Stresses In Concrete Pavements Research Articles

Fatigue damage caused by superload vehicles in concrete pavements

Superload vehicles (SLs) are typically defined as vehicles having a gross vehicle weight (GVW) greater than 890 kN. SLs often consist of unique axle configurations that may cause significant damage to pavements. Research has been mainly limited to SLs on asphalt pavements, therefore the effect of SLs on concrete pavements is not well established. In this study, fatigue stresses in concrete pavements were quantified for a database of pavement structures and SLs to identify critical conditions that contribute to fatigue damage. A series of load pulses were constructed from a database of finite element results to identify conditions and locations within the slab for peak stress development. Tensile stress greatest in thin pavements with a stiff base layer and large positive temperature gradients subjected to tandem axle SLs. Fatigue damage was calculated for the critical cases using several damage models, and significant variation was found between models based on inputs used.

Enhancing thermal behaviour of concrete pavement by incorporating vermiculite

In the current state, the use of the vehicle has rapidly increased all over the world. It happens due to the increase in population as well as vehicle users. So, it becomes necessary to provide a durable and efficient transportation system. Nowadays concrete pavements are extensively used as compared to the bituminous pavement in road construction. Concrete pavement is more durable due to its better strength and sturdiness; the however concrete pavement is affected because of temperature stresses which cause the formation of cracks inside the pavement. Cracks in the pavement develop as a result of the combined effects of thermal stress and wheel load. The study's findings demonstrate the effectiveness of extended vermiculite (EV) in reducing temperature stresses in concrete pavement. Expanded vermiculite has very low thermal conductivity. To check the behavior of expanded vermiculite, thermal stresses and compressive strength test have to be performed on M30 grade of concrete with a percentage variation of expanded vermiculite 10%, 20%, and 30% as in partial substitution with fine aggregate by volume. Alccofine is an additive material that enhances the strength. Alccofine is added 10% by the weight of cement. An outdoor heat simulation test was performed to determine thermal stresses in concrete. Results proposed a decrement in temperature stresses in the concrete pavement as the proportion of expanded vermiculite increased.

Comparison of stresses in jointed plain concrete pavement without shoulder

Concrete pavements are repeatedly subjected to the vehicular traffic loading and the environmental loading. The major advantage of construction of concrete pavement is its durability and low maintenance requirement. The combined loading develops stresses in the jointed plain concrete pavement (JPCP). These stresses are generally the reason for the development of cracks in the slab at critical locations. These stresses may lead to the failure of the pavement in terms of cracks. Stresses mainly depend on the strength of the foundation (soil-subgrade), concrete properties, the thickness of the slab, and loading type and its location. Therefore, to avoid the failure of the concrete pavement, it is necessary to estimate critical stresses precisely for the given site conditions and loading configurations. The aim of the study in this paper is to compare the variation of critical stresses in the concrete pavement without concrete shoulder for the various parameters and their combinations. In this paper, critical stresses are calculated for pavement without concrete shoulder as per the widely used design guidelines/documents. The results obtained are compared and some important conclusions and recommendations to improve the design are suggested.

Curling of Cast-in-Situ Short Slabs on Lean Concrete Base: Measured Versus Theoretical Analysis

Cast-in-situ short paneled concrete pavements (CiSPCP) are a class of innovative concrete pavements, which are being considered as a sustainable replacement for jointed plain concrete pavement. However, there is a lack of understanding of various aspects of CiSPCP such as joint spacing, long-term joint performance, dominant stresses, failure criteria, and curling behavior. In this study, the curling behavior of CiSPCP test sections with different slab sizes and thicknesses on National Highway (NH)-18 (old NH-33) were investigated during the summer of 2019 and the winter of 2020. The vertical displacements at mid-slab (longitudinally and diagonally to the slab), the effect of slab size and thickness on curling with seasonal variation were considered, along with a comparison of measured curling using theoretical analysis. The measured displacements at the edge of slabs were smaller compared with those at the center of the slab. Interestingly, the occurrence of maximum slab curl was not in tandem with the maximum temperature gradient (TG). The time lag for the response was around 2 to 4.5 h of the occurrence of a maximum TG. This observation was very significant because temperature stresses have a profound effect on stresses in concrete pavement. However, this field observation has indicated that the lag in the development of maximum TG may also lead to a lag in the development of stresses. Further, it was found that the theoretical method overestimates the curling compared with the field-measured displacements, which can be mainly attributed to the lag.

