scholarly journals THE PUSHOUT STRENGTH OF CONCRETE PAVEMENT SLAB AND CLAY SOIL LAYERS

2021 ◽  
Vol 25 (Special) ◽  
pp. 3-224-3-230
Author(s):  
Sattam D. Ghanim ◽  
◽  
Qais ѕ. Banyhussan ◽  
Thulfiqar А. Aboaljus ◽  
◽  
...  
Keyword(s):  
Concrete Slab ◽  
Stable State ◽  
Interface State ◽  
Concrete Pavement ◽  
Interface Condition ◽  
Frictional Drag ◽  
Displacement Direction ◽  
Frictional Forces ◽  
State Rate ◽  
Rate Of Movement

The frictional forces between the concrete slab and base has been combined with the movements of the horizontal slab that have been induced by variations of the moisture and temperature in concrete slabs. The frictional drag that acts on the slab bottom as a result of base friction is in an opposite horizontal slab displacement direction, and resist movements of the horizontal slab. A condition of smoother interface provides lower resistance to slab movement. On the other hand, rough interfaces are beneficial in the reduction of the load-related stresses. As bonding degree between slab and foundation affects the friction that has been mobilized at interface, a realistic evaluation of friction of the interface is required for the rational designs of the concrete pavement. In this work, push-off test has been performed. Based upon results of the friction tests, the friction characteristics of concrete and soil have been researched. The parameters that influence the maximal displacement and friction coefficient are (interface state, rate of movement) for friction and (rate of movement, interface condition) for the displacements, respectively. Finally, once the applied force reaches a stable state, the frictional force increases dramatically. The most important influence on this force is the interface state, which is accompanied by movement rate. The change of the interface from a smooth to a rough surface increases the overall coefficient of friction.

scholarly journals Estimation of Joint and Interface Parameters for the Finite Element Analysis of Jointed Concrete Pavement Using Structural Evaluation Results

2015 ◽  
Vol 16 (2) ◽  
pp. 21-38
Author(s):  
Swati Roy Maitra ◽  
K. S. Reddy ◽  
L. S. Ramachandra
Keyword(s):  
Finite Element ◽  
Concrete Slab ◽  
Concrete Pavement ◽  
Interface Condition ◽  
Accurate Estimation ◽  
Fe Model ◽  
Element Analysis ◽  
Structural Evaluation ◽  
Jointed Concrete Pavement ◽  
Joint Parameters

Abstract In the analysis of jointed concrete pavement, it is necessary to appropriately model certain aspects of the pavement for accurate estimation of its structural responses. These include load transfer at joints (doweled and aggregate interlocked) and interface condition between slab and foundation. This paper presents a backcalculation method for estimating the joint parameters, both transverse and longitudinal, and the interface parameter along with the pavement layer moduli by using the results of structural evaluation of an in-service concrete pavement. The details of the structural evaluation using Falling Weight Deflectometer (FWD) and the two-stage backcalculation procedure using a three-dimensional finite element (FE) model for jointed concrete pavement are discussed. Modulus of dowel support and modulus of interlocking joints are the transverse and longitudinal joint parameters respectively and the coefficient of friction between concrete slab and foundation is the interface parameter considered for the analysis. These parameters are the useful inputs in modeling jointed concrete pavement using finite element method.

scholarly journals EFFECT OF CYCLE OF LOADING ON SUBBASE FRICTION CHARISARITICS UNDER RIGID PAVEMENT

2021 ◽  
Vol 25 (Special) ◽  
pp. 3-195-3-202
Author(s):  
Thulfiqar A. Aboaljus ◽  
◽  
Qais S. Banyhussan ◽  
Mohammed H. Mohammed ◽  
◽  
...  
Keyword(s):  
Coefficient Of Friction ◽  
Frictional Force ◽  
Stable State ◽  
Plain Concrete ◽  
Interface State ◽  
Interface Condition ◽  
Movement Rate ◽  
The Coefficient Of Friction ◽  
Number Of Cycles ◽  
Two Stages

The coefficient of friction is a measurement of the frictional force between two objects. As the temperature of the pavement changes, it might slide against the resistance of the supporting subbase. In order for pavement to perform as anticipated, this resistance must be calculated. Concrete cracking does not occur when the pavement is joined. A membrane layer is positioned between the subbase and the plate in joint plain concrete pavements to smooth the interface. The displacement of concrete caused by temperature differences is less resistant on a smooth surface. For subbase conditions, two stages of the push-off test were performed (smooth and rough) to show the effects of movement cycles. Based on the results of the friction tests, the friction properties of the concrete and subbase were investigated. The parameters that influence the coefficient of friction and displacement are (interface state, movement rate, thickness number of movement cycles), changing the interface condition from smooth to rough leads to an increase the FRF of (6, 9 and 12 cm/hr) by (194.7, 194.4 and 189.8 %) respectively. Finally, once the applied force reaches a stable state, the frictional force increases dramatically. The most important influence on this force is the interface state, which is accompanied by movement rate and thickness. The variation of the relationship curves with number of cycles tends to be insignificant after the third to fourth cycle of slab movement.

