Concrete Research Articles

Uncertainty quantification and global sensitivity analysis of bearing capacity of push-out specimen considering randomness in bond-slip behaviour

As an artificial composite material, the uncertainty in mechanical property of concrete significantly impacts the bond-slip behaviour of the shaped steel concrete structure. To investigate the effect of the uncertainty of concrete mechanical properties on the bearing capacity of push-out specimens, based on the data of a small number of push-out test with identical design parameters, the improved Bootstrap method is utilized to execute sample augmentation for the bond stress-slip curves, and the stochastic bond slip constitutive model is established after considering five parameters (K1, …, K5) in the deterministic bond-slip model as random variables. Simultaneously, considering the randomness in elastic modulus of concrete (Ec), uncertainty quantification (UQ) of the bearing capacities of the push-out specimens is conducted using the arbitrary polynomial chaos (aPC) method. Subsequently, the global sensitivity analysis of the ultimate and residual bearing capacities is accomplished through the aPC surrogate model. The results indicate that the probability distribution types of the parameters in the stochastic bond-slip constitutive model can be arbitrary when considering the randomness of concrete material, and the aPC method with at least a third-order expansion is recommended to execute UQ for the push-out test due to the strong nonlinearty between the bearing capacities and the random parameters. The ultimate bearing capacity is primarily affected by the parameter K2, followed by K4, K3, and K5. Whereas the residual bearing capacity is predominantly influenced by the parameter K4, followed by K5, the remaining parameters exhibit negligible influence. In contrast, K1 and Ec have the greatest influence on equivalent plastic strain of the concrete near the loading end of the push-out specimen.

Performance analysis and application fields of reactive powder concrete

Reactive Powder Concrete (RPC) is a novel concrete material prepared from highly active composite admixtures, cement, fine sand, and micro steel fibers through appropriate curing and processing techniques. RPC not only exhibits ultra-high strength and durability but also demonstrates outstanding toughness, good volume stability, and excellent environmental performance. Its use can reduce the demand for natural resources, extend the service life of structures, and reduce waste generation, aligning with the direction of sustainable development and green building. This makes it an ideal choice for constructing large-span lightweight structures and structures operating in harsh environmental conditions, attracting extensive research attention in the international engineering materials field. In summary, RPC, as a new type of concrete material, has broad application prospects in the construction field. With continuous research and technological development, RPC will undoubtedly bring more innovations and new solutions to the construction industry, promoting its continuous progress and development.

Effect of biological shells aggregate on the mechanical properties and sustainability of concrete

The recycling bio-waste shells problem has grown more and more serious in recent years and many efforts have been made to solve this problem. One possible solution is to put these bio-shells into concrete and recycle them as building materials using the aggregate matrix concrete approach. To verify the engineering feasibility, the mechanical properties of bio-shells aggregated concrete were invested via gradient substitution rates at 10%, 30%, and 50% with a total of 78 groups of specimens in this paper. Our results show that the mechanical properties of the concrete were enhanced in maximum flexural strength and maximum compressive. Economic performance was also analyzed and found that the costs of frame-shear structure, frame structure, and tube-in-tube structure were reduced by 10.2%, 10%, and 10.3%. The carbon environmental assessment also shows superiority in the carbon reduction of a single specimen with various rates of the shell. In summary, compared with ordinary concrete materials, it is very possible to use waste bio-shells as a substitute for aggregates to develop the sustainable recycling development of concrete materials.

Study on Bonding Behavior between High Toughness Resin Concrete with Steel Wire Mesh and Concrete

This paper investigates the interfacial bonding behavior between high toughness resin concrete with steel wire mesh (HTRCS) and concrete. A total of five sets of fifteen double shear specimens were tested for parameters including concrete strength and material properties of HTRCS composites. The test results showed that the failure mode of DS1 specimens was partial debonding and fracture, and the rest of the specimens were the fracture of HTRCS. The concrete strength and reinforcement ratios of HTRCS composites were positively correlated with interfacial adhesion properties. When the concrete strength was increased from C30 to C40 and C50, the ultimate load increased by 43.4% and 43.2%, respectively. The ultimate load capacity increased by 32.1%, with the reinforcement ratio of HTRCS composites increasing from 1.05% to 1.83%. Moreover, the bonding slip model and the bearing capacity formula for the interface between HTRCS composites and concrete were proposed, and the calculation values were in good agreement with the test values, with an average value of 0.978.