Temperature variation and stresses in unreinforced concrete pavement containing RAP

Temperature profile and corresponding stresses in concrete pavement were investigated on prototype scale. Four prototypes were considered, conventional and 25%, 50% and 75% of fine-Reclaimed Asphalt Pavement (RAP) inclusive concrete mixes. The observed temperature profile during 270-days was nonlinear with higher degree of nonlinearity for conventional mixes. The profile could be represented in quadratic form which annuls the assumption of linear temperature variation in numerous design methodologies. The total temperature stresses were lower for RAP inclusive prototypes. Stresses with linear temperature profile assumption over or under-estimated and failed to identify the nature of the stress due to actual temperature profile.

Evaluation of the Moisture Dependence of Concrete Coefficient of Thermal Expansion and Its Impacts on Thermal Deformations and Stresses of Concrete Pavements

The coefficient of thermal expansion (CTE) is one of the material properties of concrete that has the largest impact on rigid pavement performance. Concrete CTE is typically measured in the laboratory, under saturated conditions, or estimated on the basis of the mix constituents, past experience, or both. Whichever method is used, the mechanistic-empirical design of concrete pavements traditionally assumes a constant value for this material property. This assumption has important consequences in relation to predicting thermal deformations and stresses since the CTE of concrete actually changes with the concrete’s internal moisture conditions. The experimental data presented in this study show that this assumption, together with the way CTE is measured in the laboratory, leads to systematic underestimates of thermal deformations and stresses in concrete pavements. The experimental data come from six concrete overlays of asphalt pavements that were instrumented with thermocouples, relative humidity sensors, and vibrating wire strain gauges to measure the expansion/contraction and bending of the slabs because of temperature and moisture-related actions. The apparent CTE of the overlay slabs reached values up to 65% larger than the CTE measured in the laboratory under saturated conditions. Using finite element method modeling, it was determined that thermal stresses were up to 70% larger than predicted using the saturated CTE.

Evaluation and reduction of temperature stresses in concrete pavement by using phase changing material

Due to an increase in the population, the need for good and efficient transportation becomes essential to provide better facilities to the people. Nowadays, concrete pavements are more adopted in highway construction. The concrete pavement is more efficient because of its higher strength, durability, and reliability, but concrete pavements are largely affected due to temperature stresses. This study investigates the potential use of phase changing material (PCM) for the reduction of temperature stresses in concrete pavements. To inspect compressive strength and temperature differential of concrete mixes at different substitution levels of PCM. An indoor heat simulator with temperature sensors was used to measure the temperature differential of concrete mixes. The temperature differential is a major factor for generating curling in concrete pavement. Results recommend that increment in PCM content reduces the temperature stresses in concrete pavement.

Concrete pavements subjected to hail showers: A semi-analytical thermoelastic multiscale analysis

Climate changes result in an increase of extreme weather events. Concrete pavements e.g.may be subjected more frequently to hail showers, following significant solar heating of their top surface. This scenario is studied by means of multiscale thermoelastic analysis. The semi-analytical solution of the heat conduction problem provides access to the temperature fields inside the pavement plates. The thermal expansion coefficient, the modulus of elasticity, and Poisson’s ratio of concrete are homogenized based on the Mori-Tanaka scheme. The thermoelastic analysis of pavement plates, resting on an elastic Winkler foundation, is based on the Kirchhoff hypothesis and a Vlasov-type of structural analysis. This delivers macroscopic stress states of the concrete. Finally, top-down scale transition is used to compute the average stresses, experienced by the three concrete constituents: cement paste, fine aggregates, and coarse aggregates, and by the interfacial transition zones (ITZs), covering the aggregates. This mode of analysis is applied to a realistic pavement plate. It is found that the stresses in concrete pavements subjected to temperature changes are governed by self-equilibrated thermal stresses resulting from nonstationary heat conduction. In case of a sudden hail shower, these stresses are likely to reach the tensile strength of concrete. Cracking starts at the ITZs, representing the weakest link of the microstructure. From quantitative thermoelastic analysis it is concluded that hail showers represent a serious threat for the integrity of the top layer of concrete pavements and, thus, for the long-term durability of such pavements.

