Pavement Slab Research Articles

Development of effective fiber-reinforced concrete compositions used in transportation structures

The possibility of producing fiber-reinforced concrete with high deformation properties by regulating the microstructure and using it in the design of transport structures was considered. It was found that to create high-performance transport structures, it is necessary to modify fiber mixtures with complex additives, i. e. increase the strength of fiber-reinforced concrete at the micro-level. To obtain a denser structure of the concrete matrix, complex additives were used – ultrafine additive (silica fume) and Master Air 200 B air-entraining additive. It was experimentally proved that using such additives reduces the water-cement ratio and further strengthens the concrete matrix structure. The design of the unloading structure on the railway line constructed from the Karadag station (Republic of Azerbaijan) to the SOCAR oil and gas processing and petrochemical complex using fiber-reinforced concrete modified with complex additives was made. The results of designing the fiber-reinforced concrete unloading structure were analyzed and the results of designing the fiber-reinforced concrete unloading structure and the regular concrete unloading structure were compared. As a result of the comparison, it was found that using fiber-reinforced concrete decreases the cross-section diameter of the effective reinforcement of the slab – the cross-section diameter of the effective reinforcement of the pavement slab decreases from Æ2×32 mm to Æ32 mm in the upper and Æ25 mm in the lower row, respectively. Crack resistance is also increased compared to regular concrete. Thus, in order to create structures with high transport and operational parameters, it is necessary to modify fiber-reinforced concrete mixtures with complex additives

Valorization of Plastic Waste in Ghana

Wastes from plastics are ubiquitous and have become a critical global challenge, especially in Africa. There is an urgent call to combat the menace because of its harmful impact on the ecosystem. The research methodology used is the exploratory technique. Circular economy (CE) is the answer to this global problem, especially in advanced countries. Even though some African countries have commenced recycling waste plastics, which is a contribution to circular economy, the idea is now gaining support in Ghana. The aim of this study is to propose a strategy and design a customized business model canvas for an establishment that transforms different types of waste plastics into pavement slabs and paving tiles in Ghana. The rationale is to accentuate the significance of introducing CE as a tool for effective and efficient plastic waste management in the country.

ANALYSIS OF THE EFFECT OF SLAB THICKNESS ON CRACK WIDTH IN RIGID PAVEMENT SLABS

Cracks that occur in rigid pavements include longitudinal cracks, transverse cracks, and corner cracks. The relatively large crack width not only spoils the aesthetics of the concrete structural elements but can also lead to structural failure. This study aims to determine the crack width of a rigid pavement concrete slab located above the subgrade which is considered a beam on an elastic foundation, so that a minimum rigid pavement concrete slab thickness can be recommended. The specimen will be observed at various thicknesses to obtain the optimum thickness. The load used is a centralized monotonous load, which represents the load of the truck vehicle. The research limitation is using a test object in the form of a concrete plate measuring 2000x600 mm which is placed on the ground with CBR=6 %. The quality of reinforced concrete slabs is fc'=40 MPa and fy=440.31 MPa. The thickness of the concrete slab varies between 100 mm, 150 mm, and 200 mm. The slab placed on the ground is then given a central loading in the form of a centralized monotonic load. The loading range starts from a load of 2–180 kN with a load interval of 2 kN. The experimental results show that the rigid pavement slab has a bending failure so that the crack pattern that occurs begins with the first crack on the underside of the slab. The crack pattern in terms of slab thickness variation has a similar pattern. The initial crack width on the slab is 0.04 mm. The thicker the slab smaller the crack width at the same load. Based on the maximum allowable crack width=0.3 mm. For loads between (80–100) kN (Road Class I, II, and III), a minimum thickness of rigid pavement slabs (70–80) mm is recommended. For loads between (130–140) kN, the minimum thickness of the rigid pavement slab (105–115) mm is recommended

Influence of effective texture depth on pavement friction based on 3D texture area

Pavement texture significantly affects the anti-skid performance. This study applied 3D laser technology to measure the texture of asphalt pavement surfaces with an objective to explain the variation in the friction measured using a portable pendulum tester. Pavement slab samples were prepared for six different types of asphalt mixtures (SMA-Top5, AC-10, AC-13, AC-16, SMA-13, and OGFC-13). High-precision surface texture data of the samples were then collected using a portable laser scanner (LS-40), and the friction values (BPN) were measured. The 3D image reconstruction and segmentation of the pavement texture were realized through a digital image processing technology, and the texture surface area at different depths was calculated. Finally, we performed a correlation analysis between the texture surface area at different depths and the pavement friction values. The results showed that the pavement anti-skid value and the texture surface area have a significant positive correlation in the texture depth range of 0.5–2 mm, with the lowest determination coefficient value of 0.6836. Our research confirms that the effective texture depth influencing pavement friction is 2 mm and that the texture surface area can be used as an indicator of pavement friction during its service life.

