Portland Cement Concrete Pavement Joint Sealant Practices and Performance (2021)

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41   DOT representatives from six states (Arizona, California, Iowa, Louisiana, North Dakota, and South Dakota) were interviewed to collect additional information on joint sealant practices incorporated into specific projects. The agencies interviewed were selected from among those with established requirements and practice for joint sealant, review, and field oversight. Lessons learned from case example interviews are included at the end of the chapter. Arizona In Arizona, only one-component hot-pour sealant materials that conform to the require- ments of either ASTM D3406 or ASTM D3569 are allowed. Coal-tar materials are not allowed. Emphasis is also placed on maintaining the minimum ambient temperature during applica- tion and storage (ADOT 2008). Before installation, each joint face is thoroughly cleaned. The approved cleaning method must include sandblasting and air blasting (which is oil- and water- free) to clean the joints. Afterward, the joints are further washed, so that each face is clean, dry, and dust-free. Silicone joint sealants must comply with the requirements shown in Figure 30 and be applied in accordance with the recommendations of the manufacturer. All field tests recommended by the manufacturer are performed by the engineer. An evaluation carried out in 2006 of eastbound US-60 in Mesa is summarized in Table 5 (ATRC 2006). California Caltrans responded in the questionnaire that most types of sealants maintain a service life of more than 15 years. Caltrans requires all joint sealants to be selected from an authorized material list. The agency systematically manages product approval and quality assurance but without the use of the NTPEP database for those purposes. The agency uses a joint configuration of varying widths from 1⁄4 in. to 5⁄8 in. while satisfying recommended ACPA SF guidelines for both silicone and hot-pour sealants. For quality control, Caltrans requires the contractor, before installation, to arrange for a representative from the sealant manufacturer to provide training on cleaning and preparing the joint for installation of the liquid or preformed compression sealant. Cleaning must be completed no more than 4 hours before installing backer rods, liquid joint seal, or preformed compression seals (Caltrans 2018). C H A P T E R 4 Case Examples

42 Portland Cement Concrete Pavement Joint Sealant Practices and Performance Joint cleaning consists of five processes—removing debris, drying, sandblasting, air blasting, and vacuuming—that are covered in detail by the agency’s specifications. The installation is accepted on the basis of constructed dimensions and visual inspection of completed seals for voids. Table 6 lists specific project performance data in California. Iowa The Iowa DOT was selected because of indications of having performance life over 15 years, which led to additional questions in a follow-up interview. The agency responded that it uses the NTPEP database for product approval of the sealant. The use of NTPEP data for product Figure 30. Joint configurations for SPS-4 supplemental joint seal test sites, Arizona. Question Answer* Ranking of Combination of Sealant Material and Joint Configuration** Duncan Class*** Is there a significant difference in overall 2006 seal performance? Yes Neoprene, jt. config. = C, FAIL = 134 in. A Neoprene, partially sealed, jt. config. = C, FAIL = 66 in. B Silicone, full seal, jt. config. = A and B, FAIL = 12.5 to 24.8 in. C Silicone, full seal jt. config. = C, FAIL = 1.7 in. D Is there significantly more spalling in the wheel paths? Yes Wheel path (spall length = 1.56 in.) A Nonwheel path (spall length = 1.38 in.) B Is spalling statistically more common for different materials or configurations? Yes Silicone, self-leveling, jt. config. = A and C (spall length ranges from 16.1 in. to 19.8 in.) A Silicone self-leveling, jt. config. = B, and silicone, non-self- leveling, jt. config. = C (spall length ranges from 12.3 in. to 14.3 in.) B Neoprene, jt. config. = C (spall length = 7.6 in.) C Is there statistically more faulting in the no seal than the partial- or well-sealed joints? Yes No seal (faulting = 0.03 in.) A Partial seal (faulting = 0.015 in.) B Sealed (faulting = 0.015 in.) B *Based on a significance level of 95 percent. **See Figure 30 for description on joint configuration (JC); FAIL is the total length in inches of adhesion and compression failure and spalling at the joint. ***Sealant types/configurations with the same letter are not significantly different. Using the data collected and assembled, an analysis of variance was conducted to determine joint seal effectiveness and the effect of sealing on pavement performance by Duncan’s Multiple Range Test. Table 5. Summary of statistical analysis on joint and sealant performance (ATRC 2006).

