Concrete Slab Panels Research Articles

Electrochemical study on the effect of high volume fly ash on the corrosion of reinforcement in self compacting concrete slab panels

Electrochemical study on the effect of high volume fly ash on the corrosion of reinforcement in self compacting concrete slab panels

In-plane seismic performance of precast concrete hollow-core slab panels for basement walls

In building structures, exterior basement walls should resist the soil pressure type earthquake load transmitted by the ground. Thus, the structural performance of the exterior basement walls is affected by in-plane seismic performance as well as out-of-plane load resistance. In the present study, for better constructability and cost-effectiveness of the exterior basement walls, conventional reinforced concrete walls were replaced with precast hollow core slab (HCS) panels. To investigate the in-plane earthquake load resistance of HCS for exterior basement walls, cyclic lateral loading test and numerical analysis were performed on four HCS panels with in-plane double curvature. The test and analysis results showed that the structural behavior of the HCS panels was significantly affected by the panel layout. In the test specimens using a single panel, flexural compression failure occurred at the bottom of the panel, and shear friction damage occurred at the upper and lower parts of the panel. In the test specimens using double panels, failure mode was governed by direct shear. The load-carrying capacity of the test specimens using double panels was greater than two times that of the test specimens using a single panel, because the load transfer changed from flexure into direct shear in the wall specimens using double panels. Further, to use HCS panels for exterior basement walls, a design method for prediction of in-plane seismic performance and yield displacement of HCS panels was proposed.

Experimental and numerical investigation on the behavior of concrete sandwich slab panel for a structural system

This paper proposes a simplified methodology based on a concentrated plasticity model to develop numerical analysis of concrete sandwich slab panels for structural systems. Also, a proposal for the determination of experimental damage and its evolution within concrete sandwich panels is formulated. To validate the proposed methodology, an experimental study was carried out on full-scale slab panels to analyze the flexural behavior. Eight specimens were subjected to three- and four-point bending tests. A cycle loading protocol with unloading up to zero load was performed. These specimens, constructed with either one or two joined panels, were used to assess the group action. Mechanical properties for structural analysis—such as strength, stiffness, degree of composite action, and effective moment of inertia—were determined. The tested specimens exhibit significant stiffness degradation, indicating a notable evolution of damage even at small plastic displacements. The proposed methodology proves to be effective and reliable for predicting the behavior of concrete sandwich panels under bending moments. The numerical simulations performed show an adequate description of slab panel behavior until the ultimate load, regardless of its simplicity.

Full-Scale investigation on inclined ballastless cant track using concrete slab panel at high temperature setting

The topography condition in the mountainous region has limited the construction of high-speed railways. Therefore, the proposed research aims to develop a new cant track model which is designed at a maximum inclination of 180 mm to simulate the curved sections on these highland areas. This construction methodology incorporates the advantages of the strong stress-bearing property of concrete slab panels and the robust stress distribution ability of the asphalt concrete trackbed. The installment of concrete slab and optimized asphalt concrete mixture were also used to counter the negative impact of the high temperature during summer in South Korea on the asphalt concrete layer. In this research, the performance of the cant track system was analyzed by using the Rail Load System built by the Korea Railroad Institute. There are two featured loading stages including the static load and cyclic load. The static load was designed in the loading and unloading process between 0 and 210kN with an amplitude of 30kN. Concerning the dynamic behavior on the testbed section, 3 million cyclic train loads were applied at a frequency of 7 Hz to simulate the train speed of 350 km/h. The thermal air blow system was installed surrounding the cant track to keep the temperature at the core asphalt concrete at a constant value. Overall, the full-scale testbed results confirm the positive applicability of the cant track since stress can be homogenously distributed along the track substructure. Moreover, the rail plastic displacement and tensile strain of asphalt concrete roadbed were noticeably reduced compared to the conventional long sleeper ballastless track.

Realistic Determination of Live Loads on Various Reinforced Concrete Structures

This paper presents various case studies of examined and calculated live loads on reinforced concrete structures. These case studies accumulated information and data of existing structures about their design live loads and acquired detailed drawings showing the reinforcement in their floor slab sections. The actual occupancy loads that act on the floor slabs were assessed, and the ultimate loads that an individual slab section should be able to support were calculated using the methods recommended by ACI, CP-114, CP-110, and the yield line theory. A reinforced concrete slab panel was also tested to check the validity of the theoretically predicted ultimate loads. The results were compared to find a safety margin and, if necessary, recommend lower live load outlines for cost reduction. The case studies showed that there is sufficient margin to reduce design live loads on the floor slabs of residential buildings, especially in multistory apartment blocks. Moreover, it was found that the live loads, especially on residential buildings, could be decreased to two-thirds of the code values without risking floor overloading.