Eco-friendly building materials: full-scale replacement of mineral aggregates with rice husk

In a context where sustainable construction and ecology are increasingly central, the construction industry is constantly seeking alternative materials that are both economical and eco-friendly. Concurrently, global rice production generates significant amounts of rice husks, often considered as low-value waste. This study deviates from traditional approaches that favor the use of rice husk ash (RHA) as a mineral additive, to explore the potential of rice husks themselves as a complete substitute for sand in concrete formulations. After meticulous characterization of the physicochemical properties of rice husks, several concrete formulations were designed and subjected to a battery of tests. The results are promising. They show that concrete based on rice husks exhibits satisfactory mechanical properties for a wide range of applications, from slabs to load-bearing walls. The compressive strength varies between 0.56 MPa and 5.41 MPa depending on the composition, while the thermal conductivity falls within a range of 0.070 W m−1 K−1 to 0.129 W m−1 K−1, which is comparable to other agro-concretes. This research highlights the promising potential of rice husks as a sand substitute material in concrete. It thus paves the way for more ecologically responsible and economically viable construction alternatives, while proposing a value-added solution for a widely available agricultural byproduct.

Knowledge graph-guided data-driven design of ultra-high-performance concrete (UHPC) with interpretability and physicochemical reaction discovery capability

Traditional methods for designing concrete materials typically rely on labor-intensive laboratory experiments, resulting in time and cost inefficiencies. Recently, designing concrete using artificial intelligence (AI) methods has shown high efficiency, but existing AI methods often rely solely on data, which can lead to violation with scientific principles and result in models lacking reasoning abilities. To overcome these challenges, this paper presents an interpretable knowledge graph-guided data-driven design approach. By integrating advanced computing techniques with domain knowledge via knowledge graphs, this approach enables the interpretation of data-driven models and uncovers the underlying mechanisms behind predictions. This approach is applied to ultra-high-performance concrete (UHPC) involving complex physicochemical reactions. The domain knowledge about UHPC is imparted using a knowledge graph, and UHPC properties are predicted using a machine learning model considering mixing proportions, processing methods, and physiochemical properties of materials via natural language processing. The results show that the knowledge graph displays crucial design variables and their effects on UHPC properties, aiding in selecting variables for machine learning models and interpreting their results. The prediction accuracy of the machine learning model reached 0.95. The research paves the way for more transparent and scientific AI models for material design and AI-enabled discovery of scientific knowledge.

Factors associated with mosquito control among construction workers: A systematic review.

Workers in the construction industry frequently work in construction sites with numerous areas that can potentially accumulate water, such as tanks, wet cement surfaces, or water puddles. These water collection sites become ideal breeding grounds for mosquito infestation, which leads to a higher prevalence of mosquito-borne diseases, especially malaria and dengue among construction workers. Despite that numerous factors have been identified in controlling vector-borne diseases, the specific factors that influence mosquito control at construction sites have yet to be explored. This systematic review aims to determine the factors associated with mosquito control among construction workers. Primarily, articles related to factors associated with mosquito control among construction workers were collected from two different online databases (ScienceDirect and EBSCOhost). Two independent reviewers were assigned to screen the titles and abstracts of the collected data, stored in Microsoft Excel, against the inclusion and exclusion criteria. Afterwards, the quality of the included articles was critically assessed using the Mixed Method Appraisal Tool (MMAT). Of the 171 articles identified, 4 were included in the final review. Based on the thorough evaluation, mosquito-related knowledge, practical mosquito prevention measures, and Larval Source Management (LSM) were identified as vital factors associated with mosquito control among construction workers. The significant association between mosquito-related knowledge and control practices indicates higher knowledge linked to effective practices, particularly among female workers and those who were recently infected with malaria. Concurrently, there were notable challenges regarding sustainable preventive measures and larval control methods in construction settings. Implementing effective mosquito control, including knowledge and practice on mosquito control together with vector control, is highly required to suppress the expanding mosquito population. It is recommended that employers provide continuous mosquito control education and training to their employees and reward them with incentives, while employees should comply with the guidelines set by their employers to ensure successful mosquito control and reduce the spread of mosquito-borne diseases in the construction industry.

