The evolution of construction techniques has given rise over time to the use of various materials including wood, steel, aggregates, etc. However, the most widespread construction methods today are largely based on the use of aggregates which today represent the most consumed resources after water and the majority of which is used in the construction industry. These aggregates are in fact used in numerous applications including roads, infrastructure and buildings as base materials for concrete, mortars for walls and coatings, surface coverings and as backfill materials. From a consumption point of view, whatever the field of construction, sand remains the most used material.

Togo, like several coastal countries, is full of several categories of sand in addition to marine sand. We distinguish in particular between river sand, sand from rock crushing and sand from quarries. Despite the abundance of sand extraction sites observed throughout the national territory, recognition of the granular properties of these materials remains a major challenge for local builders. Unlike the marine sands of the Togolese coast which are generally average sands (Mf~2.656) and very clean (ES~100 > 80) therefore very suitable for quality concrete [1] [2] , sands from quarries and those taken from river beds are very fine (Mf~1.966) and slightly clayey (ES~66.32 < 70) [3] - [5] . As a result, the risk that these materials are unsuitable or inappropriate, thus compromising the stability, durability and safety of the structures, is high, hence the need to ensure their qualities through an in-depth study in order to examine the possibility of using them as materials in the field of construction. It is in this context that this study takes place, the present development of which concerns the inventory of sand extracted from quarries and river beds used in construction in Togo.

Of the ninety-eight (98) elementary surfaces resulting from the grid of the study area, thirty-nine (39) were covered by the surveys, i.e. a coverage rate of 40%. The results on the different types of sand encountered in the area, their operating condition as well as their reasons for use by the population are given in Tables 1-3 . The detailed results of the reasons for use of these sands by category of actors targeted by this study are presented in Table 4 .

The results of the surveys carried out throughout the Togolese territory covered one hundred and eighteen (118) sand quarries in operation, including thirty-eight (38) silty sand quarries and eighty (80) sand quarries, rivers, i.e. 32% from river sand quarries and 68% for silty sands ( Figure 2 ).

Silt and river sands are practically exploited without authorization (92%) ( Figure 3 ).

Three (3) main reasons are the origin of choice of sand type; namely: proximity (28%), cleanliness (25%), good appearance (25%). River sands (59.43% to 84.68%) are prioritized over silty sands (15.32% to 40.57%) ( Figure 4 ).

Figure 5 shows that suppliers make more choices of sand types for reasons of proximity (27%) and appearance (26%). The proximity condition is 18%. This category of people uses river sands (67.95% to 92.85%) more than silty sands (7.14% to 32.05%).

Construction professionals opt for the use of sand because of the proximity to the location of the work (28%), their appearance (25%) and their cleanliness (23%). They also prefer river sands (70.52% to 97.46%) ( Figure 6 ).

As for non-professional users, they prefer the sands closest to their areas of use (28%), clean sands (26%). The appearance of the sands is also part of their choices (25%) ( Figure 7 ). The silty sands are more demanded (53.26%). However, river sands are often used for reasons of proximity (65.15%), cleanliness (79.94%) ( Figure 7 ).

The use of river sand dominates overall in the study area (68%) ( Figure 2 ). The exploitation of this sand takes place mainly on the banks of large rivers such as the Oti, Kara and Mono.

A predominance of silty sand exploitation is noted in the maritime region of the study area ( Figure 1 ). This results from the Togolese State’s ban on the exploitation of coastal sand by interministerial decree n˚031/MME/MERF dated May 5, 2011 in order to effectively combat the phenomenon of coastal erosion. This coastline was for a long time the main source of sand supplying this part of the study area. Added to this ban is the strong urbanization of this region which alone concentrates more than 68% of the urban population and all the industrial centers of the country [6] . This strong urbanization is accompanied by vast infrastructure construction projects and consequently a high consumption of construction materials, thus leading to a multiplication of silty sand quarries in the area, some of which are being created in defiance of environmental rules and standards.

Regarding the operating conditions of the quarries identified in the study area, the results of the study crossed with those of the initiative for transparency in the extractive industries [7] show that 92.31% of sand quarries identified in the study area operate without authorization ( Figure 3 ). The absence of authorizations is partly explained by the fact that most sampling zones are carried out at several points along the beds of watercourses or rivers and this in an informal manner. This predominance of quarries without authorization confirms the results of the study on artisanal and small-scale mining [8] according to which outside the maritime region, all the quarries identified do not have any rights mining allowing them to search for or exploit minerals. Under these conditions, environmental and social impact studies (ESIAs) making it possible to obtain operating titles or permits are almost rare or even non-existent for most of the quarries identified. Thus, the lack of studies leads to the abandonment of sites after exploitation. These data are confirmed by the same report [8] . Indeed, the study shows that 9.1% of sites after their exploitation are used as backfilling or waste recovery areas of all kinds while the sale of the site after exploitation is only observed at around 0.1% operating units. More than 90% of sites are abandoned in nature.

The reasons for choosing sand vary according to the different categories of actors (Supplier, Professional Users and Non-professional Users). Overall, for the entire area studied, the most predominant reasons for choosing river sands are respectively its appearance (84.68%), its cleanliness (83.13%) and its proximity (69. 04%) ( Figure 4 ). For the different types of actors, notably suppliers, professional and non-professional users, these reasons for choice remain dominant for river sands as shown in Figures 5-7 . The predominant choice of river sand based on its cleanliness and its appearance, is explained by the nature of its production. Indeed, just like marine sands, all samples from rivers are naturally clean because coming from moving rivers, it is practically impossible to have clay impurities on the sand grains [1] [9] - [11] . This gives them a visually good appearance and good cleanliness. For silty sand, the proximity reason outweighs the other reasons. The silty sands being extracted from quarries close to the land, are subject to contamination and are often not clean [1] [12] [13] . Thus silty sands are avoided because of their cleanliness and appearance. Indeed, according to the work of Amey K. B. (2018) [1] [14] [15] , 50% of these sands are slightly clayey (ES < 70%). Also 76% of these sands are fine (Mf < 2.1). They are therefore for the greatest proportion (50% to 76%) not suitable for concrete and hydraulic mortar work, which justifies that they are requested for construction work at 25% for their appearance and 25% for their cleanliness.

In Togo, three (3) main reasons are behind the choice for construction work: appearance, cleanliness and proximity. The choices linked to the quality of the sands (appearance and cleanliness) represent 50% while the sands are 50% to 76% suitable for construction work. These results clearly show that the Togolese population has a good culture and is aware of the quality of construction materials to be adopted for construction work.

Providing data on the characteristics of these materials, particularly sand, will be very beneficial for the works and would contribute to improving the housing conditions of the Togolese population.

This study aims to take stock of the silty sands and river sands used in construction in Togo in order to provide users with data on these materials intended for construction uses. We collected data through surveys of potential stakeholders involved in the construction chain. These data made it possible to identify in the study area a total of one hundred and eighteen (118) sand quarries in operation, including thirty-eight (38) silty sand quarries (i.e. 32%) and eighty (80) river sand quarries (i.e. 68%). The choices made by the respondents, which are essentially based in most cases on visual and physical observations, are mainly due to good appearance, cleanliness and proximity. Laboratory tests will make it possible to make available to the population data on the physical, geological and mineralogical characteristics of sands indicating the different possibilities of using said material.

This work could be done without formal logistic and financial support from FORMATEC we express our sincere gratitude to.