Evaluation of Concrete Deck Curing Regimens Using Capillary Pressure Sensing System

Evaluation of Concrete Deck Curing Regimens Using Capillary Pressure Sensing System
Author: Samuel Spann
Publisher:
Total Pages: 66
Release: 2019
Genre: Concrete
ISBN:

Early-age plastic shrinkage cracking is a common problem with the construction of concrete bridge decks due to the high surface area-to-volume ratio and exposure to potentially detrimental environmental effects. Curing regimens are utilized to mitigate cracking risk during the plastic stage of the concrete; the curing regimens evaluated for this study were wet burlap-polyethylene sheeting, two acrylic curing compounds, and one lithium compound. Capillary pressure in the water filled pores has been shown to correlate to the plastic shrinkage cracking risk of concrete. A new portable system has been developed to measure the capillary pressure that could potentially be used in the field on fresh bridge deck concrete. Individual test slabs were performed to test the curing regimens using the capillary pressure sensor system (CPSS). The system contains multiple sensors that contain pressure transducers that measure the capillary pressure changes during the plastic stage. Overall, wet burlap-polyethylene sheeting was shown to be the most effective curing regimen, with the lithium curing compound performing similarly to the control slab with no curing regimen applied. Both acrylic compounds were shown to perform comparatively well, completely mitigating early-age plastic shrinkage cracking in some instances, and allowing small shrinkage cracks to form in others. While the CPSS exhibited the ability to show when cracking occurred in most cases, the magnitude of the capillary pressure at which plastic shrinkage cracks formed varied significantly across tests.

Mitigating Shrinkage Cracking of Concrete in Bridge Decks Through Internal Curing

Mitigating Shrinkage Cracking of Concrete in Bridge Decks Through Internal Curing
Author: Daniel Robert Goad
Publisher:
Total Pages: 160
Release: 2013
Genre: Concrete
ISBN: 9781267851659

As the need for durable, long lasting infrastructure increases, new methods and techniques are being explored to prolong the service life of roads and bridges. One method to reduce shrinkage and early age cracking in concrete is internal curing. Internal curing supplies water to concrete, using pre-wetted lightweight aggregate (LWA), as needed throughout the process of hydration to reduce self desiccation, which leads to cracking. This research project analyzed two types of coarse LWA, expanded clay and expanded shale. The mixtures were developed specifically for use in bridge decks and adhered to specifications of the Arkansas State Highway and Transportation Department (AHTD). The concrete mixtures contained LWA at rates of 0, 100, 200, and 300 lb/yd3. The research was divided into two phases. The first phase measured autogenous and drying shrinkage in both plastic and elastic states using embedded vibrating wire strain gages (VWSG) cast in concrete prisms. The expanded clay LWA mixtures, with the 300 lb. replacement rate yielding the best results, were most effective in reducing shrinkage. Compressive strength decreased as the amount of LWA included in the mixture increased. However, all mixtures surpassed the 28 day compressive strength specified by AHTD. The second phase of the research project measured plastic shrinkage cracking in thin concrete test slabs. Methods and materials were investigated to produce consistent plastic shrinkage surface cracks of the concrete slabs. The extent of plastic shrinkage that occurred was quantified by measuring the total crack area of the test slabs. Implementation of 300 lb. of expanded clay LWA did not reduce the crack lengths, but did reduce the average crack widths experienced by the test slabs due to plastic shrinkage.

Behavior of Bridge with Internally Cured Concrete Deck Under Environmental and Truck Loading

Behavior of Bridge with Internally Cured Concrete Deck Under Environmental and Truck Loading
Author: Waleed Khalid Hamid
Publisher:
Total Pages:
Release: 2020
Genre: Bridges
ISBN:

The long-term performance of a bridge deck depends on its resistance to bridge cracking. Most of these cracks are initiated at the early age. Early age cracking of bridge decks is a typical issue in the U.S. that reduces bridge service life. Therefore, internally cured concrete (ICC) has been used in some states to reduce or eliminate the development of cracks in reinforced concrete decks. In this study, the early age behavior of ICC deck and the effect of the internal curing on the long-term behavior of the bridge was measured and evaluated in the laboratory and field for newly adjacent constructed bridge, which were located on Route 271 in Mayfield, Ohio. Two different types of concrete mixtures were utilized for the decks: conventional concrete (CC) and internally cured concrete (ICC). Firstly, the ICC and CC mixtures were examined in the laboratory in terms of a mechanical properties test, a plastic shrinkage test, a free shrinkage test, and a restrained shrinkage test. Second, the field behavior of an ICC deck and an adjacent CC deck during their early age and long-term performance were evaluated. Also, the shrinkage development for both decks was examined during the very early age. Instrumentation was used to measure the concrete and reinforcement strains and the temperature in both bridges. The instrumentation and results for both bridges are discussed. Laboratory results indicated that using pre-wetted lightweight concrete in the concrete mixture led to decreased density, coefficient of thermal expansion, and free shrinkage strain, and increased tensile strength and cracking time of concrete compared to conventional concrete. In the field, from the early age test, it was observed that the time to develop concrete shrinkage was approximately 5-6 hours after casting the deck of the ICC and the CC.

Curing Practices to Reduce Plastic Shrinkage in Concrete Bridge Decks

Curing Practices to Reduce Plastic Shrinkage in Concrete Bridge Decks
Author: Steven W. Peyton
Publisher:
Total Pages:
Release: 2011
Genre: Bridges
ISBN:

"The large, exposed area of concrete bridge decks makes proper curing critical and difficult. Plastic shrinkage cracks are common in improperly cured bridge decks. The objective of this research was to identify curing regimens that successfully reduce plastic shrinkage cracking. This was accomplished by surveying Arkansas Highway and Transportation Department engineers to determine the current construction practices on Arkansas bridge decks, documenting the curing of five bridge decks under construction, and studying the effectiveness of curing regimens in the laboratory. The survey responses show inconsistencies in the interpretations of the construction specifications that were also evident in the field study. Delayed curing, high evaporation rate, and increased girder deflection increased the likelihood of cracking in the decks. Inconsistent application of curing materials caused increased cracking in the laboratory study. Removing impediments, such as tined finishes, to timely curing and clarifying curing specifications would reduce cracking in bridge decks."--Project summary.

Cause and Control of Transverse Cracking in Concrete Bridge Decks

Cause and Control of Transverse Cracking in Concrete Bridge Decks
Author: M. Ala Saadeghvaziri
Publisher:
Total Pages: 206
Release: 2002
Genre: Concrete bridges
ISBN:

Many concrete bridge decks develop transverse cracking and most of these cracks develop at early ages, some right after construction and some after the bridge has been opened to traffic for a period of time. Structural design factors have not been the subject of much research in the past and they were the main thrust of this research study. Using 2-D and 3-D linear and nonlinear finite element models many design factors such as girder stiffness, deck thickness, girder spacing, relative stiffness of deck to girder, amount of reinforcements, etc., were studied. The research study also included a comprehensive review of the existing literature as well as survey of 24 bridges in the state of New Jersey. Results of each research task are presented and discussed in detail. Furthermore, based on analytical results and literature review, the effect of various factors are quantified and specific recommendations for possible consideration in design are made.