Evaluation of the Effect of Fly Ash and Slag on the Properties of Cement Asphalt Mortar

Abstract

The application of cement asphalt mortar (CAM) in modern high-speed railways has been gaining attention due to its combined merits between asphalt and cement hydration product characteristics. To promote sustainable development, it is promising to utilize by-products in the making of new CAM instead of using only cement. In this research, the cement content was partly replaced by fly ash or ground-granulated blast furnace (GGBS) slag to achieve this objective. Then, laboratory experiments were conducted to determine the effect of these admixtures on the fresh and hardened characteristics of CAM. The test results revealed that the CAM mixture with slag received better fresh properties compared to the controlled mixture. However, the poor pozzolanic property of these by-product materials may lead to the low strength development. Meanwhile, although the mixture with fly ash suffered from slow strength establishment compared to the control mix at an early age, the strength of this condition increases dramatically after 28 days. Based on the findings, the application of appropriate fly ash content in the CAM mixture will not only provide ideal workable time and mixing stability but also ensure the required strength for the design target. This combination also serves as a cost-effective and environmental solution.

A Review on Cement Asphalt Emulsion Mortar Composites, Structural Development, and Performance

“…However, it was also found in some related works of literature [10,77], that fly ash decreases the viscosity of CA mortar, thereby enhancing its workability. Le et al [23] reported that substituting cement with any fly ash or ground granulated blast furnace (GGBF) slag improves the overall fresh properties of CA mortar; these materials also prolonged the demulsification process of emulsified asphalt and retarded the hardening process of CA mortar. According to their results, though the mixture with these admixtures suffered slow early strength development as compared to the control mix, a high dosage of fly ash leads to high strength development beyond 28 days.…”

“…According to their results, though the mixture with these admixtures suffered slow early strength development as compared to the control mix, a high dosage of fly ash leads to high strength development beyond 28 days. Indeed, favorable particle size distribution, round shape, and appreciative chemical properties of fly ash provided adequate bonding with the asphalt membrane; this helps in providing uniform structure formation in the CA mortar mixture and consequently improves long-term strength development [23]. Their research proves that the utilization of appropriate fly ash in CA mortar improves its fresh and hardened properties, reduces the cost of production, and provides an environmental solution as it utilizes industrial by-products that may rather be used as landfills and eventually cause pollution.…”

“…Recent researches have indicated the potentials of CA mortar to be applied in ballasted tracks, but unlike the ballastless slab track, in a ballasted track, CA mortar is not a layer or structural member on its own, but rather it is incorporated or mixed with the ballast to form a new composite material named CA mortar-stabilized ballast. The new material is anticipated to achieve the merits of the ballastless track as well as be used as a fouled ballast rehabilitation solution, and hence reinforce the ballast layer by improving its durability and also reduce the construction time [14,23]. In related research, Le et al [23] proposed a technique that assesses the plausibility of stabilizing the ballast using CA mortar, as an eminent solution to minimize losing the track quality as a result of particle abasement and ballast settlement.…”

“…The new material is anticipated to achieve the merits of the ballastless track as well as be used as a fouled ballast rehabilitation solution, and hence reinforce the ballast layer by improving its durability and also reduce the construction time [14,23]. In related research, Le et al [23] proposed a technique that assesses the plausibility of stabilizing the ballast using CA mortar, as an eminent solution to minimize losing the track quality as a result of particle abasement and ballast settlement. Based on the technique they proposed, pouring fresh CA mortar on the ballast layer will cause the CA mortar mixture to flow through the ballast system, thereby coating the ballast particles and creating strong inter-particle bonding [24].…”

Study on the Deformation of Pavement Structure with Multiplex Organic Hydraulicity Mixture under Driving Load Based on Simulation and Experiment

“…Research on emulsified asphalt cement mortar mixtures mainly focuses on the mixing ratio [7,8], performance [5,[9][10][11][12][13][14], mixing time [15], strength formation mechanism [7,16,17], and so on. For pavement materials, understanding their performance is the priority.…”