Waterstops c 4

EM 1110-2-2102 30 Sep 95

Chapter 4 Design

4-1. Waterstops Waterstops a. Genera General. l. Waterstop Waterstopss are designed designed for hydraulic hydraulic structures to withstand continuous water pressures for the life expectancy of the structure or for cyclic water levels and pressure pressuress in floodw floodwall allss and locks. locks. Factor Factorss affect affecting ing design dimensions of metallic waterstops are largely traditional, stemming from experience rather than computation. The selection of nonmetallic waterstops is predicated to a great extent on hydrostatic considerations.

(1) Figure Figure 4-1 shows the relati relation on of materi material al thickthickness and width requirements of polyvinyl chloride waterstops versus versus the height of hydrostat hydrostatic ic head. For example example in the graph, a concrete dam or lock that is designed to resist resist a 300,00 300,000-P 0-Paa (100 (100 ft of water) water) head head of hydros hydrostat tatic ic pressu pressure re may requir requiree a PVC waters waterstop top that that is 250 mm (10 in.) wide and only 4 mm (0.16 in.) thick, whereas an 8-mm 8-mm (0.3 (0.322-in in.) .)-t -thi hick ck PVC PVC wate waters rsto top p need need only only be 100 100 mm mm (4 in.) in.) wide wide as show shown n in Figu Figure re 4-2. 4-2. A wide wide range of PVC waterstop dimensions may be used to resist a single single head pressur pressure. e. This This relati relations onship hip represe represents nts an average average value of hydrostat hydrostatic ic pressure pressure ratings ratings for various sizes of PVC waterstops and is therefore relatively insensitive sitive to small, small, subtle subtle variat variation ionss in the config configura uratio tion n of  each each indivi individua duall waters waterstop top.. Thus, Thus, the graph graph is only valid valid for use as general guidance in the design and selection of  PVC waterstops. waterstops. Additional Additional data concerning concerning the material material proper propertie tiess of PVC waters waterstop topss are presen presented ted by Hoff Hoff and Houston (1970). (2) Certain Certain waterstop waterstop sizes sizes are used much more often than than othe others rs.. Whet Whethe herr thro throug ugh h refe refere renc ncee to prev previo ious us desi design gnss or to peer peer usag usage, e, desi design gner erss prim primar aril ily y spec specif ify y 150-mm 150-mm (6-in. (6-in.)) and 225-mm 225-mm (9-in. (9-in.)-w )-wide ide waters waterstop tops. s. Thus, production, production, availability availability,, and usage have become a self-perpetuating cycle in the design requirements of nonmetallic waterstops. b. Conventio Conventional nal design considerati considerations. ons.   Design engineers must consider several factors in selecting waterstop materi materials als for possib possible le use in their project projects. s. Hydrau Hydraulic lic stru struct ctur ures es requ requir iree wate waters rsto tops ps in all all movi moving ng and and nonnonmoving moving joints. joints. The lateral lateral movemen movementt antici anticipat pated ed for a  joint wall determines the types of waterstop to be select selected. ed. The vertical vertical movemen movementt antici anticipat pated ed for a joint joint will determine the shapes of the waterstop to be selected. The anticipat anticipated ed hydrostat hydrostatic ic head of water will determine determine the the thic thickn knes esse sess and and the the widt widths hs of the the wate waters rsto top p to be

selected. selected. The anticipate anticipated d allowable allowable water migration migration for a  joint will determine both the types and shapes of the waterstop waterstop to be selected. selected. The anticipate anticipated d size of the joint openin opening g will will determ determine ine the config configura uratio tions ns or profil profiles es of  the waterstop waterstop to be selected. selected. Every structur structuree and project is diff differ eren entt and and will will be desi design gned ed for for thei theirr resp respec ecti tive ve requirements. c. Unconvent Unconventional ional design design considerat considerations. ions.   Design engineers engineers will consider consider several several other factors in selecting selecting waterstop waterstop materials materials for use in their structur structure. e. The perforperformance mance of waterstop waterstop materials materials is affected affected by factors factors prior to their use in a concrete structur structure. e. The anticipat anticipated ed exposure sure of the the wate waters rsto top p mate materi rial al at a proj projec ectt prio priorr to the the time both edges are embedded in the concrete will affect the determination determination of selecting selecting the thickness thicknesses es and widths widths of the the wate waters rsto tops ps.. The The anti antici cipa pate ted d type typess of mate materi rial alss handling procedures and techniques at a project will affect the determinati determination on of waterstop waterstop selection. selection. Many materials materials may become worn, fatigued, fatigued, or damaged damaged from excessive excessive handli handling ng and exposu exposure re to the enviro environme nmenta ntall elemen elements ts during during construc constructio tion. n. Rubber Rubber material materialss are more more suscep suscep-tible tible to ozone ozone exposu exposure re than than others others.. Polyvi Polyvinyl nyl chloride chloride materi materials als as well well as rubber rubber materi materials als are suscep susceptib tible le to oils, solvents, and other chemicals.

