The cement-based construction materials industry needs to adapt its formulations and production processes to the new paradigm characterized by sustainability, circularity and decarbonization. In this context, one of the strategies proposed by the prepared mortars industry is to seek new alternative recycled raw materials derived from industrial by-products. This paper analyses the feasibility of using mixed recycled sand (0/2 mm) derived from construction and demolition waste as a 100 % replacement for natural sand in the formulation of prepared rendering mortars. It additionally explores its concurrent use with mixed recycled ultra-fine fractions (<0.075 mm) of construction and demolition waste and/or biomass bottom ash collected from power plants. The by-products were characterized in terms of their physical, chemical and mineralogical properties. The formulations of the new eco-friendly mortars (Mix O, Mixes A–D) were then adjusted, and their properties were assessed in their powdered, fresh, and hardened states. The results indicate that incorporating these new raw materials does not adversely affect their consistency (162–166 mm) or fresh-state density (634–678 kg/m3). In addition, the new eco-friendly mortars (Mixes A–D) exhibit greater compressive and flexural strength than the conventional mortar (Mix O), presenting increases in these values at 90 d ranging from 8.6 to 23.7 % and 2.4–26.2 %, respectively, versus Mix O. The formulated mortars meet the criteria of category CS I mortar (0.4 MPa ≤ fcm ≤ 2.5 MPa), as per standard EN 998-1. Additionally, the pore structure of the eco-friendly mortars differs from that of Mix O: the volume of pores with Ø ≥ 50 μm increases when only CDWm is added and decreases when both mixed recycled sand and ultra-fine fractions are incorporated. Based on the results obtained, it can be concluded that all the formulated eco-friendly mortars would, a priori, be suitable for use as prepared rendering mortars in construction and civil engineering.

中文翻译：

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基于新型替代原材料的环保抹灰砂浆配方：性能和微观结构

水泥基建筑材料行业需要调整其配方和生产工艺，以适应以可持续性、循环性和脱碳为特征的新模式。在此背景下，预制砂浆行业提出的策略之一是寻找来自工业副产品的新型替代回收原材料。本文分析了在配制制备的抹灰砂浆中使用来自建筑和拆除废物的混合再生砂 （0/2 mm） 作为天然砂的 100% 替代品的可行性。此外，还探索了与混合回收的超细馏分（<0.075 mm）的建筑和拆除垃圾和/或从发电厂收集的生物质底灰的同时使用。副产品根据其物理、化学和矿物学特性进行了表征。然后调整新型环保砂浆（Mix O、Mixes A-D）的配方，并评估它们在粉末状、新鲜和硬化状态下的性能。结果表明，掺入这些新原材料不会对其一致性 （162-166 mm） 或新鲜态密度 （634-678 kg/m3） 产生不利影响。此外，新型环保砂浆 （Mixes A-D） 比传统砂浆 （Mix O） 表现出更高的抗压强度和抗弯强度，与 Mix O 相比，在 90 天时，这些值分别增加了 8.6% 至 23.7% 和 2.4%-26.2 %。配制的砂浆符合 EN 998-1 标准 CS I 类砂浆（0.4 MPa ≤ fcm ≤ 2.5 MPa）的标准。 此外，环保砂浆的孔隙结构与 Mix O 不同：当仅添加 CDWm 时，Ø ≥ 50 μm 的孔隙体积增加，而当混合再生砂和超细馏分加入时，孔隙体积减小。根据获得的结果，可以得出结论，所有配制的环保砂浆都适合在建筑和土木工程中用作制备的炼油砂浆。