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Durability of concrete can be enhanced by reducing the pore size/volume of pores or by entrapping the pores. This can be achieved by adding concrete admixtures that have particle size finer than cement. In this study, GNP, having particle size much smaller than cement, has been introduced/added to concrete mix to control the pore size in concrete to tape out the contribution of GNP in the durability enhancement of concrete.

Different concrete mixes, at various water–cement ratios and amounts of graphene, have been manufactured to produce concrete containing three different %ages of GNP, i.e. 0%, 0.05% and 0.1%. To demonstrate the effect on durability of the concrete through the addition of GNP, these concrete samples have been subjected to repeated Freeze-Thaw cycles. Followed by testing after 28 days of curing, including weight loss, water absorption and strength, which are directly related to the durability aspect of concrete.

It has been observed that the addition of GNP to concrete mixes reduces the weight loss and pore size distribution and enhances tensile and compressive strength of concrete, thereby increasing the durability of concrete in unfavorable circumstances like freeze-thaw i.e. alternate hot and cold weather conditions.

This investigation presents original piece of experimental work conducted on modified concrete (GNP-based concrete). The aim is to construct the civil infrastructure in deep-cold region with increased life span and better performance.

The initiative for sustainability in the construction industry has led to the innovative utilization of automobile tire waste, transforming it into value-added products, toward decarbonization in the construction industry, aligning with the development and sustainability goals of Al-Kharj Governorate. However, the disposal of these materials generates significant environmental concerns. As a payoff for these efforts, this study aims to contribute to a fruitful shift toward eco-friendly recycling techniques, particularly by studying the transformation of tire waste bead wires into recycled steel tire fibers (RSTFs) for sustainable concrete composites.

This research delves into how this technological transformation not only addresses environmental concerns but also propels sustainable tire innovation forward, presenting a promising solution for waste management and material efficiency in building materials. Recent studies have highlighted the superior tensile strength of RSTFs from discarded tires, making them suitable for various structural engineering applications. Recently, there has been a notable shift in research focus to the use of RSTFs as an alternative to traditional fibers in concrete. In this study, however, efforts have paid off in outlining a comprehensive assessment to investigate the viability and efficacy of repurposing tire bead wires into RSTFs for use in concrete composites, as reported in the literature.

This study examined the Saudi waste management, the geometrical properties of RSTFs, and their impact on the strength properties of concrete microstructure. It also examined the economic, cost, and environmental impacts of RSTFs on concrete composites, underscoring the need for the construction industry to adopt more sustainable and adaptable practices. Furthermore, the main findings of this study are proposed insights and a blueprint for the construction industry in Al-Kharj Governorate, calling for collective action from both public and private sectors, and the community to transform challenges into job opportunities for growth and sustainability.

This study pointed to thoroughly demonstrate the technological advancement in converting tire waste to reinforcing fibers by evaluating the effectiveness, environmental sustainability, and practicality of these fibers in eco-friendly concrete composites. Besides, the desired properties and standards for RSTFs to enhance the structural integrity of concrete composites are recommended, as is the need to establish protocols and further study into the long-term efficacy of RSTF-reinforced concrete composites.

Low-carbon concrete represents a new direction in mitigating the global warming effects caused by clinker manufacturing. Utilizing Saudi agro-industrial by-products as an alternative to cement is a key support in reducing clinker production and promoting innovation in infrastructure and circular economy concepts, toward decarbonization in the construction industry. The use of fly ash (FA) as a cement alternative has been researched and proven effective in enhancing the durability of FA-based concrete, especially at lower replacement levels. However, at higher replacement levels, a noticeable impediment in mechanical strength indicators limits the use of this material.

In this study, low-carbon concrete mixes were designed by replacing 50% of the cement with FA. Varying ratios of nano-sized glass powder (4 and 6% of cement weight) were used as nanomaterial additives to enhance the mechanical properties and durability of the designed concrete. In addition, a 10% of the mixing water was replaced with EMs dosage.

