Responses to Concrete Specifications Survey with Summary (2011)

Transcription

1 Responses to Concrete Specifications Survey with Summary (2011) In March of 2011, a survey was sent out by Manitoba Infrastructure and Transportation (MIT) Materials Engineering Branch to poll Department of Transportation (DOT) branches throughout the United States on their practices concerning concrete construction. Twenty-four DOTs responded to the survey along with two Canadian provinces and the feedback is documented below (Ctrl+Click questions for the actual responses). MIT is in the process of reviewing our current practices and sent out the following questions with the tallied responses: 1. Does your agency currently use epoxy coated or stainless steel dowels in concrete pavements? Concrete Dowels Stainless Steel 6% Other 17% Epoxy Coated 77% Please note that agencies reporting that they use both types of dowels were given half points for each option. Louisiana indicated they use both types of dowels for long design life pavements (bridges) but otherwise use black steel. Responses attributed to Other were from New Jersey, Florida, South Carolina, and Georgia. For the southern states, corrosion resistance was noted as not being a concern while New Jersey did not specify the reason. Washington was split into Other and stainless steel as it is one option they use for corrosion resistance (epoxy was not mentioned as a corrosion resistant option used).

2 2. Does your agency typically use an open graded drainage layer (OGDL) with a new concrete pavement? Subgrade for PCC Less Drainable Alternative 8% Open Graded Drainage Layer 19% Not OGDL (Dense Graded or Other) 73% Only three agencies explicitly stated yes they use open graded drainage layers below their concrete, however, two other agencies noted they used some less drainable layer such as untreated based course. North Carolina was considered OGDL as they use either asphalt stabilized open graded mix or base mix with reduced compaction. Although OGDL s are currently an option being used in Florida, this DOT was marked as no because they are moving to a dense graded asphalt in the future. Oklahoma, Oregon, Quebec, and New Mexico have all used it before but have since changed their specification away from this option. New Mexico in particular noted extensive problems with restraint cracking attributed to subgrade friction. Minnesota and Colorado responded no in general, however, depending on the region may use it.

3 3. Does your agency use fixed or random joint spacing for concrete pavements? Joint Spacing Fixed Random Other (Tining) 4% 4% 92% The consensus for what type of joint spacing used was by far a fixed spacing, in the majority of cases, of 15 feet. Washington State was the only DOT that reported they use primarily longitudinal tining with random spaced transverse tining on small or irregular areas. Two jurisdictions noted that either they used to have random joints or may allow it to be used in cases. Manitoba is currently using random spaced joints.

4 4. Does your agency allow diamond grinding on new concrete pavements to achieve smoothness bonus? Allow Diamond Grinding for Bonus Yes 38% No 62% The response specifically as to whether diamond grinding was allowed to achieve bonus was fairly divided. While the majority of DOT s allowed grinding for smoothness corrections, the states of New Mexico, Loiusiana, and Indiana do not provide bonus when it is used. Minnesota allows grinding corrections to correct smoothness thus becoming eligible for bonus, but noted it is typically only used to avoid penalty. Montana also honours the incentive for smoothness corrections resulting from grinding with exception to sections that exceed an index value of 15; these areas must be corrected with no bonus available. North Carolina was marked as yes because the grinding is allowed for corrections; however whether or not bonuses are given was unclear. Quebec allows the grinding (and honours bonus), however, a penalty per square metre is imposed at the same time for any ground surface. New Hampshire only has experience with one concrete project where grinding was allowed by change order for smoothness corrections and was marked no because bonus would not have been available.

5 5. Does your agency use skewed or perpendicular joints for new concrete pavements? Joint Orientation for PCC Skewed 8% Perpendicular 92% Both Manitoba and Wyoming are primarily using skewed joints. All other DOTs are using perpendicular. Oregon, South Carolina, Wisconsin and Iowa noted they have used skewed joints in the past with Oregon having success while South Carolina noted corner cracking as an issue.

6 ACTUAL RESPONSES Listed below are the responses received via from the responding DOTs: 1. Does your agency currently use epoxy coated or stainless steel dowels in concrete pavements? Utah EPOXY COATED Oregon Missouri Florida Minnesota Colorado Washington New Jersey Georgia Virginia Oklahoma South Carolina Montana New Mexico We typically use epoxy coated dowels in concrete pavements. We have used stainless steel dowels on a few experimental projects. epoxy coated. No. We use neither. We just apply a paint coating. We haven t had any corrosion problems and we obviously don t apply deicing salts to our roads. ftp://ftp.dot.state.fl.us/lts/co/specifications/workbook/jul2011/ss pdf We use both, depending upon the volume/design life. Stainless steel for 60 year design. Epoxy coated 1. WSDOT uses corrosion resistant dowel bars for new construction which may include stainless steel. ASTM A-934 bars(purple epoxy) is used for rehabilitation. See Appendix 2 for more information on WSDOT dowel bar use policy. olicy pdf No. NO VDOT Uses epoxy coated dowel bars in concrete pavement. Epoxy coated dowels bars are specified No, we do not have much winter weather down here and our use of deicers is low in comparison with colder climates. Consequently, dowel corrosion has not been a major concern. We probably need to look at some of our older PCC pavement to assess the corrosion, but the oldest sections, which are about 35 years old, are not faulting. MDT uses epoxy coated dowel bars only. [Simons, Bryce P., NMDOT] Yes, we do use epoxy coated dowels in our concrete pavements. New Hampshire [Adam Chestnut] Epoxy Coated dowels were used. North Carolina We use epoxy coated dowels. Louisiana Quebec South Dakota Wyoming Kansas Indiana Iowa We do use both stainless and epoxy coated steel when we need to for long life bridge elements (namely 100 year design). Otherwise we use black steel. Epoxy coated. We have a research project going on studying GFRP dowels and also stainless steel dowels for comparison. EPOXY YES, epoxy Yes Epoxy, Not Stainless Epoxy coated only. Epoxy

