Study on curing characteristics of cold-mixed and cold-laid asphalt mixture based on electrical properties

Abstract

Determination of the rolling time of cold-mixed and cold-laid asphalt mixture is crucial to the operational process and performance of the road. The moisture content of the cold-mixed and cold-laid asphalt mixture is directly related to its curing performance. The research purpose of this paper includes the development of a device for stably testing the electrical properties of cold mixed and cold paving asphalt mixture, the monitoring of water content, and electrical properties of cold mixed and cold paving asphalt mixture at different curing times. The electrical properties of cold-mixed and cold-laid asphalt mixture were tested by a digital bridge instrument (LCR). The relationship model between moisture content and electrical properties was established. The normalization method is used to deal with the electrical performance parameters to avoid the influence of inconsistent initial conditions. The results show that the absolute values of resistance, impedance and inductance of all kinds of emulsified asphalt and their mixtures increase with the decrease of moisture content, and the absolute value of capacitance decreases with the decrease of moisture content. Normalized resistance value, inductance value and impedance value can accurately judge whether the cold-mixed and cold-laid asphalt mixture has been fully cured. The cement absorbs water for hydration, which also increases the mixture's temperature and speeds up the curing rate. When the normalized resistance value is 10 at any A.C. frequency(100 Hz ∼ 100 kHz), it can be considered that the cold-mixed and cold-laid asphalt mixture can be rolled. When the normalized inductance value reaches 100 at a high frequency(100 kHz, 40 kHz), it can also be used as the evaluation index. From the aspects of electrical properties, this paper provided an experimental basis for the construction quality control of cold-mixed and cold-laid asphalt mixture.