# Study on Temperature Correction of Asphalt Pavement Deflection Based on the Deflection Change Rate
###### Abstract  
The pavement deflection measured by falling weight deflectometer (FWD) detection equipment can be used to determine the bearing capacity of a pavement structure through modulus backcalculation to provide suggestions for pavement structure maintenance. However, because asphalt mixtures are temperature-sensitive materials, they are greatly affected by temperature, and changes in temperature can cause their mechanical properties to vary and affect the structural bearing capacity. Therefore, this paper conducts a pavement deflection test on an in-service highway asphalt pavement at different temperatures in different seasons. The representative temperature of the asphalt layer was determined through comparative analysis. The temperature's effective influence distance on the deflection basin was found, and a more suitable temperature correction model for the deflection basin of asphalt pavement was established. The results showed that the temperature at the middle layer depth of the asphalt layer is more suitable as the representative temperature of the asphalt layer. The effective influence range of temperature on the deflection basin is 90 cm. The deflection change rate before and after the temperature correction at a radial distance of 20 cm is more appropriate for the temperature correction of the deflection basin. backcalculation. We refer to this temperature correction method as first-correction [13; 14]. Usually, the deflections should be normalized at first so that other factors (humidity, asphalt layer damage, asphalt aging, etc.) have minimal influence on the deflection-temperature correction model [15]. To better model the deflection temperature correction, an accurate representative temperature of the pavement should be obtained. The temperature of the asphalt layer varies with depth. For changes in temperature with the depth of the pavement, the temperature's influence on the stress state is more significant when the pavement's thickness is deeper. Usually, the temperature at a certain depth is selected to represent the asphalt layer temperature. Different researchers have different opinions on which depth to choose. [PERSON] and [PERSON] et al. took the temperature of the top third of the asphalt layer as the representative temperature of the asphalt layer and achieved good fitting results [16; 17]. [PERSON] et al. found that the temperature at near the center of the asphalt layer can represent the actual temperature of the entire asphalt layer [18; 19]. [PERSON] and [PERSON] investigated the effect of different load magnitudes on the deflection temperature correction factors and obtained a linear relationship between the deflection and the temperature in the middle asphalt layer in semi-logarithmic coordinates [20]. These analyses are mostly based on flexible pavements. However, semi-rigid asphalt pavement is widely used in China. The temperature in the middle asphalt layer is used as a representative temperature in most of the temperature correction model studies [13; 21]. Current asphalt pavement temperature prediction models can be divided into two categories: mathematical statistical methods and theoretical methods [22; 23; 24; 25]. The mathematical statistical method refers to the use of the actual measured pavement temperature combined with the meteorological data at that time to determine a pavement temperature calculation formula through regression analysis. The theoretical method derives the expression of the pavement temperature through the principle of heat transfer based on the thermodynamic properties and meteorological data of the pavement material. Comparing the two methods, the mathematical statistics method is relatively simple, while the theoretical method is too complicated. Although the mathematical statistics method has certain regional characteristics, it is still effective for regions with similar climates.