Concrete Research Articles

Research progress on freeze–thaw constitutive model of concrete based on damage mechanics

Abstract In cold areas, freeze–thaw damage seriously affects the long-term use and safe operation of concrete structures. The constitutive model is an important foundation for predicting deformation and strength characteristics of concrete materials and for the non-linear analysis of concrete structures. This study is based on the elaboration of methods for the constitutive model of damaged materials by using damage mechanics and others. This study focuses on the existing constitutive model results of concrete under the static axial compression load, dynamic load, and coupling environmental load, and analyzing the problems in existing studies. Research has shown that segmented models exhibit higher fitting accuracy of concrete freeze–thaw constitutive model under static axial compression loads. By defining coupled damage variables, it is possible to approach the actual freeze–thaw damage of concrete under environmental coupling, and attention should be paid to the differences or interactions between damage factors. In order to meet the actual engineering needs of high altitude and cold areas needs to expand the temperature range of freeze–thaw tests and consider the dynamic loads impact on concrete damage, the establishment of constitutive model of concrete under the actual freeze–thaw damage is the focus of frost-resistant durability research of hydraulic concrete in cold regions.

Investigation of the freeze-thaw deterioration behavior of hydraulic concrete under various curing temperatures

To address the issue of damage and deterioration of hydraulic concrete materials in cold regions, experiments were conducted to investigate the microstructural and mechanical properties of concrete under the combined effects of various curing temperatures and freeze-thaw (F‒T) cycles. The results indicate that as the curing temperature decreases, the peak compressive strength of concrete decreases, while the peak strain increases and the elastic modulus decreases. These trends become more pronounced with the progression of F‒T cycles. Additionally, during the compression failure process of concrete, the amplitude of the acoustic emission exhibits a more significant and rapid increase as it approaches the critical state, indicating a stronger brittle characteristic of concrete after F‒T damage. Microscopic test results demonstrate that the influence of curing temperature on the pore structure of concrete after F‒T primarily manifests in the mesopores and large pores. Moreover, the reduction in curing temperature increases internal defects in concrete, deteriorates the crystallinity of hydration products, and leads to the aggregation of unhydrated cement particles. Insufficient curing temperatures slow the hydration rate of cementitious materials, affecting the density and overall performance of concrete. Finally, damage prediction models based on the Weibull distribution were established, using the relative dynamic modulus of elasticity, compressive strength loss rate, and mass loss rate as damage factors. The model based on the relative dynamic modulus of elasticity was more sensitive to the number of F‒T cycles. All models exhibited a goodness of fit exceeding 0.89, indicating that they accurately reflect variations in the observed data and can be used to predict the service life of concrete under F‒T cycles. This provides theoretical references for the degradation and damage of hydraulic concrete in cold regions.

Enhancing shift current response via virtual multiband transitions

Materials exhibiting a significant shift current response could potentially outperform conventional solar cell materials. The myriad of factors governing shift-current response, however, poses significant challenges in finding such strong shift-current materials. Here we propose a general design principle that exploits inter-orbital mixing to excite virtual multiband transitions in materials with multiple flat bands to achieve an enhanced shift current response. We further relate this design principle to maximizing Wannier function spread as expressed through the formalism of quantum geometry. We demonstrate the viability of our design using a 1D stacked Rice-Mele model. Furthermore, we consider a concrete material realization - alternating angle twisted multilayer graphene (TMG) - a natural platform to experimentally realize such an effect. We identify a set of twist angles at which the shift current response is maximized via virtual transitions for each multilayer graphene and highlight the importance of TMG as a promising material to achieve an enhanced shift current response at terahertz frequencies. Our proposed mechanism also applies to other 2D systems and can serve as a guiding principle for designing multiband systems that exhibit an enhanced shift current response.

Colonization of construction materials by microbial flora of the oral cavity and its significance for prosthetics

Today there is no unified personalized approach to the selection of construction materials in orthopedic dentistry, hence it is necessary to introduce and further study the effect of construction materials on the microbiota of the oral cavity. In particular, principles of microbial adhesion to various construction materials, development of biofilm and bacterial colonization of concrete construction materials need to be analysed. The article provides a review of literature devoted to the description of the adhesive properties of oral microbiota to orthopedic materials from the groups of polymers, metals and ceramic constructions as well as the development of the negative impact of the construction material on the microbiota of a particular group of teeth and the general condition of the microflora of the oral cavity, increase of the risks of dental plaque formation, biofilms formation and a shift of microflora towards the predominance of cariogenic one.