7 Wisconsin Ohio Manitoba We predominantly use epoxy coated dowels in concrete pavement. In a select few cases (high performance concrete on key corridors), we require either a stainless steel clad, stainless steel tube or zinc clad dowel. Standard is epoxy coated. Currently evaluating stainless steel tubes, stainless steel clad, and FRP dowels under pooled fund TPF-5(188). Seehttp:// Epoxy coated. 2. Does your agency typically use an open graded drainage layer (OGDL) with a new concrete pavement? Utah UNTREATED BASE COURSE...a-1-a...drain able material Oregon Missouri Florida Minnesota Colorado Washington New Jersey Georgia Virginia Oklahoma South Carolina Montana In the past we used open graded aggregate base and asphalt treated permeable base. However, we now only specify dense graded hot mix asphalt for new concrete pavement. We observed early cracking and greater crack thicknesses in our concrete pavements (CRCP) built on top of the open graded bases. MoDOT's Type 5 aggregate base, which is normally placed as a 4-inch layer and contains 15 % or less fines, is intended to provide drainage. In some cases stabilized permeable bases are used. It is one of three drainage options and has been used on a number of projects. We are moving more to dense graded asphalt bases with edge drains. Not typically, except in the southwest part of the state. It depends upon subgrade and aggregate sources. We are beginning a project to look at creating a performance base that provides enough drainage (whatever that is J) and stability. This varies based upon the materials designer in each Region, but generally I would say no. No. WSDOT uses a dense graded HMA. No. 3" 19MM SUPERPAVE INTERLAYER Yes, VDOT uses asphalt treated drainage layer 2-3 inches thick. It is stable, but drainable at least 1500 ft/day. Used to, now we specify a lean concrete or asphalt 4"-5" thick on top of 6-12" agg. base, depending on anticipated truck traffic. Not routinely, only on unbounded PCC overlays over existing PCC, which is rare. No, MDT uses our standard crushed aggregate course that is somewhat dense graded but is low on the 200m. (slow draining but it does drain.) MDT also uses plant mix surfacing as a base for PCCP. New Mexico [Simons, Bryce P., NMDOT] No, not anymore. We believe we had extensive problems with restraint cracking in our pavements due to subgrade friction. However, we are currently planning one project that is using CTOBG topped with an asphalt treated OGB directly underneath the PCCP which will hopefully reduce the subgrade friction. New Hampshire [Adam Chestnut] The ORT concrete was placed partially on existing pavement (not OG Pavement), partially on compacted gravel, and partially on the existing concrete North Carolina Louisiana Quebec structural slab for the Toll Plaza. We use either an asphalt stabilized open graded mix (Permeable drainage layer) or a base mix with reduced compaction. No We did use it on a couple of contracts with JPCP and all of the 50 km CRCP (except the first 2 km in 2000). We will not use it anymore.

8 South Dakota Wyoming Kansas Indiana Iowa Wisconsin Ohio Manitoba NO YES No Yes, 3 inches open graded with 1 inch maximum size. Yes We do have open graded base in the specification, but have not specified it for quite a few years. We use dense graded aggregate base almost exclusively. No, Ohio DOT has a moratorium on open graded bases under concrete, see nformation/fbd_use_ pdf s/reports/2000/pavements/14652-fr(b).pdf and attached paper No. 3. Does your agency use fixed or random joint spacing for concrete pavements? Utah FIX but we are looking into allowing random Oregon In the past we specified random joint spacing. However, we are now using fixed joint spacing (typically 15 ft). Missouri Fixed. Florida Fixed transverse spacing of 15 feet. Minnesota Fixed. 15 Fixed spacing based upon design Colorado Washington WSDOT uses longitudinal tining as the standard. Random spaced transverse tining is used for small or irregular areas. New Jersey Fixed. Georgia FIXED AT 15 FEET Virginia VDOT uses fixed joint spacing, typically 15 ft. Oklahoma Fixed joint spacing of 15' South Carolina We currently use a 15-foot fixed pattern. We used a pseudo-random pattern on some projects in the later 1970s and 1980s. However, these sections were all doweled and are not exhibiting noticeable faulting at this time. In the meantime, we are seeing more prevalent transverse mid-panel cracking in the longer panels. Montana Because MDT primarily uses PCCP in curb and gutter sections the majority of our joint spacing designs are fixed. New Mexico [Simons, Bryce P., NMDOT] We use fixed joint spacing, with a maximum spacing not to exceed 15 ft. New Hampshire [Adam Chestnut] Fixed Joint Spacing was used. This was somewhat dictated by North Carolina Louisiana Quebec South Dakota Wyoming traffic loop installations. We use fixed spacing (15'). Fixed at 20 feet Fixed, between 4,5 to 5,5 m equally spaced joints. FIXED YES, fixed

