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Diagrams of Ring Specimen (Reprinted from AASHTO T334-08) 

Diagrams of Ring Specimen (Reprinted from AASHTO T334-08) 

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Technical Report
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Early-age shrinkage cracking has been observed in many concrete bridge decks in Washington State and elsewhere around the U.S. The cracking increases the effects of freeze-thaw damage, spalling, and corrosion of steel reinforcement, thus resulting in premature deterioration and structural deficiency of the bridges. In this study, the main causes of...

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Citations

... Among 14 LC-HPC bridges, four have a very high cost, six have a moderately high cost, and two cost less than the control deck (Lindquist et al., 2008). Qiao et al. (2010) investigated several bridges in Washington and recommend the optimization of concrete mix design as an appropriate mitigation strategy for early age bridge deck cracks. Twenty concrete mixes were designed and compared with two existing WSDOT concrete mixes as a benchmark. ...
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Right after construction, drying shrinkage of restrained concrete bridge decks and rails causes early-age cracking, insertion of water and chemicals, and corrosion of reinforcing steel that eventually leads to delamination and spalling of concrete. The main objective of this research is to control early-age shrinkage cracking by reducing cementitious material content in bridge deck and rail concrete mixtures. Several reduced cementitious materials concrete (RCMC) mixtures were developed by optimizing aggregate particle packing and conducting overall performance evaluation. This evaluation was carried out in three phases. The first phase investigated the feasibility of new RCMC mixtures by testing workability, compressive strength, and chloride penetrability when cementitious materials content is reduced by 50, 100, and 150 lbs per cubic yard compared to the standard bridge deck concrete mixture of Nebraska. The second phase investigated fresh properties (slump and air content), early-stage properties (setting time and heat of hydration), mechanical properties (compressive strength, modulus of rupture, modulus of elasticity, shear strength, slant shear strength, and bond strength), durability properties (freeze and thaw resistance, and chloride resistivity), and shrinkage properties (free and restrained shrinkage). The third phase investigated the batching, mixing, handling, pumpability, and finishing of the RCMC mixtures by casting mockup deck panels using ready mixed concrete. All the developed RCMC mixtures have demonstrated a comparable performance to the standard mixture while having a reduced cementitious materials content, which is expected to reduce production cost and carbon footprint due to the lower cement content.
... Qiao et al. (2010) investigated several bridges of Washington and recommend optimization of concrete mix design as an appropriate mitigation strategy for early age bridge deck cracks. 20 concrete mixes were designed and compared with two existing WSDOT concrete mixes as a benchmark. ...
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Right after construction, drying shrinkage of restrained concrete bridge decks and rails causes early-age cracking that eventually leads to delamination and spalling of concrete due to insertion of water and chemicals, and corrosion of reinforcing steel. The main objective of this research is to control early-age shrinkage cracking by reducing cementitious material content in bridge deck and rail concrete mixtures. Several reduced cementitious materials concrete (RCMC) mixtures were developed by optimizing aggregate particle packing and conducting overall performance evaluation. This evaluation was carried out in three phases: The first phase investigated the feasibility of new RCMC mixtures by testing workability, compressive strength, and chloride penetrability when cementitious materials content is reduced by 50, 100, and 150 lbs. per cubic yard compared to the standard bridge deck concrete mixture of Nebraska (known by 47BD). The second phase investigated fresh properties (slump and air content), early-stage properties (setting time and heat of hydration), mechanical properties (compressive strength, modulus of rupture, modulus of elasticity, shear strength, slant shear strength, and bond strength), durability properties (freeze and thaw resistance, and chloride resistivity), and shrinkage properties (free and restrained shrinkage). The third phase investigated the batching, mixing, handling, pumpability, and finishing of the RCMC mixtures by casting mockup deck panels using ready-mixed concrete. All the developed RCMC mixtures have demonstrated a comparable performance to the standard mixture while having a reduced cementitious materials content that reduces production cost and carbon footprint.
... The cement content, tensile strength and compressive strength are the factors affecting EAMC in bridge decks (Peyton et al. 2012, Wright et al. 2014. Qiao et al. (2010) reported that the less resistance to early age cracking is due to the low tensile strength of concrete in bridge decks. Therefore, improving tensile strength of concrete with material other than cement will results in more resistance against EAMC. ...
... The STS, ESpo, ESt and TIS of HFRC are increased up to 37%, 11%, 95% and 75%, respectively. Qiao et al. (2010) and Khan and Ali (2016) reported that improving tensile strength of concrete results in less early age micro cracking which ultimately enhances the durability of bridge deck. The increased STS will provide more resistance against EAMC ultimately results in improved durability of bridge deck. ...
