A Review of the Role of Nanomaterials in Asphalt Performance Enhancement

Experimental investigation of nano materials applicability in Hot Mix Asphalt (HMA)

Performance of hot and warm mix asphalt mixtures enhanced by nano-sized graphene oxide

In the Hot mix asphalt (HMA) is widely used in asphalt paving in most of countries. The goal of this paper is to study the effect of adding nanomaterials on the properties of asphalt binder and HMA. An experimental program has been conducted to study how to evaluate the performance of the modified asphalt binder and the modified HMA. Nanosilica (NS) and Nanoclay (NC) were used as modifiers. NS and NC were added at 3%, 5% and 7% by bitumen weight. Tests were performed to evaluate enhancement occurred in Penetration, softening point (SP), rotational viscosity (RV). Marshall stability tests, loss of stability and indirect tensile strength were performed on modified asphalt mixtures. Results were compared with control mix. Results shows significant enhancement in most of properties of asphalt binder and HMA. Penetration decreased by 24.07% at 3% NC and 20.37% at 5% NS. 3% NC and 5% NS were chosen to be optimum nanomaterial content (ONMC). Modified bitumens by 3% NC and 5% NS were used to produce modified asphalt mixtures. The modified mixtures showed a significant enhancement in stability and indirect tensile strength (IDT), but they, in contrast, had a harmful effect on the loss of stability (LOS).

Moisture susceptibility and environmental impact of warm mix asphalt containing bottom ash

The implementation of warm-mix asphalt (WMA) is becoming more widespread with a growing number of contractors utilizing various WMA technologies. Early research suggests WMA may be more susceptible to moisture damage than traditional hot-mix asphalt (HMA) mixes. The objectives of this study are to test the binder and mix properties of WMA technologies for both field- and laboratory-produced mixes to determine the performance of WMA compared to traditional HMA. Field- and laboratory-produced mixes were studied. The laboratory-produced mixes compared HMA control mixes with WMA mixes that had the same mix design. The WMA technologies used for the laboratory study were Advera, Sasobit, and Evotherm. The field study tested four WMA field-produced mixes. Each of the four mixes had a corresponding control HMA mix. The WMA technologies used in the field study included: Evotherm 3G/Revix, Sasobit, and Double Barrel Green Foaming. The three main factors for this study were WMA/HMA, moisture-conditioned/not moisture-conditioned, and reheated/not reheated. Mixes were evaluated based on performance tests. Binder testing was performed to determine the rheological differences between HMA and WMA binders to determine if binder grade requirements change with the addition of WMA additives. The conclusions of this study are as follows: (1) Reduced mixing and compaction temperatures were achieved. (2) Statistical differences were found when comparing tensile strength ratio (TSR) values for both laboratory- and field-produced mixes. In the laboratory, none of the WMA additives performed as well as the HMA. For the field mixes, all TSR values passed Iowa’s minimum specification of 0.8 but, on average, WMA is lower compared to HMA TSR values. (3) Dynamic modulus results show that, on average, HMA will have higher dynamic modulus values. This means the HMA exhibits stiffer material properties compared to WMA; this may not necessarily mean superior performance in all cases. (4) Flow number results show that WMA has reduced flow number values compared to HMA. The only exception was the fourth field mix and weather delayed production of the control mix by nine days. The laboratory mixes showed that flow number values increased significantly with the addition of recycled asphalt pavement (RAP). (5) In the laboratory study, Advera reduced TSR values. Given that Advera is a foaming agent, the increase in moisture susceptibility is likely attributed to the release of water necessary for the improvement of the workability of the asphalt mixture.

One of the ways to modify bitumen and asphalt mixture characteristics is to use recycled Crumb Rubber (CR). Although using CR improves the mechanical properties of asphalt mixtures and rheological behavior of bituminous binders, it increases binder viscosity. Warm Mix Asphalt (WMA) is a practical technology to ameliorate the disadvantage of Rubberized-Asphalt (RA) mixtures. This study aimed to investigate the effect of zeolite as a WMA additive on Hot Mix Asphalt (HMA) and RA mixtures. These modifiers' effect on the properties of asphalt mixtures and binders was studied utilizing different tests such as resilient modulus, indirect tensile fatigue, dynamic creep, moisture susceptibility (TSR and RMR), and rotational viscosity (RV). The findings indicate that the addition of zeolite and CR improved mechanical properties. 16% CR along with 6% zeolite is the optimum dosage to enhance durability. Moreover, the addition of CR to mixtures without zeolite decreased the TSR, RMR, and workability of mixtures, while zeolite increased the durability and workability of HMA and RA mixtures. The cost-effective analysis results also indicated that not only does the simultaneous proper use of zeolite and CR decreases energy consumption, but it also decreases the production cost of modified asphalt mixture.

