Biao Ma

Study on Application of PCM in Asphalt Mixture

The application of Phase Change Material (PCM) to asphalt mixture can lighten the temperature-dependent disease of the asphalt pavement and improve the usability as well as extend the operating life of it. We choose agreeable PCM with comprehensive consideration to the technical requirement of its application in the construction industry and the characteristic of asphalt mixture. Through simulating temperature experiment, we make a conclusion that incorporate the carrier accompanied PCM into asphalt mixture can reduce the increasing rate and cooling rate of the mixture, which shows that PCM can put into use of adjusting the asphalt mixture operating temperature, softening the negative influence of ambient temperature variation on asphalt mixture.

Exploration of road temperature-adjustment material in asphalt mixture

Road temperature-adjustment material (RTM) was studied in this research to adjust the working temperature for asphalt mixture. The RTM is constituted from the solid–liquid phase change material (PCM) as the main component of unsaturated organic acid and the polypropylene carrier. The effect of RTM on the working temperature of asphalt mixture was analysed by monotonic cooling test, cooling–heating cycle test and field simulation cycle test. Results of monotonic cooling and cooling–heating cycle tests indicated that RTM mixed into asphalt mixture helped to reduce the amplitude of temperature variation in the cooling and heating process, and also postponed the extreme temperature appearance time. Results of field simulation test showed that RTM helped to decrease the highest temperature during the heating process and increase the lowest temperature during the cooling process, which reduced the temperature adverse impact on asphalt mixture. Test results indicated that asphalt mixture with RTM actively adjusted the working temperature with damping effect, and also enhanced the temperature resistance capacity for asphalt mixture as well as improved asphalt mixtures adaptability to the changing environment. Therefore, RTM is an inspiration and new method to solve the worldwide problems of low-temperature cracking and high-temperature deformation of asphalt pavement in the future.

Determination of Specific Heat Capacity on Composite Shape-Stabilized Phase Change Materials and Asphalt Mixtures by Heat Exchange System

Previous research has shown that composite shape-stabilized phase change material (CPCM) has a remarkable capacity for thermal storage and stabilization, and it can be directly applied to highway construction without leakage. However, recent studies on temperature changing behaviors of CPCM and asphalt mixture cannot intuitively reflect the thermoregulation mechanism and efficiency of CPCM on asphalt mixture. The objective of this paper is to determine the specific heat capacity of CPCM and asphalt mixtures mixed with CPCM using the heat exchange system and the data acquisition system. Studies have shown that the temperature-rise curve of 5 °C CPCM has an obvious temperature plateau, while an asphalt mixture mixed with 5 °C CPCM does not; with increasing temperature, the specific heat capacities of both 5 °C CPCM and asphalt mixture first increase and then decrease, while the variation rate of 5 °C CPCM is larger than that of the asphalt mixture, and the maximum specific heat capacity of 5 °C CPCM appears around the initial phase change temperature. It is concluded that the temperature intervals of 5 °C CPCM are −18 °C–7 °C, 7 °C–25 °C and 25 °C–44 °C, respectively, and that of the asphalt mixture are −18 °C~10 °C, −10 °C~5 °C and 5 °C~28 °C. A low dosage of 5 °C CPCM has little influence on the specific heat capacity of asphalt mixture. Finally, the functions of specific heat capacities and temperature for CPCM and asphalt mixture mixed with CPCM were recommended by the sectional regression method.

Applying Method of Moments to Model the Reliability of Deteriorating Performance to Asphalt Pavement under Freeze-Thaw Cycles in Cold Regions

AbstractAccurate deterioration models play a critical role in designing and managing transportation infrastructure. Regular models simply consider loading factor and its relative uncertainties. However, climate and environment impacts are not considered, or are just used as certain variables. Thermal cracks and moisture distresses are principal distress forms in cold regions. In this study, a freeze-thaw (F-T) cycle test was used to simulate the influence of adverse weather conditions in cold regions, like moisture and temperature impact. Then method of moments was applied to analyze the pavement reliability functions with various uncertainties. The analytical results showed that the resilient modulus of asphalt concrete mixture declined under F-T cycles. Consequently, pavement structure capacity was reduced. The results also illustrated that the reliability method was capable of accommodating uncertainties in pavement parameters. The sensitivity analysis indicated that F-T cycles had a significant impact...

Loading capacity strengthening to cement-stabilised crushed gravel using reinforced wire mesh

Settlement and non-uniform deformation of frozen soil subgrade introduce fatal cracks on semi-rigid base asphalt pavements. This research aims to use reinforced wire mesh to reduce serious cracks on semi-rigid asphalt pavements in frozen regions. Three impact factors, diameter and interval as well as two types of wire mesh have been analysed by loading tests. Results have shown that after setting the reinforced wire mesh: (a) failure load and displacement of the cement-stabilised crushed gravel samples have been improved; (b) diameter and interval of the wire mesh have interactive impacts on reinforced sample load capacity; (c) the reinforced wire mesh can limit cracks by redistributing stress in the specimen; and (d) the multiple linear regression model well reflects the variation of loading properties; the results make sense from the statistics view as well. Results also represent that the strengthened wire mesh can help spread out the applied load, and increase the overall loading capacity of cement-stabilised crushed gravel. The results provided a reference for semi-rigid base asphalt pavement cracks caused by non-uniform deformation on frozen soil subgrade as well as guidelines for construction and maintenance in frozen regions.

