1 Interlocking Concrete Pavement Magazine November 2003

In 2002, over 70% of theconcrete pavers sold inNorth America graced resi-

dential walks, patios, anddriveways. Swimming poolsare seeing an increasing num-ber of pavers around them.They can be installed as partof a new pool or used to reha-bilitate the deck around anexisting one. There are thou-sands of backyard pools withconcrete pavers. Besides resi-dential settings, there arecountless public pools withconcrete pavers at countryclubs, swim clubs, apartments,condominiums, homeownerassociations, hotels, themeparks, and municipalities.

Health officials sometimesquestion the extent of mold orbacteria in the surface or joints

of concrete pavers aroundpublic swimming pools.Experience has shown thatthese are not a concern ifthere is adequate slope to thedeck (at least 1.5%) and thesurface and joints receive asealer. This article offers someadditional design and con-struction guidance to helpensure long-lasting, safe, andsanitary installations.

Advantages of PaversWhy use concrete paversaround pools? Besides theirunmatched beauty comparedto other deck surfaces, coloredconcrete pavers reduce theglare often associated withcast-in-place concrete poolsdecks. Almost every paverpool deck in Florida consists

Pool Deckswith

ConcretePavers

Backyard and public pools attract concrete pavers —

they reduce glare while providing a safe,

slip resistant surface.

Interlocking Concrete Pavement Magazine November 2003 2

of beige, coral, or buff colorsthat reduce glare from thesun. Because the units havejoints, each unit has someopportunity to release heatfaster than a monolithic con-crete deck. Therefore, theunits can be cooler underfootthan other surfaces. Concretepavers can be removed andreinstated with no uglypatches should there be aneed to repair undergroundpipes or drains common topool areas. The units havehigh resistance to chlorine, aswell as to freeze and thawcycles. Concrete pavers offera slip-resistant surface evenwhen sealed.

In-ground pools typicallyare backfilled with loose soiloutside their walls. There isoften no attempt to compactthe backfill soil or measure thedensity of each lift. Somepools walls can’t withstandcompaction equipment closeto them, or the structure ofthe walls themselves makes itpractically impossible to fit

compaction equipment nextto them.

Achieving dense backfillsoil is not practical in mostpool applications. Therefore,concrete pavers on an aggre-gate base over such backfillsoil will likely result in settle-ment. For this reason, a con-crete deck is recommendedover the backfill around newpool decks prior to placing

concrete pavers. A concretedeck or base should maintaina smooth surface throughoutthe life of the pool and theconcrete pavers. The deckshould slope away from thepool at least 1.5% so that thewater drains from the surfaceof the pavers.

Rehabilitating existing con-crete pool decks with an over-lay of concrete pavers is lessexpensive than removing andreplacing the concrete deck.To qualify for an overlay, theconcrete should not be heav-ing or faulted, as this oftenindicates severe settlement ofthe soil beneath or expansiveclay soils. In these cases, it isprobably a good idea to installsubsurface drains to removeexcess water from the soil, ortreat expansive soils with limeafter demolishing the concretedeck and before pouring anew one. The advice of a pro-fessional civil engineer familiarwith the local soils should beobtained in such situations.

Cracks in the existing con-crete base can be filled with acement-based patch to preventmigration of bedding sandinto them. The junction of theconcrete slab with the poolwall should be sealed with a

poured rubber/neoprene orurethane sealant (often appliedwith a caulking gun). Thiskeeps water from gettingbehind the pool wall andreducing support from satu-rated soil.

Coping with pool copingThere are a few ways ofinstalling concrete pavers andcoping around an existingpool deck. For existing decks,the existing pool coping isremoved and replaced withcoping made with concretepavers in most cases.Sometimes special coping“bull nose” shapes withrounded edges are used.These shapes are provided bysome ICPI member pavermanufacturers. Figure 1 illus-trates this type of coping.

Bull nose coping is oftenthicker (taller) than the oldcoping so its surface matchesthe finish elevation of the con-crete pavers placed over theexisting concrete deck. Besidesadjusting for the new height,the advantage of using bullnose coping (or pavers) sup-plied by ICPI paver manufac-turers is the coping color andtexture can match (or contrastwith) the new concrete paver

Figure 1. Bull-nose coping with mortared joints can be anchored to the pool wall with anadhesive or metal lath and mortar.

Figure 2. Large paving units are secured to the pool wall andfit against an aluminum face plate (shown in white).

3 Interlocking Concrete Pavement Magazine November 2003

pool deck. Figure 2 showslarge, thick paving units with asmooth texture placed againstaluminum face place fastenedto the pool’s edge. The jointsbetween the units should befilled with mortar or a sealantto prevent ingress of waterbehind the pool wall.

