Tiebar Installation

See FHWA’s CRCP Design and Construction Guidelines for the references included in this page. A new, more comprehensive FHWA CRCP Design, Construction, Maintenance and Rehabilitation manual is currently under development and this page will be updated upon its release in the spring of 2016.

Both traditional and multiple-piece tiebars can be used at longitudinal joints to tie adjacent lane slabs together or to tie concrete shoulders to the mainline slab similar to jointed concrete pavements. As mentioned before, transverse reinforcement may be used in lieu of conventional tiebars. Tiebars are usually placed at mid-depth of the CRCP slab, but must be low enough to avoid damage if longitudinal joints are formed by sawing.

If slipform pavers are used, multiple-piece tiebars, bent tiebars, or mechanically inserted tiebars are inserted into the concrete while still within the confines of the slipform paver. Bent tiebars are not recommended due to joint sepa- ration failures caused either by the weakened steel or failure to bend the tiebar straight before paving adjacent lanes. Mechanical tiebar inserters work well when located in the zone of vibration and should be allowed as long as the edge does not slump.

If fixed-form pavers are used, multiple-piece tiebars (or bent tiebars) are often attached to side forms.(86) Another option is to drill and epoxy tiebars in place. Tiebars should be tested to ensure they develop a pullout resistance equal to a minimum of three-fourths of the yield strength of the steel after 7 days, as determined by ASTM E 488, Standard Test Methods for Strength of Anchors in Concrete and Masonry.

Where tiebars are to be bent and later straightened, reinforcing bars of ASTM designation A 615 Grade 40 (Grade 300) should be used to prevent fatigue cracking in the bars. This requires the spacing to be somewhat less than that for Grade 60 (Grade 420) bars used as transverse reinforcement.

Good practice is to place tiebars approximately parallel to the grade, perpendicular to the longitudinal joint, and at the specified spacing. For example, a common arrangement of tiebars consists of 30 in. (760 mm) long #4 or #5, Grade 40 (#13 or #16, Grade 300) deformed steel bars, if bending is allowed, or Grade 60 (Grade 420) when no bending is allowed, spaced at 30 in. (760 mm) center-to-center, and placed with half of the length on each side of the joint.

Tiebars should be placed at the design position within a tolerance of ± 1.0 in (25 mm) vertically (or within the center 2/3 of the slab but lower than the joint saw cut) and ± 2.0 in (50 mm) horizontally.

Where corrosion is a concern, consideration should be given to the use of corrosion resistant steel or by coating the steel with a protective layer.