Mitigation of thermal curling of concrete slab using phase change material: A feasibility study

In this study, the effects of phase change material (PCM) on the thermo-mechanical behaviors of concrete pavement slabs are investigated so as to test the feasibility of utilizing PCM for mitigation of thermal curling of pavement. The PCM is elaborately stabilized in porous lightweight aggregate then loaded into concrete, without compromising strength associated with PCM incorporation. Thermal analysis indicates that the PCM introduces a latent heat capacity of about 21 J/g to the pavement slab. Two emerging fiber-optic monitoring techniques, i.e., truly distributed strain/temperature sensors and a high-resolution inclinometer, are employed to continuously monitor distributions of the temperature, strain, and tilting angle of the slabs subjected to heating and cooling, respectively. Validated by the obtained experimental results, a finite element simulation framework is established to further investigate the temperature gradient distributions, slab deformations/curvatures, and thermal strain and stress inside the slabs. The results suggest that the PCM-incorporated slab has a higher top surface temperature, a larger top-vs-bottom surface temperature difference, and thereof a larger curvature. However, the temeprature gradient reveals that heat accumulates at the upper layer before PCM melts completely, thus accounting for most of the temerpature difference. Moreover, regardless of the larger top-vs-bottom strain difference and stress nonlinearity, the linear strain of the PCM slab is smaller due to its lower coefficient of thermal expansion, and the later stage stress at the middle of the PCM slab center is smaller. Based on the findings, strategies of using PCM to control thermal curling of pavement slabs are proposed.

A laboratory prototype of automatic pavement crack sealing based on a modified 3D printer

ABSTRACT Cracking is a common fault in asphalt and concrete pavements, which causes water damage and further defects if not repaired in timely fashion. Conventional pavement crack sealing methods based on machines and manual operations are generally subjective, labour-intensive, risky, and inefficient. A laboratory prototype of an automatic pavement crack sealing platform is proposed in this paper, which uses a modified three-dimensional (3D) printer and computer vision. A modified 3D printer based on fused deposition modelling (FDM) was combined with an image capturing platform, an image processing algorithm and a path planning method to form the automated pavement crack sealing platform, which can automatically detect pavement cracks and seal them with bitumen emulsion sealant. Specimens of concrete pavement slabs with cracks were produced in the laboratory to test the proposed method, and the cracks were then detected and sealed by the proposed platform. The results show that 3D printing is an effective method for automated pavement crack sealing, which is recommended in the field of automatic road maintenance and repair.

Evaluation of the Safety of Flexible Pavement using Skid Resistance Measurements.(Dept.C)

Skid resistance is one of the important parameters used in asphalt pavement characterization. Also, recently with wide extension in roads network over the world and high vehicles speed which lead to high record in accident rates. One of the accident causes is inadequate skid resistance. Various factors affect the skid resistance; some of these are material properties, vehicle speed, surface condition, pavement age, climate and contaminant type. Therefore, this study represents the effect of various contaminants on the skid resistance of asphalt pavement mixes. Two types of asphalt mixes were used; the first was fresh mix, while the second was reclaimed asphalt pavement (RAP) mix. The selected contaminants were water, lube oil and sand. Laboratory tests were performed for hot mix asphalt during (140 days for fresh and 75 days for Rap) and temperature variation range of (10-33)0C. British Pendulum (BP) Tester was used to identify the skid resistance values. The test was carried out of leveled flexible pavement slabs for both fresh and reclaimed mixes. Two sections for every slab were tested for both control and contaminated slab. The results indicated that British Pendulum Number (BPN) values changed by the change of contaminant type. Also, it was observed that the lowest values of BPN were investigated using lube oil compared to water and sand. Finally, Significant changes have been occurred in BPN values by the variation in mix type.

