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Transverse cracking in continuously reinforced concrete pavement (CRCP) develops over time and may exhibit irregular patterns such as cluster cracks, Y-shaped cracks, and divided cracks. These undesirable cracking patterns can increase the probability of premature spalling and punchouts. Ideally, a uniform transverse cracking pattern with small crack widths leads to favorable long-term performance in CRCP. An experimental field project was constructed with internally cured concrete and active cracking to control crack initiation timing, patterns, and properties. Prewetted fine lightweight aggregate was used for internal curing, and edge notches of 2 in. depth and 2 ft length every 4 ft along the test section were sawcut for active crack control. The three experimental CRCP sections in Illinois were monitored for crack spacing, crack width, and formation of undesirable cracks over a 4-year period. Internally cured concrete significantly reduced the undesirable crack patterns relative to the control section. Internally cured concrete coupled with active crack concrete produced superior crack patterns and properties, that is, uniform crack spacing of 3.6 ft without cluster cracks, 0.2 mm surface crack width, and only a small number of undesirable cracks. Active crack control produced a higher number of transverse cracks near the terminal joint (last 150 ft) compared with the control section. Moisture and temperature management with active crack control during construction of the CRCP provided a desirable crack pattern and properties that should increase the overall service life of a pavement.

A weld cracking of the outlet pipe occurred during the operation of a low-pressure steam super-heater in the purification device. It was found that many cracks were perpendicular to the weld, which affected the equipment safe operation. In order to investigate the failure cause, the samples containing weld and cracks in the outlet pipe were cut. The experiments, including chemical composition analysis, mechanical properties testing, scanning electron microscope observation, energy spectrum analysis and metallographic analysis, were performed. The results showed that the corrosion products had loose structure, mainly consisting of iron, sodium and phosphorus oxides. The metallographic results of the fracture section indicated that there existed a mixed cracks of trans-granular and inter-granular mode, along with stepped crack characteristics. Therefore, it is believed that the weld transverse cracking in the outlet pipe may be resulted by both of alkali stress corrosion cracking and the hydrogen induced cracking. According to the failure cause analysis, the corresponding suggestions are given, such as welding, operation process and inspection.

Being immune to corrosion, and having a tensile strength up to three times higher than structural steel, glass fiber reinforced polymer (GFRP) bars are suitable for reinforcing concrete structures exposed to aggressive environmental conditions. However, a relatively low elasticity modulus of GFRP bars (in respect to the steel) favors the occurrence of relatively large deformability of cracked reinforced concrete. Lack of ductility and degradation of properties under high temperature can be also identified as debilities of GFRP bars over steel ones. Combining GFRP and steel bars can be a suitable solution to overcoming these concerns. Nevertheless, the application of such hybrid reinforcement systems requires reliable material models. The influence of the relative area of GFRP and steel bars on the tensile capacity of cracked concrete (generally known as tension-stiffening effect), was never investigated from the experimental point of view, mainly crossing results from different tools on the assessment of the cracking process. This paper experimentally investigates deformations and cracking behavior of concrete prisms reinforced with steel bars and GFRP bars in different combinations. The test results of 11 elements are reported. A tensile stress-strain diagram is conceptually proposed for modelling the tension-stiffening effect in elements with such hybrid combination of the reinforcement. The cracking process in terms of crack width and crack spacing is analyzed considering the hybrid reinforcement particularities and a preliminary approach is proposed for the prediction of the crack width for this type of reinforced concrete elements, Research Council of Lithuania (Research Project S-MIP-17-62). The second author also 590 wish to acknowledge the support provided by FCT through the PTDC/ECM591 EST/1882/2014 project

Thermal cracking is a non-load associated distress mode of asphalt pavements. Finite element models (FEM) were first introduced in this study to determine the thermally induced J-integral at the tip of thermal crack. After extensive runs of the FEM, artificial neural network models were constructed to predict the J-integral, which was used in the Paris’ law to calculate the cumulative thermal crack growth over time and thermal cracking fatigue life. Additionally, Long-term pavement performance data was collected to characterize the thermal cracking in different climatic zones. The calculated fatigue life was well correlated with the observed transverse cracking field performance.

While widened slabs have been used to mitigate transverse cracking in jointed plain concrete pavements (JPCP), it is well-known that use of such slabs increases longitudinal cracking potential in JPCP. Field investigations have been conducted in Iowa widened JPCP and it was found that: (1) all longitudinal cracks are top-down cracks; (2) longitudinal cracks start mostly from transverse joints about 0.6–1.2 m (2–4 ft) away from widened slab edges (3) sites with a tied PCC shoulder exhibited fewer longitudinal cracks than sites constructed with hot mix asphalt (HMA) shoulders. In this paper, the longitudinal cracking mechanism of widened JPCP was demonstrated and longitudinal cracking potential was evaluated using numerical analysis. The critical load configuration with the highest longitudinal cracking potential for widened JPCP was identified. Three shoulder design alternatives were also compared in terms of their contributions to mitigation of longitudinal cracking potential. Compared to the use of a widened slab, the use of a regular size slab was found to be beneficial in mitigating longitudinal cracking at the cost of increasing transverse cracking potential. The findings of this study provide explanations as to where and how longitudinal cracking is likely to be initiated as well as recommendations as to how longitudinal cracking potential could be mitigated.

