High Viscosity Modifier Research Articles

Performance evaluation of stone mastic asphalt mixture with different high viscosity modified asphalt based on laboratory tests

To seek the optimum asphalt binder used in stone mastic asphalt (SMA) mixture of steel deck pavement, the common modified asphalt in the SMA-13 mixture was replaced with high viscosity modified (HVM) asphalt, and the four kinds of HVM asphalts were selected in this paper. The different test methods such as experimental device of mixing power at different velocities, rutting test, Hamburg wheel tracking device(HWTD) test, bending test at low temperature and indirect tensile fatigue test were conducted to evaluate the construction workability, temperature stability, water stability and fatigue performance of HVM asphalt mixture. Besides the performance difference of various HVM asphalt mixture was also discussed. The results show that construction workability of SMA-13 mixture is significantly affected by the asphalt type and mixing temperature, and the influence of mixing temperature on construction workability is more obvious. Besides it is proved that the construction workability of asphalt mixture is influenced by asphalt viscosity and mineral aggregate. The SMA mixture with self-developed HVM asphalt composed by the linear and star styrene-butadienestyreneblockcopolymer (SBS) modifier has advantages in construction workability and comprehensive properties. Thus the above asphalt can be selected to prepare SMA mixture applied in steel deck pavement. The construction workability, high temperature performance and fatigue performance of HVM asphalt mixture with SBS compound modified asphalt are close to HVM asphalt mixture with TPS additive or HVM asphalt mixture with SINOTPS, and the the former low temperature performance and water stability are superior to HVM asphalt mixture with TPS additive and HVM asphalt mixture with SINOTPS. The dosage of SBS compound modifier in HVM asphalt is just 6.0%, and the blending ratio of linear SBS modifier and star SBS modifier in the compound modifier is 2:1. It means that the self-developed HVM asphalt with SBS compound modifier has the high performance-price ratio. The reduction of key modified materials in HVM asphalt will be conducive to saving the construction cost of pavement, which will promote the HVM asphalt with SBS compound modifier applying in SMA mixture of steel deck pavement.

Asphalt mixture design for porous ultra-thin overlay

In order to design a porous ultra-thin overlay (PUTO) asphalt mixture, two high-viscosity modifiers and two blended asphalts were used to prepare high-viscosity asphalt. Dynamic shear rheology (DSR) tests, 60 °C dynamic viscosity tests, Fourier transform infrared spectroscopy (FTIR) tests and physical properties tests were used to study the modification effect and modification mechanism of high-viscosity asphalt. Next, based on existing gradation design methods, two types of gradation, coarse and fine, were designed for PUTO. In addition, based on the results of draindown and Cantabro tests, the optimal asphalt-aggregate ratio was determined. Finally, the performance of the designed PUTO asphalt mixture was verified. The results show that with the increase of the amount of high-viscosity modifier, the complex shear modulus and anti-rutting factors of the four kinds of high-viscosity asphalt gradually increase, while their phase angles gradually decrease. Only SBS-I (with high-viscosity modifier contents of 14% and 16%) and SBS-II (with high-viscosity modifier contents of 14% and 16%) high-viscosity asphalt have a 60 °C dynamic viscosity exceeding 100,000 Pa·s. The main component of the high-viscosity modifier for the modification of the original asphalt is thermoplastic rubber, which forms a polymer network structure between the polymer in the high-viscosity modifier and the asphalt component, which is reflected in the infrared spectrum. That is, there is a significant characteristic absorption peak at 966 cm−1 in the fingerprint vibration spectrum region (1500–600 cm−1). After the high-viscosity modifier content reaches 14%, the penetration of SBS-I and SBS-II high-viscosity asphalt decreases, and their growth trends of ductility and softening point also slow. Considering the total cost, when the SBS-modified asphalt-high-viscosity modifier ratio is 86:14, the overall performance of the high-viscosity asphalt is optimal. According to the results of Cantabro and draindown tests, the optimal asphalt-aggregate ratios of PAC-1-I, PAC-1-II, PAC-2-I and PAC-2-II asphalt mixtures are 4.6%, 4.5%, 5.3%, and 5.3%, respectively. The performance of the four asphalt mixtures designed was verified and meets the requirements.

