Mixture Of High Polymers Research Articles

Effect of reclaimed asphalt pavement on cracking performance of asphalt mixtures with regular and high polymer modified binders

Since reclaimed asphalt pavement (RAP) provides economic savings, incorporating RAP may reduce high cost of high-polymer (HP) binder typically used to address severe cracking. However, RAP is currently not allowed in HP mixtures in Florida, because aged RAP binder may reduce benefits of HP binder. This study focused on determining whether RAP can be used in HP mixtures, while maintaining the premium performance expected of HP binder. Eight RAP sources covering a broad range of RAP characteristics were assessed using the interstitial component fracture energy (FEIC) and the mixture fracture energy (FEmix). Mixtures with HP binder exhibited better cracking resistance than those with PG 76–22 binder. However, introduction of 20% RAP in HP mixtures reduced 20–60% in FEIC and 30–45% in FEmix, depending on RAP characteristics. Therefore, RAP characteristics need to be carefully reviewed, and more caution is needed when adding RAP into HP mixtures.

Laboratory evaluation of high polymer plant-produced mixtures

Two high polymer mixtures (HPM) were placed at the 2009 National Center for Asphalt Technology (NCAT) Test Track as a field trial. These mixtures featured 7.5% polymer in contrast to the more typical 2–3% polymer contents. During construction, each mixture (one surface and one base mixture) was sampled for evaluation using laboratory performance tests. The results of the dynamic modulus test, asphalt pavement analyzer, flow number, bending beam fatigue, indirect tension creep compliance and strength test, energy ratio, and moisture susceptibility tests were compared with the results from comparable control mixtures placed in the same round of testing. The laboratory test results suggest HPM mixtures can be placed to develop more efficient (i.e., thinner) pavement cross-sections due to their enhanced fatigue and rutting resistance.

Early Stages of Nucleation and Growth in a Polymer Blend.

The early stages of nucleation and growth in a mixture of high polymers were studied by time-resolved neutron scattering. During the first 160 min, a slow clustering was evident, indicating a buildup of concentration fluctuations. The clusters formed at the end of this stage had the characteristics of ``critical nuclei,'' because phase separation proceeded rapidly after their formation. At this stage, the scattering profiles showed a peak at finite wave vectors $({q}_{\mathrm{max}})$. The scaling exponents for the time dependence of the peak intensity and ${q}_{\mathrm{max}}$ are inconsistent with current theories.

Binodal and spinodal curves: a simulation for various high polymer mixtures

Flory's equation-of-state theory has been used to predict the lower critical solution temperature behaviour of polymer—polymer mixtures. The spinodal phase boundary of numbers of high molecular weight polymer mixtures have been previously simulated using this theory. In this paper a procedure for simultaneous predictions of the binodal and the spinodal curves by equating the chemical potential of each component in the mixture is presented. The method is tested for five different mixtures. The effects of the binary and pure component state parameters on the simulated curves are discussed and the simulated phase diagrams are compared with the experimental cloud point curves. It is found that in most cases the results are more consistent with the cloud point curve being closer to the spinodal curve than the binodal.