Optimization of Structure Parameters of Airfield Jointed Concrete Pavements under Temperature Gradient and Aircraft Loads

Daily changing temperature causes significant thermal stress in concrete pavement. Tensile stress obtained can exceed flexural tensile strength when the concrete slabs are subjected to large temperature gradient and traffic loads, resulting in pavement damages. In this paper, maximum tensile stresses in concrete slabs with different slab sizes, thicknesses, and length to width (L/W) ratios were investigated by using the finite element (FE) method. The important parameters in the design of concrete pavement are the flexural tensile strength and the fatigue limit. By analyzing the comparison results between the maximum tensile stress and the fatigue limit, the optimum slab size and the critical thickness were determined. The results indicate that the maximum tensile stress obtained is higher for larger slab size with thin thickness. Furthermore, to reduce cutting work and the amount of dowel bars, the optimum slab sizes of the regional airport concrete pavement are recommended as 4 m × 4 m to 6 m × 6 m. The critical thicknesses of 4 m × 4 m slab and 6 m × 6 m slab are determined as 28.2 cm and 34.7 cm, respectively, based on the most unfavorable coupling between positive and negative temperature gradients and the Boeing 737–800 aircraft load. Moreover, the maximum tensile stress increases as the L/W ratio increases. When the slab length is less than 6 m, it is better to use square slab in airport jointed concrete pavement (JCP).

Analysis of temperature gradient in concrete pavement

The paper presents the results of experimental research that is the continuation of the research conducted as a part of a Ph.D. dissertation. The experimental research consisted in measuring the temperature at various depths inside a concrete slab, including its surface, and measuring the air temperature. The temperature distribution was measured on a concrete slab with dimensions similar to real road slab dimensions. The aim of the research was to determine the temperature gradient in the concrete slab in Polish climatic conditions and to verify the available analytical methods. Keywords: temperature gradient, concrete pavement, thermal stress in concrete pavement.

Application of a PCM-rich concrete overlay to control thermal induced curling stresses in concrete pavements

This study aims to evaluate the application of a Phase Change Material (PCM) rich concrete overlay to reduce curling stresses in concrete pavements. Curling stresses are the results of temperature gradient in pavements, and are comparable to the stresses that are induced by traffic loads. The weather conditions, which have a cyclic nature, are the source of curling stresses, and they cause cyclic tensile and compressive stresses in pavements. This phenomenon causes fatigue damage in concrete pavements and reduces their service life. The PCMs have a high latent heat of fusion and can increase the thermal inertia of concrete. When PCM is used in a concrete overlay, it tends to moderate the temperature gradient in the slab, and thus mitigate the curling stresses. The efficiency of the proposed PCM-rich overlay was evaluated under the real climatic conditions of three different cities in the US. The findings of this research demonstrated that the cumulative fatigue Damage Index (DI) resulted from repetitive curling stresses can be up to 22% in a concrete slab with the service life of 35 years. However, using a 7.6 cm bonded concrete overlay with 25 vol% PCM can moderate the curling stresses so much that the effect of curling induced fatigue damage would be virtually negligible.

Effect of Panel Size and Radius of Relative Stiffness on Critical Stresses in Concrete Pavement

Design of concrete pavements is carried out with the help of available guidelines that are generally based on single size of slab panel. However, in practice, the slab size is seen to be different than the one recommended by most of the guidelines such as PCA (Thickness design for concrete highway and street pavements, Portland Cement Assosiation, Skokie, 1984) and IRC 58 (Guidelines for the design of plain jointed rigid pavements for highways, 4th Revision, Indian Road Congress, New Delhi, 2015) , especially on curves or at the junctions. It is also established that temperature stresses vary with the plan size of the panel. The important parameter in the design of concrete pavement is critical edge stress which depends on traffic and temperature load. However, it is observed that, for the same design parameters such as traffic load and subgrade stiffness of soil, critical stress values alter largely as the panel size is diverse from the standard one. The standard panel size as specified by PCA (1984) and IRC 58 (2015) is 3.5 m $$\times $$ 4.5 m. In this paper, the effect of the size of slab panel and radius of relative stiffness on critical edge stress has been investigated. Analytical models have been developed to obtain critical edge stress for concrete pavement resting on an elastic soil foundation using finite element software. It has been found that, for smaller panel sizes with low radius of relative stiffness, critical stresses obtained are higher. Therefore, it is necessary to consider the effect of the size of slab panel and radius of relative stiffness, while designing the concrete pavement.