Condition assessment of two prestressed concrete slabs after 60 years in service

Two concrete deck slabs extracted from a Canadian bridge have been evaluated using non-destructive testing (NDT), followed by destructive testing. Throughout its service life, the bridge experienced harsh environmental conditions with frequent freeze-thaw cycles, hot and humid summers, and the use of de-icing salts during winters. This study presents the preliminary results of an exhaustive condition assessment of two prestressed concrete slab panels, where NDT techniques (visual assessments, electrochemical and concrete soundness tests) have been conducted prior to destructive testing. Although visual inspection did not indicate poor concrete quality, the results of the ultrasonic pulse velocity testing showed that both concrete slabs are of poor quality and may be suffering from internal defects. Chlorides may have also been introduced through the strand conduit anchor points. These findings raise concerns regarding the structural integrity of corrosion-affected members.

Analysis of Zone Fire Models and their Application in Structural Fire Design

This paper is focused on a comparison of zone fire modelling software tools and their application in structural fire design. The analysis of the zone models is performed for five selected computer programs, namely Argos, Branzfire, B-RISK, CFAST, and OZone. The limits and input parameters ofthe zone fire modelling software tools are described. In each software, two variants of the analysed compartment are created for simulating two types of fire scenario, including the fuel-controlled fire and the ventilation-controlled fire. The burning regimes are defined based on two heat release rate(HRR) curves, determined according to EN 1991-1-2. The HRR curves parameters are used as the main input data into the fire modelling software. The fire simulation method in each fire modelling software is selected based on the software capabilities. Although each program requires a different amount of input parameters, the aim was to create the same model in all programs and to compare the results. The fire modelling software outputs are exported into a spreadsheet. Subsequently, a comparison of the resulting graphs is performed, particularly the heat release rate graphs and the upper layertemperature evolution graphs. The fire resistance assessment of a simply-supported concrete slab panel is performed for all zone fire models and then the results are compared. The fire modelling software tools are finally quantitatively and qualitatively evaluated and compared to assess their differences.

Performance Studies on Strength, Thermal and Acoustic Properties on Concrete Panels with E-Waste (FR4) as Partial Replacement of Fine Aggregate

Reliability of FR4, (a frame retardant composite material composed of woven fibre glass cloth with epoxy resin binder) kind of electronic waste along with optimum dosage of fly ash, as partial replacement of fine aggregate in concrete had been investigated. The key objective of this study is to determine the acoustic performance in terms of sound absorbance at low and high frequencies and thermal conductivity. Acoustic & thermal conductivity tests were conducted with different percentage replacement levels of fine aggregate (5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, and 50%) in concrete slab panels having cross section dimensions of 0.3m*0.3m and varying thickness say 0.05m, 0.10m, 0.15m, 0.25m. Analysis on the mechanical properties of hardened concrete are also presented. The research outcome revealed that FR4 exhibits sound performance in terms of mechanical properties when being replaced with 5% of fine aggregate and 10% of fly ash. Also this material has the potential to act as outer-cladding-element to absorb sound in structures like skyscrapers but it needs complete examination on site.

Investigation on Structural Behavior of Bamboo Reinforced Concrete Slabs under Concentrated Load

Reinforced concrete is perhaps the most widely used building material in the world. However, the materials used for reinforcement of concrete i.e. steel is quite expensive and scarcely available in the developing world. As a result, bamboo is considered to be a cheaper replacement with high tensile strength. This research investigated the structural behaviour of bamboo-reinforced concrete slabs used for footplate foundation subjected to concentrated load. For this purpose, four different reinforced concrete slab panels were developed and analyzed. The influence of replacing steel with bamboo for the reinforcement of concrete slabs on their structural behaviour was assessed by determining the load-deflection characteristics, the ultimate load, the stiffness, the ductility, the cracking pattern, and the energy absorption capacity. The results showed that in comparison to steel reinforced concrete slabs, the strength of 82% can be acquired by the bamboo reinforced slabs. Furthermore, ductility demonstrated by the two types of specimens was almost equivalent i.e. up to 93%. Those indicated that the structural behaviour demonstrated by bamboo reinforced slabs is quite comparable to that of steel reinforced concrete slabs. Therefore, bamboo can prove to be a promising substitute for steel in concrete reinforcement. Future studies may further examine this opportunity.