scholarly journals Non-destructive ultrasonic tomography for concrete pavement evaluation: signal processing and image analysis of crucial parameters

2017 ◽  
Vol 10 (6) ◽  
pp. 1182-1191
Author(s):  
L. S. SALLES ◽  
J. T. BALBO ◽  
L. KHAZANOVICH
Keyword(s):  
Signal Processing ◽  
Concrete Slab ◽  
Low Frequency ◽  
Concrete Pavement ◽  
Ultrasonic Tomography ◽  
Transverse Cracks ◽  
Pavement Maintenance ◽  
Use Of Technology ◽  
Pavement Evaluation ◽  
Non Destructive

Abstract In recent years, due to the destructive and unproductive character of pavement specimen extraction, pavement maintenance technology intensified the use of non-destructive techniques for pavement evaluation which resulted in the development of several devices and evaluation methods. This paper describes the use of technology based on low frequency ultrasonic tomography for evaluation of concrete pavement parameters. The equipment was applied in three experimental sections with different concrete pavements built at the University of Sao Paulo campus. The ultrasonic signal processing is given. The results analysis enables the efficient and reliable identification of thickness and reinforcement position within the concrete slab. Construction problems were evidenced in one of experimental sections with thickness deficiencies and reinforcement in a position below projected. Furthermore, the use of a novel concrete quality indicator was correlated with the presence of transverse cracks and alkali-silica reaction within the sections.

scholarly journals Experimental Study on Doweled Expansion Joints on Behavior for Plain Concrete Pavement System

2018 ◽  
Vol 14 (3) ◽  
pp. 68-80
Author(s):  
Zainab Ahmed Al-kaissi ◽  
Mohammed Hashim Mohammed ◽  
Nabaa Sattar Kareem
Keyword(s):  
Failure Load ◽  
Concrete Slab ◽  
Concrete Strength ◽  
Plain Concrete ◽  
Concrete Pavement ◽  
Type I ◽  
Expansion Joints ◽  
Subgrade Soil ◽  
Dowel Bar ◽  
Bar Diameter

This paper deals with load-deflection behavior the jointed plain concrete pavement system using steel dowel bars as a mechanism to transmit load across the expansion joints. Experimentally, four models of the jointed plain concrete pavement system were made, each model consists of two slabs of plain concrete that connected together across expansion by two dowel bars and the concrete slab were supported by the subgrade soil. Two variables were dealt with, the first is diameter of dowel bar (12, 16 and 20 mm) and the second is type of the subgrade soil, two types of soil were used which classified according to the (AASHTO): Type I (A-6) and type II (A-7-6). Experimental results showed that increasing dowel bar diameter from 12 mm to 20 mm has a little effect on load-deflection behavior of the tested specimens with only 5% increase in failure load. This may be attributed to that the failure (caused by flexural crack) depends mainly on concrete strength. Results also showed that decreasing CBR value of subgrade soil from 7% to 5% decreases failure load by about 33%.

scholarly journals Finite Element Simulation and Multi-Factor Stress Prediction Model for Cement Concrete Pavement Considering Void under Slab

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5294
Author(s):  
Bangyi Liu ◽  
Yang Zhou ◽  
Linhao Gu ◽  
Xiaoming Huang
Keyword(s):  
Finite Element ◽  
Tensile Stress ◽  
Concrete Slab ◽  
Three Dimensional ◽  
Mesh Size ◽  
Maximum Tensile Stress ◽  
Concrete Pavement ◽  
Slab Thickness ◽  
Void Size ◽  
Tensile Stresses

Uneven support as result of voids beneath concrete slabs can lead to high tensile stresses at the corner of the slab and eventually cause many forms of damage, such as cracking or faulting. Three-dimensional (3D) finite element models of the concrete pavement with void are presented. Mesh convergence analysis was used to determine the element type and mesh size in the model. The accuracy of the model is verified by comparing with the calculation results of the code design standards in China. The reliability of the model is verified by field measurement. The analysis shows that the stresses are more affected at the corner of the slab than at the edge. Impact of void size and void depth at the slab corner on the slab stress are similar, which result in the change of the position of the maximum tensile stress. The maximum tensile stresses do not increase with the increase in the void size for relatively small void size. The maximum tensile stress increases rapidly with the enlargement in the void size when the size is ≥0.4 m. The increments of maximum tensile stress can reach 183.7% when the void size is 1.0 m. The increase in slab thickness can effectively reduce maximum tensile stress. A function is established to calculate the maximum tensile stress of the concrete slab. The function takes into account the void size, the slab thickness and the vehicle load. The reliability of the function was verified by comparing the error between the calculated and simulated results.

