Forbes A, Haverkamp R G, Robertson T, Bryant J, Bearsley S
ITE, Massey University, Private Bag 11 222, Palmerston North, New Zealand.
J Microsc. 2001 Dec;204(Pt 3):252-7. doi: 10.1046/j.1365-2818.2001.00955.x.
Polymer-modified bitumen emulsions present a safer and more environmentally friendly binder for enhancing the properties of roads. Cationic bitumen emulsion binders containing polymer latex were investigated using confocal laser scanning microscopy. The latex was incorporated into the bitumen emulsion by using four different addition methods and all emulsions were processed with a conventional colloid mill. The emulsion binder films were studied after evaporation of the emulsion aqueous phase. We show how the microstructure and distribution of the polymer varies within the bitumen binder depending on latex addition method, and that the microstructure of the binder remains intact when exposed to elevated temperature. It was found that a distinctly fine dispersion of polymer results when the polymer is blended into the bitumen before the emulsifying process (a monophase emulsion). In contrast, bi-phase emulsion binders produced by either post-adding the latex to the bitumen emulsion, or by adding the latex into the emulsifier solution phase before processing, or by comilling the latex with the bitumen, water and emulsifier all resulted in a network formation of bitumen particles surrounded by a continuous polymer film. The use of emulsified binders appears to result in a more evenly distributed polymer network compared to the use of hot polymer-modified binders, and they therefore have greater potential for consistent binder cohesion strength, stone retention and therefore improved pavement performance.
聚合物改性沥青乳液为增强道路性能提供了一种更安全、更环保的粘结剂。使用共聚焦激光扫描显微镜对含有聚合物胶乳的阳离子沥青乳液粘结剂进行了研究。通过四种不同的添加方法将胶乳掺入沥青乳液中，所有乳液均采用传统胶体磨进行加工。在乳液水相蒸发后对乳液粘结剂膜进行了研究。我们展示了聚合物的微观结构和分布如何根据胶乳添加方法在沥青粘结剂中变化，并且当暴露于高温时粘结剂的微观结构保持完整。结果发现，当聚合物在乳化过程之前与沥青混合（单相乳液）时，聚合物会形成明显精细的分散体。相比之下，通过将胶乳后添加到沥青乳液中、或在加工前将胶乳添加到乳化剂溶液相中、或通过将胶乳与沥青、水和乳化剂共研磨而产生的双相乳液粘结剂，都会导致形成由连续聚合物膜包围的沥青颗粒网络。与使用热聚合物改性粘结剂相比，使用乳化粘结剂似乎会导致聚合物网络分布更均匀，因此它们在粘结剂内聚力、石料保留方面具有更大潜力，从而改善路面性能。