Case Examples 43   approval and acceptance procedures and specifications used for PCC pavement joint sealants is effective for product quality assurance. The typical joint width used by the agency is 1⁄8 in. A joint sealer is used as specified in the contract documents and as recommended by the manufacturer (Figure 31). The procedure for joint preparation according to the Iowa DOT specification is as follows: 1. Use a high-pressure water blast running at a minimum pressure of 1,000 pounds per square inch, and flush the wet sawing residue away from the sawed faces within 3 hours from the Sealant Life Projects Condition Rating (Good, Fair, and Poor) Traffic (AADT/AADTT) Joint Condition (severity spalling/Total in %) (Low/Med/High) < 5 years Hwy 86 Imperial County PM R21.9/43.1 – Silicone placed in 2015 3.68 to 4.60 13,900/3,222 0.4/0/0/0.4 Hwy 58 San Bernardino County PM R22.2/ R31.1 – Preformed placed in 2015 3.80 to 4.50 14,000/5,068 0.1/0/0/0.1 I-10 San Bernardino County PM R32.9/ R37.4 – Preformed and silicone placed in 2016 4.33 180,000/18,720 1.5/0.1/0/1.6 I-5 LA County PM R45.4/R61.2 – Preformed placed in 2017 3.19 to 4.40 206,000/20,023 4.1/0.2/0.1/4.4 > 15 years of service NA NA NA NA NOTE: AADT = annual average daily traffic; AADTT = annual average daily truck traffic; NA = not available. Table 6. Joint sealant performance and joint condition data (from the 2018 Pavement Management System Condition Survey, CA). Figure 31. Specification of joint sealant configuration, Iowa (Iowa DOT 2015).

44 Portland Cement Concrete Pavement Joint Sealant Practices and Performance finished dimension. Blow the dry sawing residue from the joint with air compressors to provide moisture and oil-free compressed air within 3 hours after a seal is restored to the finished size (Iowa DOT 2015). 2. Clean joints with an air blast immediately before the installation of the sealant. Do not seal until visual inspection checks that the joint surfaces appear dry and clear of dust and contamination. Cleaning is carried out in a very specific and systematic manner, and the level of contamina- tion and humidity in the reservoir is checked through visual inspection. The basic types of distress most often experienced are shown to be aging and cohesive cracking. As in Louisiana (described next), the state’s joint preparation methods have likely contributed to relatively long joint sealant life due to the preservation of bond strength. Louisiana The Louisiana Department of Transportation and Development (LaDOTD) has experienced joint sealant performance life ranging from 11 to 15 years. On the basis of analysis of LaDOTD’s response to the survey questions, additional questions were presented in follow-up interviews highlighting a few notable items. LaDOTD responded that it uses the NTPEP database for product approval of sealant materials. Product selection of a sealant material in this manner appears to be beneficial in extending sealant life. The agency uses SFs ranging from 1.5 to 2.0 for joint sealant design following ACPA design guidance; however, joint widths are found to be 1⁄8 in. narrower than ACPA’s design recommendations. The basic type of distress most often experienced is debonding. As shown in Figure 27 in the previous chapter, most states selected debonding and adhesive separation failure as the most frequently experienced types of joint sealant distress. Debonding can be caused by loss of bond strength due to insufficient cleaning during joint preparation before installation. LaDOTD uses sandblasting followed by an oil-free air jet to thoroughly clean the joints immediately before sealing (LaDOTD 2016). LaDOTD has data on projects, including which type of sealant was used along with the ages of each. It also collects and provides traffic data. It has data for the amount of spalling on the joints, but only if that information is part of the automated data collection carried out every 2 years. The agency does not collect data on the length of debonding per joint. North Dakota (Alternative) The North Dakota DOT (NDDOT) does not seal joints but instead fills them, making North Dakota one example of a state using an alternative to joint sealing. Current specifications in NDDOT’s standards include the use of a 1⁄8 in.-wide sawcut that is cut one-third the depth of the pavement. NDDOT also mainly uses hot-pour sealants, but a variation to this practice is the use of a 1⁄2 in.-wide cut that is filled with silicone. NDDOT’s standard specifications also call for the joints to be clean and dry before installa- tion of the sealant. Compressed air is used to clean the joints. Application of the joint sealant is allowed only when the air temperature is 40°F or higher. Joints are sealed no more than 10 days after the placement of concrete (new construction) but before opening to construction and public traffic (NDDOT 2019). NDDOT has been using these standards for 7 to 8 years and has not experienced any distress associated with spalling.

