Properties of concrete with modified eggshell powder and ground palm oil fuel ash as partial cement replacement

Abstract

The recent development in the construction industry has shown that some applications requires rapid achievement of early strength such as precast concrete. However, normal concrete achieves maturity at the age of 28 days. One of the methods to attain such early strength is through the incorporation of accelerators in concrete. Most of the accelerators applied in construction industry nowadays are chemically based and might not be environmental-friendly. Therefore, this study focus on the potential use of greener supplementary cementing materials from the avicultural wastes as accelerators. The aim of this study is to investigate the reactivity of Ground Palm Oil Fuel Ash (GPOFA) and eggshell powder (ESP) that contains silicon dioxide (SiO2) and calcium oxide (CaO), respectively as the cementitious materials in order to achieve the early and later strength development of concrete. Various tests were carried out to determine the characteristics of binder including Differential Thermal and Thermo Gravimetry Analysis (DTA and TGA), X-Ray Fluorescence (XRF) spectroscopy, Scanning Electron Microscope (SEM), Particle Size Analyzer (PSA), X-Ray Diffraction (XRD), and Fourier Transform Infrared (FTIR) spectroscopy. The optimum amount of ESP and GPOFA was also determined based on fresh and hardened properties of concrete such as electrical conductivity, slump, hydration temperature, setting time, apparent density, strength activity index, ultrasonic pulse velocity, cube and cylinder compression strength, flexural strength, splitting tensile strength, chloride ion penetration, sulphate resistance, initial water absorption and carbonation test. The results show that the decarbonation ESP (DC-ESP) demonstrated the highest CaO percentage of 98% with the highest calcination temperature compared to uncarbonized ESP (UC-ESP) and carbonized ESP (C-ESP). The active CaO of ESP was obviously increased when the ESP was exposed to higher calcination temperature. The mix proportion with GPOFA and ESPs as a partial cement replacement was investigated and among all the concretes, G15DC5 (GPOFA 15% and DC-ESP 5%) concrete had achieved a significant increment of average compressive strength with 27% and 23% of improved strength compared to normal concrete and GPOFA concrete during the early and later ages. Furthermore, the DTA and TGA, XRD and SEM test on the paste sample based on optimum ESP and GPOFA concrete proven that the energetic effects of combination CaO and SiO2 had dual function ability because its provide calcium hydroxide ((Ca(OH)2) and calcium silicates hydrate (CSH) gel during the early and later strength development of concrete. The abundant amount of ready stock active CaO in DC-ESP has produced more Ca(OH)2 during cement hydration and produced more CSH gel during pozzolanic reaction. In addition, the concrete with optimum ESP and GPOFA also had demonstrated the least defects after the immersion in the sodium chloride solution, the highest compressive strength during sulphate resistance test, had the lowest value of absorption during initial surface absorption test and slightly higher depth in carbonation test. By combining pozzolan materials (GPOFA) with DC-ESP was found to have a superior synergy-reactivity for early and later age of concrete strength development. Hence, this study provides a positive impact for rapid construction technology. As a conclusion, modified ESP is a highly potential as partial cement replacement and accelerator for concrete.