الإستدامة الإنشائية للأعتاب الخرسانية خفيفة الوزن

Structural Sustainability of Lightweight Concrete girder

    Due to the limitations of natural materials which uses in concrete production, the use of waste and recycle materials in concrete production can eliminate the negative impact of concrete on the environment. Therefore, Attapulgite and crushed clay bricks were used as a coarse lightweight aggregate to produce a structural sustainable lightweight aggregate concrete. The present study includes an experimental investigation of the behavior of a simply supported beams. The experimental program consists of testing eight reinforced concrete rectangular beams. Five of these beams are tested under symmetric two-point concentrated loads (STPCL) and the others tested under one point concentrated load (OPCL). All beams have the same dimensions; 140 mm width, 180 mm depth and 1200 mm length.

   The main considered variables in the experimental study were the type of aggregate (Attapulgite aggregate, crushed clay bricks aggregate and normal weight aggregate), type of loading system and curing time. Cylinders and cubes for each concrete mix, were tested to find the mechanical properties of concrete. The experimental program shows that a structural lightweight aggregate concrete can be produced by using Attapulgite aggregate with 25 MPa cube compressive strength and 1805 Kg/m3 oven dry density and by using crushed clay bricks aggregate with 43.7 MPa cube compressive strength and 1977 Kg/m3 oven dry density. The weight of Attapulgite aggregate concrete and crushed clay bricks aggregate concrete beam specimens were lower than normal weight aggregate concrete beams by about 20.56% and 13.65% respectively at 28 days. As for the ultimate load capacities of beam specimens, the ultimate load of Attapulgite aggregate concrete beams tested under STPCL were lower than that of crushed clay bricks aggregate concrete beams and normal weight aggregate concrete beams by about 4.85% and 5% respectively. While the ultimate load capacities of reinforced Attapulgite concrete beams tested under OPCL were lower than that of reinforced crushed clay bricks aggregate concrete beams and reinforced normal weight aggregate concrete beams by about 10.3% and 10.5% respectively.

    Finally, Attapulgite aggregate concrete and crushed clay bricks aggregate concrete showed ductility and toughness less than that of normal weight aggregate concrete.