In this study, an innovative idea for a lightweight concrete slab reinforced by GFRP and testing the flexural behavior of these slabs. Six slabs were tested, each consisting of two materials: lightweight concrete (LC) and glass fiber-reinforced (GFRP) sections. The flexural test was due to three parameters: the spacing between the GFRP sections, The geometry of the GFRP cross-section, and the use of stiffeners. The ultimate load capacity of the slab was increased by 22.4 % when the distance between GFRP sections decreased from 350 to 233. Changing the geometry of the GFRP cross-section area from I to U increased the ultimate load by 20.2%. Changing the shape from I to T led to a decrease in the maximum load by 15.5%. Increasing the load depends on increasing the inertia of the cross-section. Using glass fiber stiffeners between GFRP increased maximum load by 3% .