High-Performance Concrete Bridge Decks: A Fast-Track Implementation Study Volume 2: Materials

Abstract

IntroductionConcrete bridge decks are inherently exposed to harsh environment. They are known to undergo degradation due to numerous distresses, of which the most common are corrosion of reinforcement (caused by ingress of chloride through bulk concrete), freeze-thaw damage, shrinkage cracking (aggravating both corrosion and freeze-thaw problems) and surface scaling due to deicing salts.Recently, high performance concrete (HPC) has become widely utilized in the applications where severe environment leads to premature deterioration. The premise behind the development of HPC was to address the durability issues typical of normal concrete. HPC almost always implies incorporation of mineral admixtures, such as fly ash (FA) or silica fume (SF). These materials are added to concrete for variety of reasons, of which the most important is improvement (compared to plain ordinary portland cement (OPC) concrete) of certain durabilityrelated properties. However, there are also some downsides of utilizing them in concrete. For example, fly ash is known to reduce the early age strength and early age resistance to chloride-ion penetration, as well as resistance to salt scaling and carbonation. Furthermore, fly ash concrete has been reported to be fairly sensitive to curing conditions compared to plain cement concrete. The shortcomings of incorporating silica fume, on the other hand, include increased susceptibility to shrinkage cracking and potentially reduced resistance to freezing and thawing.In the view of the aforementioned side effects associated with the use of fly ash or silica fume in binary mixtures, the ternary cementitious systems have been introduced as a potentially viable solution to address those durability issues. Superior properties of this kind of cementitious systems are commonly attributed to so-called synergistic effect taking place when both pozzolanic materials are utilized. The intuitively obvious benefit of the use of OPC/FA/SF mixtures is that the presence of fly ash in concrete compensates for the deficiencies of silica fume, and vice versa. For example, FA offsets the increase in water demand, heat of hydration and alkalinity of pore solution resulting from addition of SF. On the other hand, SF compensates for the low early age strength and sensitivity to curing (with respect to development of both mechanical and durability-related properties of FA concrete). From the economical perspective, a relatively low cost of FA counterbalances higher cost of SF. Although a fairly large amount of research has been conducted to evaluate the properties of ternary cementitious mixtures containing fly ash and silica fume, relatively little was done with the emphasis on the durability-related issues encountered when these binder systems are used in the bridge deck concrete. Up to date, no data exists on the actual performance of ternary concrete containing class C fly ash and silica fume in bridge decks.The purpose of this research was to examine the applicability of ternary binder systems containing ordinary port...

Documentation of the INDOT Experience and Construction of the Bridge Decks Containing Internal Curing in 2013

“…The second aspect of the specification that improves the performance of the mixture is a desire by INDOT to limit the design total paste volume to 25.0%. This limitation was intended to limit the shrinkage potential of high-performance mixtures, based on research presented in the FHWA/IN/JTRP-2008/29-2 report (http://dx.doi.org/10.5703/1288284314307) (Radlinski & Olek, 2010). It should be noted however that this mixture includes internal curing to mitigate significant early age shrinkage and making this limitation less necessary for the intent of shrinkage reduction (revisions to the specification in 2014 have relaxed the limit on total paste volume to 26.0% and it may be further possible to reduce this limitation with higher paste volumes).…”

Development and Application of Maturity Method for Prediction of Concrete's Resistance to Chloride Ion Penetration

“…Even though this reduction in service life of the bridge deck can be considered relatively insignificant, it seems desirable to establish how the construction date may affect the RCP value at the time to first salt exposure. As stated previously, the latter is believed to provide a good indicator of the overall quality of concrete, for example, scaling resistance (8). A period from April 14 to November 14 was considered to constitute a realistic construction season, and the temperature history from 2004 was used for the purpose of this analysis.…”

“…However, at the first time of salt exposure, the RCP of that concrete would be nearly 9,000 coulombs, which is likely unacceptable from the scaling resistance standpoint. For this particular case of concrete and temperature history, it seems that for the concrete to drop the coulomb value to 1,500 [corresponding to common maximum scaling limit of 0.80 kg/m 3 (8,9)] until the first salt exposure, the bridge deck would have to be constructed by the end of August (see Figure 6). Such calendar restriction is certainly too rigorous.…”

“…Indeed, an independent laboratory study (8) conducted on ternary concretes containing various amounts of FA and SF indicated that for the most common field curing conditions (i.e., 3 or 7 days of curing under wet burlap), concrete should exhibit maximum of 1,500 coulombs in ASTM C1202 test to satisfy the common acceptance scaling limit of 0.80 kg/m 2 (9). Therefore, the ability to predict chloride penetrability of concrete at a given age seems very desirable, for it may potentially serve as a good indicator of overall durability-related performance.While the ASTM C1202 rapid chloride permeability (RCP) test suffers from certain limitations (10, 11), it is widely used for quality control purposes since the test results correlate well with coefficient of chloride diffusion (1,8,12). Recently, Bentz introduced a virtual RCP test allowing for prediction of RCP test values based on composition of the concrete mixture and its individual constituents (13).…”

“…While the ASTM C1202 rapid chloride permeability (RCP) test suffers from certain limitations (10, 11), it is widely used for quality control purposes since the test results correlate well with coefficient of chloride diffusion (1,8,12). Recently, Bentz introduced a virtual RCP test allowing for prediction of RCP test values based on composition of the concrete mixture and its individual constituents (13).…”