Concrete Layer Research Articles

Sound Absorption Properties of Porous Concrete Layers for Noise Barrier

The porous concrete layer is an open pore material placed on the noise incident face of a sound barrier structure on the road. Pore characteristics such as diameter, area and distribution are the main characteristics of porous concrete different from conventional concrete and play a dominant role in sound absorption properties. Factors affecting the pore structure of typical porous concrete have been discussed. The effects of macroscopic properties on sound absorption properties such as maximum sound absorption coefficient (SAC max), noise reduction and noise average were reviewed. The porous concrete containing other types of aggregate such as recycle, waste material, and lightweight in porous concrete innovation were discussed. Consequently, the effect of thickness, two layers and multiple layers of porous concrete to improve sound absorption at low frequencies. Finally, the guidances were proposed for the mixture composition for producing porous layer for good sound absorbing properties.

Dynamic Response Characteristics of Composite Concrete Structures Subjected to Reactive Jet Impact

Composite concrete structures, commonly found in urban infrastructures, such as highways and runways, are pivotal research object in the protection field. To study the dynamic response of composite concrete structures subjected to reactive jet penetration coupled with an explosive effect, a full-scale damage experiment of composite structures under the action of 150 mm caliber shaped charges was performed, to derive the dynamic damage modes of different concrete thicknesses under the combined kinetic and chemical energy damage effects. The results indicated that under aluminum jet penetration, concrete layers exhibited minor funnel craters and penetration holes. However, concrete layers displayed a variety of damage modes, including central penetration holes, funnel craters, bulges, and radial/circumferential cracks when subjected to the PTFE/Al jet. The area of the funnel crater expanded as the thickness of the concrete increased, while the height of the bulge and the number of radial cracks decreased. The diameter of penetration holes increased by 76.9% and the area of funnel crater increased by 578% in comparison to Al jet penetration damage. A modified-RHT concrete model that reflected concrete tensile failure was established, utilizing AUTODYN. Segmented numerical simulations of damage behavior were performed using the FEM-SPH algorithm and a restart approach combined with reactive jet characteristics. The spatial distribution characteristic of the reactive jet and the relationship between kinetic penetration and explosion-enhanced damage were obtained by the simulation, which showed good concordance with the experimental results. This study provides important reference data and a theoretical basis for the design of composite concrete structures to resist penetration and explosion.

RS-AAT with distributed permeable pipes and alkaline water: Enhancing concrete durability through chloride reduction, pH optimization, and pore structure improvement

Reverse-seepage and Saturation based Active Anti-corrosion Technology (RS-AAT) is a novel and environmentally-friendly approach that enhances the ability of unsaturated concrete in marine alternating wet-dry areas to resist chloride ion intrusion. Comprehending its influence on ions transport and the pore structure within the concrete is vital for assessing the rationality of the technique and further predicting its service life. In this study, cross-section specimens of cast in situ concrete piles with RS-AAT were exposed to a chloride wet-dry cycling environment for 150 days. Spatiotemporal variation patterns of chloride ion content, pore fluid pH, and pore structure in the concrete cover were investigated by free chloride titration, pH determination, and mercury intrusion porosimetry (MIP). The findings indicate that RS-AAT can effectively inhibit chloride ion intrusion into the protective layer of concrete. Moreover, implementing alkaline water in RS-AAT elevates the pore fluid pH and improves the compactness of the pore structure, especially diminishing the harmful pore ratio. Besides, increasing the number of distributed permeable pipes reinforces these effects and reduces the technology's dependence on water pressure. This insight demonstrates the viability of using alkaline water and distributed permeable pipes in RS-AAT to bolster the resistance of concrete structures to chloride ion erosion in an environmentally sustainable manner.