Laboratory evaluation of performance of porous ultra-thin overlay

Porous ultra-thin overlay (PUTO) is a new type of pavement maintenance technology which combines skid resistance and drainage functions. The engineering properties of two high-viscosity modifier (type I and type II) modified asphalt and two gradations (coarse and fine) of asphalt mixtures, including high- temperature rutting resistance, low-temperature crack resistance and moisture sensitivity, were investigated. The dynamic modulus and phase angle of the asphalt mixture under dynamic loading conditions were then analyzed and master curves of dynamic modulus and phase angle were established. Finally, the drainage and skid resistance of the PUTO were evaluated. The results show that the dynamic stability (DS) of the asphalt mixture with coarse gradation is larger than that of the asphalt mixture with fine gradation. The bending strain of four asphalt mixtures shows small differences, the maximum value being 364 με larger than the minimum value, and they all meet the requirements of the specification. The excellent adhesion of the high-viscosity asphalt binder enhances the anti-stripping ability between asphalt and aggregates, enabling the mixture to resist water damage well. As the temperature increases or the load frequency decreases, the dynamic modulus decreases and the phase angle increases. By establishing the master curves of dynamic modulus and phase angle, it can be concluded that gradation as the main skeleton of PUTO asphalt mixture plays a major role in its performance and strength. Under the same rainfall conditions, the asphalt mixture with coarse gradation can transfer water on the pavement surface to the outside more quickly. Coarse gradation is beneficial for the enhancement of the macroscopic structure and improvement of the skid resistance of pavement surface.

Performance evaluation of high-elastic/salt-storage asphalt mixture modified with Mafilon and rubber particles

Snow and ice on road surface will reduce anti-skid performance between tire and pavement which will cause traffic safety problem. This research develops one kind of high-elastic/salt-storage asphalt mixture (HESAM) containing Mafilon (MFL) and rubber particles (RP) to improve the snowmelt and deicing performance of asphalt pavement. The high-viscosity asphalt (HVA) binder for HESAM was prepared by adding TPS high-viscosity modifier into common SBS asphalt to improve the functional performance. The MFL was added into mixture by replacing portion of mineral fillers, and RP was used through displacing part of fine aggregate. Five types of mixtures were prepared to investigate the pavement performance of HESAM, and the action mechanism of the modifiers MFL and RP on the functional performance of the mixture was analyzed by test results. The immersion test was designed for HVA + MFL + RP mixture and HVA + RP mixture to determine the effect of MFL on the pavement performance of asphalt mixture. An ice melting effect test was designed to evaluate the ice melting performance of HESAM which taking the loss ratio LR as the evaluation index. A wheel deicing test was designed to study the self-stress deicing effect of rubber particles in HESAM. A time effectiveness test method was also designed to evaluate the sustained release effect and estimate the duration time of MFL. The tests results showed that the high temperature, water stability and low temperature performance of HESAM decreased by 9.9%, 3.5% and 1.1% respectively compared with SBS mixture. This indicates that the pavement performance of HESAM keeps a high level. However, the salt precipitation has obvious influence on the water stability and low temperature performance of the mixture, while with only slightly effect on high temperature performance. The HESAM performed much better snowmelt and deicing performance than common SBS mixture in terms of the faster snowmelt and deicing speed. The duration of snowmelt effect for the high-elastic/salt-storage pavement can be estimated based on the time effectiveness assessment model established in this paper. All the findings proved that HESAM is a kind of pavement material with both remarkable pavement performance and snowmelt and deicing performance which shows great popularization prospect.

The effect of PPA on performances and structures of high-viscosity modified asphalt

Polyphosphoric acid (PPA) was used to improve the physical and rheological properties of high-viscosity modified (HVM) asphalt and decrease the styrene–butadiene–styrene (SBS) content. The sample preparation technique was optimized further by blending furfural extract oil and asphalt in advance. With the optimized preparation process, the major physical and rheological properties of HVM asphalt were improved further by adding the same amount of PPA comparing with other preparation processes; however, the motive viscosity, toughness and tenacity of HVM asphalt still depended on the SBS content. Various rheological tests were adopted to investigate the effect of PPA on the rheological behaviours of HVM asphalt before and after ageing. The suitable gelation accused by PPA not only improved the high-temperature rheological performances of HVM asphalt, but increased the low-temperature rheological performances. Morphology observation by using optical microscope showed the effect of vulcanization and ageing on the outline and distribution of SBS in HVM asphalt. Fourier transform infrared analysis indicated the difference of SBS content under different modifications. Thermal analysis displayed the effect of PPA on the thermodynamic behaviours of HVM asphalt and demonstrated the declined ageing susceptibility of HVM asphalt after PPA modification.