Analysis of Water-Proof Properties of Building Waterproof Materials and Concrete Components

Analysis of Water-Proof Properties of Building Waterproof Materials and Concrete Components

The mechanical and microstructural performance of waste textile and cardboard materials in concrete

AbstractWaste fiber reinforced concrete is gaining recognition as a high‐performance construction material, offering notable load‐bearing capacity, corrosion resistance, and enhanced durability features. As the building and construction industry focuses on sustainable practices, fibers derived from waste materials create an opportunity to be utilized further in composite designs. This study explores the tensile, compressive, and flexural behaviors of cardboard fibers (kraft fibers) and textile polyester fibers in concrete materials. The composite microstructure is also investigated using a scanning electron microscope (SEM) to measure the bonding performance of the fibers within the cementitious matrix. Four mix designs were created using 2.5% textile fibers as a reinforcement agent and 5% silica fume modified kraft fibers (SFKFs) as a partial cement replacement. The combination of fibers achieved 44 MPa compressive strength, equaling the control. Tensile strength was enhanced by 5% when using the combination of the two fibers, achieving 3.58 MPa in comparison to 3.41 MPa. However, flexural strength was reduced among all fibrous concrete materials. SEM images distinguished the natural and synthetic characteristics associated with the two fibers within the cementitious matrix. Namely, demonstrating the chemical bonding of SFKFs in comparison with the physical bonding properties of the textile fibers. This study serves as a valuable resource for future investigations and the broader adoption of binary waste fiber composite designs in cementitious composite applications.

Modeling time-dependent deformation in concrete: A fractional calculus method with finite element implementation

This study presents a novel numerical method to simulate the time-dependent behavior of concrete materials. The deformation response of both traditional and fractional calculus (FC) viscoelastic models is analyzed by the proposed method, in which models’ one-dimensional constitutive relationships are extended to the three-dimensional form. By applying numerical and finite difference methods based on Caputo-type fractional integration, the stress-strain behavior of the FC viscoelastic model is discretized over the time scale. This method exhibits broad application prospects, and can be employed to represent various forms of viscoelastic models. For the concrete material, suitable FC viscoelastic models are developed. To facilitate practical engineering applications of the proposed model, a numerical solution algorithm is implemented in the finite element (FE) analysis through the User-defined Material Mechanical Behavior (UMAT) interface of the commercial FE software ABAQUS. Finally, FE results are compared with the experimental results from several concrete creep tests. The consistency between the FE results and experimental data confirms the effectiveness of the proposed model in describing concrete behavior. The proposed method and model provide theoretical and numerical support for a more profound understanding and simulation of the time-dependent deformation of RC specimens in practical engineering applications.

Study on the Impact of Drainage Noise in Residential Bathrooms Based on Finite Element Simulation

Residential bathroom drainage noise is a primary source of indoor noise that directly affects quality of life and physical and mental health. Therefore, based on the acoustic theory and the finite element simulation technology, this paper proposes a method to simulate the drainage noise characteristics and its impact range jointly using the flow and acoustic fields. The pressure at the pipe wall caused by the internal flow field of the bathroom drainage pipe is calculated by the Fluent software. Simulations are carried out with the Virtual Lab software to predict the drainage noise characteristics and spatial distribution and to analyse the influence of factors such as the door position, riser position, and the partition wall material on the noise distribution. The results show that drainage noise has prominent high-frequency characteristics, the position of the bathroom drainage pipes and doors affects the spatial noise distribution, and the sound insulation performance of a par- tition wall with ordinary fired bricks in the bathroom is slightly better than that of ordinary concrete bricks, lightweight aggregate concrete blocks or fly ash blocks. This paper provides a theoretical basis and practical reference for reducing the impact of residential drainage noise and creating a healthy and comfortable indoor acoustic environment.

