Haiqin Xu

Bio: Haiqin Xu is an academic researcher from Wuhan University of Technology. The author has contributed to research in topics: Asphalt concrete & Asphalt. The author has an hindex of 2, co-authored 6 publications receiving 23 citations.

Study on Recycling of Steel Slags Used as Coarse and Fine Aggregates in Induction Healing Asphalt Concretes.

Abstract: Steel slag, a by-product of steelmaking, imposes lots of negative impacts on the environment. For alleviating negative impacts, more and more experiments have been carried out to explore the application possibility of steel slag. The purpose of this study is to explore the feasibility of steel slag being applied in induction healing asphalt concretes to replace coarse and fine aggregate. Surface texture and pore sizes of steel slag were firstly tested, and then steel slag and basalt asphalt mixtures modified with steel fibers were prepared. Moisture susceptibility, dynamic stability, mechanical property, thermal property, induction heating speed, natural cooling speed and healing property of the asphalt mixtures were evaluated. Results showed that steel slags had more obvious holes in the surface while the surface area is much larger than that of basalt. Furthermore, steel fibers and steel slag both have dynamic stability, and steel fibers contribute to increased moisture resistance while steel slag is not. Steel slag asphalt concrete showed better mechanical property and better capacity to store heating. Steel slag asphalt mixtures had a similar heating speed to basalt asphalt mixtures but a significantly slower cooling rate. Finally, the induction healing test and CT scanning test demonstrated that steel slag asphalt mixtures had a similar healing ability to basalt asphalt mixtures. It can be concluded that steel slags have the potential to replace the natural aggregates to be applied in induction heating self-healing asphalt concretes.

Silicone Resin Polymer Used in Preventive Maintenance of Asphalt Mixture Based on Fog Seal.

Abstract: The commonly used materials in fog seal are emulsified asphalt and modified emulsified asphalt. Nevertheless, there are some intractable problems including aging under ultraviolet, poor permeability, and moisture susceptibility. Therefore, silicone resin polymer was used as a kind of innovative fog seal material in this study. Physicochemical properties of solidified silicone resin were characterized. X-ray computed tomography and 3D reconstruction technology were used to evaluate permeability and distribution of silicone resin polymer in an asphalt mixture. Moisture sensitivity and high-temperature performance of the asphalt mixture maintained by silicone resin polymer were also detected. The results show that surface characteristic of silicone resin can effectively isolate moisture, thereby improving moisture resistance of the asphalt mixture. Silicone resin was found to be evenly distributed throughout the pores of a sample when the dosage was 400 or 600 mL/m2. The pore filling rate increased by 16.3% when the dosage was changed from 200 to 400 mL/m2, whereas it only increased by 3.7% when dosage increased from 400 to 600 mL/m2. Moisture damage resistance of asphalt mixtures generally increased as the dosage of silicone was increased. However, as the dosage increased from 400 to 600 mL/m2, the growth rate in residual Marshall stability (RMS) and tensile strength ratio (TSR) slowed significantly since the pore filling effect of silicone has reached the upper limit. Dosage of silicone resin has little effect on the results of the rutting test while it has significant influence on Hamburg wheel tracking test (HWT). Furthermore, it was found that 400 mL/m2 is the optimum silicone dosage for open-graded friction course (OGFC)-13 mixture in consideration of permeability, distribution, performance of mixture, and economic cost.

Characterization of Steel Slag Filler and Its Effect on Aging Resistance of Asphalt Mastic with Various Aging Methods.

Abstract: Steel slag is the by-product of the steelmaking industry, the negative influences of which prompt more investigation into the recycling methods of steel slag The purpose of this study is to characterize steel slag filler and study its feasibility of replacing limestone filler in asphalt concrete by evaluating the resistance of asphalt mastic under various aging methods Firstly, steel slag filler, limestone filler, virgin asphalt, steel slag filler asphalt mastic and limestone filler asphalt mastic were prepared Subsequently, particle size distribution, surface characterization and pore characterization of the fillers were evaluated Finally, rheological property, self-healing property and chemical functional groups of the asphalt mastics with various aging methods were tested via dynamic shear rheometer and Fourier transform infrared spectrometer The results show that there are similar particle size distributions, however, different surface characterization and pore characterization in the fillers The analysis to asphalt mastics demonstrates how the addition of steel slag filler contributes to the resistance of asphalt mastic under the environment of acid and alkaline but is harmful under UV radiation especially In addition, the pore structure in steel slag filler should be a potential explanation for the changing resistance of the asphalt mastics In conclusion, steel slag filler is suggested to replace limestone filler under the environment of acid and alkaline, and environmental factor should be taken into consideration when steel slag filler is applied to replace natural fillers in asphalt mastic

Effect of Coarse Aggregate Morphologies on the Hydrodynamic Pressure–Resulted Moisture Susceptibility of Asphalt Mixtures

Abstract: Many pavement field distresses are caused by moisture damage. However, hydrodynamic pressure is not taken into account by a common laboratorial moisture test of asphalt mixture. Furthermore...

Performance of Concrete Beams Reinforced with Various Ratios of Hybrid GFRP/Steel Bars

Abstract: This paper aims to study the flexural behavior of concrete beams reinforced with hybrid combinations of GFRP/steel bars. To this purpose an experimental program was carried out on four concrete beams reinforced with Glass Fiber Reinforced Polymer (GFRP) and twelve hybrid GFRP/steel Reinforced Concrete (RC) beams. Flexural behavior of the tested beams such as stages of response, failure modes, crack patterns, stiffness, toughness and ductility were analyzed. The experimental results showed that depending on GFRP/steel reinforcement configurations, the behavior of hybrid GFRP/steel RC beams undergoes three or four stages, namely: pre-cracking stage; after concrete cracking and before steel yielding; post-yield stage of the steel bar until peak load and failure stage. Totally six failure modes of hybrid RC beams are reported depending on reinforcement rations and configuration. The effect of reinforcement configuration and ratio of GFRP to steel ( ρ g ) on the crack patterns, stiffness, ductility and toughness of hybrid RC beams are significant. Based on the non-linear deformation model, an analytical model has been developed and validated to determine the steel yielding moment and ultimate moment of hybrid GFRP/steel RC beams. It could be seen that the experimental values were in good agreement with the predicted values.