Study on the dynamic response characteristics of lining structures in large-section tunnel blasting using JH-2 model analysis

The lining structures of tunnels are typically constructed using sprayed or cast concrete materials, and their performance and quality during tunnel excavation and blasting are crucial for the stability and safety of tunnels. Therefore, the safe distance between the lining structure and blasting source should be determined to avoid concrete damage caused by blasting vibrations. In this study, taking the subway tunnel of Danshan Station in Qingdao as an example, the JH-2 model is introduced as the constitutive model of the tunnel blasting simulation, and the JH-2 model parameters of the local surrounding rock are obtained by experiments, and finally the numerical simulation and theoretical verification are carried out to study the safety distance of shotcrete under various safety judgment standards. The results indicate that the JH-2 model can effectively simulate the propagation of stress waves under different media conditions, and the closer the strength parameters and pressure constant of the lining structure are to those of the surrounding rock, the safer the concrete–rock bonding interface. During tunnel blasting construction using the ring blasting method, the peak particle velocity (PPV) of the lining structure increases with an increase in the arch angle. Based on the numerical simulation results, we recommend that concrete lining be constructed at a distance of at least 62 m from the blasting source to avoid damage caused by vibrations. The effect of concrete tensile failure caused by longitudinal stress is much smaller than the damage to the bonding interface caused by the PPV and can be neglected.

Analysis of raw-crushed wind-turbine blade as an overall concrete addition: Stress–strain and deflection performance effects

End-of-life wind-turbine blades undergo non-selective crushing to produce Raw-Crushed Wind-Turbine Blade (RCWTB), which can be recycled as a raw material in concrete. RCWTB contains fibers from glass fiber-reinforced polymer that can add ductility and load-bearing capacity to concrete. Concrete mixes with percentage additions of between 0.0 % and 6.0 % RCWTB by volume are produced to analyze their compressive stress–strain performance, their deflection under bending forces, and their deformability under indirect-tensile stresses. Higher RCWTB contents increased deformability in the longitudinal direction under compression, the concrete material absorbing energy levels that were up to 111.4 % higher, even though additions of only 6.0 % RCWTB were sufficient to strengthen the load-bearing capacity. RCWTB fiber stitching effect was most noticeable in the transverse direction under compression, as it reduced elastic deformability and failure strain, removed the yield step caused by vertical-splitting cracking, and increased the fracture strain by up to 94.4 %. With regard to deflection, RCWTB fibers conditioned concrete compliance at advanced ages without any dependence on the modulus of elasticity, and percentage additions from 3.0 % provided load-bearing capacity. This advantage was also noted in indirect-tensile stresses for 6.0 % RCWTB. In summary, RCWTB successfully increased the ductility and load-bearing capacity of concrete per unit strength and carbon footprint.

Low tortuous permeable concrete pavement material: A new approach to improve physical properties