4-2. Preformed Preformed Joint Joint Seals Seals a. Genera General. l. Pref Prefor orme med d comp compre ress ssio ion n seal sealss are are designed designed primarily primarily for nonhydraul nonhydraulic ic structures structures to prevent prevent the introduction introduction of unwanted unwanted and harmful harmful particles particles from enteri entering ng the joint joint and causin causing g excess excessive ive compre compressi ssiona onall forces to be applied to the concrete surfaces during periods of expans expansion ion.. It is the variati variation on in joint joint conditio conditions ns and joint material properties which influence the selection of one joint material material over over another. another. The compressi compression on seal is design designed ed to be compre compresse ssed d and insert inserted ed into into design designed ed expansion and contraction joints of hardened concrete and remain remain in a compre compresse ssed d state state throug throughou houtt its life in the  joint. Although preformed compression seals are installed with lubricant lubricant/adh /adhesive esive for easy installat installation ion and bonding bonding to the concrete concrete surfaces surfaces,, they they are not design designed ed to resist resist tensile forces, therefore the designer must be aware of the antici anticipat pated ed contra contracti ction on that that may occur occur in the concre concrete te structure structure and particula particularly rly in the structural structural element. element. Preformed compression seals should always be compressed to a minimum minimum of 15 percent percent of the material material width. width. With the preformed preformed compression compression seal always always in compressio compression, n, the seal sealan antt will will chan change ge its its shap shapee as the the widt width h of the the join jointt open openin ing g chan change ges, s, ther theref efor oree the the desi design gner er must must also also be aware of the depth of the joint to allow the joint material to flex, normally downward into the joint.

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EM 1110-2-2102 30 Sep 95

WATERSTOP DIMENSIONS vs HYDROSTATIC HEAD POLYVINYL CHLORIDE WATERSTOP MATERIAL

Lines of Hydrostatic Pressure

   m    m  ,    s    s    e    n     k    c     i     h     T    p    o     t    s    r    e     t    a     W

600,000 Pa (200 ft)

525,000 Pa (175 ft)

450,000 Pa (150 ft) 375,000 Pa (125 ft) 300,000 (100 ft) 225,000 Pa (75 ft) 150,000 Pa (50 ft) 75,000 Pa (25 ft)

Figure 4-1. This graph shows the general relationship between polyvinyl chloride waterstop dimensions to the hydrostatic head pressure of water

250 mm 4 mm

125 mm

8 mm

Figure 4-2. These two polyvinyl chloride waterstops of different dimensions may be used under identical 300,000-Pa (100 ft of water) hydrostatic head pressures as depicted in the graph shown in Figure 4-1

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EM 1110-2-2102 30 Sep 95 (1) Joint Dimensions for Preformed Compression Seals. These seals have a variety of different dimensions in width and height to cover a broad range of joint dimensions. The characteristics of the joint opening dictates the characteristics of the joint material to be specified. The initial dimensions of the joint opening, width and depth, plus the anticipated movement expected in the joint opening, narrowest to widest, from temperature variations and internal and external stresses applied to the concrete, specifies the characteristics of the joint opening. The general rule of thumb for the maximum amount of vertical movement of pavements and slabs within the joint opening is that it should not exceed 6 mm (1/4 in.). (2) Preformed Compression-Seal Dimensions. Preformed compression seals are available in dozens of sizes and dimensions. The preformed compression seals may range in size dimensions from 8-mm (5/16-in.) widths and 16-mm (5/8-in.) heights to 150-mm (6-in.) widths and 140-mm (5.5-in.) heights. The preformed compression seals also have a wide variety of wall thicknesses and internal geometric designs and arrangements. In determining the correct compression seal for each individual project, the compression seal must be maintained in a

compressed state at all times but not less than approximately 15-percent compression and the compression seal must also allow for approximately 40-percent joint movement based upon the uncompressed width of the compression seal (see Figure 4-3). b. Design criteria. Design engineers must consider several factors in selecting preformed joint sealants and other joint materials for possible use. The anticipated movement, expansion, and contraction in a joint will determine the types of preformed joint material to be considered. The anticipated joint dimensions will determine the types and sizes of preformed joint material to be considered. c. Material consideration. Design engineers must select the preformed joint material based on the joint dimensions, its width, depth, and length. The joint dimensions will determine the type and nominal size of  the preformed joint material as designated by the manufacturers. The material consideration will also include the amount of lateral movement that may be anticipated during all applications, environmental conditions, and loadings. The anticipated joint movement will determine

Figure 4-3. Determination of minimum size of compression seal

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EM 1110-2-2102 30 Sep 95 the type and nominal size of the preformed joint material required for the application. Many preformed joint materials such as compression seals are designed to be in a

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minimum of 15-percent compression at all times, therefore the designers must anticipate for the maximum movement as well as the minimum joint opening for that joint.