Quantifying the Effects of Material Input Levels on Jointed Plain Concrete Pavement (JPCP) Performance and Slab Thickness

The mechanistic-empirical pavement design guide (MEPDG) is a commonly accepted design principles guide that aids in jointed plain concrete pavement (JPCP) design and performance analysis. The MEPDG uses three different design parameter input levels, referred to as level one, level two, and level three, providing increasing confidence in the analysis at the lower numbered levels, which use more locally relevant (level two) or project-specific (level one) data. The state-of-the-art pavement ME software (version 2.6.2) uses MEPDG design principles to predict pavement performance. The three performance indicators for JPCP systems (international roughness index (IRI), joint faulting, and transverse cracking) experience significant changes when simulating under a different input level. The IRI and faulting indicator changed by 78 percent when using inputs varying from level one to level three, with the cracking indicator change being more severe at 87 percent. To accommodate the change in performance indicator values between input level one and input level three, increasing the concrete slab thickness is necessary to achieve comparable pavement performance. An increase in the Portland cement concrete (PCC) layer from one inch to two inches is required when input level three simulations are performed, demonstrating the economic and sustainability benefits of using project-specific level one inputs. Understanding the impact of simulation input levels will help to meet design and sustainability goals and improve the lifecycle performance of JPCP systems.

Experimental research on bonding mechanical performance of the interface between cementitious layers

Abstract Interfaces of cementitious layers have widely existed in construction projects, and they are the weakest part of the whole building. In this article, laser scanning and ultrasonic pulse, splitting tensile, and semi-disc fracture tests were carried out to study the bonding performance of cementitious layers. Different performance metrics, such as splitting tensile bond strength, ultrasonic pulse velocity, and attenuation of first arrival, were used to evaluate the bonding characteristics of the concrete layers. The results revealed that the parameters of the interface curve decreased, and the mechanical properties of the interface became weaker with an increase of the interval time. The amplitude of the first wave was more sensitive to the presence of the interface than the ultrasonic pulse velocity. Finally, the relationships between the performance metrics were analyzed. The fracture toughness of model I and mode II was highly correlated with the parameters of the micromorphology of the layered concrete, and the correlation coefficient is not less than 0.9511. The fracture toughness of mode I was strongly related to the splitting tensile strength, with a correlation coefficient of not less than 0.9744. This study was useful for the future study of the mode I and I fracture performance, the morphology, and other physical properties of cementitious layers.

Verification of a Simplified Design Method for Timber–Concrete Composite Structures with Metal Web Timber Joists

This study presents a comprehensive analysis of a simplified design methodology for timber–concrete composite roof and floor structures employing metal web beams, also known as posi-joisted beams, easi-joist, or open web joists, validated through both laboratory experiments and finite element (FE) method analyses. The proposed method integrates the transformed section method and the γ-method, as outlined in Annex B of EN1995-1-1 for mechanically jointed beams. The investigation focuses on roof and floor structures featuring posi-joisted beams, oriented strand board (OSB) sheets connected by screws, and a layer of concrete bonded to the OSB sheets using epoxy glue and granite chips. Two groups, each consisting of four specimens, were prepared for the laboratory experiments. Each specimen comprised two posi-joisted beams, 1390 mm long, connected by OSB/3 boards measuring 400 mm in width and 18 mm in thickness. The beams had a cross-sectional depth of 253 mm, corresponding to beams of grade PS10, with top and bottom chords made from solid timber (95 mm × 65 mm). Bracing members with cross-sections of 100 mm × 45 mm were used to join the bottom chords of the beams. A layer of self-levelling mass SakretBAM, 50 mm thick, was bonded to the OSB/3 boards using SicaDur 31 epoxy glue and granite chips (16–32 mm). The specimens underwent three-point bending tests under static loads, and FE modelling, conducted using Ansys R2 2022 software, was employed for both experimental groups. A comparative analysis of results obtained from the simplified design method, FE simulations, and experimental data revealed that the simplified method accurately predicted maximum vertical displacements of the roof fragment, including posi-joisted beams, with precision up to 11.6% and 23.10% in the presence and absence of a concrete layer, respectively. The deviation between normal stresses in the chords of the beams obtained through the simplified method and FE modelling was found to be 7.69%. These findings demonstrate the effectiveness and reliability of the proposed design methodology for timber–concrete composite roofs with posi-joisted beams.