Calculation of shrinkage stress in concrete structures with impact of internal curing

This paper presents recent advances in the calculation of shrinkage stress in concrete structures, especially focus on the effect of internal curing. In the modeling, an integrative model for autogenous and drying shrinkage predictions of concrete under drying environments is introduced first. Second, a model taking both cement hydration and moisture diffusion into account synchronously is used to calculate the distribution of internal relative humidity in concrete. Using the above two models, along with the shrinkage stress model for concrete pavement under nonlinear strain along the slab thickness, the development of shrinkage stress in concrete pavements since casting made by low, middle and high strength concrete respectively is calculated. In particular, the effects of internal curing with pre-wetted lightweight aggregates on the progress of shrinkage stress are investigated and discussed. Based on the present study, the following conclusions can be drawn: (1) the progress of shrinkage stress in concrete pavements obeys two-stage mode since concrete casting, a small stress stage (close to zero) in the moisture saturated period and a gradual increasing stage with the relative humidity gradually decreasing in the concrete; (2) the closer to the drying face, the higher the shrinkage stresses; (3) the shrinkage stress is greater in high strength slab than that in low or middle strength slab; (4) internal curing with pre-wetted lightweight aggregate can greatly reduce shrinkage stress in concrete pavement, either in low strength slab or high strength slab.

Simplified approach for the evaluation of critical stresses in concrete pavement

Simplified approach for the evaluation of critical stresses in concrete pavement

Analysis of stresses in concrete pavement under a dowel according to its diameter and load transfer efficiency

The suitable load transfer between adjacent concrete slabs in transverse joint is influenced by various parameters. In this paper, the influence of different diameters and spacing of dowel bars on the slab interaction was considered. Calculations were carried out with application of 3D finite element method. Verification of the model was performed with the concrete pavement in Poland. Results of these calculations were compared with falling weight deflectometer studies. Calculations of stress concentration around dowel bars for different conditions and parameters enabled to determine a relationship between load transfer efficiency (LTE) and vertical compressive stresses in the concrete slab. It was found that application of dowels with small diameters can promote damages in the concrete slab because of concentration of vertical compressive stresses under the dowel bar. The found relationship enables to determine stresses in concrete under the dowel according to its diameter and LTE.

Computational Approach to Investigation of Crack Behaviour under Vehicular Loading of A Typical Concrete Pavement (A Case Study of Mbagathi Road in Nairobi)

Nairobi County has nearly 100% road network as bituminous roads and only 4km road network (Mbagathi Road) is concrete road. This road was a pilot project that was implemented by Kenyan Government between the years 2005 and 2007 at a total construction cost of over 400 million Kenya Shillings. The design was done based on South Africa design procedure on a 210 mm thick PJCP pavement. Performance of Plain Jointed Concrete Pavement (PJCP) depends on aggregate interlock, which is the mechanism by which loads are transferred from one slab to the adjacent one. This study attempted to use the information on load transfer mechanics in order to quantify the effect of aggregate properties to crack size as well as the propagation of any cracks formed in service. This research was undertaken in two different ways namely experimental and computer simulation. The experimental approach entailed measuring widths and depths of cracks existing in Mbagathi road, and also involved setting up concrete beams in the laboratory and loading them to failure with predetermined loads and measuring sizes of resulting cracks. On the other hand, the computational approach was verified by experimental results entailed simulating crack widths and depths with recent devised fracture models. Cracks were experimentally noticed to occur due to loading the pavement with vehicular loads bigger than safe load. Cracks generated had crack width equivalent to the measured flexural deflection and for an ideal concrete pavement crack width and crack depth exhibited an exponential relationship. It was found that vehicular loads induce stresses in concrete pavements which exceed permissible tensile stresses, hence a better understanding of the resultant cracks, as well as their propagation. This research will lead to an improvement of the design of concrete pavements in Kenyan environment.