Evaluation on mechanical behavior of asphalt concrete trackbed with slab panel using full-scale static and dynamic load test

In this study, a full-scale model of a railway track structure using an asphalt concrete trackbed with concrete slab panel (ACTSP) is developed. Slab panels are very important to develop asphalt concrete (AC) track system for minimizing the roadbed pressure due to the trainload and reducing the plastic deformation of the AC. The purpose of this study is to analyze the performance of the subgrade and the AC trackbed under different AC layer concepts. Static and dynamic loads were applied to the whole track system by using the Railway Loading System (RLS). Based on the data acquisition and instrument systems, the displacement of the rail/sleeper, the strain at the bottom of the asphalt concrete, and the pressure characteristics of each subgrade was measured. The pressure distribution efficiency along the track system was also investigated. Based on the full-scale test results, the application of asphalt concrete trackbed is very promising since this technology will noticeably mitigate the impact of pressure on the track system from the trainload. The effectiveness is more prominent in railway structures having an AC trackbed thickness of around 35 cm. In this condition, the dynamic train load results reveal that plastic deformation and tensile strain of rail and panel can substantially be reduced up to 20 and 50%, respectively, compared to the condition of 20 cm trackbed thickness. The results also indicate that the pressure distribution along the panel is improved by using a thicker AC layer roadbed concept. Overall, the findings in the research suggest that asphalt concrete trackbed with slab panel is a novel technology that will reinforce the durability of track components and prolong the service life of railway track structure.

Strengthening of defected closure strips for full-depth RC deck slabs using CFRP sheets

Two configurations of closure strips between precast reinforced concrete (RC) slab panels were fabricated and filled with either non-shrink grout or ultrahigh-performance strain-hardening cementitious composite (UHP-SHCC) material. The strips were then strengthened with externally bonded carbon-fibre-reinforced polymer (CFRP) sheets in order to compensate the drawback associated with decreasing the amount of connected steel reinforcing bars required to transfer the bending moment between panels. In total, 12 specimens divided into three groups were cast and tested under short-term non-reversed repeated patch loads simulating wheel load at the central joint. The test results showed that the UHP-SHCC filling material enabled the connected panels to exhibit more ductile behaviour compared with the panels whose closure strips were filled with non-shrink grout. On the other hand, the CFRP strengthening sheets for the first configuration of the closure strip failed to restore the ultimate capacity of the un-strengthened monolithic specimen. However, the second configuration, using UHP-SHCC filling material, enabled the connecting panels to restore lost capacity, with a performance improvement of about 14% compared with the un-strengthened monolithic specimen.

Edge-clamped two-way slabs containing low-ductility steel

This paper describes a series of full range load tests on two-way, edge-clamped reinforced concrete slab panels containing either Class L WWF or Class N deformed bars. Five rectangular slab panels were tested each with two adjacent fully restrained edges and two free edges. A point support was included under the corner of each panel at the intersection of the two free edges. Each slab specimen was loaded by four transverse loads applied symmetrically in the mid-panel region by a deformation-controlled actuator in a stiff testing frame. The continuous edge supports were provided by clamping two adjacent edges in a carefully designed and constructed testing frame. The slabs were instrumented with load cells to measure applied forces and reactions, strain gauges to measure strain in the steel reinforcement and on the concrete surfaces, linear variable displacement transducers and lasers to measure deflections at all stages of loading. The results of the tests are presented and evaluated, with particular emphasis on the strength, ductility and failure mode of the slabs.

Effect of Fire Model Parameter Variability on Determination of Fire Resistance of Concrete Structural Members

The paper is focused on the fire model parameter variability and its effect on the determination of fire resistance of concrete structural members.For the modelling of fire, the parametric temperature-time curve given in EN 1991-1-2 is used.First part of the paper is aimed on the fire model parameter variability in general.First, fire model parameter ranges are described and their combinations are created using two common sampling methods -- Monte Carlo and Latin Hypercubes.Then, the combinations are analysed, unreasonable combinations are identified, and viable combinations are illustrated.Moreover, the characteristics of the temperature-time curves obtained using the parameter combinations are discussed. Namely, we focus on the temperature evolution, duration of fire, andthe maximum temperature reached.In the second part of the paper, an illustrative example is presented.The example is focused on the analysis of the fire resistance of a concrete slab panel. The panel is placed in a fire compartment with given fire model parameter ranges. In the example, the variability of the fire model parameters is captured using the Latin Hypercubes sampling method.The thermal analysis of the slab panel as well as the subsequent mechanical analysis are both conducted by using numerical methods described in our previous work. The calculations are performed in MATLAB environment.Finally, the obtained results are presented and discussed.It is shown that the Latin Hypercube sampling can be used as an effective tool for the investigation of the effect of fire model parameter variability on the fire resistance.