Experimental Study on Seismic Performance of Prefabricated Monolithic Concrete–Polystyrene Panel Composite Wall Panels

A normal composite wall panel is a structural component composed of polystyrene insulation boards and concrete surface layers reinforced with steel wire mesh. It can be entirely prefabricated in a factory or constructed with the concrete surface layers cast on-site. A novel prefabricated monolithic concrete–polystyrene panel composite wall panel (CPC wall panel) is proposed in this study. The CPC panel features a middle part that is prefabricated in the factory while the reinforced concrete regions at its two side ends are cast on-site. To evaluate the seismic performance of the wall panel, 18 CPC specimens were designed, manufactured, and quasi-statically tested, through which the structural behaviors, failure mode, and load-bearing capacity were studied. In addition, the influences of the height-to-width ratio and the vertical compressive stress level on the seismic performance of the CPC panels were also investigated. The test results showed that the connectors spaced at 400 mm × 500 mm could ensure the concrete layers on both sides of the polystyrene board worked collectively under seismic conditions. When subjected to lateral loads, the interface between the newly poured concrete and the existing concrete exhibited good bonding. Moreover, the failure mode of the CPC wall panel was largely correlated to the height-to-width ratio that, for specimens having four steel bars of 12 mm diameter and a height-to-width ratio greater than 1, the flexural failure was initially developed, followed by diagonal shear failure. In specimens with a height-to-width ratio of 1, flexural and diagonal shear failures occurred almost simultaneously. For specimens with a height-to-width ratio of less than 1, the final diagonal shear failure was predominant. The longitudinal reinforcing bars at the two ends of the CPC panels could effectively improve their lateral load-bearing capacity, with the enhancement influenced by the height-to-width ratio, the vertical load applied to the wall panel, and the cross-sectional area of the steel bars. In practice, the lateral load-bearing capacity of the CPC panel can be conservatively evaluated using the calculation method of the reinforced concrete shear walls. Finally, the ductility of the CPC specimens was affected by the height-to-width ratio and the axial compressive stress level, such that the specimens with a larger height-to-width ratio and lower axial compressive stress exhibited better ductility.

Experimental study on protection of prestressed concrete box girder under vehicle explosion of bridge deck

AbstractThis paper presents a study on the explosion protection of prestressed concrete box girder, which is a commonly used in concrete bridges. The explosion protection tests of four prestressed box beams were designed with 1:5 scale. In order to evaluate the explosion performance of different protective layers, steel plate, ultra‐high‐performance concrete (UHPC) layer, and composite protective layer were used to protect the box girder. The experimental results revealed that under the effect of deck explosion, local penetrating failure occurred in the top plate of the box girder, which exhibited characteristics of punching failure. The web and bottom plate of the box girder as a whole exhibited bending characteristic. Compared with the unprotected box girder, the damage of the top plate of the protected box girder was less severe, whereas the damage of the bottom plate was greater. In working conditions 2–4, the UHPC protective box girder suffered less damage to the top plate, whereas the other protective box girders suffered more. The explosion dynamic responses of the box girder were compared, and the influences of different protective layers on the explosion dynamic response of box girder were studied. Based on the box girder damage, the protective efficiency of each protective layer under near‐explosion was studied. Based on the explosion tests, three‐dimensional numerical analysis model of box girder explosion was established. The accuracy of the numerical simulations of the box girder explosion were verified by comparing with the experimental failure data. Through the numerical results, the explosive energy dissipation capacity of different protective materials was compared and analyzed. Finally, based on the dynamic response of the box girder under different working conditions, the sensitivity of the protective layer to the dynamic responses of the box girder were studied. The analysis showed that the UHPC layer was sensitive to the change of prestress and explosion damage area of the box girder but had little influence on the rebars stress and the overall response of the box girder.

Evaluation Method of Fatigue Life for Asphalt Pavement on the Steel Bridge Deck Based on the Inhomogeneous Poisson Stochastic Process.

The paving layer on the steel box girder bridge deck is widely used when constructing pavements for steel bridges. Owing to the orthotropic feature of steel decks, a transverse clapboard and rib can lead to a concentration of stress. Consequently, fatigue cracks are often identified in asphalt concrete pavement layers due to re-compaction caused by heavy vehicles. This study aims to derive an evaluation method of fatigue life for asphalt pavement based on the inhomogeneous Poisson stochastic process in view of the highly random and uncertain working conditions of layered composite structures. According to the inhomogeneous Poisson stochastic process, along with Miner's fatigue damage accumulation theory and the linear elastic fracture mechanics theory, the fatigue life formula could be deduced. Meanwhile, fatigue experiments for asphalt concrete are designed to investigate the correlation between the theoretical formula and the actual fatigue damage life of the material. Compared with the test, the accuracy error is within 10%, which is better than other traditional methods. Therefore, the fatigue life prediction model could better reflect the loading order effect and the interaction between loads, providing a new path for the fatigue reliability design of steel bridge deck asphalt pavement.

