Publications

Axial Compressive and Buckling Behavior of Concrete-Filled Steel Tubes Incorporating Recycled Coarse Aggregate, Plastic Waste, and Silica Fume

This study investigates the axial behavior of steel tubes filled with concrete incorporating a hybrid mix of natural coarse aggregate (NCA), recycled concr

An exponential-trigonometric quasi-3D HSDT for wave propagation in an exponentially graded plate with microstructural defects

This work aims to investigate the wave propagation in an exponential-law-based functionally graded (FG) plate with micro-structural defects using a simple exponential-trigonometric quasi-3D HSDT that employs four variables only. In this study, the elastic properties varied across the plate's thickness using a function of volume fraction in the form of exponential power-law. Hamilton's principle is utilized to obtain the governing differential equations, and the analytical solution is processed using the Navier approach. A parametric investigation has been developed to explore the impacts of material exponent, porosity distribution, and plate thickness on the wave propagation of the exponentially graded material (EGM) varying plate. The results showed that the phase velocity in the plate decreases with increasing the percentage of porosity volume of the plate for a specific material power exponent. In contrast, the FG plate's porosity does not affect the primary frequency.

Performance and efficiency of self-healing geopolymer technologies: A review

Self-healing geopolymer (SHG) concrete is an innovative construction material that has emerged as a promising alternative to conventional Portland cement concrete due to its exceptional mechanical properties, durability, and self-repairing ability in certain environmental conditions. However, the widespread adoption of geopolymer technologies necessitates the development of self-healing materials to prevent deterioration due to cracking. Although the literature on SHG concrete is extensive, only a few studies have investigated its properties in civil engineering applications such as paste, mortar, concrete, or composites. Common geopolymer materials include fly ash (FA), granulated blast furnace slag (GBFS), and metakaolin (MK). This review provides an overview of the current state of research on SHG and the types of self-healing agents, mechanical properties, durability, and self-healing capabilities of SHG products. The review suggests that SHG products are more resistant to environmental degradation, such as freeze–thaw cycles or chemical attacks, and have higher mechanical strength than traditional Portland cement concrete, owing to the presence of healing agents. Furthermore, SHG products exhibit excellent self-healing capabilities (able to repair cracks up to 650 μm) by forming new bonds between fractured particles when exposed to moisture, such as bonding of calcium carbonate (CaCO3) crystals precipitated by bacteria. While bacteria are the most common healing agents, new healing agents such as fibers and glass frit have been introduced; however, their healing efficiency is not as high as that of bacterial agents. This paper concludes by emphasizing the need for further research to fully understand the performance and efficiency of SHG in civil engineering applications.

Strength and durability assessment of stabilized Najd soil for usage as earth construction materials

For centuries, earth materials have been used in Saudi Arabia in building construction. Globally, these materials re-emerged as one of the possible solutio

Development of eco-friendly hollow concrete blocks in the field using wasted high-density polyethylene, low-density polyethylene, and crumb tire rubber

A new configuration of hollow concrete blocks was fabricated in the field. Three distinct types of hollow concrete blocks were produced to assess the effectiveness of such blocks in the market. In addition, the experimentally determined thermal resistance was used to calculate the expenses, oil consumption, and CO2 emissions. Blocks made with crumb rubber failed in the ASTM C129 tests for non-load bearing compressive strength, whereas those made with the control and high-density polyethylene (HDPE) met the standard requirements. It was shown that the inclusion of rubber particles lowered the strength by 56%. The control block with the new configuration used in this investigation has a thermal conductivity of 53.4% lower than the commercial hollow blocks. While the inclusion material had a smaller impact than the arrangement of holes, HDPE thermal conductivity decreased by 6.4% compared to the control block. Likewise, the control-block wall's layout can reduce the power consumption by 53%. Moreover, the HDPE and low-density polyethylene (LDPE) blocks lowered the power consumption by 54 and 57%, respectively, saving roughly 4.26 ($/m2.year). Furthermore, the oil consumption and CO2 emissions were decreased by 56% when HDPE with 20% replacement was utilized. Reducing oil consumption as an energy source implies cleaner air and a lower carbon footprint. Therefore, it is recommended to incorporate these waste materials in the production of concrete blocks in order to reduce CO2 pollution in the world.

Engineered and green natural pozzolan-nano silica-based alkali-activated concrete: shrinkage characteristics and life cycle assessment

Alkali-activated concrete (AAC) or binders (AABs) have emerged as a substitute to conventional ordinary Portland cement (OPC)–based concrete owing to

NON-CARBONATE ALKALI-ACTIVATED BINDERS UTILIZING NATURAL POZZOLAN, LIMESTONE POWDER, SILICOMANGANESE FUME, AND RED MUD

This study aimed to develop non-carbonate alkali-activated binders utilizing natural and industrial waste materials in addition to small quantity of ordinary Portland cement (OPC) as precursor materials. Precursor materials were activated using the mixture of sodium hydroxide and sodium silicate solutions. Initial trials were carried out to optimize the proportioning of the precursor materials and the levels of activation parameters and to select suitable curing regimes. Using three combinations of natural pozzolan and OPC and keeping percentages of other precursors and activation parameters invariant at their optimum levels and two selected curing regimes, six mixtures of alkali-activated concrete (AAC) were prepared. The AAC mixtures were tested to determine their microstructural and mechanical properties, drying shrinkage, and durability characteristics. Test results exhibited the significant effects of the percentage of OPC and curing regime on the properties of AAC with optimum performance at an OPC content of 20% and curing using steam.

