# Long-Term Deformations and Mechanical Properties of Fine Recycled Aggregate Earth Concrete
## 1 Introduction  
Carrying out construction with earth is an ancient building approach that dates back thousands of years, with different possible techniques, such as wattle and daub, cob, rammed earth and compressed earth block [1]. Earth construction materials are very interesting because of their low cost, recyclability and their limited energy consumption. In addition, they posses good thermal and insulation properties compared to normal concrete with sufficient mechanical strength [2]. A new earth construction material designed to be portable, called earth concrete, has been recently considered [3, 4, 5]. On the other hand, the increasing construction works, continuous industrial development, infrastructure activities and residential market growth generate a huge amount of construction and demolition waste (CDW). CDW includes the waste generated from construction and demolition of buildings and infrastructure, in addition to road planning and maintenance. Over 10 billion tons of CDW are produced globally each year [6]. The European Union (EU) contributes to about 1 billion ton annually [7]. [PERSON] et al. [6] reported an overall 88-90% of recovery rate of CDW in EU in 2018. An improvement has been noticed compared to past years. Croatia, for instance, achieved a recovery rate of 2% in 2010, and has reported a value of 78% in 2018. The Netherlands continues to attain a 100% of recovery rate since 2010 due to its policy that considers such waste as abase in road construction [8]. However, new markets need to be developed for an effective circular economy and a sustainable development of the construction industry while reducing the environmental impact of concrete [2]. Fine recycled aggregate or recycled sand (RS) accounts for about 50% of CDW [9; 10]. The construction activities that involve concrete are numerous; however, RS is still applied only at a concrete laboratory scale. This is due to the fact that RS is generally porous and of high water absorption capacity, which negatively affects the mechanical and durability properties. In fact, the lack of standards can be behind the restriction of RS applications at construction sites [11]. Nevertheless, the consideration of RS as earth material component may still yield satisfactory results [2; 11]; thus, this may permit to consider earth materials as alternative market for RS. Moreover, it would be interesting to assess the combination of RS as it is porous and clay constituted of fine particles which can have an important potential for energy conservation in buildings as it may reduce the thermal conductivity in addition to the reduction of CO\({}_{2}\) emissions and cost [2; 12]. In this study, RS earth concrete mixture has been tested and compared to the behavior of NS earth concrete mixtures. More particularly the long-term deformations have been considered. In fact, few studies have been conducted in the literature on the effect of RS on mechanical properties and long-term deformations of earth concretes [12]. The structures are subjected to different mechanical loadings in addition to temperature and humidity variations during their lifetime [13; 14; 15]. Autogenous shrinkage and drying shrinkage are a result self-desiccation and drying, respectively [16; 17]. The capillary pressure, disjoining pressure, surface tension and interlayer water theory may be behind such deformations. In normal concrete, a 66-83% decrease and 15-80% increase would be generally reported for the complete replacement of natural aggregate (NA) by recycled aggregate (RA) for autogenous and drying shrinkage, respectively [18; 19]. In earth concrete, [PERSON] [20] reported swelling rather than shrinkage up to 200 um/m for autogenous assessment and a decrease of drying shrinkage from 2000 um/m to almost 1200 um/m when 31% of NA are replaced by RA.