Bond strength recovery of tack coat in RCC-base composite pavements

Tack coat materials, which are typically emulsified bituminous products, are used to provide a sufficient bond between asphalt concrete (AC) layers/lifts. Owing to construction limitations and severe temperature variations in cold regions, agencies are investigating the use of fast curing and non-tracking emulsions as tack coat materials. The objective of this study is to evaluate the performance of various tack coat products in cold climates. Several tack coat products were installed during a field study in Saskatchewan, Canada. The tack coat products included slow setting, medium setting, and three proprietary fast curing/non-tracking emulsions. Core samples were collected three weeks after construction to evaluate the initial interlayer shear strength (ISS) for typical construction conditions in cold regions. Although the ISS values for all of the products, except one SS-1 section, varied in a narrow range, this does not indicate that all products will have a similar long-term performance. The modes of failure for the bond strength samples were classified into two types according to the shape and location of the failure surface: type A and type B. Failure type B indicates that the tack coat material can successfully provide sufficient bond strength to make the two AC lifts behave as one thick homogenous layer. The results showed that the failure mode should be included as an evaluation criterion in addition to ISS. The results showed that the energy required to reach peak shear stress is a comprehensive parameter that should also be considered when evaluating tack coat materials.

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Effects of Tack Coat Type and Surface Characteristics on Interface Bond Strength

New Frontiers in Road and Airport Engineering ◽

10.1061/9780784414255.004 ◽

2015 ◽

Cited By ~ 1

Author(s):

Weidong Huang ◽

Quan Lv ◽

Jianjun Tian

Keyword(s):

Bond Strength ◽

Surface Characteristics ◽

Tack Coat ◽

Interface Bond Strength ◽

Interface Bond

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Effects of Tack Coat Application on Interface Bond Strength and Short-Term Pavement Performance

Transportation Research Record Journal of the Transportation Research Board ◽

10.3141/2633-02 ◽

2017 ◽

Vol 2633 (1) ◽

pp. 1-8 ◽

Cited By ~ 7

Author(s):

Ramendra Das ◽

Louay N. Mohammad ◽

Mostafa Elseifi ◽

Wei Cao ◽

Samuel B. Cooper

Keyword(s):

Shear Strength ◽

Bond Strength ◽

Pavement Performance ◽

Interface Bonding ◽

Short Term ◽

Surface Type ◽

Tack Coat ◽

Interface Bond Strength ◽

Interface Bond ◽

Coat Material

The objectives of this study were to evaluate the effects of pavement surface type, tack coat material, and application rate on the interface bond strength between a hot-mix asphalt overlay and underlying pavement layers in the field. The effects of interface bonding on short-term pavement performance were also investigated. Three field projects that included 14 in-service test sections were constructed with four types of emulsified tack coats applied at different residual application rates. Specimens were cored from the test sections, and the interface shear strength (ISS) was measured at different service times with a direct shear test device, the Louisiana interlayer shear strength tester. The results of the study showed that, with respect to surface type, the ISS was largely dependent on the type of pavement surface receiving tack coat materials and surface texture. With respect to tack coat material type, the use of a nontracking (rapidly setting) tack coat resulted in a greater ISS than the use of slowly setting (SS-1 and SS-1H) tack coats, a result that was primarily attributed to the stiffer base asphalt cement used in the nontracking tack coat material. With respect to the effects of service time, the interface bonding strength increased with service time in all field projects and for all surface types. This phenomenon was primarily attributed to tack coat curing, which was more pronounced with slowly setting tack coat materials. Laboratory ISS test results correlated well with short-term field performance. All test sections except those that did not meet the minimum ISS threshold of 40 psi, recommended by NCHRP Project 9-40, exhibited satisfactory cracking performance.

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BOND STRENGTH RECOVERY OF FIRE-DAMAGED CONCRETE AFTER POST-FIRE-CURING

Proceedings of International Structural Engineering and Construction ◽

10.14455/isec.res.2015.63 ◽

2015 ◽

Vol 2 (1) ◽

Author(s):

Zhuguo Li ◽

Yasuhiro Ryuda

Keyword(s):

Bond Strength ◽

High Strength ◽

Test Results ◽

Strength Concrete ◽

Pull Out ◽

Strength Recovery ◽

Steel Bars ◽

Bond Strengths ◽

Normal Strength ◽

Curing Age

The effects of post-fire-curing on the bond strength recovery of fire-damaged concrete were investigated in this study. Normal strength concrete (NSC) and high-strength concrete (HSC) specimens with deformed steel bars were prepared respectively. We measured the bond strength of unheated NSC and HSC, and exposed other NSC and HSC specimens to high temperatures of 300℃, 400℃, and 500℃, respectively for 120 minutes. Following by rapid cooling with water, the bond strengths of heated NSC and HSC were measured instantly without re-curing, the remains were cured in water for 28 days, or further in the air of 20℃, 60% R.H. for 56 ~62 days. After the re-curing, the pull-out tests were conducted. The test results indicate that the post-fire-curing contributes to a substantial bond strength recovery of heated concrete. The longer the re-curing in water, the greater the recovery extent. At 90 days of re-curing age, the bond strength rose up to around 77% for NSC, and around 70% for HSC, respectively.

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