The pavement industry is one of the industries that has considered using waste to partially replace the aggregates in asphalt mixtures. Despite its many environmental and technical benefits, the use of crushed glass increases the moisture damage potential of asphalt mixtures. Therefore, in the present study, the aim was to investigate the effects of two nano anti-stripping additives called nano iron oxide (Fe2O3) and nano aluminum oxide (Al2O3) on the moisture susceptibility of hot mix asphalt (HMA) mixtures containing crushed glass. The glass asphalt mixtures were made by replacing 0, 5, 10, 15, and 20% of the fine aggregates with glass cullets. In order to investigate the effects of nano-materials on the moisture susceptibility of glass asphalt mixtures, the modified Lottman test (AASHTO T283) and the surface free energy (SFE) method were used. The results showed that the addition of nano-materials improved the adhesive force between asphalt binders and aggregates (crushed glass and aggregates with acidic properties) by reducing the acidic and increasing the basic properties of the modified asphalt binder. Moreover, asphalt modification with nano-materials increased the initial energy required to separate asphalt binder from the aggregate surface and reduced the risk of moisture damage by increasing the total SFE of asphalt binder.

Effect of impregnated organophilic (hydrophobic) nano clay on asphalt binder properties and performance

ABSTRACTThis study investigated the effect of short-term and long-term ageing on the dynamic modulus of foamed warm mix asphalt (WMA) produced by water injection and traditional hot mix asphalt (HMA). Four asphalt binders (PG 64-22, PG 64-28, PG 70-22 and PG 76-22) and one aggregate (limestone NMAS 12.5 mm) were used in the preparation of the laboratory-produced asphalt mixtures. The short-term and long-term ageing of the asphalt mixtures were simulated using AASHTO R 30. The experimental test results showed lower dynamic modulus values for foamed WMA than those obtained for traditional HMA for both short-term and long-term oven-aged specimens. By comparing the dynamic modulus values of the short-term and long-term oven-aged specimens, it was observed that some mixtures, such as those prepared using PG 64-22, had a smaller increase in dynamic modulus for foamed WMA mixtures than traditional HMA mixtures, while a comparable increase in dynamic modulus for both foamed WMA and HMA was observed for other mixtures, such as those prepared using PG 70-22 and PG 76-22. This suggests that the binder type plays a significant role in determining the ageing characteristics of foamed WMA and HMA mixtures.

Laboratory evaluation of composed modified asphalt binder and mixture containing nano-silica/rock asphalt/SBS

Warm-mix asphalt(WMA) technology has been developed to allow asphalt mixtures to be produced and compacted at a significantly lower temperature. The WMA technology was identified as one of means to lower emissions for and has been spread so quickly in the world. Recently, two innovative WMA additives has been developed to reduce mixing and paving temperatures applied in asphalt paving process in Korea. Since the first public demonstration project in 2008, many WMA projects have successfully been constructed in national highways. In 2010, the WMA field trial was conducted on new national highway construction under Dae-Jeon Regional Construction Management Administration. The two different WMA loose mixtures(WMA and WMA-P) and a HMA mixture were collected at the asphalt plant to evaluate their mechanical performance in the laboratory. The Third-scale Model Mobile Loading Simulator(MMLS3) was adopted to evaluate rutting resistance and moisture damage under different traffic and environmental conditions. In this study, plant-produced WMA mixtures using two WMA additives along with the conventional hot mix asphalt(HMA) mixtures were evaluated with respect to their rutting resistance and moisture susceptibility using MMLS3. Based on the limited laboratory test results, plant-produced WMA mixtures are superior to HMA mixtures in rutting resistance and the moisture susceptibility. The WMA additive was effective for producing and compacting the mixture at lower than the temperature for the HMA mixture.