Automated Prefabricated Slab Splitting Design Using a Multipopulation Coevolutionary Algorithm and BIM

The prefabricated composite slab (PCS) is an essential horizontal component in a building, which is made of a precast part and a cast-in-place concrete layer. In practice, the floor should be split into many small PCSs for the convenience of manufacturing and installation. Currently, the splitting design of PCS mostly relies on sound knowledge and valuable experience of construction. While rule-based parametric design tools using building information modeling (BIM) can facilitate PCS splitting, the generated solution is suboptimal and limited. This paper presents an intelligent BIM-based framework to automatically complete the splitting design of PCSs. A collaborative optimization model is formulated to minimize the composite costs of manufacturing and installation. Individuals with similar area information are grouped into a subpopulation, and the optimization objective is to minimize the specifications and quantities of PCSs. Through the correlation information within the subpopulation and the shared information among each other, the variable correlation is eliminated to accomplish the task of collaborative optimization. The multipopulation coevolution particle swarm optimization (PSO) algorithm is implemented for the collaborative optimization model to determine the sizes and positions of all PCSs. The proposed framework is applied in the optimized splitting design of PCSs in a standard floor to demonstrate its practicability and efficiency.

Experimental Research on Fatigue Behavior of Reinforced UHPC-NC Composite Beams under Cyclic Loading.

Ultra-high-performance concrete (UHPC), a new cement-based material that offers high mechanical strength and good durability, has been widely applied in construction and rehabilitation projects in recent years. An optimum bending system is achieved by positioning the UHPC layer at the bottom tensile zone of the composite beam and placing the normal-strength concrete (NC) layer at the upper compression zone, which is described as the UHPC-NC composite beam. The fatigue behavior of reinforced UHPC-NC composite beams was described in this study, with an emphasis on the effects of UHPC layer thickness and fatigue load level on the fatigue life of the beam, deformation of the interface between UHPC and NC layers, as well as the bending stiffness of the beam. A total of 9 reinforced UHPC-NC composite beams were tested under cyclic loading. The test variables include UHPC layer thicknesses (zero, 200, and 360 mm), reinforcement ratios (1.184% and 1.786%), and the upper load levels (0.39~0.65). The results showed that good bonding had been achieved without delamination between UHPC and NC layers prior to the final fatigue failure of the beam, and the bending stiffness of the composite beam experienced a three-stage reduction under cyclic loading. Furthermore, an equation was proposed to predict the stiffness reduction coefficient of UHPC-NC composite beams under cyclic loading.

Experimental characterization of a cost‐competitive tailor‐made HPFRC mix design for wide application in precast girder of roadway bridges

AbstractThis paper presents a comprehensive study on the development of a cost‐effective, high‐performance fiber reinforced concrete (HPFRC) for the construction of a 60 m‐span U‐girder roadway bridge without stirrups in the webs, meeting the design requirements of fck ≥ 100 MPa and the post‐cracking flexural strength fR3k ≈ 8–10 MPa. The main objective of this research is to develop a F5 workability class HPFRC that meets the specified design criteria without exceeding 2.5–3.0 times the cost of a C70/85. To achieve this goal, the concrete mix was obtained using 500 kg/m3 of cement and 50 kg/m3 of silica fume. This mix was investigated with nine different combinations of fibers and fiber contents, resulting that 80 kg/m3 of 4D‐fibers (lf = 60 mm) provided the optimal fR3k without compromising workability and cost. Subsequently, an extensive experimental campaign was conducted to cast the U‐girder following the conventional casting techniques involving casting prismatic samples, L‐shaped and rectangular‐shaped panels to represent different parts of the U‐girder. Innovative techniques were used to study the effect of different waiting times between concrete pours. Results from the testing of the prismatic specimens evidenced the need of stitching by means of a poker vibrator planes between successive concrete layers. Furthermore, the study of the panels evidenced that a waiting time of 90 min allows the HPFRC to achieve enough bending and compressive strength to bear internal vibration of the element without liquefying and, at the same time, avoiding cold joints. The results confirm the applicability of the developed HPFRC for the structural element under study following conventional casting techniques.

