In this study, six full-scale APT pavement sections, each 71.7 ft. long and 13 ft. wide, were constructed at the LTRC's Pavement Research Facility (PRF) using normal pavement construction procedures. The test sections include three RCC thicknesses (4 in., 6 in., and 8 in.) and two base designs: a 150 psi unconfined compressive strength (UCS) cement treated soil base with a thickness of 12 in. and a 300 psi UCS soil cement base with a thickness of 8.5 in. over a 10 in. cement treated subgrade. A heavy vehicle load simulation device (ATLaS30) was used for APT loading. In situ pavement testing, instrumentation, and crack-mapping were employed to monitor the loadinduced pavement responses and pavement cracking performance. The APT results generally indicated that a thin RCC pavement (thickness of 4 to 6 in.) would eventually have a structurally fatigue cracking failure under the repetitive traffic and environmental loading due to a combined effect of pavement cracking and pumping. The visible cracks first showed up on pavement surface as a single or several fine cracks along the longitudinal traffic direction within the wheel paths. The longitudinal cracks were then extended and gradually propagated to transverse and other directions under the continued loading, and finally merged into a fatigue cracking failure. Post-mortem trenching results showed that the majority of the cracks were bottom-up, but some did show developed as the top-down. The results further showed that all tested thin RCC pavement structures over an adequate base support would have superior load carrying capability. The 6-in. RCC sections carried an estimated 87.4 million and 19.4 million ESALs to failure for the soil cement and cement treated base, respectively. The 4-in. RCC section over the soil cement base performed well with an estimated 19.2 million ESALs to failure. The data also indicated that the more substantial base (i.e., soil cement) support generally provided additional structural capacity as compared the less substantial cement treated soil base. The APT results were then used to evaluate the pavement fatigue life, cracking pattern and failure mode of thin RCC-surfaced pavements, which led to the development of a set of RCC fatigue models for thin RCC fatigue damage analysis. Finally, a thickness design procedure that includes a fatigue model suitable for analyzing a thin RCC surfaced pavement structure was proposed and the corresponding construction cost savings when implementing thin RCC-surfaced pavement as a design option for a low volume pavement were estimated.

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Three full-scale roller compacted concrete (RCC) pavement sections built over a soil cement base were tested under accelerated pavement testing (APT). The RCC thicknesses varied from 102 mm (4 in.) to 152 mm (6 in.) and to 203 mm (8 in.), respectively. A bi-directionally loading device with a dual-tire load assembly was used for this experiment. Each test section was instrumented with multiple pressure cells and strain gages. The objective was to evaluate the structural performance and load carrying capacity of thin RCC-surfaced pavements under accelerated loading. The APT results generally indicated that all three RCC pavement sections tested in this study possessed very high load carrying capacity; an estimated pavement life in terms of equivalent single axle load (ESAL) for the thinnest RCC section (i.e., RCC thickness of 102 mm) evaluated was approximately 19.2 million. It was observed that a fatigue failure would be the primary pavement distress type for a thin RCC pavement under trafficking. Specifically, the development of fatigue cracking was found to originate from a longitudinal crack at the edge or in the center of a tire print, then extended and propagated, and eventually merged with cracks of other directions. Instrumentation results were used to characterize the fatigue damage under different load magnitudes. Finally, based on the APT performance of this experiment, two fatigue models for predicting the fatigue life of thin RCC pavements were developed.

As a durable, economical, and low-maintenance concrete material, roller compacted concrete (RCC) is steadily becoming the preferred choice for many pavement applications. However, the fatigue models in current pavement thickness design procedures have generally been found to over-predict the RCC pavement fatigue damage under in situ heavy truck loading. In this study, a comprehensive beam fatigue test experiment was performed using field saw-cut RCC slab samples from two full-scale accelerated pavement testing (APT) sections to investigate the fatigue behavior of in situ RCC pavements. This is the first research study to investigate the fatigue behavior of field RCC beam samples prepared and constructed with a high-density asphalt-type paver and a vibratory roller. The results indicate that a well-compacted RCC pavement can achieve higher flexural strength and exhibit better fatigue life than conventional concrete pavement. Based on the beam fatigue test results and in situ fatigue performance of APT test sections, an RCC fatigue-life model was developed, providing a more accurate solution for estimating the allowable number of load repetitions of RCC pavements subjected to vehicular fatigue loading. This model could be used in RCC thickness design procedures to determine the optimum RCC design thickness and long-term fatigue performance of RCC pavements for roadway application.