An increased awareness of sustainability in the pavement industry has encouraged the use of warm mix asphalt (WMA) technologies. Compared to conventional hot mix asphalt (HMA) that requires a high production temperature, WMA has several benefits, such as saving fuel and energy, reducing greenhouse gas emissions, and improving the work environment. However, systematic analysis of long-term field performance for pavements containing WMA mixtures has been scarce. Therefore, the objectives of this paper are to evaluate the field performance of flexible pavements using WMA technologies (referred as WMA pavements in this paper) and compare the general trend of the longer-term performance between WMA and HMA pavements across the United States. Specifically, 28 WMA pavement projects along with their companion HMA pavements were evaluated for an extended performance period in terms of transverse cracking, longitudinal cracking, rutting, and moisture damage. A companion HMA pavement refers to the an pavement that shares similar pavement structure, climate, traffic conditions and mixture design with the WMA pavement; the main differences are the usage of WMA technologies in the surface layer and the reduced production temperature for WMA mixtures. The selected projects include five projects constructed during the course of the study, and 23 in-service projects covering different service ages, traffic volumes, pavement structures, WMA technologies, and four climatic zones across the United States. It was found that pavements containing various WMA technologies exhibited comparable long-term field performance as compared to that of the companion HMA pavement in terms of transverse cracking, wheel path longitudinal cracking, and rutting. No moisture-related distress was found in the field for either HMA or WMA pavements. Overall, cracking and rutting performance show a clear pattern of climate influence. Cracking distress appears to be more of a concern within wet climatic zones while less typical in dry climatic zones, which suggests that moisture should be considered in evaluating the cracking potential of asphalt mixtures. Results presented herein were part of NCHRP Project 9-49A on the Performance of WMA Technologies: Stage II—Long-Term Field Performance.

Field pavement transverse cracking typically can be grouped into two categories, namely thermal cracking that initiates at the surface of the pavement and propagates downward, and reflective cracking that initiates at the pavement layer above the existing pavement cracks or joints and propagates upward. Recently, another transverse cracking phenomenon was noticed in some field investigations but was less studied. Cracks were observed from both the surface and the bottom of field cores, but they cannot be visually observed from the middle layer. In addition, the surface and the bottom cracks lined up well, showing the tendency of meeting each other. This study aimed to evaluate the causes of such transverse cracking phenomena by laboratory tests. Hamburg equipment was used as the evaluation equipment. Some samples were prepared with a saw cut notch 0.33 inches in depth and 0.25 inches in width, and some samples were prepared without the notch at the bottom. The results showed that such a crack type could have happened when samples are aged, the base below the sample is soft, and a notch exists in the bottom layer. A potential mechanism is when the wheel load moves on one side of the existing transverse cracking (the near side), as the specimen on this side tends to bend downward under the wheel load, especially when the support is relatively soft. If without constraint, the other side of the specimen (the far side) should consequently be tilted upward. However, the bonding with the base layer and the self-weight of the specimen restrict the upward movement of the far-side specimen. Therefore, the tensile stress at the surface of the specimen directly on top of the bottom crack is created. At the same time, the bottom crack has the potential of being squeezed and pushed together.

Asphalt concretes are made from aggregates, binders, and modifiers. In this chapter, a brief description is given on the ingredients of asphalt concretes. Different modes of deterioration in asphalt concretes including cracking (i.e., fatigue cracking, longitudinal cracking, transverse cracking, block cracking, slippage cracking, reflective cracking, and edge cracking), surface deformation (i.e., rutting, corrugation, shoving, depression, and swell), disintegration (i.e., pothole and patch), and surface defects (i.e., raveling, bleeding, polishing, and delamination) are then introduced.

Low-temperature cracks reduce the road surfaces quality, increase the cost of their repair. This problem is relevant in the regions with seasonal soil freezing. Analysis of the literature showed that, despite the large research work, the multidisciplinary problem of low-temperature cracking requires further research. In the present work, the object of study is a two-layer structure as a model of a straight section (segment) of an unpaved highway in the stage of seasonal freezing. Subject of research: the conditions for frost cracking in the upper layer of the road during seasonal freezing. Objective: to simulate the conditions for transverse cracking in the upper layer during seasonal freezing of the dirt road, taking into account the influence of temperature on the coefficient of thermal expansion. The paper presents a mathematical model of the frost cracks formation. The results of the modeling are consistent with data known in the literature. From a practical point of view, the results can be used to predict the state of logging roads at the stage of soil freezing in the off-season periods.

Random forest is a powerful machine learning algorithm with demonstrated success. In this study, the authors developed a random forests regression (RFR) model to estimate the international roughness index (IRI) of flexible pavements from distress measurements, traffic, climatic, maintenance and structural data. To validate the model, more than 11,000 samples were collected from the database of long-term pavement performance (LTPP) program, with 80% randomly sampled data for training and 20% of them for testing the RFR model. The performance of the RFR model was then compared with that of the regularized linear regression model. The results showed that the RFR model significantly outperformed the linear regression model, with coefficients of determination ( R 2 ) greater than 0.95 in both the training and test sets. The variable importance score obtained from the RFR revealed that the initial IRI was the most important factor affecting the development of the IRI. In addition, the transverse cracking, fatigue cracking, rutting, annual average precipitation and service age had important influences on the IRI. Other distresses such as longitudinal cracking, edge cracking, aggregate polishing, and potholes exerted little impact on the evolution of the IRI.

The cast-in-place concrete base plate is a main member of the China Railway Track System (CRTS) III ballastless track structure that is prone to generating early transverse cracking. Such cracks can dramatically affect the performance and service life of the railway track structure. This study investigated the influence of temperature and moisture boundary conditions on early cracking behavior of the CRTS III base plate by using approaches of both in situ measurements and numerical modelling. In-site measurements of strain and temperature were made in four test series of CRTS III base plates under the same natural environmental condition but cured with different regimes, and a total of 96 measuring positions were monitored for up to 150 days. The results showed that the strain magnitude and distribution in the field base plate, the initial time at cracking, and the observed cracking pattern varied significantly between the different test series. In order to understand the mechanisms that create these transverse cracks and to provide guidelines for the current curing strategy during construction, the characteristics of temperature-induced and moisture-induced stresses were analyzed by using 3D numerical modelling and by considering early-age concrete creep properties, meteorological factors, and the influence from environmental boundary conditions. The calculated results revealed that early-age transverse cracking in CRTS III base plate depends more on drying shrinkage stress than temperature stress. By conducting this study, we expect to provide guidance for reducing or eliminating early cracks of CRTS III concrete base plate.