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Nowadays the use of different fibers in concrete for the application of bridge deck has showed better performance against early age micro cracking (EAMC). On the other hand, use of calcium carbonate (CaCO 3) whisker also results in less cracking. Therefore, EAMC can be controlled with the use of CaCO 3 whisker, steel and basalt fibers. In this work, the effect of different basalt fiber content on splitting-tensile properties of hybrid fiber reinforced concrete (HFRC) will be investigated. The mix design ratio of HFRC is 1:2:1.5:0.05 (cement: sand: aggregate: CaCO 3 whisker) with a water cement ratio of 0.42. The steel and basalt fiber length is 35 mm and 12 mm, respectively. Different basalt fiber contents of 2%, 4% and 6%, by cement mass, are added to prepare HFRC2, HFRC4 and HFRC6, respectively. For each batch, cylinders are cast and will be tested under splitting-tensile load as per ASTM standard. It is found that, with increasing content of basalt fiber up to 4%, there is an increase in tensile strength of hybrid fiber reinforced concrete. This may ensure the reduction of EAMC in bridge deck. Future recommendation is to optimize the basalt fiber content in HFRC for the application of bridge deck.
... Moreover, shrinkage that occurs in the concrete structure is highly dependent on the proportion of (area/volume) ratio of the structural member [29,79]. In concrete structures, there are several types of shrinkages that can contribute to cracking of the concrete in various degrees,such as: drying (free and restrained), plastic, autogenous and carbonation shrinkage [80][81][82]. ...
... ng practices on early shrinkage behavior of shotcrete and develop test methods for long-term performance and durability, in comparisons with cast-in-place (CIP) concrete. The testing results for CIP concrete can be found from previous reports of WSDOT projects: WSDOT T4120-08 "Mitigation Strategies for Early-Age Shrinkage Cracking in Bridge Decks" (Qiao et. al., 2010) and ...
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Shotcrete has become attractive and holds potential to replace cast-in-place (CIP) concrete for elements like retaining walls and slope stabilization. However, this practice is still limited due to concerns of drying shrinkage cracking, long-term durability, and debonding from reinforcing bars or existing structures. To provide best practices of shotcrete for wall fascia and slope stabilization, a comprehensive review on the state of knowledge of shotcrete is first provided. A desirable shotcrete mixture and a CIP concrete mixture from WSDOT benchmarks are tested for their basic mechanical properties, early age shrinkage, and long-term durability performance. The restrained ring test procedures adopted from AASHTO T334 are identified to be capable of evaluating early-age shrinkage cracking tendency of shotcrete, and the fracture energy test procedures based on three-point bending beam are considered to be more sensitive than the dynamic modulus of elasticity test in screening degradation effect of materials under rapidly repeated freezing and thawing action. Prolonged watering provide best practices to mitigate shrinkage cracking. In comparison with CIP concrete, the “before shooting” shotcrete mixture studied in Phase I exhibits better early age shrinkage resistance as well as long-term freeze-thaw resistance. The Phase II study will be conducted for evaluating “after shooting” shotcrete and their early age shrinkage and long term durability performance.
... ng practices on early shrinkage behavior of shotcrete and develop test methods for long-term performance and durability, in comparisons with cast-in-place (CIP) concrete. The testing results for CIP concrete can be found from previous reports of WSDOT projects: WSDOT T4120-08 "Mitigation Strategies for Early-Age Shrinkage Cracking in Bridge Decks" (Qiao et. al., 2010) and ...
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Shotcrete has become attractive and holds potential to replace cast-in-place (CIP) concrete for elements like retaining walls and slope stabilization. However, this practice is still limited due to concerns of drying shrinkage cracking, long-term durability, and debonding from reinforcing bars or existing structures. To provide best practices of shotcrete for wall fascia and slope stabilization, a comprehensive review on the state of knowledge of shotcrete is first provided. A desirable shotcrete mixture and a CIP concrete mixture from WSDOT benchmarks are tested for their basic mechanical properties, early age shrinkage, and long-term durability performance. The restrained ring test procedures adopted from AASHTO T334 are identified to be capable of evaluating early age shrinkage cracking tendency of shotcrete, and the fracture energy test procedures based on three-point bending beam are considered to be more sensitive than the dynamic modulus of elasticity test in screening degradation effect of materials under rapidly repeated freezing and thawing action. Prolonged watering provide best practices to mitigate shrinkage cracking. In comparison with CIP concrete, the “before shooting” shotcrete mixture studied in Phase I exhibits better early age shrinkage resistance as well as long-term freeze-thaw resistance. The Phase II study will be conducted for evaluating “after shooting” shotcrete and their early age shrinkage and long term durability performance.
... On the other hand, it can be claimed that EAMC can be reduced with increased compressive strength by using low cement content. Qiao et al. reported that low tensile strength in bridge decks resulted in less resistance to early age cracking [16]. When tensile stresses in bridge deck increased from the tensile strength of concrete, the cracks would occur [17]. ...
... Qiao et al. reported that low tensile strength in bridge deck results in less resistance to early age cracking [16]. In current work, an increase of 11% and 8.4% in STS of GFRC and NFRC, respectively, compared to that of PC is being observed. ...