Stress Analysis for Cement Concrete around Joint Dowel after Loosing

2013 ◽  
Vol 857 ◽  
pp. 222-226
Author(s):  
Rong Guo Hou ◽  
Kai Min Niu
Keyword(s):  
Shear Stress ◽  
Stress Concentration ◽  
Load Transfer ◽  
Concrete Slab ◽  
Concrete Pavement ◽  
Cement Concrete ◽  
Transfer Capability ◽  
Cement Concrete Pavement ◽  
Contraction Joint ◽  
Increasing Load

The stress concentration will appear in cement concrete around joint dowel set in contraction joint of cement concrete pavement with repeated loads. And concrete around joint dowel will damage gradually.In this paper, the stress of concrete around joint dowel and deflection of concrete slab are analyzed when joint dowel loosing. It is indicated that the shear stress is key to damage of concrete around joint dowel. when the loosing width reaches certain extent. With loosing width increasing, load transfer capacity will decrease gradually. And it is shown that the load transfer capability will lower rapidly when the loosing width comes in 4cm.

Research of Zero Stress Temperature Gradient in Cement Concrete Pavement

2013 ◽  
Vol 723 ◽  
pp. 163-170 ◽  
Author(s):  
Xiang Shen Hou ◽  
Xin Kai Li ◽  
Bo Peng ◽  
Guang Hui Deng
Keyword(s):  
Temperature Gradient ◽  
Concrete Beam ◽  
Concrete Slab ◽  
Strain Sensor ◽  
Concrete Pavement ◽  
Early Age ◽  
Cement Concrete ◽  
Setting Process ◽  
Cement Concrete Pavement ◽  
Design Guidance

There is no temperature stress and temperature curling according to the present cement concrete pavement design, when the temperature gradient of cement concrete pavement in service is zero, and it does not consider the effect of Built-in curling caused in early-age setting process of cement concrete to cement concrete pavement in service. In fact, there is Built-in curling in cement concrete slab when it is after the completion of the cement concrete slab is poured, and the curling is mainly upward. It is in the setting process, when cement concrete is on the final set, the cement concrete is at the critical moment when is just able to bear load, and it exists temperature gradient but no strain in the pavement slab, the temperature gradient is known as "Built-in construction temperature gradient" in AASHTO2002 design guidance, and it is the important part of the Built-in curling. In this paper, cement concrete beam specimens were poured in outdoor and temperature sensor and strain sensor were buried in the cement concrete specimens to detect early-age internal temperature field and strain field, and then the study of Built-in curling and Built-in construction temperature gradient were carried out.

Temperature Gradient of Concrete Pavement Slab Overlaid with Asphalt Surface Course

2000 ◽  
Vol 1730 (1) ◽  
pp. 25-33 ◽  
Author(s):  
Tatsuo Nishizawa ◽  
Shigeru Shimeno ◽  
Akinori Komatsubara ◽  
Masashi Koyanagawa
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Stress ◽  
Temperature Gradient ◽  
Numerical Simulations ◽  
Structural Design ◽  
Concrete Slab ◽  
Concrete Pavement ◽  
Reduction Effect ◽  
The Relationship

In the structural design of composite pavement with a concrete pavement slab overlaid with an asphalt surface course, it is very important to estimate the temperature gradient in the concrete slab. An asphalt surface course reduces the temperature gradient in an underlaid concrete slab, resulting in the reduction of thermal stress of the concrete slab. This effect was investigated by temperature measurement in model pavements and by thermal conductivity analysis. Thermal properties were estimated by a backanalysis by using measured temperatures over 1 year. From the numerical simulations varying the thickness of asphalt surface and concrete slab, the relationship between the reduction effect and the asphalt thickness was derived as a function of the thickness of asphalt surface course, which can be used in the structural design of the composite pavement.

Numerical Simulation of the Process of Partial Void Formation under Cement Concrete Pavement Slab

2011 ◽  
Vol 97-98 ◽  
pp. 241-246
Author(s):  
Xiao Chun Zhang ◽  
Shu Shu Liu ◽  
Shi Kui Hu ◽  
Ning Zhang
Keyword(s):  
Numerical Simulation ◽  
Finite Element Method ◽  
Concrete Slab ◽  
Void Formation ◽  
Concrete Pavement ◽  
Void Size ◽  
Cement Concrete ◽  
Center Edge ◽  
Cement Concrete Pavement ◽  
D Model

The damage of void under cement concrete slab is one of the main diseases in cement concrete pavement. By finite element method, a 3-D model of cement concrete pavement structure was established to simulate the partial void under the cement concrete pavement slab with different loading conditions. The process of the division between the subgrade and the slab with a soft area under the slab are reappeared. The changing rules of the void size with the number of cycle load in case of different tie pressure and loading location (at the center, edge or corner of the slab).

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