The 2016 Kaikoura earthquake resulted in shaking in excess of design level demands for buildings with periods of 1-2s at some locations in Wellington. This period range correlated to concrete moment frame buildings of 5-15 storeys, many of which had been built in Wellington since the early 1980s, and often with precast concrete floor units. The critical damage states used to assess buildings during the Wellington City Council Targeted Assessment Programme are described and examples of observed damage correlating to these damage states are presented. Varying degrees of beam hinging were observed, most of which are not expected to reduce the frame capacity significantly. Buildings exhibiting varying degrees of residual beam elongation were observed. Cases of significant beam elongation and associated support beam rotation resulted in damage to precast floor unit supports; in one case leading to loss of support for double-tee units. The deformation demands also resulted in damage to floor diaphragms, especially those with hollowcore floor units. Cracking in floor diaphragms was commonly concentrated in the corners of the building, but hollowcore damage was observed both at the corners and in other locations throughout several buildings. Transverse cracking of hollowcore floor units was identified as a particular concern. In some cases, transverse cracks occurred close to the support, as is consistent with previous research on hollowcore floor unit failure modes. However, transverse cracks were also observed further away from the support, which is more difficult to assess in terms of severity and residual capacity. Following the identification of typical damage, attention has shifted to assessment, repair, and retrofit strategies. Additional research may be required to determine the reduced capacity of cracked hollowcore floor units and verify commonly adopted repair and retrofit strategies.

International audience; Multi-cracking of brittle thin layers and coating is a phenomenon difficult to model especially because of the large number of cracks that may occur. It is overcome herein by conducting calculations, not on the whole structure, but only on a simplified cell that is representative of the structure by periodic duplication. The coupled criterion is applied within this representative cell (RC) and allows to predict the crack density under an increasing applied load, the length of the RC being a variable parameter of the model. Based on the simultaneous fulfilment of an energy and a stress conditions, it allows to take into account thin layers where the crack onset is energy driven and thicker layers where the stress condition governs the transverse cracking. Results are in a good agreement with various experiments found in the literature, conducted on cross-ply laminates and coated substrates.

Cracking has become a primary mode of distress in recent years that frequently drives the need for rehabilitation of asphalt pavements. Meanwhile, asphalt mix designs are becoming more and more complex with the increasing uses of recycled materials, recycling agents, binder additives/modifiers, and multiple warm mix asphalt technologies. Thus, there is an urgent need to identify reliable cracking tests that can be used for routine mix design to eliminate brittle mixes. This paper critically reviewed cracking mechanisms and laboratory tests. A total of 12 cracking tests were discussed at a cracking test workshop held as part of the National Cooperative Highway Research Program Project 9-57. Seven cracking tests were selected for further laboratory evaluation and field validation. Four of the simpler cracking tests from the seven were evaluated in this paper, these being the Texas Overlay Test (OT), Disk-shaped Compact Tension (DCT) test, Semi-Circular Bend test from the Louisiana Transportation Research Ce...

High quality predictive program provides an alternative to assess the long-term performance of asphalt pavements if well-evaluated based on field performance. The asphalt pavement performance models embedded in the Pavement ME Design program were developed based on hot mix asphalt (HMA) pavements, and the predictive quality varies depending on specific conditions. The applicability of the Pavement ME Design program as well as the embedded performance models to warm mix asphalt (WMA) pavements is even unclear. In addition, the ability of the Pavement ME Design program in differentiating HMA and WMA performance, if any, has not been evaluated. Therefore, the objectives of this study are to determine the predictive quality of the Pavement ME Design program for the field performance of WMA pavements, and further to evaluate the capability of Pavement ME Design program in detecting performance difference between HMA and WMA pavements if there is any. A total of 43 asphalt pavements (both HMA and WMA) from 16 projects were evaluated based on their field measured and predicted performance, in terms of rutting, transverse cracking and top-down longitudinal cracking. Results indicate that (1) The Pavement ME Design program can predict the field rut depth well for HMA and WMA pavements, in terms of both numerical values and rankings. However, the software in general over-estimates the field rut depth; (2) The Pavement ME Design program cannot predict field transverse cracking or field longitudinal cracking correctly irrespective of pavement type; (3) The results suggest that the effect of moisture should be considered in the Pavement ME cracking models for both HMA and WMA pavements, and (4) Overall, the predictive quality of the Pavement ME Design program for HMA and WMA is similar, either in good or poor prediction results. The WMA technology does not fundamentally alter the behavior of asphalt materials in pavement application. We suggest treating WMA similarly as HMA while applying the Pavement ME Design program for performance prediction. However, the corresponding WMA material properties should be used as input values.

Transverse cracking is probably the first and most dominant mode of damage in composite materials. In this paper, transverse cracking of cross-ply [02/90n]s (n = 2,3,4) laminates under uniaxial tension load was studied by means of experimental and numerical methods. In the numerical simulations, a simplified computational strategy only focusing on the damage of the resin was proposed and the mechanical response of the cracking cross-ply laminates was studied by finite element analysis of multi-scale representative volume elements (RVEs). In the RVEs, the longitudinal 0&deg, plies were represented by macro-scale, homogeneous, orthotropic elastic solids while the 90&deg, plies were modeled by the discrete fibers and the surrounding matrix resin in micro-scale. Based on researching the critical longitudinal mechanical strain &epsilon, x which initiates the cracks, the in-situ transverse ply strength and the stiffness degradation of the transverse plies, the simplified computational strategy proposed was proven correct. In addition, the crack initiation is sensitive to residual stress. Higher process-induced residual stress levels are dangerous to laminates, leading to early crack initiation.

