**1. Introduction**

Due to the increase in coarse aggregates consumption and the availability of large quantities of sand in Algeria, as well as the complexity of designs and reinforcement details in modern structural members, producing fluid concretes for easy implementation and no compaction has become one of the main desires and challenges for building industry. Flowable sand concrete is a new type of concrete that make part of the important building materials permitting to valorize some local resources and waste (dune sand, fillers, waste, garbage and under local products).

In the last years, construction and demolition waste provides a substantial source of natural raw materials for building works by using construction site waste. In addition, the amount of ceramic waste, presents the highest fraction of construction and demolition wastes. Therefore, disposal of a variety of ceramic wastes in an ecofriendly way is the thrust area of today's research.

Several studies have been done on the use of ceramic waste as coarse aggregate, powder and filler in the preparation of cement mortar [1–6], concrete [7–13] and self-compacting concretes [14–16], high strength concrete [17, 18] and ultra-highperformance concrete [19, 20]. Many of them, explored that the use of ceramic waste, as a material in concrete composite, leads to a decrease in workability and density of mixture [2, 3]. The mechanical properties of mortar and concrete incorporating ceramic waste have also studied and analyzed by several researchers [3, 10]. The majority of results showed that, for up to optimum percentage replacement of natural sand by ceramic waste, the mechanical strength of concrete is similar or even better than those containing natural aggregates. Tabak et al. [21] studied the effect of ceramic waste as aggregate (CW), dust (FTDA) and combinations of them to produce concrete. They found an increasing of about 13.53, 16.70, 2.91% and 23.21, 0.10, 19.47% for compressive and flexural strength respectively, at 2, 7 and 28 days. The similar results were also stated by Abadou et al. [5]. They studied the effect of partial replacement for natural sand by ceramic waste with different percentage (10, 20, 30, 40 and 50%) on the performance of ordinary concrete. And they observed that the mechanical properties of ceramic waste mortar increase with replacement of natural dune sand by CW.

The durability properties of concrete counting ceramic wastes were also investigated by several researchers. It found in the study of many authors [1, 5, 10, 18] that there is no significant change in the basic trend of permeation characteristics of this recycled aggregate concrete when compared to the conventional concrete. Tabak et al. [21] demonstrated a reduction of about 0.17% in water absorption of concrete made with recycled ceramic aggregate, when compared to conventional concrete. Elçi [10] studied the effect of total replacement of natural sand by ceramic waste on water absorption and shrinkage of cement concrete. It was observed an increasing in the values of drying shrinkage and water absorption compared to the conventional concrete. Abadou et al. [5] found that the addition of CW in dune sand mortar increases its acids resistance property. It was observed that the mortar made with ceramic waste aggregate shows better resistance to sulfuric (H2SO4) and hydrochloric (HCl) acid solution attack than reference mortar. Hence, the mortar with CW performs well in durability aspect, this addition of ceramic waste, improves the behavior of mortars subject to attacks HCl and H2SO4 acids.

The aim of this research is to study the possibility of recycling ceramic waste without any prior treatment except crushing in order to produce low cost flowable sand concrete. For this the influence of partial replacement of natural sand by ceramic waste on the workability and physic-mechanical properties of the new composite material has been studied and compared to the control FSC. And the optimal proportion of ceramic waste substitution which can give the ecofriendly lightweight flowable sand concrete was then determined.
