Performance analysis and reuse of construction and demolition waste stone using fractal and gradation theory.

This study aims to control the processing technology of granite aggregate through fractal theory, and to optimize the gradation of concrete to solve the reuse of waste stone derived from the construction and demolition wastes in China. This study applies the waste stone from construction and demolition wastes in concrete and provide a case example for the construction industry to implement the recycle, reuse and reduce principle to affect the management policy of waste stone. The demand for concrete is surging with the continuous expansion of global infrastructure construction. This study presents the process the waste stone produced by excavation along the line to concrete aggregate is a serious problem to be solved. The fractal and gradation theory are employed to investigate the effects of aggregate shape and gradation distribution on the concrete performances, including compressive strength, frost resistance and chloride ion permeability. The larger the fractal dimension of aggregate was, the worse the performance of concrete was. There was always an optimal gradation to optimize the performance of concrete. The 28-day compressive strength of C1 aggregate concrete with larger fractal dimension was 2–3 MPa lower than that of C2 and C3 aggregate concrete. In the freeze-thaw cycle test, the loss of C1 aggregate was 1% more than that of the other two aggregate. 100 times, 200 times and 300 times, the loss of C1 aggregate was reduced by 3–4%, 7–13% and 20% in average. In terms of chloride ion permeability, the impact to chloride ion permeability of graded concrete was greater than that of fractal dimension, and the RCM value of two concrete with worse gradation was about twice as much as that of better gradation concrete. This study conducts the performance analysis and optimize the overall calculation for mix design. The result indicated that larger fractal dimension of aggregate would lead to the worse appeal performance of concrete. When the ratio of 5 mm–10mm aggregate to 10 mm–20mm aggregate is close to 30:70 and the performance is the best. The C50HPC overall calculation method for mix design has achieved better results in engineering practice. Image 1 • The index and method for calculating the fractal dimension of aggregate are proposed. • The relationship between different gradation and fractal dimensions and the main properties of concrete is analyzed. • The proposed mix design method improves the performance guarantee rate of concrete. [ABSTRACT FROM AUTHOR]