© 2018 Elsevier Ltd Voids are an important type of manufacturing defects in fiber-reinforced composites. Matrix cracking is sensitive to the presence of voids. Although this cracking occurs at the ply scale, its dynamics is strongly affected by ply's microstructure, in particular, fiber distribution, fiber content, and the presence of voids. In the current study, a computational approach to simulate the influence of intra-laminar voids on cracking in composite laminates is developed. The approach combines finite element models of two scales: a micro-scale model, where the fibers and voids are modeled explicitly, and a meso-scale model, where the cracking phenomenon is captured on the ply scale. The micro-scale model, incorporating plasticity and damage in the matrix, provides input for the meso-scale model, which simulates the progressive cracking by means of the extended finite element method. The methodology is applied to investigate the effect of voids on the density of transverse cracks in cross-ply laminates in function of the quasi-static tensile load. Different sizes and contents of voids, which are chosen based on experimental micro-computed tomography data, are simulated. The numerical experiments show that the presence of voids leads to earlier start of the cracking, with the crack density evolution less sensitive to voids. ispartof: COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING vol:117 pages:180-192 status: published

The long-term performance of asphalt concrete (AC) overlays using mixtures containing reclaimed asphalt pavements (RAP) is compared with the performance of overlays using virgin mixtures. Data from 18 sites of the long-term pavement performance (LTPP) program are used for analysis. Each site consists of 8 side-by-side experimental sections that vary in overlay thickness and pre-overlay treatment method. The selected performance indicators include fatigue cracking, longitudinal cracking, transverse cracking, rutting, and roughness. Explorative data analysis, non-parametric survival analysis, and pair- t tests are used to compare possible performance differences. The analysis results suggest that there are interactive effects between the use of RAP-containing mixtures, overlay thickness, and pre-overlay treatment method. With relatively thin (51 mm) overlay and minimal pre-overlay treatment, undesirable performance of RAP-containing mixtures is expected. Conversely, with relatively thick (127 mm) overlay and intensive pre-overlay treatment, RAP-containing mixtures outperform virgin mixtures in rutting and roughness, without inducing additional cracking-related distresses. The field performance of RAP-containing mixtures is believed to be driven by their fundamental properties, i.e., the reduced cracking resistance and increased stiffness.

A method for assessing the susceptibility of a weld to transverse cracking is proposed based on a newly designed test specimen featuring a transverse gap in the centre to control restraint and produce a large residual stress in the weld metal. Through FEM simulation of the effects of the weld bead length on the longitudinal residual tensile stress (σx) after welding, it is confirmed that the transverse gap can significantly increase σx after welding. Furthermore, with a fixed transverse gap length, σx increases monotonically with the length of the weld bead. Two different commercial weld wires were used to check the effectiveness of this method; the experimental results obtained indicate that the critical cracking length of the weld bead differs depending on the weld wire used. The critical length of the weld bead can therefore be used as an effective index of its susceptibility to transverse cracking.

With the growing awareness of sustainable construction practices and because warm-mix asphalt (WMA) is environmentally friendly, WMA is gaining popularity for pavement construction in the United States. Currently, it is generally believed that rutting and moisture damage are two major concerns for WMA pavements, but because WMA requires less aging, its cracking resistance is expected to be improved. One of the primary cracking distresses of concern is transverse cracking, which could be thermal cracking in asphalt pavement or reflective cracking in asphalt overlay caused by underlying thermal cracking. Thus, transverse cracking is another primary distress. This study investigated the long-term field transverse cracking of 28 pavement projects, including WMA pavements and corresponding hot-mix asphalt (HMA) control pavements across the United States, covering different climate zones, WMA technologies, service years, pavement structures, and traffic volume levels. Two distress surveys were conducted at an interval of 2 years, and the material properties of the asphalt mixtures and binders were determined with field cores and extracted binders. The long-term field performance of the WMA and HMA pavements were compared for transverse cracking. The study found that HMA and WMA pavements exhibited comparable transverse cracking. Fracture work density obtained from indirect tensile testing at 14°F was found to be the significant determinant for transverse cracking. Significant mix design parameters were identified that can affect the resistance of mixtures to transverse cracking and that can be employed to guide the development of a well-performing mix design.

Asphalt pavements in colder climates encounter significantly shortened service lives because of excessive transverse cracking. This paper presents the results for 26 pavement sections in Minnesota that were studied to evaluate the effects of asphalt mix designs on pavement cracking performance. The field performance is presented with various cracking measures and compared with mix design aspects such as amount of asphalt binder, binder grade, and amount of recycling. The disk-shaped compact tension (DCT) fracture energies measured on the field cored samples are also compared with cracking performance. In this study, asphalt pavement sections from several locations were evaluated to encompass various types of asphalt mixtures and asphalt construction types that were commonly used in Minnesota. The amount of transverse cracking for each section was converted into a newly proposed cracking performance measure that accounted for the amount, rate, and timing of cracking. The comparisons between asphalt mixture attributes and cracking performance measures showed that the amounts of total asphalt binder and recycled asphalt binder may not be sufficient. Performance testing, in addition to currently used controls (mix volumetrics and constituent properties), is recommended to ensure good cracking performance. The DCT fracture energy results for companion sections show that mixtures with higher fracture energies exhibit lower amounts of transverse cracking.

The present study evaluated the long-term effectiveness of preventive maintenance treatments (PMTs) on pavement performance using the data collected in the Specific Pavement Studies-3 (SPS-3) of the Long-Term Pavement Performance (LTPP) program. The PMTs included thin overlay, slurry seal, crack seal and chip seal. Pavement performances included roughness, rutting, transverse cracking, longitudinal cracking and alligator cracking. A new framework was established in this study to evaluate pre-treatment pavement condition. Weighted distress was adopted to describe average long-term performance and a new indicator was proposed to characterize average long-term effectiveness increment. Scatterplot analysis, cumulative frequency distribution, average long-term effectiveness increment and pair-samples t-test were conducted to investigate the long-term effectiveness. Results indicate that the results from the four analysis methods are similar, so the proposed new indicator is capable of evaluating the long-term effectiveness of PMTs. Meanwhile, thin overlay and crack seal are the best and worst PMTs on each performance, respectively. In addition, there may be a critical original pavement condition in terms of the long-term effectiveness of PMTs on each performance respectively. The findings in this study may supply guidelines for the implementation of preventive maintenance decision-making.

