m³, which fulfilled the density requirement of structural lightweight aggregate concrete (LWAC). The creep strain of concrete increased by increasing AS content. When the coarse aggregate was replaced by 100% AS, the strain of AS100 mixture at 380 hours was 16.84 × 10⁻⁴. The results indicate that LWAC with an acceptable performance can be produced by using AS as coarse aggregates in concrete.

The use of the polypropylene fibre and glass fibre with different volume fractions to improve the mechanical properties of peach shell lightweight concrete was investigated in this study. The volume fractions of 0.25%, 0.50%, and 0.75% were used for each fibre. The results showed that, as the polypropylene fibre and glass fibre were added into peach shell concrete, the density was reduced by up to 6.1% and the compressive strength, splitting tensile strength, and flexural strength were increased by 19.1%, 54.3%, and 38.6%, respectively. The highest compressive strength, splitting tensile strength, and flexural strength of 29.3 MPa, 2.87 MPa, and 3.09 MPa, respectively, were produced by peach shell concrete with 0.75% glass fibre. The results indicated that the incorporation of fibres significantly enhanced the postfailure toughness of peach shell concrete. It was found that the glass fibre was more effective than the polypropylene fibre in improving the mechanical properties of peach shell concrete. Although the incorporation of fibres slightly increased the water absorption and porosity, the type and content of fibres had no significant effect on water absorption and porosity. Therefore, the mechanical properties of peach shell lightweight concrete can be improved by adding polypropylene fibres and glass fibres.

The heat-treated apricot shell can be utilized as coarse aggregates for producing sustainable bio-based lightweight concrete with good compressive strength but poor tensile strength. In order to improve the tensile properties of apricot shell concrete (ASC), the effects of polypropylene (PP) fibre, glass (G) fibre and basalt (B) fibre at various volume fractions (V_f) (0.25%, 0.5% and 0.75%) on the performance of ASC were investigated. The results indicated that the fibre type had no significant effect on the physical properties of ASC such as slump, density, water absorption and permeable porosity. However, the slump of ASC decreases with an increase in fibre content. The B fibre has a better improvement in mechanical properties than the PP fibre and G fibre thanks to the better elastic modulus and tensile strength. When the V_f was 0.5%, the compressive strength, splitting tensile strength, flexural strength and modulus of elasticity of ASC reinforced with B fibre were increased by 16.7%, 29.1%, 29.2%, and 18.1%, respectively, compared to ASC without any fibres. The magnesium sulfate attack results showed that the incorporation of the B fibre decreased the mass loss and compressive strength of ASC exposed to a MgSO₄ solution for 6 months because the fibre arrested the microcracks caused by the expansive stress. It is concluded that the mechanical properties of bio-based ASC and its resistance to magnesium sulfate attack can be significantly improved by incorporating 0.5% B fibre.