Mechanical-robust and polymer-based superhydrophobic coating toward self-cleaning and anti-corrosion

The corrosion of reinforced concrete materials severely threatens cross-sea bridges, buildings and marine ships. The unique air layer on the superhydrophobic coating surface can effectively minimize the reinforced concrete corrosion, which not only extends the long-term usability of concrete but also reduces economic losses and environmental pollution. It is necessary to design a superhydrophobic coating on substrate surfaces to accommodate the requirement for corrosion prevention due to their anti-corrosion and self-cleaning properties. Despite gradually developing superhydrophobic coatings to meet diverse needs, they still encounter limitations in engineering preparation and applications. For example, the rough micro-/nano structure of the superhydrophobic surface is easily damaged by mechanical impact or physicochemical damage, which could affect the antiseptic properties. Moreover, designing and preparing all polymer-based superhydrophobic micro-/nano structures using amorphous elastomer materials is vital for enduringly industrial applications, yet it remains a challenge. Here, we design and fabricate a mechanical-robust superhydrophobic coating composed of amorphous polyurethane (PU) and epoxy resin modified with amino-terminated polysiloxane (APT-PDMS) via a scalable atomization spraying method. A quartz sands impact abrasion test evaluates the mechanical durability of the PU superhydrophobic coating (PU-SC). The superficial PU particles can form elastic micro-protuberances, absorbing impact and preventing fracture through elastic deformation during friction. Furthermore, the as-prepared PU-SC can also resist some chemical mechanical damage, including acids/bases/salts solution corrosion, UV radiation, knife scraping treatment, 3M tape-stripping, water flow impact, outside sunlight shining treatment and temperature treatment. Notably, the robust PU-SC can be efficiently produced on a large scale and applied to prevent electrochemical corrosion in a simulated seawater environment. The corrosion protection efficiency (PE) can reach 98.1%. We believe that the design and development of a mechanical-robust and polymer-based superhydrophobic coating has the prospect of actual application on marine corrosion.

Enhancing sustainability in concrete production: A novel compression casting technique for optimizing cement usage

Cement manufacturing is a major source of carbon dioxide (CO2) emissions. This study focuses on using the compression casting method to reduce the cement content in concrete manufacturing. No such work is present in the existing literature. For this purpose, five concrete mix designs of normal concrete (NC) and compression cast concrete (CCC), targeting compressive strengths of 50 MPa, 30 MPa, 25 MPa, 20 MPa, and 15 MPa, were considered. Moreover, considering the reduced cement content, five additional concrete mixes of NC and CCC were also prepared. All concrete specimens were tested in axial compression to study the stress-strain behavior. The findings reveal that CCC specimens exhibit higher stress-strain curves compared to NC specimens for the same mix design. The post-peak behavior of CCC specimens is observed to be more brittle than that of NC specimens. The reduction in density, compressive strength, and elastic modulus with the increase in the water-to-cement (w/c) ratio is more pronounced in NC specimens than in CCC specimens. The results indicate that the compression casting method allows for a reduction in cement content by approximately 25–50 % while achieving the desired compressive strengths, ranging from 30 to 50 MPa. A correlation is clearly demonstrated to determine the potential cement savings for specific concrete strengths. In summary, adopting compression casting technology effectively lowers cement requirements, leading to cost and carbon emission reductions in the construction sector and significantly enhancing the durability of concrete materials.

Coupled Effects of High Temperature and Steel Fiber Content on Energy Absorption Properties of Concrete.

The associated effects of temperature and steel fiber content on the energy absorption properties of concrete were examined using quasi-static uniaxial compression tests of concrete materials with varied steel fiber contents (0%, 0.5%, 1%, and 1.5%) at various temperatures (20 °C, 200 °C, 400 °C, and 520 °C). The experimental findings demonstrate that steel fibers can greatly boost concrete's ability to absorb energy and that the toughness index rises with steel fiber concentration. The energy absorption capacity of concrete under high-temperature conditions also significantly decreases as temperature rises, and the energy absorption ability of steel fiber concrete under the same temperature is superior to that of plain concrete. The coupled influence factor K of temperature-steel fiber percentage characterizing the energy-absorbing ability of concrete was determined, and the coupled influence law of temperature and steel fiber content on the energy-absorbing capacity of concrete materials was summarized and analyzed on the basis of the experimental data of high-temperature compression. Equivalent equations for steel fiber reinforcing and temperature weakening effects when they are comparable (K = 1) are developed and equivalent parameters for concrete materials are given.