The widely-utilized multispan simply-supported adjacent (side-by-side) box girder bridges often suffer from problems of deterioration attributable to transverse cracking in link slabs betwe...

A freely vibrating test stand for experiments with carbon fibre reinforced (CFRP) cross-ply specimens loaded in pure bending, is presented and used for fatigue testing. The developed test stand does not generate out-of-plane shear forces within the specimens, thus minimises specimen heating and enables testing at high frequencies above 100 Hz.

Rehabilitation of existing jointed plain concrete pavements (JPCP) by using unbonded concrete overlay (UBCO) is increasingly being used all over the world. The design and performance of un-bonded overlays is affected by various factors including climate, traffic volume, concrete material properties, existing pavement condition and future design life. Modulus of rupture (MOR)/flexural strength of concrete is an important material property that has significant impact on the performance of concrete pavements. A true estimation of modulus of rupture would improve the accuracy of cracking prediction. This study examines the impact of variability of flexural strength of concrete on the mechanistic-empirical performance predictions of UBCOs. Simulations were conducted using pavement ME design software with varying flexural strength values and keeping all other design variables as constant. The results indicated that MOR has a significant impact on overlay performance. With decrease in concrete’s MOR, the performance of UBCOs is adversely affected with increased transverse cracking. The adverse effects of lower flexural strength can be compensated by increasing the thickness of overlay concrete slab or by decreasing the transverse joint spacing.

Quasi-static damage in multidirectional polymer composite (PMC) laminates developing during manufacturing and quasi-static loading degrades the modulus and strength. A model to predict simultaneous evolution of quasi-static transverse cracking in multiple plies and its effect on modulus of multidirectional PMCs is presented. A 3-D variational analysis formulating the in-plane and out-of-plane stresses of the plies in occurrence of multiple cracking has been developed to work within a lamination theory-based model framework. The stress state in the plies is determined using the lamination theory during an incremental change in loading. The strain energy, determined using this stress state, is compared to strain energy-based failure criteria to determine if a ply cracks after the increment. If crack is predicted, crack density of the ply is updated and the variational analysis is used to determine the perturbation in ply stresses due to cracking. The new stress state is used to determine the laminate modulus after cracking and the ply stresses for the next increment. This procedure is repeated to determine the crack evolution and modulus until reaching the desired load. Model predictions compare very well with experimental results for a [± θ m /90 n ] s laminate at two elevated test temperatures of 80 °C and 180 °C.

A model to predict time-dependent evolution of simultaneous transverse cracking developed in multiple plies during creep loading and its effects on creep of multidirectional polymer matrix composite laminates is presented. The stress states in the intact regions of the plies are determined using the lamination theory during an incremental change in time. The stored elastic energy, determined using this stress state, is compared with a critical stored elastic energy value for damage to determine if a ply would fracture after the increment. If fracture is predicted, variational analysis is used to determine the perturbation in ply stresses due to cracking. This procedure is repeated to determine the crack evolution and creep strain. Model predictions compared well with experimental results for a [±θm/90n]s laminate.

The first damage mode in cross-ply laminates under tension is broadly accepted as transverse cracks normal to the loading direction in the 90° layers, but there is not the same agreement about the second damage mode. While most of the analytical and experimental results are based on delamination induced by transverse cracking, another type of damage, oblique cracks within the 90° layers, has also been observed as the second damage mode in [0/904]s laminates. To understand the cause of this phenomenon, FE analyses considering damage development at the interfaces were performed. The obtained results indicate that the main reason for the oblique cracking damage mode is the higher toughness of the material in mode-II compared with mode-I: when the value of shear toughness is close to the opening toughness, the second damage mode in cross-ply laminates under tensile loading is delamination induced by transverse cracks, however, if the difference between the two values is large, oblique cracks in the 90° layers are likely to appear. In the specific tested and analysed laminate, if the mode II toughness is double the mode I toughness, oblique cracking occurs but if the values of mode I and mode II toughness are close, delamination is the second damage mode.

This chapter discusses the most common forms of failure in asphalt mixtures, i.e., rutting, fatigue cracking, transverse cracking, moisture-induced damage, bleeding or flushing, and the influence of aging on these distresses. The chapter discusses the mechanism of failure for each one of these distresses. Two different approaches to measure the resistance of mixtures to any of these distresses are discussed: (i) the measurement of empirical performance indicators, and (ii) the measurement of fundamental material properties that can be combined with numerical models to measure the performance of the mixture. Examples based on each of the above two approaches for each distress type (rutting, fatigue cracking, low-temperature cracking, and moisture damage) are discussed. These discussions also provide a context for the mechanistic tools that are discussed in Part 2 of this book.

A model to predict off-axis crack evolution in multidirectional laminates subjected to multiaxial loading is proposed. The model applies multi-scale stress and local fracture mechanics analyses to distinguish between two microscopic damage mechanisms, which govern the damage evolution, as well as determining the magnitude of the damage evolution rate associated with each microscopic damage mechanism. The multi-scale analysis is based on the GLOB-LOC off-axis crack damage model, which is extended to include substantial new capabilities such as the influence of crack face sliding interaction and prediction of variations in the stress field due to the local crack density. The extension of the GLOB-LOC model introduces physically based multiaxial fatigue criteria for off-axis crack initiation and mixed-mode off-axis crack propagation. The extended GLOB-LOC model is implemented and it is demonstrated that good predictions are obtained for the damage evolution under various multiaxial stress conditions. Furthermore it is shown that the model only requires input from two different multiaxial stress states to obtain the material parameters for a given FRP ply.