Numerical investigation of the shear behavior of reinforced ultra‐high‐performance concrete beams

This computational investigation focused on numerical modeling of the shear behavior of ultra‐high‐performance concrete (UHPC) beams reinforced longitudinally with high‐strength rebars and ordinary‐strength steel (stirrups). Nonlinear three‐dimensional finite element model, using the concrete damaged plasticity model and material properties obtained from uniaxial compressive and tensile laboratory tests, was conducted to simulate UHPC concrete beams within a commercial finite element software package ABAQUS 6.13. This investigation included the effects of various parameters; shear span‐to‐effective depth ratio ( a/d ), volume fraction of steel fibers, V f , longitudinal reinforcement ratio, ρ , and stirrups spacing, s , on shear behavior of UHPC beams. Numerical results compared with previously obtained experimental results in terms of shear force–midspan deflection and cracking‐propagation behaviors. The results showed that finite element analysis predicted the shear behavior of UHPC beams in good agreement with the experimental data and predicted the response of the beam with variation in various parameters with a good accuracy.

Enhancing unreinforced masonry wall resilience through nano-silica modified steel fiber reinforced mortar: A study on in-plane cyclic loading

Strengthening existing unreinforced masonry (URM) structures with plaster is a common technique used to improve the structural integrity and durability of buildings. However, using a thin layer of plaster alone may not provide sufficient reinforcement to adequately enhance the URM wall's resistance to lateral or other types of loading. Therefore, incorporating additional materials, such as steel fibers and nano-silica, into the plaster mix has been explored in this study to further improve the URM wall's resilience performance. The effect of nano-silica modified steel fibers reinforced (NS-SFR) mortar plastering on the axial and lateral load capacity of concrete masonry walls was experimentally investigated. The investigated URM walls were constructed with a dimension of 830×810×100 mm (length × width × thickness) using hollow concrete masonry blocks. These walls were categorized as a reference wall, plastered on one side only wall, and plastered on both sides wall. During the experimental testing, each sample was exposed to a combination of precompression and cyclic in-plane loading to assess its shear capacity. The tests also involved closely observing and identifying any cracks or types of failures that occurred. The results of the tests indicated that the walls that were strengthened with NS-SFR mortar exhibited a significant improvement in their compressive strength, shear strength capacity, and stiffness, in comparison to the walls that were not strengthened. Applying NS-SFR mortar as a plaster on the URM wall resulted in significant improvements in both compressive strength and shear capacity. Specifically, for the one-side plastered wall, the use of NS-SFR mortar increased compressive strength and shear capacity by 18.5% and 40%, respectively, while for the two sides plastered wall, the increase was even more significant, with improvements of 86.5% and 132% in compressive strength and shear capacity, respectively.

Optimum design and performance of a base-isolated structure with tuned mass negative stiffness inerter damper

In order to increase the efficiency of the structures to resist seismic excitation, combinations of inerter, negative stiffness, and tuned mass damper are used. In the present work, the optimum tuning frequency ratio and damping of the tuned mass negative stiffness damper-inerter (TMNSDI) for the base-isolated structure were determined by employing the numerical searching technique under filtered white-noise earthquake excitation and stationary white noise. The energy dissipation index, the absolute acceleration, and the relative displacement of the isolated structure were considered as the optimum parameters, obtained by their maximization. Evaluations of base-isolated structures with and without TMNSDI under non-stationary seismic excitations were investigated. The efficiency of the optimally designed TMNSDI for isolated flexible structures in controlling seismic responses (pulse-type, and real earthquakes) were evaluated in terms of acceleration and displacement. A dynamic system was used for deriving the tuning frequency and tuned mass negative stiffness damper inerter (TMNSDI) for white noise excitation by using explicit formulae of the curve fitting method. The proposed empirical expressions, for design of base-isolated structures with supplementary TMNSDI, showed lesser error. Fragility curve results and story drift ratio indicate reduction in seismic response by 40% and 70% in base-isolated structure using TMNSDI.

An integral four-variable hyperbolic HSDT for the wave propagation investigation of a ceramic-metal FGM plate with various porosity distributions resting on a viscoelastic foundation

This work studies the dispersion relations of wave propagation in infinite advanced functionally graded (FG) ceramic-metal plates. A simple integral hyperbolic higher-order shear deformation theory (HSDT), with undetermined integral terms and only four unknowns, is used to formulate a solution for the waves' dispersion relations. The effective functionally graded materials' (FGM) properties follow the power-law with three different types of uneven porosity distributions. The effect of foundation viscosity is investigated by considering the damping coefficient in addition to Winkler's and Pasternak's parameters. The wave propagation's governing equations are derived based on the present integral hyperbolic HSDT using Hamilton's principle. The eigenvalue problem describing the porous FG plate dispersion relations resting on a viscoelastic foundation is analytically determined. The theory accuracy is validated by numerically comparing the results with previously published works. Finally, the influences of gradation power, porosity parameters, and the viscoelastic foundation parameters on wave propagation in an FG plate are examined and discussed.

