In reinforced concrete design, the concrete in the tensile zone is assumed to be ineffective and increase the dead load of the structural elements. In order to reduce the self-weight, this paper examines the structural behavior of reinforced concrete beams containing lightweight concrete in the tensile region and normal weight concrete in the rest of the beam. The lightweight concrete was made from waste polystyrene. Four reinforced concrete beams were prepared with different depth of lightweight concrete. The control beam B1 consists of normal concrete. In Beams B2, B3 and B4, the depth of lightweight concrete was 25%, 50% and 75% of the total depth of the beam measured from the bottom surface respectively. A four-point bending test was conducted on all beams. The beams were loaded in increments until failure. At each load increment, the central deflection was determined. Cracks initiation and the mode of failure were observed during the experiment. The failure load was found to decreases with the increase of depth of lightweight concrete. The presence of lightweight aggregate tends to cause brittle failure. In addition, the mode of failure for reinforced concrete beams containing lightweight concrete was a shear failure. arabic 11 English 79
Hakim S. Abdelgader(6-2020)

Although there are visible signs of its gradual acceptance in North Africa through its limited use in construction, Libya has yet to explore the feasibility and applicability of self-compacting concrete (SCC) in new construction. The current study revolves around SCC made of locally available materials and the harsh environmental conditions. This paper deals with the investigation into the effect of the water to powder ratio and limestone powder (LSP) on the fresh and hardened properties of SCC. arabic 7 English 54
Hakim Salem Abdelgader Abdelgader (3-2019)

The construction sector has embraced digitalization and industrialization to boost production, reduce material consumption, and improve workmanship. The 3D-printed concrete technology (3DPCT), more broadly recognized as the design of a 3D object via a computer-aided design (CAD) model or a digital 3D model, has accelerated considerable progress in these areas in other industries. Although 3DPCT has advanced remarkably in recent years, producing an appropriate 3D printing material that improves performance while reducing material consumption, which is really important for CO2 reduction, is urgently needed. The present 3DPCT faces many obstacles, one of which is the limited range of printable concretes. To tackle this limitation, extensive studies on developing creative approaches for formulating alkali-activated materials (AAMs) for 3DPCT for modern building applications have been conducted. AAMs are maintainable substitutive binders to ordinary Portland cement. Therefore, the need to undertake a comprehensive literature review on the current status of AAM performance on 3D-printable concretes for building applications is substantial. This article comprehensively reviews the quality requirements, advantages, disadvantages, common techniques, delivery, and placement of 3DCP. This literature also delivers indepth reviews on the behaviors and the properties of AAM-based concrete composites used in 3D-printed construction. Moreover, research trends are moving toward a wide-ranging understanding concerning the economic benefits and the environmental footprints of 3DCP for building applications with AAMs as suitable concrete materials for the emerging robust eco-friendly concrete composite for digital construction constructions nowadays. Given the merits of the study, several hotspot research topics for future investigations are also provided for facilitating the wide use of 3DPCT in real applications to address rapidly the gap between demand and supply for smart and cost-effective homes for upcoming generations.
Hakim S. Abdelgader(2-2022)