Man-made composites, like reinforced and fiber-reinforced concrete elements, behave similarly to natural composite structures (e.g., brittle rocks lying on a ductile substratum). In both cases, the cracking phenomenon of brittle layers depends on the scale of observation and is ruled by the Golden Ratio. Thus, a unique size-effect relationship, herein called Golden Scaling Law (GSL), is introduced and used to predict the crack pattern of concrete and rock structures. In accordance with several experimental data, GSL permits to calculate the values of crack width and crack spacing when the geometry of crack patter is known at a lower scale. Moreover, GSL can be applied to large composite structures without knowing the material performances, but by testing prototypes of lower dimensions.

Journal article A unique insight into damage formation in CF/PEEK laminates before, during and after cryogenic cycling, using optical microscopy and 3D X-ray computed tomography (CT), is presented. Thicker laminates were found to exhibit significantly greater microcrack density and delamination when compared to thinner laminates, with lay-up and material type also being important contributing factors. Thermal residual stress induced microcracking was also found in thicker laminates post-processing. 3D rendering software was used to prove the presence of through thickness crack networks within the laminates, as well as the extent of cracking through the specimen width. Crack opening in inner and off-axis ply groups was found to be significantly less than outer plies, implying the importance of these plies in limiting laminate permeability. The presence of voids was found to influence crack nucleation and growth paths within the laminates, with full void volume characterisation presented. (C) 2014 Elsevier Ltd. All rights reserved. European Space Agency Network Partnering Initiative; Irish Research Council Enterprise Partnership Scheme peer-reviewed

The Nevada Department of Transportation has long used CMS-2S emulsion for cold in-place recycling (CIR) projects and has recently introduced solvent-free (Reflex) emulsion and polymerized asphalt surface sealer (PASS) emulsion. An observed difference in CIR performance with changing emulsion technology prompted the assessment of long-term performance of CIR pavements throughout Nevada. The evaluated CIR projects were divided on the basis of rehabilitation type and then subdivided on the basis of emulsion technology. The study revealed that CIR followed by a hot-mix asphalt (HMA) overlay and a surface treatment performed much better on high-volume roads than did CIR with surface treatment on low-volume roads. Transverse and longitudinal cracking were the major types of distresses in CIR pavements. Approximately 50% of pavements constructed with HMA overlay and surface treatment and 95% of pavements constructed with only surface treatment experienced transverse cracking during service life. About 30% of pavements constructed with HMA overlay and surface treatment and 70% of pavements constructed with only surface treatment experienced longitudinal cracking. The CIR technology with HMA overlay and surface treatment significantly improved rutting resistance and pavement roughness. Climatic condition, CIR layer thickness, and surface treatment types were found not to affect performance of roads with CIR. The CMS-2S projects constructed with surface treatment and 1.5- to 2.5-in. HMA overlay were predicted to reach a pavement condition index value of 60 for rehabilitation in 15 years. The CMS-2S projects constructed with 3 to 4 in. of HMA overlay performed excellently up to 9 years and were expected to last more than 20 years before rehabilitation. The CIR with CMS-2S and PASS emulsions constructed with surface treatment were predicted to reach the index value of 60 after 15 and 19 years, respectively. However, Reflex emulsion was predicted to need rehabilitation after only 6 years.

International audience; The results of stress field distribution in damage cross-ply laminates prompt us to elaborate an energy criterion. This criterion is based on the partial parts’s computation of the strain energy release rate associated with each damage type and for all loading modes. In the related criterion, based on the linear fracture approach, several hypotheses are used to simplify the damage criterion. The main objective with this approach is to estimate the onset of transverse and longitudinal cracking mechanisms and the development of the damage. Only results from numerical simulations are proposed for one material; numerous numerical simulations, with other materials and laminate architectures, give similar evolutions of matrix cracking damage.

Cracking in single-span concrete bridge decks was investigated. An assessment of the cracking as it relates to in situ concrete strength was performed. In cracked decks, concrete was of uniform quality and the compressive strength obtained from cores was in excess of the design strength. Evaluation of cores using an optical technique revealed that the cracks in the bridge decks formed at an early age, when the strength of the cementitious matrix is less than the strength of the coarse aggregate. Tests on mature concrete obtained from bridge decks indicate that the cementitious matrix is stronger than the coarse aggregate, resulting in aggregate fracture under tensile loading. Findings indicate that transverse cracking in the midspan portion of bridges with elastomeric bearings and longitudinal cracking at the supports in bridges with integral abutments result from restraint of early-age thermal movement of the bridge deck. The available evidence suggests that cracking in the bridge decks occurs in...

When subjected to in-plane loading, carbon-fiber laminates experience diffuse damage and transverse cracking, two major mechanisms of degradation. Here, we investigate the effect of pre-existing diffuse damage on the evolution of transverse cracking. We shear-loaded carbon fiber-epoxy pre-preg samples at various load levels to generate controlled configurations of diffuse damage. We then transversely loaded these samples while monitoring the multiplication of cracking by X-ray radiography. We found that diffuse damage has a great effect on the transverse cracking process. We derived a modified effective transverse cracking toughness measure, which enabled a better definition of coupled transverse cracking/diffuse damage in advanced computational models for damage prediction.

