Papers by Author: Jin Xiang Hong

Abstract: To find out the toughening mechanism of in-situ toughening telechelic polymers (ITTP) in concrete, SEM & EDS and Nano indenter were used to research the variation of concrete hydration products and the interfacial transition zone between the cement paste and aggregate. The results indicate that the toughening effect of ITTP is not carried out by film formation. And the proportion of LD C-S-H in cement hydration products increased significantly and the CH content decreased after introducing the ITTP into concrete. Nano indentation test results show that the non-dense area ratio of ITZ decreased, and the CH content in ITZ increased slightly. The Ca/Si blurred from mutation pattern with decreasing the distance to aggregate surface in the region of interfacial transition zone between aggregate and cement paste, and the thickness of ITZ increased. The conclusions show that the ITZ and hydration products are both key micro-structures which affect the toughness of concrete, and it provides us some guidance for realizing concrete toughness ascension through microstructure adjustment.

Abstract: Semi-flexible pavement (SFP) has some excellent characteristic such as high carrying capacity, good wearing resistance, water stability and durability. However, the SFP appears low temperature crack and fatigue cracking seriously because there are large differences in the interfacial bonding property and the elastic modules between its two major parts: Lag gap asphalt mixture (LGAM) and cement mortar. All of these are caused by the large stiffness of cement mortar. In order to improve the crack resistance property of SFP, six kinds of cement-emulsified asphalt mortars (CEAM) were developed to enhance the adhesive property and reduce the elastic modules. The cement-emulsified asphalt mortar semi-flexible pavement material (CEAMSFP) was obtained by using this kind of CEAM. In the CEAM and the CEAMSFP, six emulsified asphalt-to-cement (A/C) ratios were considered in the study: 0, 0.1, 0.2, 0.3, 0.4 and 0.5 by weight of emulsified asphalt. The results indicated that the increasing of the A/C ratio improved the bonding interface and the flexible of the CEAM. The increasing of the A/C ratio improved the low temperature resistance and fatigue life of the CEAMSFP. It was also shown that the A/C ratio of 0.3 was found to be the optimum ratio that achieved a balance in performance and the value of the pavement. In this condition, the adhesion level between LGAM and cement grout reached 5，the elastic modules of mortar decreased by 62.5% and the fatigue life of SFP increased by 43.6%.

Abstract: Research in the laboratory was carried out to determine if addition of warm mix asphalt additive (Sasobit) has potential to reduce the temperature comparison with control mix. To fulfill this purpose five types of asphalt binders have been produced with a Sasobit additive in concentration range from 0 to 10% by weight of the asphalt. Viscosity test and dynamic shear rheometer test are conducted for the investigation of effects of Sasobit on rheological properties characteristics of binders. Viscosity tests on binders indicated that the Sasobit binders had significantly lower viscosities compared to control binders at the temperature above 100°C, indicating that Sasobit can reduce the mixing and compaction temperatures above the melting point of Sasobit. Sasobit modified binders are more sensitive cracking and had more excellent rutting resistance properties at service temperatures compared with original bitumen. Based on the test results, the suggest content of Sasobit addition is 3% by weight.