The results obtained showed a significant positive impact on resistance and durability properties when replacing 10% of the mixing water with effective microorganisms (EMs) broth and incorporating nanomaterial additives. The optimal mix ratios were those designed with 10% EMs and 4–6% nano-sized glass powder additives. However, it can be concluded that advancements in eco-friendly concrete additive technologies have made significant contributions to the development of sophisticated concrete varieties.

This study focused at developing nanomaterial additives from Saudi industrial wastes and at presenting a cost-effective and feasible solution for enhancing the properties of FA-based concrete. It has also been found that the inclusion of EMs contributes effectively to enhancing the concrete's resistance properties.

The purpose of this paper was to prepare a ternary hierarchical rough particle to accelerate the anti-corrosive design for coastal concrete infrastructures.

A kind of micro-nano hydrophobic ternary microparticles was fabricated from SiO₂/halloysite nanotubes (HNTs) and recycled concrete powders (RCPs), which was then mixed with sodium silicate and silane to form an inorganic slurry. The slurry was further sprayed on the concrete surface to construct a superhydrophobic coating (SHC). Transmission electron microscopy and energy-dispersive X-ray spectroscopy mappings demonstrate that the nano-sized SiO₂ has been grafted on the sub-micron HNTs and then further adhered to the surface of micro-sized RCP, forming a kind of superhydrophobic particles (SiO₂/HNTs@RCP) featured of abundant micro-nano hierarchical structures.

The SHC surface presents excellent superhydrophobicity with the water contact angle >156°. Electrochemical tests indicate that the corrosion rate of mild steel rebar in coated concrete reduces three-order magnitudes relative to the uncoated one in 3.5% NaCl solution. Water uptake and chloride ion (Cl^-) diffusion tests show that the SHC exhibits high H₂O and Cl^- ions barrier properties thanks to the pore-sealing and water-repellence properties of SiO₂/HNTs@RCP particles. Furthermore, the SHC possesses considerable mechanical durability and outstanding self-cleaning ability.

SHC inhibits water uptake, Cl^- diffusion and rebar corrosion of concrete, which will promote the sustainable application of concrete waste in anti-corrosive concrete projects.

This study investigates the impact of the fire decay phase on structural damage using the sectional analysis method. The primary objective of this work is to forecast the non-dimensional capacity parameters for the axial and flexural load-carrying capacity of reinforced concrete (RC) sections for heating and the subsequent post-heating phase (decay phase) of the fire.

The sectional analysis method is used to determine the moment and axial capacities. The findings of sectional analysis and heat transfer for the heating stage are initially validated, and the analysis subsequently proceeds to determine the load capacity during the fire’s heating and decay phases by appropriately incorporating non-dimensional sectional and material parameters. The numerical analysis includes four fire curves with different cooling rates and steel percentages.

The study’s findings indicate that the rate at which the cooling process occurs after undergoing heating substantially impacts the axial and flexural capacity. The maximum degradation in axial and flexural capacity occurred in the range of 15–20% for cooling rates of 3 °C/min and 5 °C/min as compared to the capacity obtained at 120 min of heating for all steel percentages. As the fire cooling rate reduced to 1 °C/min, the highest deterioration in axial and flexural capacity reached 48–50% and 42–46%, respectively, in the post-heating stage.

The established non-dimensional parameters for axial and flexural capacity are limited to the analysed section in the study owing to the thermal profile, however, this can be modified depending on the section geometry and fire scenario.

The study primarily focusses on the degradation of axial and flexural capacity at various time intervals during the entire fire exposure, including heating and cooling. The findings obtained showed that following the completion of the fire’s heating phase, the structural capacity continued to decrease over the subsequent post-heating period. It is recommended that structural members' fire resistance designs encompass both the heating and cooling phases of a fire. Since the capacity degradation varies with fire duration, the conventional method is inadequate to design the load capacity for appropriate fire safety. Therefore, it is essential to adopt a performance-based approach while designing structural elements' capacity for the desired fire resistance rating. The proposed technique of using non-dimensional parameters will effectively support predicting the load capacity for required fire resistance.