The negative binomial (NB) and zero-inflated negative binomial (ZINB) models were employed to simulate the development of pavement transverse cracks on asphalt overlays and to evaluate the influence of different designs of asphalt overlays on crack development. Pavement transverse crack data were collected from 15 long-term pavement performance (LTPP) SPS-5 test sites. Analyzed factors include traffic level, overlay thickness, mixture [using reclaimed asphalt pavement (RAP) or virgin], intensity of surface preparation (mill or no mill) before overlay, total thickness of pavement, and freeze index. Analysis results indicate that the NB and ZINB models were effective in simulating the development of pavement transverse cracks by addressing the overdispersion. In addition, the ZINB model outperformed the NB model by explaining the excess zeros in the cracking count data to capture both the initiation and propagation of cracking. The regression analysis indicates that mill before overlay is effective in retarding the initiation of cracks, but not the propagation of cracks. Thicker overlay appears to reduce transverse cracking. High traffic level or using RAP is likely to increase the number of transverse cracks. Total thickness of pavement and freeze index are not significant for the development of transverse cracks.

Concrete service life models have proliferated in recent years due to increased interest in designing infrastructure elements with at least a 75-year service life, along with greater emphasis on life-cycle costing. While existing models consider a variety of concrete material and environmental factors, at varying levels of complexity, in predicting the time until the onset of chloride-induced corrosion of the steel reinforcement, the influence of cracking is generally beyond their current scope. This paper presents a preliminary strategy for examining the influence of transverse cracking on chloride ion penetration into concrete that includes a graphical approach for adjusting the predicted service life provided by current models to reflect this influence. Comparison to experimental data for saturated concretes indicates that the contributions of binding of the chloride ions by the cement paste play a significant role in slowing the ingress of chlorides and should be accounted for in any modeling efforts.

In addition to manufacturing cost and production rates, damage resistance has become a\ud major issue for the composites industry. Three-dimensional (3D) woven composites have superior\ud through-thickness properties compared to two-dimensional (2D) laminates, for example, improved\ud impact damage resistance, high interlaminar fracture toughness and reduced notch sensitivity.\ud The performance of 3D woven preforms is dependent on the fabric architecture, which is determined\ud by the binding pattern. For this study, angle interlock (AI) structures with through-thickness binding\ud were manufactured. The AI cracking simulation shows that the transverse component is the one that\ud leads to transverse matrix cracking in the weft yarn under tensile loading. Monitoring of acoustic\ud emission (AE) during mechanical loading is an effective tool in the study of damage processes in glass\ud fiber-reinforced composites. Tests were performed with piezoelectric sensors bonded on a tensile\ud specimen acting as passive receivers of AE signals. An experimental data has been generated which\ud was useful to validate the multi-physics finite element method (MP-FEM), providing insight into the\ud damage behaviour of novel 3D AI glass fibre composites. MP-FEM and experimental data showed\ud that transverse crack generated a predominant flexural mode A0 and also a less energetic extensional\ud mode S0

The Mechanistic-Empirical approach in rigid pavements design, allows to achieving the superstructure damage by calculating incremental degradation. This study has examined two different pavements typologies: JPCP (Jointed Plain Concrete Pavements) and CRC (Continuously Reinforced Concrete Pavements). Referring to the AASHTO Design Guide the superstructure performances are evaluated in terms of Joint Faulting and Transverse Cracking for JPCP, Punchouts for CRCP, and IRI (International Roughness Index) for both pavements typologies. The performances have been determined using ME-PDG software that is able to evaluate, for JPCP design, the structural fatigue distresses related to Transverse Cracking of PCC slabs and differential deflection related Transverse Joint Faulting. For CRCP, the principal structural distress considered is edge Punchouts. The authors propose the comparison between the different typologies of pavements with the objective of identifying the design solutions more effective with equal materials performance and traffic conditions. These comparisons were carried out by varying the soil class, the climatic conditions and the type of cement concrete. The numerous analyzes performed have enabled to evaluate the influence of different design parameters and then to define useful suggestions that can be used by rigid pavement designers to reduce the occurrence of premature cracking, so as to increase the service life of pavement system.

Corner cracking in medium C electric arc steel was experienced after continuous casting of square billets. This led to the investigation of the influence of high N levels on hot ductility. Steels microalloyed with V, Ti and B were subjected to in situ melting followed by cooling according to typical off-corner temperature profiles. Steels containing moderate amounts of V resulted in good ductility at the estimated off-corner temperature during unbending of 900°C due to the suppression of precipitation. Ti additions to V, Al, Si and B containing steels, although beneficial at low N levels, are detrimental to hot ductility when the N content is high due to a higher precipitate volume fraction. High Ti–B steels produced the worst hot ductility in medium C steels containing high N.

It is well known that age-hardening is a major deteriorating factor for cracking in the asphalt pavement, while healing may play a beneficial role in enhancing pavement fatigue life, though healing potential of hot mix asphalt (HMA) mixture may decrease with ageing. However, there is limited direct evidence and understanding of the combined effects of these two factors on cracking performance, particularly in full-scale pavements. In this article, the effects of ageing and healing on top-down cracking performance were evaluated on the basis of three full-scale tests conducted in the Florida Department of Transportation's accelerated pavement testing (APT) facility using the heavy vehicle simulator (HVS). The test results showed that ageing and potential healing appeared to have played key roles in the cracking performance of the asphalt pavement in the APT facility. When the pavement was subjected to slight-to-moderate ageing, it may be able to maintain a relatively high level of healing which helped to e...

A variety of heating and cooling programmes have been examined for plain C–Mn and high strength low alloy steels to examine their suitability in a hot tensile test for assessing the likelihood of transverse cracking occurring in the straightening operation. A tensile test temperature of 800°C was chosen for comparison, this being the temperature that generally results in poor ductility. For steels with 1·4–1·75%Mn, the simple procedure of heating to ∼1300°C to take all the microalloying additions into solution, followed by cooling to the test temperature, was found to be the easiest and most suitable. For high strength low alloy steels containing Ti and low Mn, high S steels, melting is required. For these steels, it is also advisable to have both primary rapid cooling followed by a slower secondary cooling stage, simulating more accurately the actual industrial operation. The addition of thermal oscillations to simulate slab roll contact makes the cycle even closer to the commercial process and g...

