Performance Of Asphalt Mortar Research Articles

Coal gangue in asphalt pavement: A review of applications and performance influence

The comprehensive utilization of coal gangue is low, and this causes serious environment problems and security risks. The physical and chemical properties of coal gangue were analyzed in this paper, and the estimated value of different chemical components of coal gangue was counted. The physical properties of coal gangue aggregate were analyzed, and performance and its influencing factors of base course mixture with coal gangue aggregate were studied. The influence of coal gangue powder and coal gangue aggregate on performance of asphalt mortar and asphalt mixture was analyzed, and possible influencing factors and function mechanism were discussed. The results showed that heavy metal elements of coal gangue applied into asphalt pavement is not seeped out. The crushing value, water absorption and flat elongated particles content of coal gangue aggregate are generally high, but the compressive strength of base course with coal gangue aggregate is verified to meet the strength requirement. The performance, volume stability and durability of base course with coal gangue aggregate are closely related to aggregate gradation, the type and dosage of cementations materials and aggregate. The high temperature performance, temperature susceptibility and viscosity of asphalt mortar are improved by the addition of different coal gangue powder, and improvement effect of activated coal gangue powder on asphalt mortar performance is better. The low temperature performance and adhesion property of asphalt mortar with chemical activated coal gangue powder are improved. The physical reaction between asphalt and different coal gangue powder is only taken place. The temperature stability of asphalt mixture with coal gangue coarse aggregate has achieved the specification requirement. The water stability and low temperature fracture performance of asphalt mixture with fine aggregate replaced by coal gangue are improved. However, the high temperature performance of above mixture is lower than conventional hot mix asphalt mixture. The research results will provide reference for coal gangue applied into asphalt pavement.

High titanium heavy slag powder as a sustainability filler and its influence on the performance of asphalt mortar

High titanium heavy slag powder (HSP) is a typical waste with vast reserves but lacks effective disposal. This paper investigated for the first time the potential of reusing HSP as a sustainable mineral filler for asphalt mixtures. Firstly, a comprehensive comparison and analysis of the physicochemical properties of HSP and limestone powder (LSP) were conducted. Subsequently, asphalt mortars were designed, incorporating four filler-to-asphalt ratios (F/A of 0.2, 0.3, 0.4, 0.5) and five levels of HSP substitution for LSP (0%, 25%, 50%, 75%, 100%). Finally, selected properties of twenty types of asphalt mortar were tested. Compared with LSP, the HSP presented a coarser surface, more pores, smaller particle size and larger specific surface areas, which were conducive to the formation of more “structured asphalt”. Moreover, the chemical composition of HSP was complex, but it did not leach toxic elements, and the volume stability, high temperature stability, radioactivity met the requirements. However, its alkalinity was significantly lower than that of LSP, indicating weaker interactions with the asphalt. At F/A ratios of 0.2 and 0.3, the replacement of LSP with HSP resulted in a slight decrease in high temperature properties of asphalt mortars, but an improvement in low temperature performance. However, a further increase in the F/A ratio revealed an opposite trend. The properties of asphalt mortars were influenced by the combined effects of the chemical composition and physical properties of HSP. The FTIR test results indicated that no new functional groups were formed between the HSP and asphalt, suggesting primarily physical interactions.

Effect of Phosphogypsum Based Filler on the Performance of Asphalt Mortar and Mixture.