Permeable pavement is an environmentally beneficial material that can ease urban problems and mitigate the effects of climate change, such as flooding, urban heat islands, and groundwater decrease. However, it is susceptible to clogging, has limited strength, and demands frequent maintenance. To overcome these problems, an untraditional fiber-reinforced permeable pavement with a low tortuosity pore structure that has an excellent infiltration rate and strength while being resistant to clogging has been studied in this research. Straight pore channels of various sizes and quantities were introduced into self-compacting concrete to create this permeable pavement. High-strength pervious pavement (HSP) samples with porosity ranging from 3.60 to 8.30% and 0–0.2% fiber content were tested. In all cases, HSP showed high infiltration rate (>1 cm/s), high compressive strength (>27 MPa) and tensile strength (1.5 MPa), low mass loss in potential resistance to degradation by impact and abrasion (>25%). However, it did not clog despite extensive cyclic exposure to flow containing sand, clay, and combined ‘sand & clay’. PP fiber content of 0.1%. The 3.60% porosity was found to be optimum considering all properties, whereas 8.30% porosity gave a higher infiltration rate with compromised properties. This permeable pavement can maintain sufficient porosity and permeability for stormwater infiltration without frequent maintenance. Adding polypropylene fiber reduces compressive strength marginally but increases split tensile strength, degradation and potential resistance. This novel fiber-reinforced HSP has the potential to expand the material's applicability. The results obtained from this research are expected to lead the way for a broader application of HSP in various contexts and initiatives that were not previously considered appropriate. This will eventually enhance the design and implementation of a new generation of flood-resistant infrastructure and significantly improve the ability to mitigate urban floods.

Determination of Clay and Sand Volume Using Vertical Electrical Sounding

This study presents the results of an electrical resistivity survey conducted in Agudama Epie, Yenagoa local government area, Bayelsa State, Nigeria. The primary objective of the survey was to estimate the volume of clay and sand within a rectangular land parcel measuring 100 m by 200m in the study area. The survey employed the Schlumberger electrode configuration and utilized nine vertical electrode sounding (VES) points.Data was collected using a Terrameter SAS 1000 and was processed using IPI2win software. The geophysical analysis revealed the presence of four distinct geoelectric layers across the study area, identified as layers 1 to 4 in the VES profiles. Layer 2, characterized by clay, exhibited an average thickness of 21.2 meters, while layer 3, consisting of sand, had an average thickness of 8.15 meters. The apparent resistivity values ranged from 8.45 to 79.43 ohm-meter to a depth of 10.14 meters for the clay layer and 8499.86 to 15013.11 ohm-meter to a depth of 33.5 meters for the sand layer. The study estimated a substantial presence of approximately 746,240 tonnes of clay and approximately 261,126 tonnes of sand in Agudama Epie. This discovery offers significant economic potential, including job creation, the establishment of small and medium-sized enterprises, and opportunities within the construction industry. The local extraction and processing of clay can drive economic growth and facilitate the production of concrete and building materials. Additionally, the availability of sand in the region can reduce transportation costs and stimulate local construction projects, thereby fostering economic activity and infrastructure development.

Manufacturing Of Sand Based Aerated Concrete Bricks With Fibre Reinforcement- An Experimental Study

Manufacturing Of Sand Based Aerated Concrete Bricks With Fibre Reinforcement- An Experimental Study

Bolted connections in prefabricated cantilevered cap beam-column structures: A comprehensive experimental and numerical study

Prefabricated cantilevered beam-column structures have gained popularity in mountainous road construction. However, a notable research gap exists regarding the beam-column connections. To fill this gap, a new bolted connection method was introduced for the cantilevered beam-column structure. The mechanical performance of this novel structure was systematically investigated through reduced-scale experiments and finite element analysis. The structure's response under three critical loading conditions was experimentally examined, revealing the efficacy of bolted connections in preserving structural integrity and highlighting pronounced strain concentration at the connection region of the cap beam. Furthermore, to enhance structural design, a finite element model of this beam-column structure was established to simulate the influence of various materials and structural parameters on structural response and damage. Simulation results indicated that the anchor rod angle and the number of bolts had a minor impact on load-bearing capacity and damage modes. In contrast, the choice of concrete material and steel reinforcement ratio significantly influenced load-bearing capacity. The insights derived from this study offer valuable guidance for optimizing and extending the application of this structural design.