Computational Approach to Investigation of Crack Behaviour under Vehicular Loading of A Typical Concrete Pavement (A Case Study of Mbagathi Road in Nairobi)

Nairobi County has nearly 100% road network as bituminous roads and only 4km road network (Mbagathi Road) is concrete road. This road was a pilot project that was implemented by Kenyan Government between the years 2005 and 2007 at a total construction cost of over 400 million Kenya Shillings. The design was done based on South Africa design procedure on a 210 mm thick PJCP pavement. Performance of Plain Jointed Concrete Pavement (PJCP) depends on aggregate interlock, which is the mechanism by which loads are transferred from one slab to the adjacent one. This study attempted to use the information on load transfer mechanics in order to quantify the effect of aggregate properties to crack size as well as the propagation of any cracks formed in service. This research was undertaken in two different ways namely experimental and computer simulation. The experimental approach entailed measuring widths and depths of cracks existing in Mbagathi road, and also involved setting up concrete beams in the laboratory and loading them to failure with predetermined loads and measuring sizes of resulting cracks. On the other hand, the computational approach was verified by experimental results entailed simulating crack widths and depths with recent devised fracture models. Cracks were experimentally noticed to occur due to loading the pavement with vehicular loads bigger than safe load. Cracks generated had crack width equivalent to the measured flexural deflection and for an ideal concrete pavement crack width and crack depth exhibited an exponential relationship. It was found that vehicular loads induce stresses in concrete pavements which exceed permissible tensile stresses, hence a better understanding of the resultant cracks, as well as their propagation. This research will lead to an improvement of the design of concrete pavements in Kenyan environment.

Estimation of Critical Stress in Jointed Concrete Pavement

Pavements are subjected to repeated traffic loads along with temperature variation throughout their service life. In concrete pavement, critical stresses are developed due to the combined effect of wheel load and positive temperature differential leading to initiation of cracks. In this paper, a methodology has been presented for evaluating the critical stress in concrete pavement based on finite element technique. A generalized expression for estimating the critical stress has been developed considering various combinations of pavement configurations, axle loads and temperature differential. This equation can be effectively utilized to obtain the critical stress in concrete pavement for any combination of axle load and nonlinear positive temperature gradient without performing a rigorous finite element analysis. Based on the generalized expression, a modification on Bradbury's temperature stress coefficient (C) has been suggested.

Temperature Gradient and Curling Stresses in Concrete Pavement with and without Open-Graded Friction Course

Curling stresses of concrete pavement can be very damaging, and reducing the temperature swings would be very beneficial. This study includes a field instrumentation effort with pavement temperature sensors to quantify the thermal behavior of concrete pavement with and without an open-graded asphalt rubber friction course. The study shows a nonlinear temperature profile across slab thickness, with a large change in temperature between day and night at the top of the concrete slab, and little change at the bottom of the slab. Adding an open-graded friction course over the concrete pavement reduces the temperature fluctuation between day and night as a result of the aeration effect, which is increased by traffic. A three-dimensional (3D) finite-element analysis with a nonlinear temperature gradient shows that adding the friction course reduces the curling stresses in the summer. Furthermore, since traffic increases the aeration effect, sections without traffic show lower effect of friction course on reducin...

A STUDY ON TEMPERATURE DISTRIBUTION OF AIRPORT CONCRETE PAVEMENT

Thermal stress caused by temperature distribution in pavement slab is important in the structural design of airport concrete pavements. Airport concrete pavement slab is very thick, therefore, temperature in the pavement slab varies nonlinearly throughout the slab depth. Thermal stress caused by the nonlinear temperature distribution would be different from that of linear temperature distribution. In this research, following issues were investigated to evaluate the thermal stress in concrete pavement. 1) Thermal stress caused by nonlinear temperature distribution was calculated using temperatures and restraint strains measured in an experimental concrete pavement with a 46cm thick slab. 2) Temperature distribution in concrete pavement was evaluated by thermal analysis. 3) Thermal stress was calculated considering the nonlinear temperature distribution by 3DFEM.