Performance study about ductility behaviour in electronic waste concrete

In this investigation aims in reutilizing the electronic waste in concrete mix with an objective to replace the conventional fine aggregate. The fine aggregate in the concrete is being partially replaced by Electronic waste (E-Waste) in its powder form and tested for its strength characteristics for comparison with the parent material. Polychlorinated biphenyl (PCB), a major component of the Electronic waste powder plays a major part in substituting the fine aggregate’s work in the concrete mix. The sand is being replaced by 10, 15, 20 and 25% of electronic waste replacement is made in concrete mix samples and basic strength tests like compressive, tensile and flexure tests were carried out for strength comparison for using electronic waste. In addition to this concrete slab panels of size 500 × 500 mm are cast, subjected to test ductility behaviour of the specimen. Deflections are recorded by various percentage replacements and different percentage replacement of Electronic waste are turned out graphically. Reutilization of electronic waste is a very good alternative advancement for construction materials.

FIRE RESISTANCE PROVIDING OF HOLLOW‐CORE CONCRETE SLABS USING SHEET BUILDING MATERIALS

Introduction. This paper deals with the analysis of world experience in fire resistance providing of hollow‐core concrete slabs. To protect concrete structures are used many structural applications: thermal coatings and materials. The research first analyzes main methods and hypothesis using to make temperature analysis of solution fire resistance of concrete structures. Problem of making temperature analysis of hollow‐core concrete slabs are nonlinear thermal material properties and radiation heat transfer in the hollow-cores. The aim of this paper is to establish the temperature distribution in hollow‐core concrete slab considering radiation heat transfer in the hollow-cores in case of fire in compartment that is spreading by standard temperature-time curve. In addition, the aim is to substantiate the possibility of using gypsum panels to provide fire resistance of hollowcore concrete slabs. Material statement. The paper reports the results of modeling the process of heat transfer in hollow‐core concrete slab, between compartment space and slab surface and in hollow‐cores. To calculate temperature fields in hollow‐core concrete slab considering nonlinear thermal material properties and radiation heat transfer in the hollow-cores was used finite element model. At addition, the results of finite elements simulations show temperature fields in hollow‐core concrete slab and gypsum panels that installed under concrete slab. Scientific novelty. The paper reports results of theoretic substantiated of possibility of using gypsum panels to protect of hollow‐core concrete slabs considering nonlinear thermal material properties, radiation heat transfer between surfaces and radiation heat transfer in the hollow-cores. The results indicate that using gypsum panels to protect of hollow‐core concrete slabs reduces speed heating of concrete elements to critical temperatures that increase fire resistance of hollow‐core concrete slabs to 20.4 %.

Application of Recycled PET Fibers for Concrete Floors

High consumption of plastics leads to production of large amounts of plastic waste. Plastic is non-biodegradable so its disposal has been a problem. In order to resolve this problem, recycled PET fibers were proposed to be used as reinforcement in concrete. This paper has discussed the effect of adding Polyethylene terephthalate (PET) fiber to the blended cement mixed concrete floor slab panel. This research consists of two main stages. In first stage, different volumes of recycled PET fibers, i.e. 0%, 0.5%, 1.0% and 1.5% have been added as percentages of concrete by volume. The results showed that the maximum volume of PET fiber for a desired compressive and tensile strength was 1.0%. It was observed that 15.3 % of increase in compressive strength, 22.44% of increase in flexural strength and 18.77% of increase in split tensile strength for the addition of 1.0% PET fibers to the concrete. In second stage, optimum fiber percentage (1.0%) selected from the first stagewas used to produce slab panels. Inorder to investigate the structural performances of the slab panel, center-point line loading test, dropping weight test and energy absorption test were conducted. It has been found that recycled PET fiber introduced slab panels showed better performance compared to the conventional floor slab panel.