Performances evaluation of epoxy asphalt mixture containing snow-melting agent

The performance degradation of the asphalt mixture blended with the snow-melting agent can inevitably occur although it can be relieved by adding the high viscosity modifier or Nanopowder. The thermosetting epoxy asphalt binder, different from the conventional thermoplastic asphalt as SBS modified asphalt, was adopted in this research to solve this problem. Experiments were carried out to test the road engineering performances, conductivity, deicing and snow melting performances of epoxy asphalt mixture with the snow-melting agent content of 6%, 7% and 8%, substituting the equivalent amount of mineral filler, and then the results were compared with SBS modified asphalt mixture. The results show that snow-melting agent has a slight influence on the engineering performance of epoxy asphalt mixture. With snow-melting agent content or environmental temperature rising, the snow-melting agent release amount and rate of epoxy asphalt mixture increase, but are lower than those of SBS modified asphalt mixture under the same condition. The epoxy asphalt mixture with snow-melting agent can provide preferable snow melting performance and low ice adhesion. This thermosetting mixture with snow-melting agent possesses engineering application potential due to its excellent performance and long snow melting life.

The research for low-temperature rheological properties and structural characteristics of high-viscosity modified asphalt

High-viscosity modified (HVM) asphalt was prepared by the addition of styrene–butadiene–styrene, furfural exact oil (FEO, plasticizer), sulphur (crosslinker). The low-temperature rheological properties of HVM asphalt were investigated by using bending beam rheometer, and different analysis ways including Fourier transform infrared (FTIR) analysis, thermal analysis, 1hydrogen nuclear magnetic resonance (1NMR) analysis, elemental analysis, optical microscopy were used to investigate the structural characteristics of modified asphalts and FEO. Rheological tests demonstrated the effect of each modifier on low-temperature rheological performances of asphalt and displayed the structural characteristics of each binder to some extent. FTIR analysis indicated the effect of ageing and modifier on the distribution of functional groups of modified asphalt before and after ageing. Morphology observation showed the distribution of polymer in asphalt with different modifications or ageing. The thermal analysis showed the effect of each modifier on thermal behaviour of asphalt before and after ageing and confirmed the result of FTIR analysis and morphology observation further. Besides, the constituents of base asphalt and plasticizer were also investigated and compared further by adopting elemental analysis, and 1HNMR and FTIR tests.

The composition and ageing of high‐viscosity and elasticity asphalts

Different kinds of plasticizers and crosslinkers were used to prepare high‐viscosity modified (HVM) asphalt and high‐elastic modified (HEM) asphalt and the major physical properties were studied and compared. The kinds of plasticizers were optimized and the difference in composition between HVM and HEM asphalts was clarified. The plasticizers with different thickness and flexibility were available for HVM or HEM asphalts respectively. The kinds of crosslinkers were also compared and optimized and it was found that the most effective crosslinker was sulfur. The effect of anti‐ageing reagent on HEM asphalt was confirmed and it was found that one of the most effective way to retain the properties of HVM and HEM asphalt before ageing was to increase the SBS content further. POLYM. COMPOS., 38:2509–2517, 2017. © 2015 Society of Plastics Engineers

Preparation and properties of high viscosity modified asphalt

High viscosity modified (HVM) asphalt was prepared by the addition of styrene–butadiene–styrene (SBS), plasticizer, crosslinker. The effect and proportion of each modifier in the preparation of HVM asphalt were studied. SBS was the major modifier and determined the basic properties of HVM asphalt. Plasticizer (furfural exact oil) and crosslinker (sulfur) as additional modifiers were necessary in improving the workability, stability, and aging resistance of modifier. The effect of aging and additional modifiers on the structure and rheological behavior of SBS modified (SM) asphalt was displayed by adopting various rheological tests. Plasticizer declined the rutting resistance of SM asphalt and increased the viscous behavior of SM asphalt after aging. The use of crosslinker led to the formation of polymer network and improved the aging resistance of SM asphalt. The morphology observation shows crosslinker led to the formation of polymer network and improved the compatibility between SBS and asphalt. Plasticizer prompted the swelling and dispersion of SBS in asphalt and improved the effect of crosslinker further. Aging destroyed the polymer phase seriously and there was still residual polymer phase in asphalt. POLYM. COMPOS., 38:936–946, 2017. © 2015 Society of Plastics Engineers