The fire-resistant requirements for reinforced concrete structures are generally established based on standard fire exposure conditions, which account for the fire growth phase. However, it is important to note that concrete structures can experience internal damage over time during the decay phase of fires, which can be quantitatively determined using the proposed non-dimensional parameter approach.

The purpose of this study is to explore the interfacial adhesion between superhydrophobic coatings FC-X (X = 1%, 2%, 3%, 4% and 5%) and the concrete substrate, along with the impact of FC-X on the water repellency characteristics of the concrete substrate.

One synthetic step was adopted to prepare novel F-SiO₂ NP hybrid fluororesin coating. The impact of varying mass fractions of F-SiO₂ NPs on the superhydrophobicity of FC-X was analyzed and subsequently confirmed through water contact angle (WCA) measurements. Superhydrophobic coatings were simply applied to the concrete substrate using a one-step spraying method. The interfacial adhesion between FC-X and the concrete substrate was analyzed using tape pasting tests and abrasion resistance measurements. The influence of FC-X on the water repellency of the concrete substrate was investigated through measurements of water absorption, impermeability and electric flux.

FC-4% exhibits excellent superhydrophobicity, with a WCA of 157.5° and a sliding angle of 2.3°. Compared to control sample, FC-X exhibits better properties, including chemical durability, wear resistance, adhesion strength, abrasion resistance, water resistance and impermeability.

This study offers a thorough investigation into the practical implications of enhancing the durability and water repellency of concrete substrates by using superhydrophobic coatings, particularly FC-4%, which demonstrates exceptional superhydrophobicity alongside remarkable chemical durability, wear resistance, adhesion strength, abrasion resistance, water resistance and impermeability.

Through the examination of the interfacial adhesion between FC-X and the concrete substrate, along with an assessment of FC-X’s impact on the water repellency of the concrete, this paper provides valuable insights into the practical application of superhydrophobic coatings in enhancing the durability and performance of concrete materials.

The purpose of this study is to use the corrected stress field theory to derive the shear capacity of geopolymer concrete beams (GPC) and consider the shear-span ratio as a major factor affecting the shear capacity. This research aims to provide guidance for studying the shear capacity of GPC and to observe how the failure modes of beams change with the variation of the shear-span ratio, thereby discovering underlying patterns.

Three test beams with shear span ratios of 1.5, 2.0 and 2.5 are investigated in this paper. For GPC beams with shear-span ratios of 1.5, 2.0 and 2.5, ultimate capacities are 337kN, 235kN and 195kN, respectively. Transitioning from 1.5 to 2.0 results in a 30% decrease in capacity, a reduction of 102kN. Moving from 2.0 to 2.5 sees a 17% decrease, with a loss of 40KN in capacity. A shear capacity formula, derived from modified compression field theory and considering concrete shear strength, stirrups and aggregate interlocking force, was validated through finite element modeling. Additionally, models with shear ratios of 1 and 3 were created to observe crack propagation patterns.

For GPC beams with shear-span ratios of 1.5, 2.0 and 2.5, ultimate capacities of 337KN, 235KN and 195KN are achieved, respectively. A reduction in capacity of 102KN occurs when transitioning from 1.5 to 2.0 and a decrease of 40KN is observed when moving from 2.0 to 2.5. The average test-to-theory ratio, at 1.015 with a variance of 0.001, demonstrates strong agreement. ABAQUS models beams with ratios ranging from 1.0 to 3.0, revealing crack trends indicative of reduced crack angles with higher ratios. The failure mode observed in the models aligns with experimental results.

