Key Engineering Materials Vol. 599

Abstract: The large production of tailings has caused soil, water and air pollution and serious potential safety hazard. The composition, particle morphology, particle size distribution of the silica-calcium tailings are investigated to assess the feasibility of using it in concrete in this paper. The silica-calcium tailings are mainly composed of quartz, calcite and dolomite. The results show that the tailings powder can stimulate the hydration of cement and fill the gradation gap between fine aggregate and cementitious materials in concrete as micronized sand to meet the requirements of concrete. The incorporation of silica-calcium tailings in concrete reduces the ultimate total shrinkage, autogenous shrinkage and drying shrinkage at early age.

Abstract: The production of steel slag, a byproduct of the steel refining keeps increasing rapidly and it reached 90.42 million tons in 2011 in China, but its comprehensive utilization ratio is only 22% and far less than the ratio of 65% in Europe. Main chemical compositions of steel slag are CaO, SiO2, Al2O3, FeO, Fe2O3, MgO, MnO, P2O5 and so on, C3S, C2S, C3MS2, RO phase are its common minerals. Due to its high reactivity and Ferro content, steel slag has high potential utilization as supplementary hydraulic cementitious materials or cement clinker meal in cement industry. A method of multiple phased sintering was presented, it can break through the bottlenecks for the steel slag using in the cement industry, e.g. volume stability and grindability ,the carbon emission of cement industry is slashed, it is an effective new approach to massively utilize steel slag in cement industry.

Abstract: Based on the expressway construction from Xilinhaote to Sanggendalai in China, this paper discussed difficulties and solutions of asphalt mixture using andesite aggregate used as pavement lower surface. There are a lot of andesite reserves in Ximeng area, China. However, andesite aggregate has poor adhesion with asphalt bitumen because of its fragile textures, dense surface and low water absorption rate .Consequently the moisture stability of asphalt mixture using andesite aggregate is poor. Meanwhile, the mixture can not be compacted easily due to the hardness of andesite aggregate. In this paper, in order to solve the problem on the poor adhesion and compaction for asphalt mixture using andesite aggregate, different methods were investigated. The results show that adding adhesion agent or using limestone fine aggregate is an effective way to make the asphalt mixture acting as pavement lower surface.

Abstract: Anti-rut agent, named RPS-3000,was added into AC-25 asphalt mixture and its effects on high temperature stability, low temperature cracking resistance, water damage resistance and fatigue life were investigated in this paper. Results showed that the high temperature stability and low temperature crack resistance of the asphalt mixture improved significantly, the water damage stability increase slightly due to the introduction of anti-rut agents. Besides, the result of fatigue life test presented that excess amount of anti-rut agent may lead a deterioration of fatigue life. Keywords: Anti-rut agent; High temperature stability; Asphalt mixture

Abstract: The fine aggregate plays a vital role in the performances of asphalt mixture. In this paper, four kinds of fine aggregates with different lithology, apparent density and water absorption rate were discussed. Asphalt mixture according to AC-13 is prepared by these four kinds of fine aggregates and the volumetric properties, water stability performance and high temperature performance of asphalt mixture were tested. Research shows that: the aggregate performance and the performance of mixture have obvious corresponding relation, which provides the theoretical basis for the engineering application of composite aggregates.

Abstract: The rapid development of expressway construction has imposed huge pressure on the supply of superior aggregates in China. Gneiss rarely gets applied in pavement construction due to its weak adhesion with asphalt binder. Adhesion strength is directly related to moisture resistance of asphalt mixture. Therefore the main objective of this research was to estimate the effect of composite filler, consist of limestone powder and Portland cement with different proportions, on moisture resistance of gneiss based hot mix asphalt mixture (HMA). X-ray fluorescence (XRF) was applied to determine average chemical composition of raw materials. The effects of composite fillers on moisture resistance were carried out by immerged Marshall test and tensile strength ratio test. Results show that Portland cement significantly improves moisture resistance of gneiss based HMA.

Abstract: The ultraviolet aging effects on fatigue properties of asphalt were studied by using Dynamic Shear Rheometer (DSR). The low-temperature fatigue performance of asphalt has been tested in this paper with the strain-controlled mode of DSR. The samples were compacted under the temperature of 10°C and the constant strain of 2.0% in strain-controlled mode fatigue test. And the results showed that ultraviolet aging decreases the fatigue life-span of asphalt significantly.

Abstract: In order to explore the feasibility of waste edible animal oil used as the asphalt rejuvenator, this study investigated the effect of waste edible animal oil on softening point, penetration, ductility and viscosity of aged asphalt binders. The aged asphalt binders were obtained from the indoor simulating aging processes by using Thin Film Oven Test (TFOT) and Pressure Aging Vessel (PAV). The results show that the dosage of waste animal oil has different effect on physical properties of aged asphalt. Both 70^# asphalt and SBS modified asphalt have the optimal content of waste edible animal oil to achieve the best physical properties. The optimal contents of waste edible animal oil for 70^# asphalt and SBS modified asphalt are 6% and 4%, respectively.

Abstract: Based on the asphalt rejuvenation theory and some related studies, waste cooking oil can be used for asphalt regeneration. The objective of this study is to investigate the high temperature properties of aged asphalt binder with waste edible vegetable oil. The materials used for this study included three sources of virgin asphalt (60-80 grad, 40-60 grad, SBS modified asphalt), three sources of aged asphalt (virgin asphalt aged by RTFOT and PAV), and waste edible vegetable oil with five percentages (3.0, 4.0, 5.0, 6.0, and 7.0% of rejuvenating asphalt). The high temperature characteristics of these rejuvenated asphalts were tested including viscosity and rutting resistance factor (phase angle and complex modulus). The results indicated that three aged asphalt with an appropriate amount of waste edible vegetable oil can respectively achieve the demand of virgin asphalt in rutting resistance factor, phase angle and complex modulus. It means that waste edible vegetable oil could recover high temperature performance of aged asphalt to the level of original asphalt at a certain amount. Moreover, waste edible vegetable oil can slightly reduce the viscosity value of the aged asphalt and thus decrease the mixing and compaction temperature of the mixture.

Abstract: Rejuvenating seal, widely used due to its economic benefits and convenience, is one of the preventive maintenance methods. The rejuvenating seal materials (RSM) work on the surface course of asphalt pavement. This paper described the effects of RSM on the physical properties and rheological properties of aged SBS modified asphalt (ASMA). Two RSM, R and C, were involved in this research. The dosage of each RSM was 2%, 4%, 6%, 8%, and 10% of ASMA by weight. Physical properties, including softening point, penetration and ductility, were tested. Rheological properties were carried out by means of dynamic shear rheometer (DSR). Results show that RSMs, R and C, have improved the low-temperature performance and fatigue resistance. R has more positive effect on low-temperature performance and fatigue resistance of ASMA compared to values of C.