Preparation of neutron activated concrete reference material for gamma-ray spectrometry measurement

Preparation of neutron activated concrete reference material for gamma-ray spectrometry measurement

A Voronoi-based gaussian smoothing algorithm for efficiently generating RVEs of multi-phase composites with graded aggregates and random pores

This paper presents an innovative numerical modeling framework capable of generating highly realistic 3D mesoscale multi-phase concrete models with unprecedented efficiency and accuracy. Addressing a significant wide range in aggregate volume fraction (0 to 80%) and featuring rapid model generation capabilities, our framework marks a breakthrough in reducing computational time—achieving simulations of 1 million elements within mere 30 s on readily available hardware. By analyzing randomly generated concrete samples across varying compositions, our algorithm can provide deep mesoscopic insights into their compressive properties, validated against a wide array of experimental results. Additionally, our comprehensive analytical model sheds light on the intricate roles of aggregate volume fraction and porosity, enhancing understanding of the meso-scale compressive behavior. We also make the source code available on GitHub, offering a valuable tool for the engineering and research community to optimize concrete material design and performance.

Alternative concrete aggregates - Review of physical and mechanical properties and successful applications

Concrete is one of the most widely used construction materials, yet its production is associated with significant environmental impacts. One approach to mitigate such impacts is to use alternative aggregates. However, the limited knowledge about the availability and benefits of these unconventional materials, as well as concerns about their quality and performance, have hindered their adoption. This paper aims to analyse the potential benefits and limitations of using alternative aggregates in concrete by reviewing examples from three primary sources: construction and demolition waste (CDW), end-of-life materials (i.e., tyre rubber, glass, and plastic), and forest and agricultural waste (i.e., rice husk, wood, and hemp). First, the main sources and treatment needs are analysed. Then, a comprehensive macro analysis is provided on the physical and mechanical properties of concrete materials, discussing the results in terms of the aggregate nature and substitution ranges. The collected experimental data are also compared with estimations based on different models from two published codes, suggesting that more specific design-oriented models need to be developed to relate concrete's physical and mechanical properties using different waste-type aggregate replacements. Selected data analyses are presented to help the readers obtain the optimum content for specific structural or non-structural applications. Examples of successful application of alternative aggregates in construction projects and products are also provided and discussed.

Application of Generalized S-Transform in the Measurement of Dynamic Elastic Modulus

Resonance is commonly used for in situ measurement of the dynamic elastic modulus to evaluate the strength of concrete samples. Many researchers are also exploring the application of this convenient measurement technology for safety monitoring. Nevertheless, the presence of cracks and variations in curing conditions within samples can impact the resonance frequency range, potentially leading to potential inaccuracies in measurements. In order to improve the measurement accuracy of resonance frequency, this study introduces the Generalized S-Transform (GST) algorithm for measuring the dynamic elastic modulus, which utilizes its high time-frequency resolution to scan the power peak-point in non-stationary and transient excitation signals to determine the resonance frequency. For concrete materials with lower consistency, the experimental results verify the high accuracy of this algorithm in measuring resonance frequency compared with Fast Fourier Transform (FFT). This provides a reference for using the algorithm to measure the dynamic elastic modulus in civil engineering applications, such as buildings and bridges.

Global decarbonization potential of CO2 mineralization in concrete materials

CO2 mineralization products are often heralded as having outstanding potentials to reduce CO2-eq. emissions. However, these claims are generally undermined by incomplete consideration of the life cycle climate change impacts, material properties, supply and demand constraints, and economic viability of CO2 mineralization products. We investigate these factors in detail for ten concrete-related CO2 mineralization products to quantify their individual and global CO2-eq. emissions reduction potentials. Our results show that in 2020, 3.9 Gt of carbonatable solid materials were generated globally, with the dominant material being end-of-life cement paste in concrete and mortar (1.4 Gt y-1). All ten of the CO2 mineralization technologies investigated here reduce life cycle CO2-eq. emissions when used to substitute comparable conventional products. In 2020, the global CO2-eq. emissions reduction potential of economically competitive CO2 mineralization technologies was 0.39 Gt CO2-eq., i.e., 15% of that from cement production. This level of CO2-eq. emissions reduction is limited by the supply of end-of-life cement paste. The results also show that it is 2 to 5 times cheaper to reduce CO2-eq. emissions by producing cement from carbonated end-of-life cement paste than carbon capture and storage (CCS), demonstrating its superior decarbonization potential. On the other hand, it is currently much more expensive to reduce CO2-eq. emissions using some CO2 mineralization technologies, like carbonated normal weight aggregate production, than CCS. Technologies and policies that increase recovery of end-of-life cement paste from aged infrastructure are key to unlocking the potential of CO2 mineralization in reducing the CO2-eq. footprint of concrete materials.

