RESUMO
In this study, raw grinded groundnut shell (RGGNS) was used as a fine aggregate in the brick industry to reuse agricultural waste in building materials. In this study, an experimental approach was used to examine a new cement brick with raw groundnut shells integrated with compressive strength, water absorption and dry density optimization utilizing response surface methodology (RSM). The raw ground-nut shell content improved the fine aggregate performance of the 40%, 50%, and 60% samples. The 28-day high compressive strength with the raw ground-nut shell was 6.1 N/mm2 maximum, as needed by the technical standard. Samples made from 40%, 50%, and 60% raw groundnut shells yielded densities of 1.7, 2.2, and 1.9 kg/cm3 for groundnut shell (GNS) brick, respectively. A product's mechanical properties meet the IS code standard's minimum requirements. RSM was then utilized to develop a model for the addition of raw groundnut shell to concrete. R-square and Adeq precision values indicated that the results are highly significant, and equations for predicting compressive strength, water absorption, and dry density have been developed. In addition, optimization was performed on the RSM findings to determine the efficiency optimization of the model. Following the optimization results, experiments were conducted to determine the applicability of the optimized model.
RESUMO
Metakaolin (MK) is one of the most sustainable cementitious construction materials, which is derived through a direct heating procedure known as calcination. Calcination process takes place substantially lower temperatures than that required for Portland cement, making it a more environmentally sustainable alternative to traditional cement. This procedure causes the removal of hydroxyl water from the naturally occurring kaolin clay (Al2Si2O5(OH)4 with MK (Al2O3·2SiO2) as its product. Kaolin naturally exists in large amount within 5°29'N-5°35'N and 7°21'E-7°3'E geographical coordinates surrounding Umuoke, Obowo, Nigeria. Alumina and silica are the predominant compounds in MK, which provide it with the pozzolanic ability, known as the 3-chemical pozzolanic potential (3CPP), with high potential as a cementitious material in concrete production and soil stabilization. Over the years, researchers have suggested the best temperature at which MK is derived to have the highest pozzolanic ability. Prominent among these temperature suggestions were 800 °C (3CPP of 94.45%) and 750 °C (3CPP of 94.76%) for 2 h and 5 h' calcination periods, respectively. In this research paper, 11 different specimens of Kaolin clay obtained from Umuoke, Nigeria, were subjected to a calcination process at oven temperatures from 350 to 850 °C in an increment of 50 °C for 1 h each to derive 11 samples of MK. The MK samples and Kaolin were further subjected to X-ray fluorescence), scanning electron microscopy (SEM) and X-ray diffraction (XRD) Brunauer-Emmett-Teller (BET) tests to determine the microstructural behaviour and the pozzolanic properties via the 3CPP as to exploit the best MK with the highest cementing potential as a construction material. The results show that the MK heated at 550 °C and 800 °C produced the highest pozzolanic potentials of 96.26% and 96.28%, respectively. The enhancement in pozzolanic potential at optimum calcination temperature is attributed to an increase in the specific surface area upon calcination of kaolinite confirmed by BET results. The SEM and XRD results further supported the above result with the strengthened crystal structure of the MK at these preferred temperatures. Generally, 550 °C is more preferred due to the less heat energy needed for its formulation during 1 h of calcination, which outperforms the previous results, that suggested 750 °C and 800 °C in addition to longer hours of heat exposure.