Analysis of coupled thermo-mechanical response and damage behaviour of curved ramp bridge deck pavement using a 3D multiscale method

A three-dimensional (3D) multiscale modelling approach was developed in this study, which considers a two-way coupling of material properties and mechanical responses between macroscale (pavement level) and mesoscale (mixture level) finite element (FE) models. Both thermal and mechanical properties at the two scales were linked through a homogenisation method, and the boundary response was transferred from the macroscopic target element to the mesoscale model using a mapping procedure. The results show that seasonal temperature variations have a significant effect on the coupled thermo-mechanical response within bridge deck pavement. In winter, the deck pavement is subject to tensile stresses, the maximum values of which mainly occur at the tire edges and the dual-tire clearance centre; while the deck pavement experiences compressive stresses in summer, and the stress difference within the asphalt concrete layer increases with the temperature.

Flexural behavior of two-layer reinforced concrete slab with hollow cores

Flexural behavior of a concrete slab system with an optimal weight-to-strength ratio comprising layered and hollow-core slab structures was investigated using two-layered slabs with hollow cores (LS/HCS). Six slabs with dimensions of 180, 450, and 1600 mm were tested experimentally and numerically using ANSYS software. Each layered slab comprises a 90-mm-thick lightweight concrete bottom layer and a 90-mm-thick high-strength concrete top layer. Three parameters were studied: core diameter (58, 86, and 110 mm), reinforcement ratio (0.37%, 0.53%, 0.95%), and treatment type (bonding agent, nails). Treatment types were analyzed via push-out testing; both nails and agents connected the slabs with sufficient bond strength. A control slab with 86-mm core diameter, shear-span-to-effective-depth ratio of 4, reinforcement ratio of 0.53%, and agent material was used. Concrete, steel bars, and loading support plates were modeled using SOLID65, LINK180, and SOLID185 elements, respectively. Analytical results were validated experimentally. A parametric study analyzed other parameters affecting LS/HCS behavior, including compressive strength, opening numbers, core shape, applied loading type, added top steel reinforcement, slab type, and slab height. Core diameter reduction, increased reinforcement ratios, and using nails enhanced the failure load. The LS/HCS gives an optimum weight-to-strength ratio with a 33.672% reduction compared with solid slabs.

Monitoring and Accelerating Methods of Corrosion for Reinforced Concrete: A Review

AbstractCorrosion is the irreversible, interfacial reaction of metals in the presence of an electrochemical environment which ultimately results in the deterioration of metals. Corrosion of reinforcement is the major problem in the reinforced concrete (RC) structure. Corrosion of reinforcement is a slow process because of the protective layer of concrete. Even in a severely corrosive environment corrosion process takes time to be initiated and propagated. Since to carry out research work, some techniques are required to accelerate the corrosion process in the shortest period. To overcome this problem, in the past, many researchers use a different method to accelerate the corrosion of steel in concrete. In this paper, a review is presented of various techniques used for accelerated corrosion testing. The suitability of reviewed methods on corrosion acceleration for several research works is presented. After that few case studies review to make use of various predicted empirical models and an experimental technique for predicting corrosion rate and the assessment of the remaining life of the structure. And finally, the paper is concluded by comparing the natural method of corrosion and the accelerated method of corrosion and the future scope of accelerated corrosion.

Influence of bonding condition of different interfaces on the mechanical responses and failure mode of asphalt pavement

In this study, a finite element model was established to compute the responses of asphalt pavement with various bonding conditions between the asphalt concrete layers (AC-AC interface) and between the asphalt concrete layer and base (AC-Base interface). The influence of bonding conditions of different interfaces on failure mode of asphalt pavement was discussed. The results indicated that poor bonding condition would increase longitudinal tensile strain at the bottom of the AC layers and vertical compressive strain at the top of subgrade, and the negative effects of two interfaces on pavement would enhance each other. It was observed that insufficient bonding strength would reduce the predicted life of pavement and, more importantly, debonding of AC-AC interface or two interfaces simultaneously would change pavement failure mode. Additionally, it should be noted that the fully-unbonded condition of AC-AC interface would affect the critical location for crack initiation in AC layers.

