Feasibility study on the use of shell sunflower ash and shell pumpkin ash as supplementary cementitious materials in concrete

Abstract This study proposes that Shell Sunflower Ash (SSA) and Shell Pumpkin Ash (SPA) partially replace cement in concrete as pozzolanic materials. To trace the chemical composition of raw SSA and SPA, X–Ray diffraction (XRD) and scanning electron microscopy (SEM) were utilized. Cement was replaced with 5, 10, 15 and 20% of the SSA and SPA. The slump of fresh concrete, elastic modulus, compressive strength, ultrasonic pulse velocity (UPV) test, SEM, energy dispersive x–ray (EDX), XRD and thermo-gravimetric analysis (TGA) of the sample were studied. Pozzolanic reaction with percentage of SSA and SPA was lower than the control specimen in the early ages. The addition of the SSA to the mix by up to 15% increased the compressive strength of the sample by 27.3% at 28 days. The SEM and EDX results illustrate the replacement of cement with the SSA and the SPA can improve the microstructure of the mixtures at 28 days. The SEM also showed that the addition of 15% the SSA and the SPA decreased the voids in the matrix. XRD and TAG results also demonstrated the effect of SSA and the SPA on reduction of CH content due to pozzolanic reactions. The result show that use of the SSA and SPA as replacement of cement is feasible.