This study is interested in the connection between steel and concrete with recycled gravel. The work is carried out in the civil engineering laboratory of the Ecole Nationale Supérieure des Travaux Publics ENSTP and then completed in the mechanical engineering laboratory of the Institut National Supérieur des Sciences et Techniques d’Abeché INSTA. Two types of concrete are formulated, one with 100% ordinary crushed gravel and the other with 100% recycled gravel. In terms of compressive strength, the present study with 100% recycled gravel varies from 19 to 32 MPa at 28 days for the different dosages. And the concrete with ordinary crushed gravel offers a strength ranging from 22 to 37 MPa. Regarding steel concrete bonding, several types of reinforced concrete specimens are manufactured by anchoring a steel bar in the concrete. These specimens are subjected to the test of extracting the steel bar from the concrete. The values of the bond stress at rupture are calculated according to the formulas given by the Euro code, the BAEL, and then calculated experimentally. These values vary according to the compressive strength of the concrete.

The purpose of this study is to determine the dry and wet mechanical resistances after immersion in water of bricks of 15 x 20 x 40 cm3 in sand mortar (cinder blocks) and 10 x 14 x 28 cm3 compressed lateritic mortar bricks (BTC) stabilized with cement. The experimental results obtained show that the 28-day compressive strength values of the 12% cinder blocks and those of the 10% cement Btcs are respectively 2.55 MPa and 7.90 MPa. These values are in accordance with the normative values recommended by the Building Materials Centre (CMC) in N'Djamena (2.4 MPa) and the Land Materials Research Centre (CRATerre) (5 MPa). In the presence of moisture, the loss of resistance is only 28% for BTC and 46% for cinder blocks. Also, the bricks have a suction capacity ranging from 2.50 to 5.02 g/cm² S1/2 for BTC and 6.12 to 10.90 g/cm². S1/2 for cinder blocks. These values are all less than 20 g/cm². S1/2, a value imposed by NF P 554. A comparison of the results of this work shows that, with the same cement content, during dry seasons as in rainy seasons, Btcs are more resistant and more economical than cinder blocks.