A Comprehensive Review on Effects of Material Composition, Mix Design, and Mixing Regimes on Rheology of 3D-Printed Geopolymer Concrete

Recent years have witnessed a significant growth in the research and development of additive manufacturing methods involving concrete and cementitious materials, with technologies like three-dimensional (3D) printing becoming more widely used in the construction industry. Construction has the possibility to be revolutionized, not only in the context of cost savings but also in the context of increased sustainability and functionality. 3D printing of concrete is a cutting-edge technology that has the potential to speed up construction, reduce labor costs, give architects more creative freedom, improve precision, obviate requirements for formwork, and result in less construction wastes. In addition, 3D printing can be a long-term solution for both economy and environment. Even though 3D printing in concrete has made tremendous strides recently, developing an effective 3D-printable material that decreases material usage and enhances performance is critical for carbon dioxide reduction. Robust geopolymer formulations for 3D printing concrete technology in current construction applications have emerged as the subject of much research among scientists to find novel ways to circumvent this constraint. This study intends to highlight the current state of the art in developing 3D-Printed Geopolymer Concrete (3DPGC) with a comprehensive review related to the material composition, mix design, and mixing regimes on rheology of 3DPGC. The rheology of 3DPGC in terms of printability and buildability is discussed. The mixing regimes employed for the preparation of one-part and two-part 3DPGC are tabulated and commented on. Lastly, the research gaps are identified and summarized, and several research directions are also provided for future investigations to expedite the ubiquitous use of 3DPGC in versatile construction applications.

Investigation of Compressive Strength of Concrete River Sand Together with sea sand as a constituent material for concrete

Penelitian ini bertujuan untuk menganalisis kuat tekan beton pasir laut yang layak sebagai agregat halus perkerasan kaku (Rigit Pavement) jalan pantai. Penelitian ini menggunakan metode eksperimental dengan benda uji kuat tekan berbentuk silinder dengan diameter 150 mm dan tinggi 300 mm dengan persentase pasir laut 0%, 10%, 15%, 20% dan 25% pada umur umur 3, 7, 14, 21 dan 28 hari. Berdasarkan hasil pengujian kuat tekan beton, terjadi peningkatan kekuatan pada beton yang memakai pasir laut persentase 10%, 15%, 20% dan 25% pada saat umur 7, 14, 21 dan 28 hari. Kuat tekan terbesar terjadi pada beton dengan persentase 25% pasir laut sebesar 26,29 MPa pada umur perawatan 28 hari, sedangakn kuat tekan terendah terjadi pada umur perawatan 3 hari sebesar 16,00 MPa. Semakin lama umur perawatan beton maka semakin meningkat kuat tekan beton yang dihasilkan.

RESEARCH SOLUTIONS FOR PRECAST CONCRETE REVETMENTS USING ALB-REBAR TO RETAIN CORAL SAND FOR OFFSHORE ISLANDS IN VIETNAM

Gravity revetment solutions are a popular choice for shore protection at atolls under the harsh conditions of ocean waves. The precast revetment option is preferred to reduce shipping costs for materials and ensure quick construction. This article studied precast concrete revetments with ALB composite material reinforcement and conducted experimental research to determine the shear resistance characteristics of coral sand and the friction characteristics of concrete materials with coral sand. Based on the experimental parameters, the authors calculated the stability of the ALB embankment structure against the effects of wave loads during storms. With experimental data obtained from coral sand samples prepared with equivalent density in the field, the results showed that the stability coefficient of the revetment is significantly higher than the one obtained from the traditional calculation concept.

Seismic mitigation performance of a periodic foundation for nuclear power structures considering soil-structure interactions

Periodic structures may be designed as periodic foundations to reduce the seismic response of engineering structures. The periodic foundation is more suitable for the seismic mitigation of nuclear power structures because of its wide attenuation domain. Based on the dispersion relationship of infinite periodic structures, this research constructs a one-dimensional layered periodic foundation using rubber and concrete materials, determines the attenuation domain frequency band gap that meets the seismic design requirements of nuclear power structures, and optimizes the raft design of nuclear power structures. At the same time, with the scarcity of bedrock sites, the site selection of nuclear power structures is inevitably shifted to soft rock sites. Therefore, this paper also considers the influence of the soil-structure interaction (SSI) on the seismic response of nuclear power structures. A three-dimensional finite element model of the nuclear power structure-periodic foundation-site system was established, and a detailed parameter analysis of the seismic performance of the periodic foundation of nuclear power structures considering the SSI effect was carried out. The results show that the seismic response of nuclear power structures can be significantly reduced by designing the attenuation domain of the periodic foundation.