During the service period, asphalt materials are affected by various natural factors, including heat, ultraviolet light, oxygen and moisture, etc., resulting in the reduction of pavement performance, the increase of pavement distress and shortening of service life. This study aims to investigate the aging performance of asphalt under multiple aging conditions of heat, UV and aqueous solution. Thermal-oxygen aging, UV aging and hydrostatic erosion tests were carried out sequentially on asphalt. The rheological properties, chemical structure and element composition of asphalt were characterized before and after aging, and the effect mechanism of multiple conditions was discussed. The results show that the multiple conditions of heat and UV can increase the rutting resistance and weaken the cracking resistance of asphalt. However, the effect degree of UV decreases gradually with the deepening of aging degree. Additionally, the effect of water on the physicochemical properties is less than that of UV; however, water can increase the sensitivity of physicochemical properties to UV. In summary, this study explored the short-term cycling effect of heat, light and water on asphalt and provided an idea for simulation test of asphalt under multiple aging condition.

@en

In this paper, a method to predict the healing effect of induction heating asphalt concrete at vertical depths was proposed and verified. At first, AH-70 asphalt concrete and SBS modified asphalt concrete of AC-13 gradation were designed and prepared. R-DT (Relationship of Depth and Temperature) was quantified through induction heating test. R-HT (Relationship of Healing rate and Temperature) was quantified through fracture-healing–fracture test and X-ray micro computed tomography test with oven heating. Then, linear regression was used to verify the rationality of R-HT compared with the pre-relationship in previous studies. Finally, R-DH (Relationship of Depth and Healing rate) was predicted by fitting approach. It was found that R-DT and R-HT presented significant linearity, the existence of which was independent from the type of asphalt materials. While, more sensitive of SBS modified asphalt concrete showed that the response to gradient characteristics of R-DT was related to the higher overall temperature. Additionally, R Square-values = 0.963 of linear regression proved the oven heating method was suitable for the quantification and prediction of gradient characteristics. Furthermore, the prediction of R-DH was obtained successfully, which established the continuous distribution of the healing effect at vertical depths and revealed the linear relationship of the continuous distribution.

@en

This paper presents an experimental investigation on the potential utilization of one natural zeolite as an internal curing agent for mitigation of self-desiccation and the subsequent autogenous shrinkage of cement paste with low w/b ratio (0.25). Incorporation of 20% zeolite by mass leads to higher internal relative humidity (90.4%) during the first 7 d compared to that of control sample (78.1%). It is indicating that the zeolite under investigated shows partially elimination effect on the self-desiccation and the autogenous shrinkage as well based on the time-zero defined by the onset of internal relative humidity drop. To obtain improved internal curing property, attempts have been done to modify the pore structure of zeolite by acid treatment and/or thermal treatment. However, both nitric acid treatment and thermal treatment shows negative effect on the improvement of internal curing property of zeolite. Because nitric acid treatment tends to increase the BET surface area of zeolite by increasing the volume of 2–7 nm pores, and the thermal treatment tends to reduce the porosity rather than to enlarge the pore size of zeolite.

@en

The present study aims to evaluate the characterization of combustion ash of miscanthus and its possible application for self-desiccation and autogenous shrinkage mitigation in cement-based materials. Comprehensive tests were performed on the sealed samples to evaluate the behavior of self-desiccation and autogenous shrinkage of low water/binder ratio (0.25) cement pastes blended with miscanthus ash (MA). The lab-generated MA is featured by high content of amorphous silica and porous structure. Its porous structure with pore size distribution mainly within the range of 30–50 nm in diameter makes it a potential internal curing agent for self-desiccation and autogenous shrinkage mitigation. Incorporation of 20% by weight MA into cement paste shows high efficiency in self-desiccation mitigation, contributing to the significantly reduced autogenous shrinkage. Decreasing the mean particle size from 20.43 µm to 6.67 µm lowers the self-desiccation mitigation efficiency of biomass ash MA in the blended cement pastes.@en

The aim of present study was to investigate the potential utilization of one cogeneration generated biomass ash Napier grass ash (NGA) as SCMs in cement-based materials. The chemical and mineral composition of NGA and its morphology characterization were investigated by means of XRF, XRD and SEM. In addition, the effect of NGA addition on the hydration of blended mixtures was studied by means of isothermal calorimetry. Furthermore, the effect of NGA addition on the properties of blended mortars was characterized by flowability and mechanical strength. The results show that the NGA from the industrial process presents irregular shapes with roughness and porosity surface textures and contains high silica content as well as high LOI. Further thermal treatment at 400 °C was applied aiming to reduce the LOI. The cement replacing by NGA (20% by mass) can partially contribute to the cement hydration. The mechanical strength results indicate that the NGA can meet the requirement to classify the material as a pozzolan no matter whether a further burning process was applied or not. In the present study, the pozzolanic behavior of NGA is slightly higher than that of FA, in terms of compressive strength. It will be of great interest to optimize the combustion technology to produce NGA ashes with lower LOI, aiming to improve its performance in mortar preparation.@en

A 2D lattice model was constructed to simulate crack process of in shell-interlayer-cement paste zone. The simulated tensile strength was validated by an experimental uniaxial tensile test and used as the input for a 3D lattice model, which was constructed to perform mechanical analysis based on a series of 2D X-ray microtomography images. The fracture behaviour of the 3D lattice model with assigned mechanical properties gave a similar crack pattern and tensile strength as the real structure. This study is expected to provide a feasible approach for investigating the fracture and trigger behaviour miccrocapsules embedded in a self-healing cementitious system.

@en