Laboratory performance and aging resistance evaluation of zinc oxide/expanded vermiculite composite modified asphalt binder and mixture

High-volume traffic with ultra-heavy axle loads combined with extremely hot weather conditions increases the propagation of rutting in flexible pavement road networks. Several studies suggested using nanomaterials in asphalt modification to delay the deterioration of asphalt pavement. The current work aims to improve the resistance of hot mix asphalt (HMA) to rutting by incorporating Nano Silica (NS) in specific concentrations. NS was blended into asphalt mixtures in concentrations of 2, 4, and 6% by weight of the binder. The behavior of asphalt mixtures subjected to aging was investigated at different stages (short-term and long-term aging). The performance characteristics of the asphalt mixtures were evaluated using the Marshall stability, flow, and wheel tracking tests. Field Emission Scanning Electron Microscopy (FESEM) was utilized to understand the microstructure changes of modified asphalt and estimate the dispersion of NS within the asphalt. The results revealed that using NS–asphalt mixtures as a surface layer in paving construction improved pavement performance by increasing stability, volumetric characteristics, and rutting resistance before and after aging. The FESEM images showed adequate dispersion of NS particles in the mixture. Results indicated that adding 4% of NS to asphalt mixtures effectively enhanced the pavement’s performance and rutting resistance. Doi: 10.28991/CEJ-SP2023-09-01 Full Text: PDF

Hot-mix asphalt (HMA) fatigue cracking is governed by external factors, including temperature, precipitation, and traffic loading, alongside internal factors, such as bitumen type, bitumen percent, air void, and the aggregate’s mineralogy and physical properties. As a critical external factor, moisture, particularly runoff with varying acidity, exacerbates fatigue cracking through physical and chemical interactions. The use of advanced additives such as nanomaterials in HMAs enhances their performance against various types of distress. Carbon nanotubes (CNTs) and nano-graphene oxide (NGO) are nanomaterials that exhibit exceptionally high elastic resistance and desirable hydrophobic properties. Their application has shown promising results in the contaminated water treatment industry. Given that the providing solutions to mitigate the negative effects of acidic and alkaline waters on the intermediate-temperature performance of HMAs has not been widely discussed, this study employs CNTs and NGO to mitigate the damaging effects of acidic and alkaline runoff from surface pollutants on the fatigue performance of bitumen and HMAs. This study employed dynamic shear rheometer (DSR) and semi-circular bending (SCB) tests under dry, neutral wet, acidic wet (pH = 5 and 6), and alkaline wet (pH = 8 and 9) conditions to evaluate the fatigue cracking potential in different bitumens and asphalt mixtures. Limestone and siliceous aggregates, differing in moisture susceptibility, were combined with PG 58–22 bitumen to fabricate HMA. Carbon nanotubes (CNTs) and nano-graphene oxide (NGO) were also incorporated at 0.3% and 0.6% by the bitumen’s weight. Test results on the bitumen and HMAs under different moisture conditions show that altering the pH of pure water significantly degrades the bitumen’s rheological properties and the mixture’s mechanical fracture resistance. Conversely, CNTs and NGO substantially reduced G*Sinδ while boosting fracture energy and toughness. In other words, these two nanomaterials reduced the fatigue parameter of the bitumen under dry, acidic, and alkaline moisture conditions, demonstrating their outstanding performance in enhancing the fatigue resistance of the modified bitumen against intermediate temperature cracking under various moisture exposures. Furthermore, the mixtures modified with CNTs and NGO withstood higher energy for cracking at intermediate temperatures when exposed to acidic and alkaline moisture conditions, while also increasing the critical stress threshold required for final failure. This indicates that CNTs and NGO, even when the detrimental effects of acidic and alkaline runoff dominate their properties, improve the performance of both the bitumen and the mixture against intermediate-temperature cracking. The specimens with 0.6% NGO exhibited exceptional fatigue resistance across all conditions. These findings highlight NGO at 0.6% concentration as a superior enhancer of asphalt resilience against runoff-induced fatigue deterioration.

This study proposed an asphalt mixture modified by basalt fiber and diatomite. Performance of diatomite modified asphalt mixture (DAM), basalt fiber modified asphalt mixture (BFAM), diatomite and basalt fiber compound modified asphalt mixture (DBFAM), and control asphalt mixture (AM) were investigated by experimental methods. The wheel tracking test, low-temperature indirect tensile test, moisture susceptibility test, fatigue test and freeze–thaw cycles test of four kinds of asphalt mixtures were carried out. The results show that the addition of basalt fiber and diatomite can improve the pavement performance. Diatomite has a significant effect on the high temperature stability, moisture susceptibility and resistance to moisture and frost damage under freeze–thaw cycles of asphalt mixture. Basalt fiber has a significant effect on low-temperature cracking resistance of asphalt mixture. Composed modified asphalt mixture has obvious advantages on performance compared to the control asphalt mixture. It will provide a reference for the design of asphalt mixture in seasonal frozen regions.