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Superloads, defined as vehicles with a gross vehicle weight of over 890 kN, are believed to overload jointed plain concrete pavements (JPCPs) and have the potential to cause significantly more fatigue damage than typical truck traffic. It is anticipated that the fatigue damage is greater when the superload is applied later in the life of the JPCP. In this study, the stress pulses generated by superloads on JPCPs were characterized using finite element modeling and related to fatigue damage through the fatigue testing of concrete beams. Concrete beams subjected to loading profiles that simulate those of a superload were observed to accumulate fatigue damage at an accelerated rate when applied after 70% of the fatigue life of the concrete was consumed. Moreover, through the collection of fatigue life and beam response data, the effects of stress ratio, stress range, flexural strength, and damage state at the time of loading on the fatigue damage imposed by a superload movement were elucidated.

Monitoring alkali-silica reaction in pavements requires methods to quantify strain and deterioration. Typically, surface strain is measured using a detachable mechanical gauge, while deterioration features are measured following the damage rating index (DRI). External restraint from adjacent pavement or subgrade friction potentially affects strain and deterioration in the travel, transverse, and vertical directions differently, potentially decreasing deterioration in the restrained directions. Limited experimental data are available regarding states of stress observed in concrete pavements. The objective of this study was to evaluate the potential redistribution of strain and deterioration toward the unrestrained direction (vertical). Herein, surface strain and DRI methods were used to quantify and compare deterioration in restrained and unrestrained concrete cube specimens with self-reacting external restraint. The results were compared to previous studies to validate the findings. External restraint was found to limit strain and deterioration in the restrained directions, with a lesser effect on the unrestrained directions.

In this study, an optimal curing method was established for very early-strength latex-modified concrete (VES-LMC), which is frequently used in partial-depth repair (PDR) of deteriorated concrete pavements. The appropriate starting time of curing, when the surface of the VES-LMC was not damaged, was found for various curing conditions such as ambient air, polyethylene (PE) sheet, blanket, curing membrane, PE sheet on curing membrane, and blanket on curing membrane. The hydration characteristics of the VES-LMC and ordinary portland cement concrete (OPCC) were then compared by evaluating their respective properties such as water loss, bleeding, autogenous shrinkage, and compressive strength. In addition, the optimal curing method was investigated by determining the water loss, water absorption, drying shrinkage, and compressive strength of the VES-LMC specimens cured under the aforementioned conditions. The test results revealed that VES-LMC performed better than OPCC as a PDR material. In addition, covering the VES-LMC with a PE sheet 3 minutes after placement was observed to be the most effective curing method in PDR.

Burning or landfilling worn tires has irreversible destructive effects on the environment. The recycling of crumb rubber in concrete not only helps to solve one of the main environmental pollutants but may also enhance concrete ductility and energy absorption. The disadvantage associated with this practice, however, is that crumb rubber weakens concrete in terms of its mechanical properties and reduces its durability because of the hydrophobicity of crumb rubber that causes weak contact between the cement paste and the crumb rubber. To improve the adhesiveness of the interface surfaces, different additives have been considered for modifying the crumb rubber surface. For the present study, some 230 samples were prepared in which crumb rubber was used to replace fine aggregate over a range of 0 to 60% (approximately 25% of total aggregates volume) and polyvinyl acetate was used as a rubber surface modifier. Investigation of the mechanical properties and durability-related parameters of concrete containing different percentages of rubber thus modified revealed that crumb rubber surface modification improves concrete compressive, flexural, and tensile strengths by up to 12 to 18%. Also, durability-related parameters were observed to improve significantly as revealed by reductions of 68% and 30% in water absorption and water penetration depth, respectively. Moreover, chloride ion penetration and carbonation depths were found to decrease by 17% and 15%, respectively. The use of polyvinyl acetate as a modifier by improving the adhesion of crumb rubber and cement paste improves the strength characteristics and prevents the penetration of water and destructive substances into the concrete, which is very important for concrete pavements.

Although internal vibration has been widely implemented in concrete pavements, reports about concrete deterioration caused by improper vibration have been emerging. This study investigates the transmission of vibration energy, water movement, and air movement in concrete under vibration to provide the experimental basis for a better understanding of vibration in different concrete mixtures. An innovative experimental method was developed to measure energy transmission in concrete. The mixtures varied by air content, slump, and water-reducing admixture addition and were prepared to test the vibration energy, water absorption, and the air-void system for a range of vibrator frequencies. The vibration energy transferred through the mixture generally displayed a linear rise, then a slight drop, and, finally, stability, indicated by both measurements of transferred energy and voltage demand of the vibrator. The magnitude of vibration energy transferred through the mixtures increased with an increasing slump. For all samples tested, water appeared to move away from the vibrator, most markedly with an increasing frequency. There is a clear indication of air movement to the surface of the concrete in all tested samples.