Ahed Habib

Bio: Ahed Habib is an academic researcher from Eastern Mediterranean University. The author has contributed to research in topics: Pendulum & Dissipation. The author has an hindex of 5, co-authored 10 publications receiving 54 citations.

Shrinkage Behavior of Conventional and Nonconventional Concrete: A Review

Abstract: Concrete is indeed one of the most consumed construction materials all over the world. In spite of that, its behavior towards absolute volume change is still faced with uncertainties in terms of chemical and physical reactions at different stages of its life span, starting from the early time of hydration process, which depends on various factors including water/cement ratio, concrete proportioning and surrounding environmental conditions. This interest in understanding and defining the different types of shrinkage and the factors impacting each one is driven by the importance of these volumetric variations in determining the concrete permeability, which ultimately controls its durability. Many studies have shown that the total prevention of concrete from undergoing shrinkage is impractical. However, different practices have been used to control various types of shrinkage in concrete and limit its magnitude. This paper provides a detailed review of the major and latest findings regarding concrete shrinkage types, influencing parameters, and their impacts on concrete properties. Also, it discusses the efficiency of the available chemical and mineral admixtures in controlling the shrinkage of concrete.

Column repair and strengthening using RC jacketing: a brief state-of-the-art review

Abstract: Seismic retrofitting and/or the strengthening of RC columns has been a popular area of research for decades. Currently, reinforced concrete jacketing is considered as the most common technique for repairing and strengthening of deficient and/or damaged RC columns. In general, this technique is a practical solution to recover and improve the load-carrying capacity and stiffness of reinforced concrete columns in earthquake-prone countries. It is a simple method that can be applied to any column cross section for rehabilitating structural elements by encasing the old member in a stiff jacket. The importance of this approach comes from its ability to improve the load-carrying capacity, strength, and stiffness of any column section significantly without the need for experienced labor or complicated installations process. This paper summarizes and compares general conclusions of recent investigations on columns retrofitting using reinforced concrete jacketing. As a part of this study, experimental, analytical, and numerical studies were reviewed and their findings were collected and discussed.

Structural Performance and Finite Element Modeling of Roller Compacted Concrete Dams: A Review

Abstract: There is no doubt that concrete is one of the most consumed materials all over the world. It is a composite mix widely used for constructing structures and infrastructures to sustain environmentally induced stresses such as thermal and seismic. As the mainstream of construction industry is tended to find out feasible solutions, Roller Compacted Concrete (RCC) was introduced to play an essential role in the development of dams and pavements, where over 550 RCC dams were created by the end of 2012. In fact, this material has the same basic constituents of conventional concrete with a zero-slump and a significant difference in the placing process. The majority of available studies in the literature are composed of numerical investigations to assess the thermal and seismic behavior of RCC dams and to provide a clear view on how to improve its performance under various loading conditions. This paper summarizes and compares the general conclusions of recent works on evaluating the structural performance of RCC dams.

Performance of Concrete Beams Reinforced with Various Ratios of Hybrid GFRP/Steel Bars

Abstract: This paper aims to study the flexural behavior of concrete beams reinforced with hybrid combinations of GFRP/steel bars. To this purpose an experimental program was carried out on four concrete beams reinforced with Glass Fiber Reinforced Polymer (GFRP) and twelve hybrid GFRP/steel Reinforced Concrete (RC) beams. Flexural behavior of the tested beams such as stages of response, failure modes, crack patterns, stiffness, toughness and ductility were analyzed. The experimental results showed that depending on GFRP/steel reinforcement configurations, the behavior of hybrid GFRP/steel RC beams undergoes three or four stages, namely: pre-cracking stage; after concrete cracking and before steel yielding; post-yield stage of the steel bar until peak load and failure stage. Totally six failure modes of hybrid RC beams are reported depending on reinforcement rations and configuration. The effect of reinforcement configuration and ratio of GFRP to steel ( ρ g ) on the crack patterns, stiffness, ductility and toughness of hybrid RC beams are significant. Based on the non-linear deformation model, an analytical model has been developed and validated to determine the steel yielding moment and ultimate moment of hybrid GFRP/steel RC beams. It could be seen that the experimental values were in good agreement with the predicted values.

Review of dynamic behaviour of rubberised concrete at material and member levels

Abstract: The reuse of waste tyres satisfies the requirements of sustainable development. Many researchers mix concrete with recycled rubber particles obtained from waste tyres to produce rubberised concrete, which exhibits improved mechanical properties. Although numerous studies have been performed on the mechanical behaviour of rubberised concrete, most of these were focused on its static behaviour, which is the shortage for rubberised concrete research. The achievement of dynamic behaviour of rubberised concrete is limited. It has been demonstrated that the addition of rubber particles can improve the fatigue performance, seismic performance, impact resistance, and explosion resistance of concrete. Therefore, it is necessary to summarise the dynamic behaviour of rubberised concrete materials and members to further civil engineering practitioners’ understanding of rubberised concrete and thereby, promote its application and development. This paper systematically summarises the mechanical properties of rubberised concrete under fatigue loads, earthquake loads, impact loads, and explosion loads from the material level to the member level. It also proposes a feasible direction for future research on rubberised concrete under dynamic loads.

Influence of Waste Tire Rubber Particles Size on the Microstructural, Mechanical, and Acoustic Insulation Properties of 3D-Printable Cement Mortars

Abstract: 3D printing technologies of construction materials are gaining ground in the building industry. As well documented in the literature, these advanced manufacturing methodologies aim to reduce work-related injuries and materials waste, enhancing architectural flexibility which would enable more sophisticated designs for engineering and aesthetic purposes. In this framework, the development of functional and eco-sustainable printable materials represents an extremely attractive challenge for research, promoting digital fabrication to reach its maximum cost-effective and technological potentials. The use of recycled tire rubber particles in 3D printable Portland-based compounds is an exclusive contribution in this field. This line of research aims to integrate the well-known engineering performances of rubber-cement materials with the advanced peculiarities of additive manufacturing methodologies. As an innovative contribution, the authors propose here a detailed study on the possible relationship between rubber particle size and technological properties of the 3D printable mix. Specifically, two groups of continuous size grading polymer aggregates (0-1 mm rubber powder and 1-3 mm rubber granules as fine and coarse fractions, respectively) were analyzed in terms of impact on rheology, print quality, microstructure, mechanical properties, and acoustic insulation performance. Concerning the print quality, rubber aggregates altered the fluidity of the fresh mix, improving the adhesion between the printed layers and therefore enhancing the mechanical isotropy in the post-hardening sample. A remarkable influence of the rubber gradation on the compounds’ behaviour was found in hardened properties. By comparing the rubberized compounds, the fine polymer fraction shows greater interfacial cohesion with the cement paste. However, more significant mechanical strength loss was found due to a greater reduction in density and increased porosity degree. On the other hand, mortars doped with larger rubber particles tend to have a higher unit weight, finest pore distribution, minor mechanical strength drop, and higher ductility but worse interface binding with the matrix. Regarding the acoustic insulation properties, a proper balance between rubber powder and granules in the mixes allows to obtain comparable/superior performance compared to plain mortar but the effect of the aggregate size is strongly dependent on the sound frequency range investigated. Future findings revolve around applicability studies of these formulations in civil and architectural fields, benefiting from the design flexibility of 3D printing. Doi: 10.28991/cej-2021-03091701 Full Text: PDF