This article provides a reference for the shear bearing capacity formula of geopolymer reinforced concrete (GRC) beams, addressing the limited research in this area. Additionally, an exponential model incorporating the shear-span ratio as a variable was employed to calculate the shear capacity, based on previous studies. Moreover, the analysis of shear capacity results integrated literature from prior research. By fitting previous experimental data to the proposed formula, the accuracy of this study's derived formula was further validated, with theoretical values aligning well with experimental results. Additionally, guidance is offered for utilizing ABAQUS in simulating the failure process of GRC beams.

Rebar corrosion in reinforced concrete is the major reason for the durability degradation, especially under harsh environment. This paper presents an experiment conducted to investigate the influence of freeze-thaw cycles on the rebar corrosion in reinforced concrete. The purpose of this paper is to provide fundamental information about rebar corrosion under frost environment and improvement measures.

The related elastic modulus and compressive strength of different concrete specimens were measured after different freeze-thaw cycles. The accelerated rebar corrosion test was carried out after different freeze-thaw cycles; additionally, the value of calomel half-cell potential was determined. The actual rebar corrosion appearance was checked to prove the accuracy of the results of calomel half-cell potential.

The results show that frost damage aggravates the rebar corrosion rate and degree under freeze-thaw environment; furthermore, the results become more obvious with the freeze-thaw cycles increasing. Mixing the air-entrained agent into fresh concrete to prepare air-entrained concrete, increasing the cover thickness and processing the surface of concrete with a waterproofing agent can significantly improve the resistance to rebar corrosion. From the actual appearance of rebar corrosion, the results of calomel half-cell potential can well reflect the actual rebar corrosion in reinforced concrete.

The durability of reinforced concrete is mainly determined on chloride penetration that brings about rebar corrosion in chloride environments. Furthermore, the degradation of concrete durability becomes more serious in the harsh environment. As the concrete exposure to the freeze-thaw cycles environment, the freeze-thaw cycles accelerate the concrete damage, and the penetration of chloride into the concrete becomes easier because of the growing pore and crack sizes. In addition, rebar corrosion caused by chloride is one of the major forms of environmental attack on reinforced concrete. The tests conducted in this paper will describe the rebar corrosion in reinforced concrete under freeze-thaw environment.

This paper aims to present a research finding that establishes a regression model between ultrasonic pulse velocity (UPV) tests and actual strength of high performance concrete (HPC).

In this study, a total of 270 cube samples were made from six different mix proportions. The mixes were grouped in two series that consist of nominal maximum aggregate sizes of 10 mm (A₁₀) and 19 mm (A₁₉). Silica fume were used as mineral admixtures at 5 percent, 10 percent and 15 percent of cement in both series. UPV tests were conducted for each of the specimens, followed by destructive strength tests. The tests were carried out for concrete at different ages of between three to 56 days. The destructive test results were used as the true strength of the mixes and the UPV test results were used as strength estimation.

Concrete strength correlations between UPV and destructive tests were analysed for each mix proportions and in each series. These correlations are presented in the form of regression equations that displays standard error of between ±2.4 to ±5.7 MPa regardless of mix for the concrete in series A₁₀. Similarly, in series A₁₉ concrete, standard errors of between ±3.2 to ±6.7 MPa were found. Strength prediction models using UPV for high performance concrete are proposed. The models have overall correlation coefficients above 0.80 for all the mixes.

There are no standard relationships that had been established for high performance concrete strength with UPV test methods. The proposed relationship can be used for concrete strength estimation that is normally required in building or structural assessment, especially with the present trend of constructing modern structures using high performance concrete.

Discusses the properties of concrete and the process of carbonation which can lead to corrosion and its ultimate destruction. Outlines the conditions which lead to carbonation, detailing design faults which facilitate the process, and suggests preventatives which can protect the surface. Examines the results of carbonation, the forming of distressed concrete and mentions tests which can be performed to check the health of the structure. Assesses the impact of additional factors leading to corrosion and offers advice on remedial actions.