This paper presents an investigation to improve the flexural behavior of reinforced lightweight concrete beams made
of light-weight expanded clay aggregate (LECA) as 50% replacement (by volume) to the normal -weight aggregates and
addition of foaming agent as percentage of weight of cement. A series of 44 lightweight reinforced concrete
(LWRC) beams of 700 mm length and a rectangular cross section of 100x100 mm were cast, strengthened and then
tested under three-points bending test to study the effectiveness of using externally applied glass fiber-reinforced
polymer (GFRP) composites as a method of increasing the flexural strength of under-reinforced LWRC beams. The
variables considered for this study was four concrete mixes and the number of GFRP layers with and without sulfate
attack. The behavior of the tested beams was analyzed in terms of mode of failure load , ultimate carrying load, ultimate
deflection, and toughness . Despite the experimental results illus trated that the beams strengthened with GFRP laminates
exhibited better performance. Also the results show that the use of GFRP as an external reinforcement to strengthen or
repair concrete structural members (pre-loaded) is more effective