There is a large variety of wall formwork hardware available from Dayton Superior for concrete formwork construction and that variety may, perhaps, make form hardware selection a difficult decision. However, by classifying this hardware in two ways, it will help simply the selection process. The first matter is to classify form ties by their use as listed below.
These ties are so named because the entire tie rod extends through the wall as well as through both form sides. There are four types of through ties offered by Dayton Superior – rod clamps and pencil rod, snap ties and wedges, loop ties and wedge bolts or taper ties which use nut washers as eh clamping member.
Advantages
- inexpensive
- easy to install
- readily available
- carpenters and labors are generally familiar with installation procedures
- pencil rod is a field emergency tie for unusual/unexpected forming
Disadvantages
- pencil rod & taper ties do not have a form spreader feature
- Pencil rod must be chiseled back for the break back
- taper ties leave a hole through the wall
- patching costs are expensive
- pencil rod and snap ties may cause rust stains on exposed wall after a period of time
- loop ties require the use of special forms
Dayton Superior She bolts
The she bolt has external threads on the outer end to provide adjustment for variable form thickness. The inside rod is threaded at each end and fits into the threaded tapered end of the she bot. Various sizes of walers for bearing on the walers are available, as well as wing nuts or hex nuts to fir on the running thread of the she bolt.
Advantages
- she bolts have inside rods and hardware can be bench assembled
- both sides of the form can be erected and the she bolt assembly fed through the forms
- inside rods are available with machine thread (NC) rod coil threads
- contractor can make up emergency inside rods by cutting all thread or cold rod to the required length
- she bolt system can be used for various form grips or form thickness
- can be used to re-anchor to an inside rod in a previous placement
- coil threads have a faster pitch machine threads are self cleaning and will not cross thread.
Disadvantages
- no positive internal spreader action unless adaptor cones are used then it requires a seven pieces to make up an assembly.
- adaptor cones reused the she bolt assembly cannot be fed through both sides of the forms
- reinforcing steel may be in the way when feeding the tie through the forms
- she bolt has a high initial cost but can be reused hundreds of time depending on care
- danger of cross threading with machine thread
- it is difficult to inspect the nose of the she bolt for wear
Dayton Superior Coil Ties
The coil system consists of the he bolts, washers, screw on cones, and a coil tie. The he bolt are fed through the round or flat washers then through one of the form sides. The plastic screw on cone is an accessory that acts as an internal form spreader and assures a proper setback of the coil tie form the face of the form. Continues coil threaded rod can be cut in the field to handle emergency conditions and a wing nut would then be the final clamping device.
Advantages
- coil threads are self cleaning
- no chance of cross threading
- easy to examine hardware
- positive attachment to one side of the form so iron workers cannot place reinforcing steel in from of the tie hole
- working parts can usually be rented
- excellent re-anchor tie
Disadvantages
- high initial cost for the external hardware cannot be used as a feed through tie assembly
- one side of forms must be erected
- form ties attached
- reinforcing steel positioned and the closure form erected
- the remaining hardware installed