Investigating of the usage of rice husk ash as a puzolone in concrete production

Concrete is the leading material used in the construction industry. Pozolonic materials are used to improve concrete properties, increase durability and produce more economical concrete. Many materials can be used as pozzolans in concrete, among which ashes obtained by burning biofuels produced from many agricultural waste materials are also used. One of the agricultural products used as biofuel is rice husks. In this study, it was aimed to determine the effects of using the ashes formed as a result of the burning of rice husks as a pozzolan in the production of concrete on the physical, mechanical and thermal properties of concrete. For this purpose, concrete samples were poured by replacing rice husk ash with cement in four different dosages, 200, 250, 300 and 400, and at 0%, 5%, 10% and 20% weight percent. Unit weight (UW), water absorption, compressive strength, splitting tensile strength, freeze-thaw resistance, thermal conductivity tests were carried out on the produced samples. In addition, the microstructures of the samples for each additive ratio and each dosage amount were examined with the help of SEM images. According to the results of the research, the highest UW values in hardened unit weights were obtained in the concrete with rice husk ash added at 400 dosage, and the lowest UW values were obtained for 20% rice husk ash substitution. It has been determined that the ash substitution of 20% in rice husk at 400 dosage has reduced the UW value by 4.96% compared to the sample without ash, and it has been determined that it has a significant effect in terms of reducing dead load in agricultural structures where high dosage and high strength concretes are used. In the samples produced using rice husk ash at 250 dosage; Compared to the witness sample, increases in compressive strength were observed in the samples with 5% rice husk for all curing times. Although this gives an important idea about the ideal ash percentage that can be used in 250 dosage concrete, this ratio was evaluated to be 5%. In regions where the temperature difference is high, for the optimum dosage in terms of cement amount, the dosage where the compressive strength loss is less than 20% after the freeze-thaw cycle compared to the witness sample was seen only in the 200 dosage rice husk ash substituted concrete group, and this strength loss was more than 20% in the other groups. As a result, when rice husk ash is used as a weight percent between 5 and 10%; It may be possible to produce stronger, more environmentally friendly and more economical concretes.