For existing and new pools,coping is typically applied tothe top of steel or concretepool walls with a polymeradhesive or with a metal lathand a mortar bed. The jointsfacing into the pool can besealed with a high grade caulkto prevent water from infiltrat-ing under the coping. Thecoping units are typicallyspaced about 3/8 in. (10 mm)apart and are filled with highgrade mortar. The mortar isprecisely applied with a largecaulking gun or a large bagsimilar to that squeezed bybakers in decorating a cake.The joints are filled and tooledsmooth. Wet mortar is imme-diately wiped from the surfaceof the coping to preventstains. Any excess mortar pro-truding above the joint slight-ly is removed after curing witha carborundum stone. Thisrenders a smooth-to-the-touch surface with no risk ofscratching users.

The pool wall and its cop-ing will move differently thanthe deck. Therefore, the jointbetween the coping and theedge of the paver field shouldbe filled with a rubber or ure-thane sealant typically used inpools. Prior to placing thesealant, foam expansion jointfiller is placed into the joint.The foam supports thesealant. There should be a gapof about 3/8 in. (10 mm)between the coping and theedge pavers so it can receivethe foam and the sealant.Figure 3 illustrates this con-struction detail.

The purpose of sealing thisjoint is to prevent water from

(1O

O M

M)

MIN

. 4 in

.

MIN. 2 in. (50 MM) THICKCOMPACTED AGGREGATE SUB BASE-

SOIL BACKFILL

POOL WALL

MORTARED JOINTSADHERED TO POOL WALL WITHCONC. PAVER “BULL NOSE” COPING

3/8 IN. (10 MM) FOAM EXPANSION JOINT FILLER

JOINT SEALANT

WITH SURFACE SEALERCONC. PAVERS OR CONC. TILES

BEDDING SAND- MIN. 1/4 IN. (6 MM) THICK

CONC. SLAB- MIN. SLOPE 1.5%

Figure 3. The gap between the pool coping and the edge pavers requires a foam expansionjoint filler and a sealant to prevent ingress of water behind the pool wall.This also minimizesrisk of damage from expansion due to freeze-thaw cycles.

draining behind the pool walland weakening the supportingsoil, not to mention possibledamage from freeze and thaw.

The pavers can be placedon a thin layer of beddingsand, typically 1/4 to 3/4 in. (7 to 13 mm).

There will need to be edgerestraints at the outer edge ofthe pool deck. Some contrac-tors apply pavers with polymeradhesives directly to the edgeof the concrete deck under-neath. The units can be thick-er than those in the field ofpavers to compensate for thethickness of the bedding sand.A 12 in. (300 mm) wide layerof geotextile is placed aroundand turned up against theedge pavers after the polymeradhesive has cured. (Mostadhesives cure in a few hours.)

The geotextile contains thebedding sand, keeping it frombeing lost through the jointsbetween the edge pavers.

The bedding sand is spreadand screeded smooth, and thepavers are installed. The con-crete pavers are compactedinto the bedding sand withsmall plate compactor makinga few passes. The joints arefilled with sand and the unitsare compacted again. After athorough sweeping or blow-ing clean of the surface, sealeror joint sand stabilizer isapplied to secure the jointsand and further protect thepavers from spills and chlo-rine. These are recommendedin all pool deck applications.

An installation techniquepopular in Florida (and othernon-freezing areas) is applying

thin concrete tile paversdirectly over a concrete deck.This approach has been usedon countless private and pub-lic pools to spare the expenseof removing and replacing theexisting concrete deck. Thintile pavers typically rangebetween 1 to 11/2 in. (25 and40 mm) thick and are about 4in. (100 mm) wide by 8 in.(200 mm) long. They aredirectly applied to the existingconcrete deck whose crackshave been patched. Edgepavers are secured with a poly-mer adhesive or mortar. Finesand is swept and washed intothe joints until they are full.

After the surface is com-pletely dry (usually 24 hours),it receives a coating of sealerto hold the sand in the joints.The sealer is typically reapplied

4 Interlocking Concrete Pavement Magazine November 2003

every three to five years tomaintain the sand in the jointsand protect the surface. Thecombined rehabilitation andmaintenance costs are consid-erably less expensive thanreplacing the entire concretedeck.

Figure 4. This pool has a cast-in-place concrete deck covering the back-filled area adjacent to the pool. The concrete pavers, bedding sand,and compacted aggregate base are placed over unexcavated, undis-turbed soil.