INCREASING ULTIMATE STRENGTH OF REINFORCED CONCRETE SLAB BY USING GEOGRID

The main purpose behind the search is to study the punching shear behavior of nine specimens of two way flat plate slabs with geogrid mesh, all slabs are dimensioned in (400*400*60) mm and F'c is (30)MPa and all slabs contain a (6 mm) diameter of steel reinforcement and all slabs contain geogrid pieces of different shapes and dimensions except the reference slab (R000), geogrid is used as strips with a dimensioned (10*38)cm in slabs (NGI0, NGI-, NGX0) in deferent shapes (I, +, X)  respectively,  It was used in squares with different dimensions (15,20,25)cm in slabs (NGS15, NGS20, NGS25) respectively, and it was used as a complete piece with dimensions (38*38)cm with steel reinforcement in slab (NGST) and without steel reinforcement in slab (NG00). Laboratory tests show that the first crack of the slab (NGST) more than the reference slab (R000) by (100) % and ultimate load more than the reference slab (R000) by (132.43) % as the deflection is reduced in this model where it was (5.44) mm, the reason is that the geogrid worked with steel reinforcement as a single piece, which increased the resistance of the model and at the same time worked to reduce the deflection. either in the slab (NG00) It was the F.C.L less than the reference slab (R000) by (38.46) % as well U.L less by (16.67) % and the deflection it was more than a reference slabby (66.5) % The reason is that the slab contains a whole piece of geogrid without steel reinforcement. the other slabs showed an increase in bearing and a decrease in deflection.