installation of waterstops

7/27/2019 Installation of Waterstops

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The performance of watersto is to a greatd e g ree dependent upon the care andskill with which they are installed, and it isthe purpose of this article to discuss someof the basic pro c e d u res which experi e n c eindicates will assure best results. In the dis-cussion that follows it is necessarily as-sumed that the joints have been pro p e r l ydesigned, located and formed, and the pro-c e d u res which are discussed relate whollyto the handling and installation of water-stops.

First off, analyze the joint across whichthe waterstop is to be installed. The type( co n traction, isolation, expansion, etc.) Aswell as the spacing of the joint will have agreat bearing on the amount of movementto be expected and, therefore, the waterstopto be used. Choose the shape and size ofwaterstop that is best suited to the job athand. (See Waterstops in Revie w, Conc ret eConstruction, December 1959, page 5.)

There are so many varieties of waterstopson the market today that it would be im-

INSTALLATION OF WATERSTOPS

Some job site practices which will help assure maximum effectiveness.

These drawings show how flat or keyed watertight joints are made using waterstops in combination with split forms.

Heating the ends of diaphragm-typewaterstops in preparation for butt

splicing. The splice is completed byholding the ends together until they

form a bond.


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p ractical to try to present detailedinstallation instructions for each ofthe many va ri a t i o n s. We will, how-ever, give a few suggestions that ap-ply to most waterstops. The variousmanufacturers are prepared to sup-ply details based on wide experi-ence with their own part i c u l a rtypes.

Ssplices

A crucially important aspect ofwaterstop instal lation is the carewith which spl ices are made. Mo s tflexible waterstops are available in50- to 125-foot rolls; this means thatfor many structures in which water-stops are used there will be a con-siderable number of splices. If thesesplices are made haphazardly, waterleakage is sure to be objectionablygreat.

T h e re are a number of jointingpa tt e rns commonly used in water-stop work, and some manufacturersp rovide a range of fittings to facili-tate handling in the field. The water-stop must be cut neatly and to a trueangle if an effective splice is to bemade. Be sure the knife used for cut-ting is sharp.

For polyvinylchloride materi a l s,heat to 450 degrees F. a 1/4-inchsteel plate on a plumbers torch (seep i c t u re series). Apply the two cut

edges of the waterstop to the plateuntil melting of the plastic com-mences. This will take from 15 to 50s e c o n d s, depending on the thick-ness and composition of the mater-ial. Hold the two edges together un-til they have cooled completely andfused together. If a splice is to bemade with one section of the water-stop already installed in a slab, thehot steel plate can be held againstthe waterstop. While the plastics arep robably the easiest of the water-stop materials to splice, the tensiles t rength (resistance to stre t c h i n gforces) at splices will usually be on-ly 60 to 70 percent of that of the un-spliced sections.

Rubber waterstops can be coldlap spliced. In this technique, theends of the waterstop are ove r-lapped about three inches with flat

Nails should be drivenin only about 1/ 2-inchinto t he form

The drawing above shows a labyrinth-type wat erstop nailed t o wood forms inpreparation for forming a watertight vertical joint in a wall.

Some of the special wat erstop fit tings w hich have been developed to speed upinstallation in the field.


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surfaces pressed together. Coatingsof rubber cement and uncured gumrubber are placed on the surfaces incontact at the splice and are held to-gether by bolting between flat stain-less steel plates. Cold lap splices arere l a t i vely easy to make and do notre q u ire any electri ci t y; but the ten-sile strength provided at the joint is

l ow. A considerably stronger splicecan be made by vulcanizing. For thistype of splice, small portable vul-canizers are used which commonlyare electrically heated. The edges tobe butted are beveled to 45 degreesor flatter. Rubber cement and un-cured gum rubber are then appliedto the ends and vulcanized, usuallyat around 290F.

Metal waterstops are spliced bymeans of welding. Although thisproduces a very watertight splice, it

necessitates special equipment,e l e c t ri c i t y, skilled workmen andmuch timeespecially when part ofthe metal waterstop is embedded inc onc ret e. In addition, metal water-stops requi re more splices becausethey cannot be conveniently han-dled in long sections.

Since the integrity of the jointswill depend to such a high degre eupon the workmanship in makingwaterstop splices, especially carefulsup ervision must be exercised over

this aspect of installation.

Ot her points

Be f o re casting concre t e, makes u re that the waterstop material isclean. If it is cove red with dirt and

g rime or if foreign materials havebecome lodged between the ri b s(especially likely when the materialhas been prot ruding for some timefrom a cast section) it will be impos-sible to achieve intimate contactwith the concre t e. Without suchcontact, pull-out is a much grea terlikelihood.

Flexible waterstops should bebraced against nearby rebars to ren-der them better able to resist thedisrupting effects of concrete place-ment. Thoroughly vibrate concre t enear the waterstops to make surethat it is completely consolidatedaround all the configurations of the

waterstop. Be certain that the centerb u l b, V-bend or other provision inthe waterstop shape for joint move-ment is positioned directly at thejoint opening.

Often a period of seve ral dayspasses while concrete is curing andp re p a rations are underway for thenext placement. Du ring this timethe exposed half of the waterstopshould be protected from damageby impact and thermal extremes.

After both portions of the con-crete have been cast there re m ai nsstill the application of the joint filler.T h e re are a number of exc e l l e n tp re p a rations on the market todaythat provide both a high degree of

water imper meability and gre a telasticity to accommodate jointmovement. They protect the water-stop material from the adverse ef-fects of the atmosphere (especiallyimportant when using rubber). Suf-

ficient time should elapse after cast-ing before application of the jointfiller to allow the greater part ofs h rinkage caused by dr ying of theconcrete to occur. The filler materi-al will then be called upon to ac-commodate only the move m e n t scaused by loading and thermal vari-ations.

Waterstops have come to play animportant role in modern concretec o n s t ruction. Their part in achiev-ing watertight structures should notbe underestimated. Through theconstant re s e a rch carried on bymanufactu rers and others interest-ed in promoting quality constru c-tion, the waterstop has become aneasily installed, inexpensive anddurable device to insure watert ightjoints in walls, floors and decks.

PUBLICATION #C600026Copyright 1960, The Aberdeen Group

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installation of waterstops

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