Analysis of the Coupling Effect of Thermal and Traffic Loads on Cement Concrete Pavement with Voids Repaired with Polymer Grout

Under the repeated action of traffic and thermal loads, a cement concrete pavement slab may partially lose contact with its base course, and voids may develop underneath the slab. Such distress will greatly impact the pavement performance. To fill the voids and restore the base support to the slab, the technology of polymer grouting has been increasingly adopted in recent years due to its advantages of quick application and high efficiency. There is, however, a lack of research on the mechanistic responses and performance of such a repaired rigid pavement under coupled influences of thermal and traffic loads. Existing literature has mainly focused on normal cement concrete pavement structures (i.e., without polymer grouted voids). This study intends to fill the research gap by investigating the time-domain characteristics of thermal stress response of a cement concrete pavement with underlying voids filled with polymer grout, along with design traffic loads. The finite element method was adopted with a 3-dimensional nonlinear temperature field within the pavement. A program module was developed in the Abaqus FEA software environment for temperature effect analysis. It was found that under the coupling action of thermal and traffic loads, thermal stress had a greater influence on the critical slab stress at the slab corner than those at other slab locations. Through the comparative analysis before and after polymer grouting repair, the critical tensile stress at the slab corner under the vehicle and thermal loads can be effectively reduced. The polymer performance is stable after three years.

USE OF EXPERIENCE IN CONSTRUCTION OF MONOLITHIC CEMENT-CONCRETE PAVEMENT OF THE AIRPORT «ODESSA» IN THE DEVELOPMENT OF A NEW NATIONAL STANDARD FOR THE AIRFIELD DESIGN

Inspection of the monolithic cement-concrete pavement of the «Odessa» airport runway was carried out. Visual inspection of the runway surface, taxiways and apron for defects has been performed. The condition of the runway pavement was assessed as "excellent", destruction category I. In addition, strength tests of the rigid concrete pavement upper layer were carried out using non-destructive testing methods and core testing. The obtained strength characteristics correspond to the design requirements; the concrete has a grade of at least C32/40. Based on the processed data and own scientific developments, proposals were drawn up for a new standard (instead of SNyP 2.05.08-85 "Aérodromy") regarding the requirements for materials, concrete mixtures and concretes based on them for the runways construction in Ukraine. Modern requirements for monolithic cement-concrete airfield pavements require an extension of their service life up to 40 years. To ensure such indicators of serviceability, in addition to high strength indicators, it is imperative to ensure the rigid pavements durability using high-performance modified concretes. The proposals indicate the cement type, aggregates and chemical admixtures that can be used in the manufacture of concrete for airfield pavements. The requirements for the concrete and concrete mixture properties, the process of concrete curing are also presented. Taking into account the modern superplasticizers and the requirements for the workability of concrete mixtures for the construction of monolithic cement-concrete airfield pavements, the maximum W/C should be in the range of 0.3-0.35. To increase the flexural strength and crack resistance, it is desirable to use dispersed concrete reinforcement. To ensure the service life and satisfactory operational condition of the runway pavements, it is necessary to conduct an annual inspection for the timely identification and correction of arising defects.

Reflection Crack Analysis of Asphalt Overlay on Cement Concrete Pavement Based on XFEM

Based on the improved Paris formula, the reflection cracking characteristics of asphalt overlay on the cement concrete pavement are carefully scrutinized. The fatigue life is also predicted through the indoor simulation tests and establishing the two- and three-dimensional extended finite-element method (XFEM) models. Four fracture factors of the Paris formula in the asphalt mixture are appropriately calculated by fitting the N-a curve of the indoor test, and their predicted values are then exploited in the numerical simulations. The obtained results show that the numerical model can successfully predict the results of the indoor simulation test. It indicates that the XFEM has apparent advantages in examining the reflection cracking of the asphalt overlay on the cement concrete pavement.