This study introduced phosphogypsum coupled with steel slag powder to prepare the phosphogypsum based filler (PF) for asphalt mixture. Penetration, penetration index, softening point, ductility, equivalent softening point, moisture stability of asphalt mortars with different steel slag powder content, filler-asphalt ratio, and PF content were studied. Mechanical properties of PF based asphalt mortar (P-AM) were then analyzed to determine the optimum steel slag content in PF. Overall desirability method was used to determine the optimum replacement ratio of PF content in limestone filler. Rheological properties of P-AM were also analyzed through dynamic shear rheometer. Volumetric performance, high-temperature performance, low-temperature performance, and moisture stability tests were carried out on PF based AC-20 asphalt mixture. Results showed that P-AM presented the optimum performance when the content of steel slag powder was 23% by mass of phosphogypsum. Fatigue and rutting factor of asphalt mortar were enhanced by PF. The optimum PF content in replacing limestone filler was 75% through overall desirability evaluation. PF developed the high-temperature performance and moisture stability of asphalt mixture. Additionally, volumetric and low-temperature performance were not significantly affected by PF. It is suggested that using PF which is based on phosphogypsum as a filler of asphalt mixture to partially replace traditional limestone filler was adequate.

Fine solid wastes as a resource-conserving filler and their influence on the performance of asphalt materials

Abstract Currently, the reuse of fine solid wastes (FSW) as cleaner production, instead of raw material, helps in improving road performance, easing excavation of virgin material and reducing environmental pollution. Nevertheless, concerns over poorer pavement performance caused by the addition of FSW have hindered the prevalent reusing of FSW in pavement engineering. Therefore, seven types of filler with five filler-binder volume ratios (FBv) were selected to prepare thirty-five types of asphalt mortar, in this study. The relationships among diversities of physical and chemical indexes of seven types of filler were firstly analyzed. Then, stripping test was applied to investigate the moisture sensitivity of asphalt mortar. After that, the effect of FBv and Rigden void of filler on the performance of asphalt mortar was evaluated. Moreover, the mechanism for the impact of FSW on the property of asphalt materials was comprehensively studied based on the rheological, mechanical and microscopic performances. Additionally, environmental impact of filler and mixture in the early stage was evaluated. In conclusion, the moisture damage mechanism of mixture in terms of surface free energy theory and asphalt mortar system was revealed, which indicated that the effect of filler on binder can be classified into four mechanisms; “physical hardening”, “chemical bonding”, “moisture instability” and “polarity enhancement”.

High‐ and Low‐Temperature Properties and Thermal Stability of Silica Fume/SBS Composite‐Modified Asphalt Mortar

Recently, China has started paying more attention to environmental protection, and the efficient utilization of exhaust gases produced by smelting has emerged as a key problem concern. The silica fume collected from the exhaust gases produced by smelting ferrosilicon or industrial silicon was often used as a cement concrete admixture. Using silica fume as an asphalt modifier can make exhaust gases profitable. In this study, silica fume/SBS composite‐modified asphalt mortar was prepared to improve the performance of asphalt. The effects of the silica fume content, temperature, and ratio of filler asphalt on the composite‐modified asphalt mortar were studied through the cone penetration, softening point, viscosity, dynamic shear rheological (DSR) test, and bending beam rheometer (BBR) test. The thermal stability of composite‐modified asphalt was analyzed through the thermal analysis test. The results showed that with the increase of silica fume content and ratio of filler asphalt, the high‐temperature performance of asphalt mortar was improved; the content of silica fume had a great influence on the low‐temperature performance of asphalt mortar, the optimum silica fume content was 7%; increasing the ratio of filler asphalt reduced the low‐temperature cracking resistance of asphalt mortar; the incorporation of silica fume enhanced the initial decomposition temperature, thermal residual rate, temperature in which the weight loss rate reaches the maximum, and the endothermic peak of maximum temperature and improved the properties of asphalt.

Effect of Mineral Powder on Performance of Unaged and Aged Asphalt Mortar

In order to analyze the effect of mineral powder on the high-temperature rut resistance and fatigue cracking resistance performance of unaged,short-term and long-term aged asphalt mortar, Dynamic Shear Rheometer (DSR) was used to study different powder/bitumen ratio of asphalt mortar. The results indicate that increasing mineral powder content can improve high-temperature rut resistance performance of asphalt mortar, but decrease its fatigue cracking resistance performance. As the experiment temperature rises, high-temperature rut resistance performance of different asphalt mortar will decrease, on the contrary, rising fatigue cracking resistance performance.