A comparative study of mechanical and environmental properties of concrete using jujube nucleus as a coarse aggregate

The ever-increasing generation of aggregates in the construction industry has caused a serious burden on the environmental protection of mountains and ecosystems. The shortage of natural coarse aggregate provides an impetus for the utilization of agricultural waste. Aiming to provide a cleaner option for the production of agricultural waste concrete originating from agricultural by-products jujube nucleus, the viability of using jujube nucleus as a substitute for coarse aggregate in the preparation of agricultural waste concrete is experimentally investigated in this study. The workability, weight loss, mechanical and environmental properties of jujube nucleus concrete (JNC) were evaluated with the variation of five different jujube nucleus (JN) replacement ratios (i.e., 0 %, 25 %, 50 %, 75 %, and 100 %), and five different temperatures (i.e. 20 °C, 200 °C, 400 °C, 600 °C, and 800 °C). The results show that as the JN replacement ratio increases, the slump values of JNC decreased gradually whilst the weight loss of JNC is more obvious than that of ordinary concrete with the increase in the elevated temperature, which is probably due to the growing amount of ettringite having chemical-bound water caused by sucrose molecules. In addition, the increase in the JN replacement ratio would decrease the compressive strength of JNC as compared to ordinary concrete, with a minimum and maximum reduction of about 26 % (25 %) and 97 % (100 %) respectively. As the elevated temperature increases, the compressive strength of JNC with 25 % JN replacement ratio also decreases, with a minimum and maximum reduction of approximately 28 % (100 °C) and 37 % (400 °C) respectively. A series of calculation formulas are established to predict the compressive performance of JNC by considering the JN replacement ratio and the elevated temperature. The cost and EI assessment indicate that the utilization of jujube nucleus in concrete material could reduce the consumption of non-renewable resources and ozone depletion to a certain extent. On a whole, the JNC with the 25 % JN replacement ratio may be the appropriate solution for the usage of jujube nucleus in agricultural waste concrete production. This paper provides a theoretical basis for the application of jujube nucleus in concrete materials, paving a way to exploit the JNC products as an alternative solution for a sustainable built environment.