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One of the major defects in concrete bridge decks are the formation of early age micro cracking which ultimately reduces its durability. The inclusion of fibers in concrete slabs has showed satisfactory performance with improved mechanical properties and reduced early age micro cracking (EAMC). The relative high compressive strength (CS), achieved by using high cement content, is the main cause of early age micro cracking in concrete. The low tensile strength (TS) also results in less resistance to early age cracking. Other factors causing EAMC include temperature rise, water content and shrinkage strain. The EAMC can be reduced by increasing CS and TS with use of economical materials other than cement. In this work, mechanical properties of glass fiber reinforced concrete (GFRC) and nylon fiber reinforced concrete (NFRC) are determined for the application of concrete bridge decks. The effectiveness of glass fibers (GF) and nylon fibers (NF) in concrete will be checked by comparing mechanical properties of GFRC and NFRC with that of plain concrete (PC). The mix design ratio of PC is 1:3.33:1.67 (cement:sand:aggregate) with a water cement ratio of 0.71. The GF and NF having a length of 50 mm and a fiber content of 5%, by mass of cement, are added in the concrete mixture for the production of GFRC and NFRC. Standard specimens are tested for determining compressive, splitting-tensile and flexural strengths of PC, GFRC and NFRC. Pre-crack energy absorption and toughness indices are also studied for different types of loadings i.e. compressive, splitting-tensile and flexural loadings. There is a decrease in compressive strength and an increase in splitting-tensile and flexural strengths of GFRC and NFRC compared to that of PC. Even though pre-crack energy absorption of GFRC and NFRC is less but their toughness indices are more than that of PC. Thus, GFRC and NFRC are suitable for reducing EAMC in bridge decks.
... Some researchers (Gara et. al, 2013;Kwak et al., 2000a,b;Qiao, 2010) suggested models that take into account hydration heat, endogenous and drying shrinkage, providing a temperature curve for the first days after slab casting and transforming the effect of hydration heat into a kind of equivalent "thermal shrinkage". ...
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Early age endogenous deformations due to concrete hydration heat, shrinkage and creep can represent a real cracking risk for composite bridge beams. The phenomenon is very complex and difficult to be taken into ac-count by designers of composite bridges, as it takes place when material properties of concrete are quickly changing in time. Recommendations on this topic in design codes and literature are generally scarce and some-times ambiguous; for instance, EN 1994-2 and SETRA Guidance book Eurocodes 3 and 4 give contradicting indications. The aim of this work is to perform three sets of non-linear thermo-mechanical analyses on three different bridges: a simply supported one with two-beam girder (50 m span) and two continuous ones, the first with two-beam girder (40+50+40 m spans), and the second with orthotropic box shaped section (60+80+60 m spans). The analyses will show the differences between the bridge typologies and will help to understand the relevance of the hyperstatic behaviour in continuous beams.
... The free shrinkage test specified in ASTM C157 [31] is a simple and widely used test to assess shrinkage of a given concrete mixture. Due to its simplicity, the free shrinkage limits have been set up based on ASTM C157 test by many agencies, including Unified Facilities Guide Specifications (UFGS) [32] and some state DOTs [33][34][35][36]. The Federal Highway Administration (FHWA) has also implemented a single value shrinkage limit in the new specifications (FP-14) [37]. . ...
... Washington DOT [36] 320 microstrain at 28 day *UFGS -Unified Facilities Guide Specifications, for military service constructions; **HVFA -High volume fly ash, minimum 50% class F fly ash. ...
... To assess the cracking potential of HPC, the restrained ring test has been used by many researchers [35,36,[42][43][44][45][46][47] in the last decade. This test had been standardized as ASTM C1581 [48] and AASHTO T334 [49] (formerly known as AASHTO PP34-98). ...
... On the one hand, RCA mixtures should exhibit higher shrinkage due to adhered mortar. A higher paste content system will experience more shrinkage compared to a similar system with lower paste content [58,59]. On the other hand, the more angular particle shape of the aggregate and rougher surface texture may provide a better mechanical bond between the aggregates and the paste thus helping to reduce shrinkage [60,61]. ...
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This study tested the hypothesis that concrete produced with recycled concrete aggregate (RCA) has increased cracking resistance compared to concrete incorporating natural aggregates. Two sources of RCA were used: (1) a laboratory created RCA produced by crushing previously produced laboratory concrete; and (2) a field RCA obtained from a demolished airfield pavement. Mechanical properties, and shrinkage and cracking due to drying of concrete produced with RCA replacement were studied. Adequate compressive strength (39.3-43.4 MPa), splitting tensile strength (3.7-4.4 MPa), and modulus of elasticity (27.2-28.3 GPa) were obtained in mixtures including coarse RCA, even at 100% replacement levels. The use of RCA did not significantly increase the drying shrinkage of concrete. It was shown that the use of RCA significantly reduced the cracking risk of concrete from "high" to "moderate-high" when incorporated into a high cracking risk mixture.