Effect of metakaolin-based geopolymer concrete on the length of rigid pavement slabs

Rigid pavement is one of the pavement methods used specially in high traffic zones. Up till now, Portland cement concrete (PCC) is the most commonly used material for rigid pavement. One of the problems that faces PCC is the allowable spacing for transverse joints in rigid pavements’ plain concrete slabs. As recommended by different standards and design manuals, the recommended length of slabs is about 4.5–5 m (In PCA, Thickness Design for Concrete Highway and Street Pavements. Engineering Bulletin EB109P. Skokie, IL, (1984); In ECP, Egyptian code of practice for urban and rural roads part 4: road material and its tests. Housing and Building National Research Center, Egypt, (2018); In FDOT, Rigid Pavement Design Manual. Pavement Management Office, Document No. 625-010-006-e, Tallahassee, Florida, (2009)), this is referred to the thermal volumetric changes in PCC. The low allowable transverse joints spacing in rigid pavement reduces the implementation rates and increases the cost. Geopolymer concrete (GPC) is one of the innovative types of concrete that is eco-friendly than gain early strength in ambient temperature and can gain higher strength by heating. In this research, GPC was investigated to determine its drying shrinkage and thermal expansion behavior and therefore affect the length of concrete slabs in rigid pavement. This different type of concrete showed an acceptable performance against drying shrinkage and thermal expansion more than PCC.

Incorporating super-fine stainless wires to control thermal cracking of concrete structures caused by heat of hydration

Super-fine stainless wires (SSWs) with micron diameter can form a widely distributed heat conduction network in reactive powder concrete (RPC) at low volume fraction, thus endowing RPC with high thermal conductivity and low specific heat. This shows great potential to reduce the thermal cracking risk of RPC structures caused by heat of hydration. Therefore, both experiments and finite element simulations were performed to investigate the effects of adding SSWs on the thermal and stress fields inside RPC specimens and structures, and then the thermal cracking risk of specimens and structures fabricated with SSW reinforced RPC were evaluated. The results show that incorporating only 0.5 vol% SSWs can effectively decrease the temperature rise in the center position and the temperature gradient between the core and surface positions inside RPC specimens and structures due to heat of hydration. When the content of SSWs is 1.5 vol%, the temperature gradients for pavement slab (with a size of 4.5 m × 5 m × 0.4 m) and pier cap (with a size of 3 m × 2 m × 1 m) are dropped by 6.9 ℃ and 10.7 ℃, and the maximum thermal stresses are reduced by 0.90 MPa and 1.43 MPa, respectively. As a result, the specimens and structures fabricated with SSW reinforced RPC have little or no thermal cracks at early ages. Therefore, adding SSWs into RPC is an effective way to inhibit the thermal cracking of structures caused by heat of hydration through improving temperature uniformity, reducing temperature gradient and decreasing thermal stress.

Determination of Stresses and Displacements in Rigid Pavement Slabs, Through Finite Element Analysis

Determination of Stresses and Displacements in Rigid Pavement Slabs, Through Finite Element Analysis

Convolutional neural network for automated classification of jointed plain concrete pavement conditions

AbstractThe detailed monitoring of jointed plain concrete pavement (JPCP) slab condition is essential for cost‐effective JPCP maintenance and rehabilitation. However, existing visual inspection practices for detailed slab condition classification are time‐consuming and labor‐intensive. In this paper, we proposed an automated JPCP slab condition classification model based on convolutional neural networks (ConvNets), which is the first to perform multi‐label classification on the JPCP slab condition based on both crack types and severity levels. To handle the different scales between JPCP slab condition states, the model includes a novel global context block with atrous spatial pyramid pooling, denoted as a GC‐ASPP block. The block can be flexibly applied to any ConvNets to effectively model the global context of images with the extraction of multiscale image features. The proposed model was evaluated using real‐world 3D JPCP surface data. With the GC‐ASPP block, our best model achieved an average precision of 85.42% on multi‐label slab condition classification.

A novel distributed sensing method for support condition monitoring under concrete pavement

ABSTRACT Accurate monitoring of concrete pavement support condition is critical for pavement maintenance. This paper proposed a novel support condition monitoring method using distributed optical fiber sensing (DOFS) technology. The DOFS-based method can precisely monitor the support condition on a larger scale. Single-mode optical fiber with a particular rubber encapsulation was applied as a compression sensor, measuring the interfacial compression status between the concrete pavement slab and the pavement base through a compression-to-strain transfer mechanism. Finite element analysis (FEA) and laboratory experiments were conducted to compression-to-strain transfer mechanism. It was revealed that the average compression-to-strain transfer efficiency reached over 1900 μϵ/mm. The design parameters of the compression sensor were also provided based on the FEA and experiment results. A quasi-distributed sensing system was developed to capture the two-dimensional support condition by connecting the sensors in a particular path. The sensing system's effectiveness was demonstrated by conducting full-scale tests and using the pressure-sensitive film (PSF) as a comparison. The test results showed a great deal of applicability for support condition monitoring under concrete pavement.

