# The Properties and Durability of Self-Leveling and Thixotropic Mortars with Recycled Sand
## 1 Introduction
Other than the above-mentioned technical and production process limitations, social aspects, such as a public awareness and acceptance of the products from recycled materials by public, prevent their actual massive use or commercialization [40]. The practical application of RAC is still limited and its use in structural application is even more so [16]. According to the authors, cementitious products based on recycled aggregate for non-structural application could achievebetter acceptance by public in the status quo. Several papers have been recently published on this topic. [PERSON] et al. [41] investigated the effect of washing and sieving the recycled aggregate on the properties of a mortar produced according to standard UNI EN 196-1. [PERSON] et al. [42] studied the influence of the mortar fine recycled aggregate ratio and the mixing sequence on the behavior of mortars using modified Brazilian standard NBR 7215 and two-stage mixing approach (TSMA), while [PERSON] et al. [43] investigated the effects on the fresh and hardened properties of a rendering mortar at different replacement ratios. [PERSON] et al. [44] presented a study of incorporation at 0%, 20%, 50%, and 100% (by volume) of demolition waste aggregate (CDW) in rendering mortars and evaluated their workability, mechanical strength, water absorption, shrinkage, open porosity, and durability. [PERSON] et al. [45] evaluated the performance of masonry mortar manufactured by replacing natural sand with pre-wettedrecycled fine aggregate (RFA) and using a commercial plasticizer. In all the aforementioned works, the performance of the cement mortars with recycled aggregate was investigated only as a function of the percentage of replacement or of the mixing approach method used. In few cases, a plasticizer was used to adjust the workability. A higher percentage of recycled aggregate lead to lower workability and mechanical properties, partially compensated by adopting the different mixing methods. However, the performance, fresh and hardened properties, and durability of most of the commercial mortars and concrete are achieved or altered by adding chemical admixtures. The type and amount of the used chemicals depend on the specific application of concrete and mortars. Chemical admixtures also alter physical, chemical, and surface chemical properties of the mortars' components. Therefore, they reasonably affect the performance of recycled aggregate mortar. Based on the aforementioned information, authors evaluated the fresh and hardened properties and the durability of two commercial products, a self-leveling and a thixotropic mortar, whose mix design includes two specific chemical admixtures kits. They compared the results with those obtained when their mix design was modified by replacing the 100% the natural sand with recycled aggregate. Self-leveling mortars (SLMs) are building materials with the property of leveling by gravity. They can be used over a subfloor before the installation of floors as underlayment to smoothen out any surface and correct the irregularities that the concrete could have [46]. Their high fluidity, good flatness, high compressive strength, and thin leveling layer also make them ideal for finished flooring in large supermarkets, shopping malls, parking lots, factory workshops, and warehouses. Cements, fine aggregates, mineral fillers, and chemical admixtures compose conventional SLMs [47]. Portland cement (PC) is commonly used as binder. However, SLMs that contain it struggle to meet the early strength requirements and show cracks and curls that commonly appear at the corners and perimeter. The low early strength and serious drying shrinkage of PC are responsible of the behavior [48]. In order to avoid the aforementioned issues, binary or ternary cementitious systems containing PC, calcium aluminate cement (CAC) or sulphoaluminate cement (SAC), and calcium sulfate (CS) are used [47].