Strength Properties of Concrete Using Canarium Kernel Shell and Polypropylene Fiber

Abstract

This study investigated the strength performance of concrete incorporating 
Canarium kernel shell (CKS) as a partial replacement for conventional coarse 
aggregate and polypropylene fibre (PPF) as reinforcement, addressing concerns 
associated with unsustainable natural aggregate consumption, cement-related CO₂ 
emissions, and agro-waste disposal. A factorial experimental design was adopted, 
with CKS replacing coarse aggregate at 0%, 5%, 10%, and 15% by weight, while PPF 
was incorporated at 0%, 0.5%, 1.0%, and 1.5% by volume. A total of 54 concrete 
specimens were produced and evaluated. The CKS was appropriately processed and 
pre-soaked before mixing, while a superplasticizer was used to optimize workability. 
The specific gravity of CKS ranged from 2.36 to 2.42 kg/m³. Increasing CKS content 
increased slump while maintaining medium workability and reduced concrete density 
by 24%, satisfying lightweight concrete criteria. The mixture containing 5% CKS 
exhibited the best mechanical performance, attaining compressive, tensile, and 
flexural strengths of 29 MPa, 3.5 MPa, and 5.85 MPa, respectively. At 15% CKS 
replacement, corresponding strengths were 24 MPa, 2.6 MPa, and 4.65 MPa, 
respectively, exceeding applicable Nigerian minimum strength requirements. PPF 
incorporation enhanced concrete toughness and crack-control capacity. Overall, 
CKS–PPF concrete was technically viable at CKS replacement levels up to 15%, 
providing a beneficial pathway for agro-waste valorization. A 5% CKS replacement is 
recommended for structural elements, while 10–15% is suitable for secondary 
members, combined with 0.5–1.0% PPF. Further investigations should evaluate long
term durability and microstructural characteristics.