Experimental study on fatigue strength of airport concrete pavement slab

Indoor full-scale pavement slab fatigue tests were conducted on pavement structures with four different foundation types. Cyclic loading was completed on 15 large-scale slab specimens, and loading plate test was conducted to measure the reaction modulus of the foundation. The testing program measured the effects of stress ratio n, joint load transfer coefficient Tw, and foundation reaction modulus K on the concrete slab fatigue resistance. A pavement slab fatigue equation was obtained considering the joint load transfer coefficient Tw and the foundation reaction modulus K. The fatigue strength of pavement slab exhibited a linear relationship with stress ratio n, joint load transfer coefficient Tw, and foundation reaction modulus K on a logarithmic scale. The maximum flexural–tensile stress showed a linear relationship with the ACN/PCN. According to the largest flexural-tensile stress calculated by using the various ACN/PCN, the number of damage cycles could be obtained by using the fatigue equation. The data provided in this study can be used to provide evidence for pavement overload operational standards.

Sustainable Engineering: Load Transfer Characterization for the Structural Design of Thinner Concrete Pavements

Concrete pavements are characterized by their high durability and low conservation costs. However, concrete production causes large amounts of harmful emissions. In this context, short slab pavements allow us to reduce the slab thickness and the amount of concrete used in their construction. These benefits are only valid if the design assumptions are fulfilled, one of which is the provision of enough Load Transfer Efficiency (LTE) by the aggregate interlock. However, the current design method for short slabs does not relate the LTE with the Crack Width (CW) under the joints. This can jeopardize the sustainable benefits of short slabs. The objective of this study is to propose a method to develop the LTE–CW relationship for the short slabs’ design. The sustainable and accessible approach adopted in the proposal represents a paradigm shift compared to the traditional methods, which are limited to laboratories with sufficient resources to perform real-scale testing. The results show that it is possible to develop the LTE–CW relation in a sustainable manner. Furthermore, the aggregates that fulfill the technical specifications for pavements provide enough LTE when most of the joints are activated. When that happens, short slab pavements reduce environmental and human health impacts by 33% and 26%, respectively.

Formulation and properties of a newly developed powder geopolymer grouting material

This paper aims to develop a new kind of powder geopolymer grouting material (S-F powder Geopolymer) and investigate the properties. The slag powder, fly ash, alkali activators A and B, chemical additive, reinforcing material and water were employed to prepare this material. The single factor and orthogonal tests were conducted to study the composition of S-F powder Geopolymer. The physical and mechanical properties were evaluated by a series of laboratory tests such as fluidity, bleeding and expansion rate, mechanical properties tests et al. The results show that the optimum formula of S-F powder Geopolymer is that slag powder to fly ash is 80:20, the alkali activators A and B are 8% and 6.5%, the reinforcing material is 9% and the water reducing agent is 1%. In addition, the S-F powder Geopolymer has good physical and mechanical properties, which can ensure the performance of road repaired by this material. The S-F powder Geopolymer can be used to fill void beneath cement pavement slab and to repair crack of cement-stabilized base of asphalt pavement. The results of this paper will help the practice to have better understanding on the powder geopolymer grouting material and give recommendations to guide future field application of this material.

Hydrodynamic pressure distribution in saturated void beneath cement concrete pavement slab

ABSTRACT The void beneath cement concrete pavement slab (CCPS) is one of the common defects, which can cause the pavement cracking when heavy vehicle load is exerted on the pavement. The void expands when the water trapped inside erodes the inner surfaces of void circularly, bringing more cracks easily. Due to the close relationship with the erosion of the void, the hydrodynamic pressure distribution in saturated void beneath CCPS is investigated in this paper. Firstly, a theoretical expression of the hydrodynamic pressure in saturated void is proposed taking in account the law of mass conservation and the theorem of momentum. Secondly, the deformation patterns of the CCPS and the fluid-structure interaction (FSI) are discussed based on the proposed method. The results show that the hydrodynamic pressure and the water flow velocity in the void are overvalued while the rigid deformation pattern of CCPS is employed and the FSI is ignored. Finally, some influence factors are discussed. It is obtained that, both the maximum hydrodynamic pressure and the average velocity of water increase with the increase of the load amplitude, the vehicle speed and the void dimension. The conclusions are helpful for the prevention and maintenance of void beneath the CCPS.

