This paper reviews the structural performances of reinforced concrete beams and slabs filled with lightweight materials to identify the research gaps in the area for future research development. Data is extracted from the research works done by different researchers. It was then recomputed to analyze the effects of concrete replacement regions, geometrical properties and spacing of lightweight materials on the ultimate strength of the structural elements. The lightweight materials were found to be more effective in reducing the weight of the slab without significantly affecting its strength as compared with the beam. The lightweight materials are recommended to have round corners, spaced out and positioned at the neutral axis or the compressive region for better strength performance so that the effective strength to weight ratio exceeds 1.0.
This paper presents an experimental study to investigate the effects of circular transverse opening in the reinforced concrete beam. Understanding its behaviour would allow such beams to be safely used, particularly for the passage of pipes and ducting. A total of eleven beams with a cross-sectional area of 150 mm x 300 mm and a clear span of 1500 mm were tested under four-point load setup until failure. This comprised two beams without opening as the control beams, six beams with an opening (50 mm, 75 mm and 100 mm in diameter) positioned at the mid-span and near to the support, and three beams with the reinforcement at the opening. The effects of the opening size, the position of the opening and different reinforcing methods on beam performance were studied. The beam failed with severe cracking surrounding the opening. The test results showed that the opening affected the ultimate strength and ductility of the beam. For the beam without reinforcement at the opening to maintain 80% strength, the opening size should not exceed 0.25 times the beam’s height. The diagonal bar reinforcing method was found effective in reinforcing the opening not exceeding 1/3 of beam height.