Influences of Different Boundary Conditions and Hygro-Thermal Environment on the Free Vibration Responses of FGM Sandwich Plates Resting on Viscoelastic Foundation

This paper investigates the free vibration of functionally graded material (FGM) sandwich plates supported by different boundary conditions and influenced by a three-parameter viscoelastic foundation and hygro-thermal changes. Three types of FGM sandwich plates are studied and discussed, in which the FGM layers vary according to the power law rule and consist of ceramic and metal materials. An efficient and simple four-variable integral higher-order shear deformation theory (HSDT) is employed to model the analytical solution of the considered problem. Hamilton principle is implemented to obtain the plates’ governing equations and to derive the eigenvalue equation for the free vibration study. The model is verified by comparing numerical results with previous studies on the vibration of exponentially graded plates. New results are presented in this paper showing the influences of different boundary conditions, hygro-thermal changes, viscoelastic parameters, vibration modes, material exponents, and geometric dimensions.

Long-Term Field Monitoring of Slabs on Ground

In the last two decades, lightweight and non-corrosive glass-fiber reinforced polymer (GFRP) bars have been widely used in several applications targeting more than 100 years of service life, faster construction, and life-cycle costs comparable to steel reinforcement. A remarkable example is the world’s largest GFRP bar reinforced structure, the 21.3 km-long flood mitigation channel in Jazan, Saudi Arabia, constructed as a slab on ground. The design of GFRP reinforced slabs on ground is based on empirical equations derived from steel reinforced slab practice. The lack of field performance data, low modulus of elasticity, and creep rupture stress features warrant research on the design aspects of GFRP bars for grade-supported structures. This study, which has the sole objective of reporting the experiment outcomes, involves long-term field monitoring of eight large-scale slabs on ground specimens. Slabs of plan dimensions 6000×1100 mm2, resting on a lean concrete subbase over compacted soil subgrade and exposed to harsh ambient environment, were monitored for 525 days using more than 65 sensors mounted on the GFRP bars and embedded in the concrete. The major parameters of the study are reinforcement type (ribbed GFRP, sand-coated GFRP, and conventional ribbed steel), reinforcement spacings (200 mm and 300 mm), slab thickness (100 mm and 200 mm), and contraction joint. The effect of these parameters on crack widths, crack patterns, and concrete and reinforcement strains were observed. The slabs with both types of GFRP bar and spacing developed a transverse mid-panel shrinkage crack at an early-age, and the maximum widths of the cracks over the long-term were within code limits. The GFRP bars spacing in slabs on grade could be increased from 200 mm c/c to 300 mm c/c without any adverse effect for the 200 mm thick slabs monitored in the field.

An Experimental Investigation on the Effect of CO ₂ Curing on the Strength Response of Pozzolanic Based Alkali-Activated Binder Treated Expansive Soils

No abstract is provided for this article.

Exploring the Acceptability of Compact Housing as a Sustainable Strategy to Enhance Housing Affordability in Saudi Arabia

Saudi Arabia is undergoing a significant rise in housing development, propelled by increasing demand for affordable housing. This demand surge posi tions compact housing as a viable sustainable approach to meet housing needs efficiently. This study employs a mixed-method approach, integrating qualitative and quantitative methods, to assess the acceptance of compact housing in Saudi Arabia. Through a comprehensive survey, it investigates public attitudes of various compact housing design features. The findings reveal a fair degree of acceptance for compact housing solutions, with an average agreement score of 3.12 out of 5. While open-plan layouts with reduced partitions and the integration of contempo rary furniture were the most preferred design features, certain elements, such as shared walls with neighbours and the merging of guest and living spaces, were less favoured. These observations provide insights into the preferences and attitudes of Saudi residents towards compact housing. The study suggests that promoting col lective housing types, such as attached, semi-attached, or apartment-style homes, may play a key role in lowering housing costs and broadening availability. How ever, achieving these goals will necessitate a comprehensive understanding of the socio-cultural preferences of residents to ensure the suitability of these housing options now and in the future.

Correction: Properties of concrete incorporating recycled coarse aggregates and recycled plastic fine aggregates

A Review of the Shear Design Provisions of ACI Code and Eurocode for Self-Compacting Concrete, Recycled Aggregate Concrete, and Geopolymer Concrete Beams

Shear failure in RC beams can lead to sudden and catastrophic collapse, posing significant risks to the occupants and the structure itself. The computation

Indigenous Minerals and Industrial By-Products for Non-Carbonate Cementitious Materials: A Critical Review