ФАКТОРЫ, ВЛИЯЮЩИЕ НА ДОЛГОВЕЧНОСТЬ ВИБРОПРЕССОВАННЫХ БЕТОННЫХ ИЗДЕЛИЙ

When organizing a modern, comfortable urban environment, it becomes relevant to manufacture and use concrete paving slabs, tactile slabs for the visually impaired, concrete side stones and landscape design elements. The main requirements for such elements are: resistance to intensive operation, the use of deicing reagents. In the course of a series of tests, it has been proved that the most resistant to the effects of deicing reagents is products made by semi-dry vibropressing.

Numerical approach to predict zero-stress temperature in concrete pavements

Zero-stress temperature (ZST), defined as an inelastic indicator for the behavior of concrete elements in early-age, is one of the critical factors affecting the behavior and performance of concrete pavements. However, available and reliable methods for selecting this parameter are still limited. In this paper, a numerical approach to predict ZST in concrete pavement slabs was proposed. A one-dimensional (1D) finite-difference method to predict the temperature distribution in a hardening concrete slab was developed. To calculate the early-age stress in concrete slab subjected to the environmental loads, a two-dimensional (2D) finite-element analysis was also developed. The results of the temperature prediction obtained from the 1D finite-difference method were used and incorporated in the calculating of the early-age concrete stress to establish ZST. The results of ZST obtained from the proposed numerical model showed a good agreement compared with the field experiments. Using the proposed model, the sensitivity analysis of the ZST showed that the construction seasons, concrete placement times, concrete mix proportions, and pavement thicknesses have significant effects on ZST. The proposed numerical model is helpful and useful to predict ZST in concrete pavement slabs for given environmental conditions, concrete placement time, concrete mixture, and slab geometry.

Fiber optic sensors enabled monitoring of thermal curling of concrete pavement slab: Temperature, strain and inclination

An intellectual system is developed to monitor concrete pavement slab subjected to external temperature fluctuations. Truly distributed fiber-optic temperature and strain sensors and an innovative Fabry-Perot interferometer-based optical fiber inclinometer are installed in the concrete pavement slab so as to monitor and evaluate its thermal curling process. The system is demonstrated to be effective in detecting the thermal curling of slab. The results substantiate that the top surface of the slab has a fast reaction rate to the heating/cooling process. The bottom surface temperature has a time-lag comparing to the top surface, which results in a sharp increase then a slow reduction in the top-vs-bottom temperature difference. In the light of the inclinometer, it is proven that the tilt angle of the curvature of the slab has a high degree of synchronization with the top-vs-bottom temperature difference. The temperature/strain distribution maps are also presented and uneven distributions of temperature and strain are captured. Moreover, taking the advantage of the multiplexing capacity of the distributed fiber-optic sensors, the coefficient of thermal expansion (CTE) of the slab can be easily obtained and used to feed a finite element model. Finally, a three-dimensional finite element model is established to completely understand the curling process measured from the monitoring system. The model and the experimental data agree well with each other. While the sensors output realistic temperature and deformations at certain locations, the validated model is able to reveal more details of the nonlinearity inside the slab.

Mechanical Enhancement Mechanism of Recycled Concrete Pavement

In pavement engineering, concrete is the most widely used building material, but it has its own shortcomings such as low tensile and flexural strength, brittleness and poor durability, which easily lead to pavement damage. Common cement concrete repair materials have a long construction period, which affects traffic. Therefore, it is necessary to adopt fast repair materials to meet the requirements of traffic in a short time. The addition of fibers in pavement cement concrete can significantly improve the tensile and flexural strength and durability of concrete, and play a role in strengthening toughness. Compared with the single fiber concrete, which is relatively mature at present, this paper aims at strengthening and repairing the defects of waste concrete subgrade and base cracks, void at the bottom of pavement slab, etc. The fluidity and mechanical properties of recycled aggregate grouting material are studied through experiments, and on this basis, the mechanical properties of recycled concrete grouting are further analyzed. The results reveal the relationship between the amount of recycled fine aggregate, ambient temperature and the fluidity of recycled aggregate grouting, and the influence of the amount of recycled fine aggregate and the water-cement ratio on the mechanical properties of recycled aggregate grouting and grouting recycled concrete.