Investigation of the applicability of infrared thermography detection of grouting voids in prestressed tendon ducts under hydration heat excitation

Infrared thermography (IRT) has been successfully utilized to identify void defects in external prestressed tendon ducts (without concrete protective layers) under hydration heat excitation. Nonetheless, applying IRT technology for the inspection of internal prestressed tendon ducts presents challenges due to the presence of the thicker concrete protective layer, which can significantly influence the detection results. Therefore, this paper proposes a method for detecting void defects in internal prestressed tendon ducts using IRT technology under hydration heat excitation. The influence of the depth, length and compactness of the void on the detection ability is investigated and the influencing factors such as duct materials are analyzed. The results show that under the hydration heat excitation of the grouting material, IRT can detect complete void defects with a depth of 110 mm below and a length of 350 mm. In addition, the detection effects of metal ducts, tubeless ducts and plastic ducts decrease in turn. Finally, this paper recommends that the IRT detection time be 0.5–2 h and 13–23 h after grouting, which can reduce the cost of post-maintenance by timely detection and repair.

Comparative life cycle assessment of sprayed-UHPC sandwich panels over brick & block cavity construction

This paper presents a novel developed Sprayed Ultra-High-Performance Cementitious Sandwich Panel (SUHPC-SP) for structural applications. The SUHPC-SP features sprayed UHPC outer layers making it suited for structural load bearing applications, and a foamed concrete core layer offering high thermal properties. With the development of enhanced material properties and novel production methods, the established SUHPC-SP can achieve optimal mechanical performance while minimising the volumes of material required. As such, this study assesses SUHPC-SP potential to increase sustainable outputs over reference Brick and Block (B&B) construction; by quantifying and comparing the whole life cycle environmental and economic impacts of the two methods. A comparative life cycle assessment (LCA) of these types of construction products is presented for the first time in this paper. The study found that integrating SUHPC-SP over typical B&B construction can reduce environmental impacts by as much as 500% and costs by up to 180%. This informs sustainable construction decisions, offering an effective alternative to conventional inefficient building methods and materials.

Study on the influence law of cavities behind the shotcrete lining on the lattice girders

The field monitoring data showed that a small amount of main reinforcement bars of lattice girder at the arch of a tunnel were pulled, and the calculation showed that the initial support structure should be compressed. To find out the reason for the tension of the main reinforcement, the geological radar was used to detect the cavity in the sprayed concrete layer at the tension position. In order to clarify the tension mechanism of the main reinforcement and the influence of factors such as the position and size of the cavity on the main reinforcement, numerical simulations were carried out. The results show that the cavity causes the eccentric compression of the shotcrete layer, resulting in moment of the lattice girder and the change of the stress distribution of the main reinforcement. The main reinforcement experiences tensile stress when the cavity size surpasses 3 m × 0.2 m, reaching a tensile stress of 81 MPa at a cavity size of 6 m × 0.2 m. Notably, the cavity located at the foot of the arch is more likely to produce substantial tensile stress on the primary reinforcement compared to those at the arch crown and waist. The research results provide a theoretical basis for the interpretation and analysis of tunnel lattice girder monitoring data.

Reporting the Bearing Capacity of Airfield Pavements Using PCR Index

Airfield pavements are important assets that have to secure the safe operation of an airport. On this basis, assessing and reporting the bearing capacity of an airfield runway pavement is a critical task. Recently, the Aircraft Classification Rating-Pavement Classification Rating (ACR-PCR) system has been introduced, which uses the PCR index for expressing the bearing capacity of an airfield pavement. In order to accurately determine PCR, the mechanical characteristics and the thicknesses of the individual layers of a pavement are required. For this purpose, it is not seldom that in the absence of resources dedicated to detailed pavement evaluation procedures, assumptions for the material characteristics of the pavement considering typical materials may be made, while pavement thicknesses may be derived by pavement design records. The present paper highlights the importance of using Non-Destructive Testing (NDT) for accurately assessing the in-situ condition of a flexible runway pavement and determining the PCR index. In order to achieve the goal of the investigation, measurements were performed along the flexible pavement of an airport runway. In addition, the paper focuses on the impact of the variation of the thickness and of the mechanical characteristics of the asphalt concrete layers on the PCR index and on the interpretation of the results considering the acceptance of aircraft operations by airport authorities.