Petrella Andrea, Di Mundo Rosa, Notarnicola Michele
Dipartimento di Ingegneria Civile, Ambientale, Edile, del Territorio e di Chimica, Politecnico di Bari, Via E. Orabona, 4, 70125 Bari, Italy.
Materials (Basel). 2020 Feb 22;13(4):988. doi: 10.3390/ma13040988.
In the present work the rheological, thermo-mechanical, microstructural, and wetting characteristics of cement mortars with recycled expanded polystyrene (EPS) were analyzed. The samples were prepared after partial/total replacement of the conventional sand aggregate with EPS having different grain size and size distribution. Lightness and thermal insulation were relevant features for all the bare EPS composites, despite the mechanical strengths. Specifically, EPS based mortars were characterized by higher thermal insulation with respect to the sand reference due to the lower specific mass of the specimens mainly associated with the low density of the aggregates and also to the spaces at the EPS/cement paste interfaces. Interesting results in terms of low thermal conductivity and high mechanical resistances were obtained in the case of sand-EPS mixtures although characterized by only 50% in volume of the organic aggregate. Moreover, sand-based mortars showed hydrophilicity (low WCA) and high water penetration, whereas the presence of EPS in the cement composites led to a reduction of the absorption of water especially on the bulk of the composites. Specifically, mortars with EPS in the 2-4 mm and 4-6 mm bead size range showed the best results in term of hydrophobicity (high WCA) and no water penetration in the inner surface, due to low surface energy of the organic aggregate together with a good particle distribution. This was indicative of cohesion between the ligand and the polystyrene as observed in the microstructural detections. Such a property is likely to be correlated to the observed good workability of this type of mortar and to its low tendency to segregation compared to the other EPS containing specimens. These lightweight thermo-insulating composites can be considered environmentally sustainable materials because they are prepared with no pre-treated secondary raw materials and can be used for indoor applications.
在本研究中，对含有再生膨胀聚苯乙烯（EPS）的水泥砂浆的流变学、热机械、微观结构和润湿性特征进行了分析。在使用具有不同粒度和粒度分布的EPS部分/全部替代传统砂集料后制备了样品。尽管存在机械强度，但亮度和隔热性是所有纯EPS复合材料的相关特性。具体而言，基于EPS的砂浆相对于砂基准具有更高的隔热性，这主要是由于试样的较低比重，这与集料的低密度以及EPS/水泥浆界面处的空隙有关。在砂-EPS混合物的情况下，尽管有机集料的体积仅为50%，但在低导热率和高机械抗性方面获得了有趣的结果。此外，基于砂的砂浆表现出亲水性（低接触角）和高透水性，而水泥复合材料中EPS的存在导致水吸收的减少，尤其是在复合材料的主体上。具体而言，珠子尺寸范围为2-4毫米和4-6毫米的含有EPS的砂浆在疏水性（高接触角）方面表现出最佳结果，并且内表面没有水渗透，这是由于有机集料的低表面能以及良好的颗粒分布。这表明在微观结构检测中观察到配体与聚苯乙烯之间的内聚力。这种特性可能与观察到的这种类型砂浆的良好工作性及其与其他含EPS试样相比的低离析倾向相关。这些轻质隔热复合材料可以被认为是环境可持续材料，因为它们是用未经预处理的二次原料制备的，并且可用于室内应用。