This research evaluates the reasonableness of the Mechanistic-Empirical Pavement Design Guide (MEPDG) version 1.0 to predict the joint faulting and transverse cracking of jointed plain concrete pavements (JPCPs). This is accomplished by carrying out a full factorial sensitivity analysis, considering material properties, pavement design features, climates and traffic. This study considers the interaction and correlation between these inputs and was designed to reflect the real conditions that occur in practice. Based on over 3000 runs, the sensitive parameters in the joint faulting model and the transverse cracking model were identified. In general, the analysis indicates JPCP models perform well. However, some counterintuitive results were also found.

Acoustic emission with near-field detection and optical video microscope monitoring was proposed to investigate the pitting corrosion caused by a small magnesium-chloride droplet. Four types of the detected waveforms were characterized by the wavelet analysis to investigate the corrosion of work-hardened SUS304 stainless steel. After high-activity AE signals observed, the corrosion product sheet grew with or without low-activity AE signals. With the cross-section observations, the detected AE signals were mainly attributed to longitudinal and transverse cracking around the covered pitting, cracking of the oxidation products, and the early stage of corrosion potential fluctuation. [doi:10.2320/matertrans.M2011399]

Restraint of volume change in concrete accompanies the development of stress in concrete structures. When concrete is placed in the field, the stress development becomes very complicated at early ages due to the hydration and environmental interaction. This study investigates quantitatively the effects of various factors on the stress variation of early-age concrete decks in composite bridges under environmental loading. The test members were made to exhibit the early-age behavior of a composite bridge. The effects of parameters related to thermal and drying shrinkage stress were analyzed through a numerical model and compared with measured data. The risk of transverse cracking in early-age concrete decks was evaluated in the numerical parametric study. The present study provides better understanding of the behavior of early-age composite bridge under environmental loading, which can be efficiently utilized to reduce the risk of cracking at early ages.

The Minnesota Department of Transportation (DOT) adopted the use of performance-graded (PG) asphalt binders in 1997. In 1999 the Minnesota DOT required PG XX-34 binders for all new (not overlay) bituminous construction with the objective of reducing the amount of transverse cracking. Pavement management data were used to track the development of transverse cracking on PG XX-34 projects. The transverse cracking rate of the PG XX-34 projects was then compared with the cracking rates for similar projects from the pre-PG era. The comparison found that after 7 years of service, transverse cracks on the PG projects were developing at approximately 1/10th the rate experienced before performance grading was implemented.

The Specific Pavement Studies Experiment 5 (SPS-5) in the Long-Term Pavement Performance program was designed to study the effects of overlay rehabilitation type on typical distress measures. The rehabilitation treatments compared overlay thickness, overlay type, and surface preparation before rehabilitation. The thicknesses used were 50- and 125-mm overlays. The overlay types were virgin asphalt mix and recycled asphalt that contained approximately 30% reclaimed asphalt pavement (RAP). Surface preparation consisted of either milling or not milling the existing pavement before rehabilitation. Eighteen states and provinces in North America built SPS-5 projects between 1989 and 1998. Seven distress parameters from these test pavements were analyzed, including international roughness index (IRI), rutting, fatigue cracking, longitudinal cracking, transverse cracking, block cracking, and raveling. Analyses were conducted to determine which factors affected overlay performance as measured with the above parameters. Further statistical testing compared the performance of the virgin mix sections directly with equivalent sections that contained 30% RAP. Overlays with mixes that contained 30% RAP were found to perform as well as overlays with virgin mixes in terms of IRI, rutting, block cracking, and raveling. Thicker overlays improved pavement performance, except for rutting. Milling before rehabilitation decreased IRI, fatigue cracking, and transverse cracking but increased rutting.

With the advancement in rigid pavement design and advent of AASHTOWare Pavement Mechanistic-Empirical (ME) Design (American Association of State Highway and Transportation Officials, Washington, DC) as the latest design tool, increasing emphasis is being laid on the coefficient of thermal expansion (CTE) of concrete. The CTE affects the performance of rigid pavements in a significant manner, with a higher CTE corresponding to greater curling and resulting in greater pavement distresses. Prior research has conflicting views regarding CTE variation with age, and there has been very little to no research on the effects of CTE on the performance of unbonded concrete overlays (UBCOs). This study is performed to investigate the variation of CTE with concrete age through laboratory testing and further quantify the effects of CTE variation on UBCO design. To facilitate, four concrete paving mixes with different types of coarse aggregates and different mix properties from different districts of New Mexico were collected. The cast specimens from each of the mixes were tested for CTE as per the AASHTO T-336, Coefficient of Thermal Expansion of Hydraulic Cement Concrete, protocol, at the ages of 7, 14, 28, 60, 90, 120, and 180 days, respectively. The test results were analyzed, and it was observed that there is an increase in CTE over the range of 3.49 % to 9.77 %, between 28 days and 180 days. Further analysis was conducted with simulations in Pavement ME Design Version 2.3® that indicated a significantly deteriorated performance of the UBCO with increased CTE. The impact on transverse cracking and joint faulting is the most significant, with up to 13.3 % increase in cracking and up to 19.7 % increase in faulting distress. An unbonded overlay designed with 28 days CTE value may not perform for the design life because of the increase in CTE with age progression.

The matrix cracking transverse to loading direction is usually one of the most common observations of damages in composite laminates. The initiation and propagation of transverse cracks have been a longstanding issue in the last few decades. In this paper, a three-dimensional stress analysis method based on the state space approach is used to compute the stresses, including the inter-laminar stresses near transverse cracks in laminated composites. The stress field is then used to estimate the energy release rate, from which the initiation and propagation of transverse cracking are predicted. The proposed method is illustrated by numerical solutions and is validated by available experimental results. To the best knowledge of the authors, the predictions of crack behaviour for non-symmetrical laminates and laminates subject to in-plane shearing are presented for the first time in the literature.