Applicability of GPR and a rebar detector to obtain rebar information of existing concrete structures

Much of Canada’s existing infrastructure was constructed during 1950s, 1960s and 1970s. These include all transportation infrastructures such as bridges, highways, tunnels, etc. It is important to know the condition of these aging infrastructures in terms of their load carrying capacity to ensure their safety and serviceability. There are several old reinforced concrete slab bridges within the network of Ministry of Forests in B.C. Canada that have unknown rebar spacing, cover and diameter. This research paper discusses the application of Ground Penetrating Radar (GPR) and a Rebar detector in obtaining valuable information about rebar diameter, spacing and cover depth required to determine the structural capacity (load rating) of bridge decks. For this, GPR and the rebar detector have been applied on an existing bridge deck, a precast bridge girder and a reinforced concrete test slab panel available in the materials lab at the Facility for Innovative Materials and Infrastructure Monitoring (FIMIM) at the University of Victoria (UVic). To assess the applicability of GPR and Profoscope (Rebar Detector) in obtaining rebar information, the results obtained using both the techniques were compared in terms of their errors in determining all three parameters of rebar; diameter, spacing and cover depth. The results were validated by measuring the actual diameter, spacing and cover depth of the rebar in the reinforced concrete test slab available in the lab at UVic.

Briefing: Dynamic mode couplings of railway composite track slabs

Steel–concrete composite railway track slabs are a financially viable alternative for the modular construction of railway slab tracks and for the replacement of resilient timber transoms on railway bridges, and design and experiments have been carried out to investigate their technical feasibility. Extended findings based on dynamic eigenvalue analyses of a precast steel–concrete composite slab panel for a track support structure are presented in this paper. The natural frequencies of the railway composite slab were investigated using the finite-element package Abaqus. Dynamic eigenmodes were then extracted using the Lanczos method. Modal cross-over phenomena were clearly observed when the design mass of the track slab was changed. This paper highlights the unprecedented dynamic mode coupling effects on composite track slabs over a railway bridge. This insight can be used to improve practical noise- and vibration-control technologies through composite material design, resulting in quieter railway track slabs.

Experimental evaluation of bamboo reinforced concrete slab panels

Reinforced concrete structural members are primarily subjected to static gravity loads. The conventional steel reinforcement is used to provide additional tensile strength and energy absorption capacity to concrete members. But conventional M.S. (Mild steel) or HYSD (High Yielding Strength Deformed) bars are heavy in weight, costly, nonrenewable and un-ecofriendly material. Aiming to mitigate this concern a sustainable, renewable, ecofriendly material like bamboo has been used as substitute to steel in the present work. Bamboo-concrete Bond behaviour was first studied through a series of pull-out tests. Bond strength investigation has resulted in a unique bamboo strip profile along with a surface treatment the combination of which exhibited maximum bond strength under uniaxial loading. This new bamboo strip is further used as main reinforcement in concrete slab panels. Feasibility and effectiveness of this unique bamboo profile used as reinforcement was investigated through experimental testing of concrete slab panels. A total 15 concrete slab panels were fabricated and tested as per Eurocode EN-1448-5 (2006). The effect of total replacement of main steel reinforcement by bamboo on the flexural behaviour of slabs in terms of load-deformation characteristics, energy absorption capacity, crack patterns and failure modes have been studied. Test results show that there is improvement in the load carrying and deformation capacity when proposed bamboo strip is used as reinforcement in concrete slab panels as compared to that of PCC (Plain Cement Concrete) and RCC (Reinforced Cement Concrete) slabs. Interestingly the structural behaviour of slabs using newly developed bamboo reinforcement has shown significant improvement in flexural performance and it was marginally better than the RC slabs having M.S. bars as main reinforcement.

Lightweight steel concrete structures slab panels load-bearing capacity

Lightweight steel concrete structures (LSCS) - an innovative building structure type that can be used both as load-bearing and as enclosing one. They consist of profiled steel usually galvanized and cold-bent - filled with a monolithic foam concrete with a 200kg/m3 density, and with fiber cement sheets sheathing. These structures can be used in industrial and civil buildings as internal and external bearing and enclosing wall structures, and as slabs. According to the LSCS production method, prefabricated panels (walls and slabs) and building site performed constructions are distinguished. The article presents the LSCS subspecies, representing slabs panels made of galvanized profiled steel, density medium grade D400 monolithic foam concrete and sheets “Steklotsem” sheathing, bearing capacity experimental studies results. The paper confirms that such panels can be used in civil buildings and withstand the appropriate load, regulated by the current codes and rules. Moreover, it has been experimentally proved that the foam concrete, despite its own extremely low strength class, actually includes in the operation, preventing such effects as stability local loss, crushing and profile steel elements cross-section warping and increases the slabs overall load capacity by 20-25%.