9 Kansas Fixed at 15 Indiana Fixed, between 15 to 18 feet. Iowa Fixed Wisconsin Fixed Joint Spacing, 15. Ohio 15' fixed Manitoba Random joint spacing. 4. Does your agency allow diamond grinding on new concrete pavements to achieve smoothness bonus? Utah No Oregon No. Missouri Yes. Florida We currently require continuous diamond grinding for both smoothness and lower tire/pavement sound. Yes, they can earn a 3% incentive for smoother pavement. ftp://ftp.dot.state.fl.us/lts/co/specifications/specbook/2010book/352.pdf Minnesota Colorado Washington Its allowed, but typically the only time the contractor does it is if they are in the penalty situation. Then they grind and are eligible for incentive. Yes, but not 100% grinding of the surface Not intentionally. We had a recent project that following construction diamond grinding a significant portion of the roadway was required due to smoothness concerns. Generally, a diamond grinding incentive is not provided. We have provided an incentive on a recent project to see how it works out. New Jersey Yes. Georgia NO Virginia No. Oklahoma No, however the contractors are required to grind bumps ( > 0.60 in.) in any 25' sections South Carolina Yes, we require a diamond-ground surface as the final texture on new PCC pavement for limited access facilities. For lower-speed sections, we require transverse tining with spot grinding for bumps. However, if more than 52 linear feet within a 528 foot by 12 foot segment has been ground, regardless of transverse width of the grinding, the entire segment has to be ground for aesthetics. Montana MDT, allows corrective grinding and may grind to meet the smoothness bonus, but with an exception. Incentive will not be paid on sections with an initial index exceeding 15. (Using a Profilograph.) New Mexico [Simons, Bryce P., NMDOT] Yes, we do allow one grinding pass to improve New Hampshire North Carolina Louisiana Quebec smoothness, but no bonus can be paid in those areas that are ground [Adam Chestnut] We did Diamond Grind the concrete. This was a change order that resulted from a poor finish on the concrete and a desire to remove the top surface of the concrete where a high water cement ratio exists. We have used diamond grinding to achieve ride quality, but encourage contractors to achieve ride quality beginning at the subgrade and building to achieve ride in every layer. We allow, but only for 100% pay (NO Bonus) Yes, but we have a penalty of 5,40 $/m2 of grinding. (Contractor) will have a bonus if he has under 1,2 m/km, with or without grinding.

10 South Dakota Wyoming Kansas Indiana Iowa Wisconsin Ohio Manitoba NO NO Yes Yes, but contractor doesn t receive more bonuses after grinding. No. They can only grind to avoid disincentive. If grinding is used to repair bumps/rough areas, these repairs will be considered before assigning roughness penalties, but no bonus is paid on the corrected surface. No, grinding can be used to reduce a negative pay adjustment but not to achieve an incentive. see Proposal Note 420 at salnotessupplementalspecificationsandsupplements.aspx No. 5. Does your agency use skewed or perpendicular joints for new concrete pavements? Utah Perpendicular Oregon Missouri Florida Minnesota Colorado Washington New Jersey Georgia Virginia Oklahoma South Carolina Montana New Mexico New Hampshire North Carolina Louisiana Quebec South Dakota Wyoming Kansas Indiana We juse perpendicular joints for new concrete pavements. we have used skewed joints in the past with success. Perpendicular. Perpendicular. Perpendicular. Perpendicular WSDOT uses perpendicular joints. Perpendicular. PERPENDICULAR VDOT uses perpendicular joints. Perpendicular joints only. Perpendicular. We used skewed joints on a few projects in the early 1970s. The skewed joints did greatly reduce faulting, but corner cracking has been an issue with these sections. Our agency began using perpendicular dowel joints in 1976 and that has been our standard since that time. MDT uses perpendicular joints only. [Simons, Bryce P., NMDOT] We use perpendicular joints. [Adam Chestnut] Perpendicular Joints in this case. We only use perpendicular joints. Perpendicular joints Perpendicular. PERPENDICULAR YES, skewed Perpendicular Only perpendicular.

11 Iowa Wisconsin Ohio Manitoba Skewed for about 25+ years then switched to Perpendicular 5 years ago. Our joints are perpendicular to the Centerline. In the past we used skewed joints, but this practice was stopped around Perpendicular Skewed.