Study on Road Performance of Phase-Change Temperature-Adjusting Asphalt Mixture

Mixing the composite phase change material (CPCM) to asphalt mixture is a new way to solve the worldwide problem of the low-temperature cracking and high temperature rutting of the asphalt pavement. Asphalt mixture with CPCM can remain in the ideal working temperature range for a relatively long time. This paper analyzes the influence of the contents of CPCM on its road performance by laboratory testing. The study shows that mixing CPCM to asphalt mixture had little effect to the optimal asphalt content. For CPCM prepared by polymer shape-stabilized method, the high-temperature stability and the water stability of asphalt mixture increases firstly and then decreases the low-temperature anti-cracking stability decreases firstly and then increases with the increasing of CPCM. For CPCM prepared by carrier-adsorbed packaging process, the high-temperature stability decreases, low-temperature anti-cracking stability decreases firstly and then increases, the water stability increases firstly and then decreases with increasing of CPCM. The results indicate that CPCM has significant influences on its road performance. The optimal content of CPCM is around 0.3%.

Effect of Composite Shape-Stabilized Phase Change Material on Asphalt Mixture Temperature

It provides a new way to solve the worldwide the low-temperature cracking and high temperature rutting distresses of the asphalt pavement, by mixing the composite shape-stabilized phase change material (CSPCM) to asphalt mixture. The effect of CSPCM on the temperature of asphalt mixture is analyzed by the monotonic cooling test, the monotonic heating test and the outdoor simulating cycle test. The results of monotonic cooling and heating tests indicate that mixing CSPCM into asphalt mixture can increase the temperature of asphalt mixture during cooling process and decrease the temperature of asphalt mixture during heating process. It has a temperature damping effect as well. The results of outdoor simulation test shows that mixing CSPCM into asphalt mixture decreases the maximum temperature of the bottom of the specimen and increases the minimum temperature of the bottom of the specimen. It cannot change the critical temperature occurring time of the bottom of the specimen. The test results indicate that mixing CSPCM into asphalt mixture could actively adjust the working temperature of asphalt mixture, prolong the ideal temperature of asphalt mixture and improve asphalt mixture’s adaptability to the changing environment.

Impact of freeze-thaw cycles on compressive characteristics of asphalt mixture in cold regions

Low average temperature, large temperature difference and continual freeze-thaw (F-T) cycles have significant impacts on mechanical property of asphalt pavement. F-T cycles test was applied to illustrate the mixtures’ compressive characteristics. Exponential model was applied to analyze the variation of compressive characteristics with F-T cycles; Loss ratio model and Logistic model were used to present the deterioration trend with the increase of F-T cycles. ANOVA was applied to show the significant impact of F-T cycles and asphalt-aggregate ratio. The experiment results show that the compressive strength and resilient modulus decline with increasing F-T cycles; the degradation is sharp during the initial F-T cycles, after 8 F-T cycles it turns to gentle. ANOVA results show that F-T cycles, and asphalt-aggregate ratio have significant influence on the compressive characteristics. Exponential model, Loss ratio model and Logistic model are significantly fitting the test data from statistics view. These models well reflect the compressive characteristics of asphalt mixture degradation trend with increasing F-T cycles.

Shape-memory behaviors of epoxy-functionalized polyhedral oligomeric silsesquioxane/epoxy organic–inorganic hybrid resin systems:

A series of organic–inorganic hybrid resin systems are prepared using hydroepoxy, 1,3-bis(aminomethyl)cyclohexane, and epoxy-functionalized polyhedral oligomeric silsesquioxane (POSS-Ep). The thermomechanical properties and shape-memory behaviors of the hybrid materials are systematically investigated by differential scanning calorimetry, thermogravimetric analysis (TGA), dynamic mechanical analysis, bend test, and shape recovery test. Results indicate that the glass transition temperature (T g) and rubber modulus gradually increase as the POSS-Ep content increases. The thermal stabilities of the hybrid materials gradually increase with increasing POSS-Ep content. The bend strength of the hybrid materials increases firstly and then decreases as POSS-Ep content increases, showing an extreme value for the hybrid materials with 3.17 mol% POSS-Ep content. Finally, investigation of the shape-memory behavior of the hybrid materials reveals that full recovery can be observed after only several minutes when the temperature is equal to or above T g. The shape recovery time decreases at first and then increases as POSS-Ep content increases at T g, T g + 10°C, and T g + 20°C. These results are attributed to the increase in POSS-Ep content.

Effect of a tetra functional epoxy monomer on the thermomechanical properties of shape-memory epoxy resin

The effect of a tetra functional epoxy monomer on thermomechanical properties and shape recovery performance of a shape-memory epoxy resin system was studied. The system is prepared using hydro-epoxy, tetra functional epoxy monomer (AG-80), and glutaric anhydride. The molecular structure of the shape-memory epoxy resin system can be changed by varying AG-80 content. Fundamental trends are established between the chemical structure, cross-link density, glass transition temperature (Tg), rubber modulus, bend strength, and shape-memory properties. The thermal and thermomechanical properties of shape-memory epoxy resin system are characterized by differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA), and the results indicate that the Tg and rubber modulus increase as AG-80 content increases. The room-temperature bend strength increases at first and then decreases with increasing AG-80 content. Shape memory properties are also studied using a U-type shape-memory test. Results show that full recovery is achieved after only several minutes when the temperature is equal to or above Tg. Shape recovery time decreases initially and then increases with increasing AG-80 content, thereby showing an extreme value for the system with 8.33 mol% AG-80 content. These results are attributed to the increase in AG-80 content.