Anchorage Bond Strength of Glass Fibre Polymer Reinforced Concrete with Palm Kernel Shells as Partial Coarse Aggregate

Abstract

In recent years, the use of GFRP reinforcing bars in place of steel reinforcing bars in concrete structures such as, buildings, roads, and bridges cannot be overlooked as they offer advantages such as higher tensile strength, corrosion resistance, reduced weight and cost effectiveness compared to steel reinforcing bars. The use of PKS as partial coarse aggregate in steel reinforced concrete has been studied by several researchers and found to produce lightweight concrete and reduce construction cost but, the application of GFRP reinforcing bars in LWC such as PKSC, presents a unique structural material with possibly different mechanical and structural properties which requires further studies and this study specifically focused on determining the anchorage bond strength of Glass Fibre Polymer reinforced concrete with PKS as partial coarse aggregate since the bond strength between concrete and reinforcing bars is a crucial prerequisite for the design of  reinforced concrete as a composite material. Normal weight concrete of mix ratio 1:1.5:3 with water-cement ratio (w/c) of 0.5 and lightweight concrete with 10% of the volume of coarse aggregate replaced by PKS were used in a total of forty-eight (48) double pull-out prismatic specimens of dimension 100mm x 100mm x 300mm for control and test specimens respectively, embedded with 12mm and 16mm diameter GFRP reinforcing bars at varying end-to-end embedment lengths (100mm, 125mm and 150mm) and 300mm continuous embedment. Average anchorage bond strength of 4.684N/mm2 and 3.558N/mm2 were respectively recorded for the PKSC with 12mm and 16mm diameter bars and 100mm embedment length and 3.051N/mm2 and 2.899N/mm2 respectively for PKSC specimens with 12mm and 16mm diameter bars and 150mm embedment length, indicating a decrease in anchorage bond strength with increasing (end-to-end) embedment length. However, the highest average anchorage bond strength of 6.174N/mm2 and 4.581N/mm2 were respectively recorded for PKSC specimens with 12mm and 16mm GFRP reinforcing bars and continuous (300mm) embedment length. Comparatively, the average percentage anchorage bond strength values ranging between 75.5-97.9% of that of NWC were recorded for PKSC and an increase in GFRP reinforcing bar diameter resulted in a decrease in anchorage bond strength. Splitting failure was observed for most of the specimens with longitudinal and transverse crack patterns developed after load application regardless of the size of GFRP reinforcing bar or concrete mix but the extent and visibility of the cracks formed reduced in specimens with continuous bar embedment.