Case Examples 45   South Dakota SDDOT indicated projects with joint sealants demonstrating performance greater than 15 years of service life. Its practices include a 3⁄8 in. reservoir width for joint sealants, as shown in Figure 32. SDDOT also limits the allowable range in widths to the tolerances (Table 7). For hot-pour sealants, 1⁄8-in. and 1⁄4 in. widths are used for filled joints, as shown in Figure 33. Both silicone and hot-pour material are used in a recessed sealant configuration, with the sealant placed slightly below the pavement surface. SDDOT has adopted the practice of using silicone sealants on rural high-speed routes and hot-pour sealants on urban slower routes that typically include curbs and gutters. In the agency’s experience, silicone seals in urban pavements often fail much sooner than silicone seals in rural pavements. It was determined that in urban pavements the accumulation of dirt, sand, snow, and ice in the joint reservoir would pack down under traffic on top of the silicone sealant, making it “punch” down and causing an adhesion failure. With regard to hot-pour sealants, SDDOT specifies that any material spilled on the surface of the concrete pavement must be removed as soon as the material has cooled. The engineer judges when removal of material has been carried out to a satisfactory level. Also, SDDOT inspectors are trained in the use of a black glove finger wipe test that is essentially the same as the ACPA wipe test. NOTE: The first sawcut to control cracking will be a minimum of one-fourth the thickness of the pavement. Additional sawing for widening the sawcut to provide the width for the installation of the low-modulus silicone joint sealant will be necessary. The backer rod will be a non-moisture-absorbing resilient material approximately 25 percent larger in diameter than the width of the joint to be sealed. Figure 32. Joint sealant specification for silicone sealant, South Dakota (SDDOT 2015). A Min. (in.) A Max. (in.) B Min. (in.) B Max. (in.) 3/16 5/16 1/8 1/4 Table 7. Low-modulus silicone sealant allowable construction tolerances, South Dakota.

46 Portland Cement Concrete Pavement Joint Sealant Practices and Performance SDDOT reported that important factors in improving the performance of joint sealant are • “for silicone sealants, to ensure during Inspection the necessary cleanliness to promote a good bond between the sealant and the concrete; also, to recess the sealant a little below the surface of the pavement to minimize contact with the passing traffic while maintaining the proper shape factor” and • “for hot-pour sealant, again to ensure during Inspection the necessary cleanliness prior to sealing to promote bond and enough depth of sealant to prevent loss of bond during the winter months.” SDDOT practices include having its maintenance forces carry out occasional spot-fixing with hot-pour sealants on an as-needed basis. Project-level resealing is done only by contract and tends to occur every 12 to 25 years. Table 8 lists specific project performance data in South Dakota. Joint Sealant Specifications Summary Table 9 shows a summary of the joint sealant specifications of DOTs that participated in follow-up interviews to ascertain examples of joint sealants and alternative practices. Although such a link is not directly stated in the responses, analysis of the data suggests that the use of the NTPEP database for product approval and quality assurance tends to positively influence the life span of the sealant, as shown in Table 10. It also appears that the quality assur- ance of the installation process regarding the initial bond of the sealant outweighs the effect of meeting SF design criteria in extending the life of the joint sealant. Lessons Learned from the Case Examples A review of the case examples reveals the following lessons learned: • Interviewed DOTs mostly use approved lists for sealant selection. SDDOT has a very specific and systematic product approval process and manual. NOTE: If an early entrance sawcut does not develop the full transverse crack, then the sawcut to control cracking will be a minimum of one-fourth the thickness of the pavement. Figure 33. Sealant specification for hot-pour filled joints, South Dakota (SDDOT 2015).