Utilization of fly ash and bottom ash from TanjungJati B Coal-Fired Power Plant in Jepara, Central Java, on the quality of cellular lightweight concrete

The research aims to address waste-related issues by producing Cellular Lightweight Concrete (CLC) bricks using fly ash and bottom ash as fine aggregates. The variations used encompass cement, fly ash, bottom ash, and sand compositions. The ratio between cement and fine aggregates utilized is 1:3. The variations in the composition of fine aggregates include P (100% sand), F (100% fly ash), B (100% bottom ash), F1B1 (50% fly ash and 50% bottom ash), F1B2 (33.3% fly ash and 66.7% bottom ash), F1B3 (25% fly ash and 75% bottom ash), F2B1 (6.7% fly ash and 33.3% bottom ash), and F3B1 (25% fly ash and 75% bottom ash). The parameters employed comprise compressive strength testing, density, and water absorption evaluation of the CLC bricks at ages 14, 28, and 35 days, also thermal conductivity at the 35-days sample. The sample age exhibits a proportional relationship with compressive strength and water absorption, while displaying an inverse relationship with density. At the 35-day sample age, the F composition demonstrates the highest compressive strength (14.74MPa) and the lowest water absorption (11%). Meanwhile, the B composition exhibits a compressive strength value of 5.9MPa and the lowest density (1.12g/cm2). Conversely, the P composition showcases the highest density (1.59g/cm2). Density affects thermal conductivity, the lower the density, the lower the thermal conductivity, which means that the heat conductivity will be smaller.

Impact of heating strategies towards energy-efficient buildings

Mitigating climate change and its impact requires intensive efforts to reduce greenhouse gas emissions, transition to renewable energy sources, and implement sustainable practices. Intermittent heating is considered a sustainable and effective way to achieve energy savings compared with continuous heating mode. However, recent studies have found that energy savings from intermittent heating depend on several factors, namely the building envelope solution. Therefore, this work intends to fill the research gap by comparing the energy efficiency and thermal performance of different construction systems, using two real-scale test cells, one built with a Light Steel Framing (LSF) solution and the other with concrete and Hollow Brick Masonry (HBM) solution. An experimental monitoring campaign was performed during the heating season, aimed at analysing the energy consumption, the responsiveness of the test cells to the heating system, and the influence of the outdoor climate on energy consumption, considering different heating strategies (intermittent patterns and continuous). In general, the LSF test cell registered lower energy consumption when compared to the HBM test cell. However, the LSF test cell presented significant fluctuations of the indoor temperature, confirming that it is more susceptible to the outdoor climate conditions. This research concluded that a system with lower thermal inertia has superior energy saving potential.

Soil-cement columns for high-rise buildings: design–testing–construction–monitoring: A case study of green solution in Vietnam

Soil cement columns (SCCs) are commonly used to reinforce soft ground to support roads and railway embankments, or to withstand horizontal pressure for deep excavations. This study presents another application of SCCs as load-bearing foundations for high-rise building projects. SCCs with a diameter of 800 mm, length of 10 m, cement content of 350 kg/m3, and an unconfined compressive strength (UCS) of 3.6 MPa were applied. In this study, five single columns and one group constituting two columns were constructed, and core drilling and axial static load tests were conducted. The test results indicated that the SCC could achieve a load of 1,650 kN for a single pile and 3,300 kN for the group constituting two columns. In total, 1,123 columns were designed and constructed for this project. Compared with conventional reinforced concrete pile methods, a project using SCC could save 30 construction days and 20% of the total cost. Moreover, SCC can be considered a green and environmentally friendly foundation solution because it does not use concrete or steel materials and does not produce waste soil.

Experimental characterization of bond between concrete and HDG steel tubes for mixed steel-concrete structures

Bond between concrete and reinforcement material is crucial for the structural behaviour and design of reinforced concrete or mixed steel-concrete structures. When considering applications in harsh environments, such as severe marine exposure or submerged conditions, hot-dip galvanized (HDG) steel seems to be a promising solution, as part of new mixed steel-concrete structural systems. Although it is essential to guarantee an effective composite response, the interaction and bond behaviour between materials is not yet sufficiently well understood. This experimental investigation aimed to study the bond behaviour between concrete and HDG steel tubes, including the influence of adopting concrete pin connectors by creating holes in the tube profile, and also the influence of the galvanic surface state. The impact of bond length on the bond behaviour of the galvanized steel tube embedded in different concrete mixtures was analysed. Pushout tests were conducted to obtain the load end versus slip responses, as well as the failure modes. The results showed that the embedment lengths and the concrete compositions had no relevant effect on the overall shape of the pushout experimental responses, with the exception of the specimens that include the concrete pin connector. However, both variables clearly influenced the bond stress, dissipated energy during pushout until failure, and residual pushout force. The addition of the concrete pin significantly improved the adherence mechanism, while the contamination of the galvanic surface showed to significantly reduce the bond strength.