Sealant Life Projects Condition Rating(0–5) Traffic (ADT) Joint Condition (0–5) < 5 years na na na na > 15 years of service Hwy 83 from 14 Junction N. to Onida (2 projects) — silicone placed in 1996 and 1997 (resealing scheduled for 2020) 3.68 to 4.60 1,814 3.71 to 4.00 Hwy 79 from Hot Springs Junction N. to Hermosa (2 projects) — silicone placed 2007 and 2012 3.80 to 4.50 4,366 3.83 to 4.57 I29 SB S. of Junction City — silicone placed in 2009 4.33 6,427 4.37 I90 EB and WB Rapid City E. and W. of Exit 60 — hot-pour (test section) placed in 2006 3.19 to 4.40 15,000 3.47 to 3.70 NOTE: na = not applicable. Table 8. Joint sealant performance and joint condition data, South Dakota. ADOT Caltrans Iowa DOT LaDOTD NDDOT(Alternative) SDDOT Product approval Department’s Approved Products List shall be used. Authorized Material List NTPEP database NTPEP database NTPEP database Authorized Material/Product List Sealant configuration Specified by DOT and use manufacturer recommendation. Use manufacturer recommendation. Use manufacturer recommendation. Specified by DOT Use manufacturer recommendation. Specified by DOT Preparation Contractor shall clean the joints by sandblasting. The joints shall then be further cleaned by use of high-pressure air jets so that each face is clean, dry, and dust-free. Joint cleaning consists of five processes: 1. Removing debris 2. Drying 3. Sandblasting 4. Air blasting 5. Vacuuming Within 3 hours, high-pressure water blast. Blow the dry sawing residue. Clean joints with an air blast immediately before installation. Keep the sandblasted joint faces dry and dust- free prior to sealant installation. Air temperature at the time of placement shall be at least 50°F. Apply joint sealant to clean and dry joints. Use an air compressor to clean the joints. Apply joint sealant when the air temperature is 40°F or higher. Cleaning shall be accomplished by sandblasting and other tools as necessary. Just prior to sealing, each joint shall be blown out using a jet of compressed air. Inspection Not specified Engineer accepts joint seals based on constructed dimensions and visual inspection of completed seals. Do not seal until visual inspection checks. Do not install the sealant until joint verification for cleanliness. Not specified Black glove finger wipe test (same as the ACPA wipe test) Table 9. Summary of joint sealant specification of DOT case examples.

48 Portland Cement Concrete Pavement Joint Sealant Practices and Performance • Joint sealant design either follows the manufacturer’s instructions or is carried out within the scope of ACPA design recommendations. • Most joint preparation procedures are carried out at least twice before installation. These procedures include careful cleanup and removal of dust, moisture, and oil. In the event that joint sealing is delayed after cleaning, joint cleaning is systematically repeated just before installation takes place. • Inspection of joint preparation operations is found to be populated with a variety of custom- ized tests. Three states require inspection before installation. It is anticipated that such joint inspection protocols will prevent or reduce the incidence of bond or adhesive failure (in the early stage of pavement life) of the joint sealant. Joint Sealant Performance Life Experienced by Agencies 5–10 Years More than 10 Years Usage of the NTPEP database product approval and quality assurance Number of agencies (share of responses) Number of agencies (share of responses) Yes 2 (22%) 4 (67%) No 7 (78%) 2 (33%) Principle distress type(s) most frequently experienced Debonding and adhesive separation 7 (64%) 4 (40%) Aging and cohesive cracking, displacement 4 (36%) 6 (60%) Table 10. Relationship between joint sealant performance life and joint sealant practice.