The behavior of reinforced concrete frames exposed to high temperature under cyclic load effect

Continued use of the structure through minor renovations and repairs without a complete and accurate determination of the extent of damage to the structure and its elements exposed to high temperature effects due to fire, etc. will cause more loss of life and property in the event of an earthquake that may occur later. The aim of this study is to determine the losses on the lateral load and energy damping capacities and stiffness of reinforced concrete frames exposed to 200, 400, 600 and 800 ℃ high temperatures for 60, 120 and 180 min. For this purpose, 13 reinforced concrete frame test elements with the same concrete and steel material properties and dimensions were produced. All reinforced concrete frame test members were brought to the specified target temperature within one hour and exposed to high temperature effects for 60, 120 and 180 min at these target temperatures. The test members then allowed cooling down on their own and when they reached room temperature, they removed from the oven and subjected to cyclic lateral loading tests. The data obtained from the cyclic lateral loading tests processed to obtain lateral load - horizontal displacement, stiffness - horizontal displacement, cumulative energy consumption - horizontal displacement and strength envelope curves for each test element. According to the results of the cyclic lateral loading tests, it was determined that the lateral load carrying capacities of the test members exposed to high temperature for 60, 120 and 180 min decreased by 24 %, 33.33 % and 36 % in push, and by 25.76 %, 37.6 % and 38.72 % in pull, respectively. In addition, the energy consumption of the test elements exposed to high temperature for 60, 120 and 180 min decreased by 30.98 %, 42.41 % and 39.62 %, respectively, compared to the reference test element. The initial stiffness of all test elements exposed to the high temperature effect decreased compared to the initial stiffness of the reference test element not exposed to the high temperature effect. According to these results, the effect of high temperature causes losses in many parameters that are of vital importance in the building elements, but also highly affects the earthquake behavior of the building.

Numerical simulation of the influence of different heating directions on charging performance of the cubic combined sensible-latent heat storage structure

The sensible and latent heat storage system (CSLHS) has become a research hotspot. In this paper, we construct a thermal storage unit structure by using the method of cubic macro-encapsulation, and its charging performance is simulated by CFD. The material of sensible heat storage is magnesia brick or concrete, and the material of the latent heat storage is molten salt. First, we analyze the effects of different heat surfaces on the charging performance of the CSLHS. The charging performance is better when heating from the bottom than when heating from the top or the side. Then, the heat storage of concrete brick and CSLHS is compared, under the premise of heating from the bottom surface. When the PCM starts to melt, the heat transfer inside the hybrid configuration is 39% higher than the solid heat storage structure. When the heat storage is nearing completion, its temperature distribution is more uniform than the solid heat storage structure, and its heat transfer inside the hybrid configuration is at the same level as the concrete.

Numerical evaluation of seismic response of corroded bridges

Traditional seismic analyses of concrete bridges mainly focus on new bridges, ignoring the effect of durability on the performance, which causes limitations. Research on the seismic performance of corroded bridge piers considering the modal period of the piers is of utmost importance. The corrosion process of steel bars under chloride-ion erosion is simulated based on Faraday’s law, and the time-varying law of the performance degradation of reinforced concrete materials is calculated. Subsequently, a finite-element model of the bridge structure is established using the OpenSees platform. Two seismic waves are selected to analyze the time history within the established finite element model. Considering the influence of the pier modal period, the seismic capacity, and dynamic characteristics of a bridge exposed to a chloride-ion environment are evaluated. This study serves as a robust source of technical support for the comprehensive study of vulnerability analysis, encompassing the assessment of the risks associated with chloride-ion-induced corrosion degradation and seismic hazards.