The Art & Science of Creating Driveways

A herringbone pattern joins these pavers on a residential driveway. Like most driveways, this site drains from the garage to the street. To ensure a snug fit, the contractor started laying pavers at the street and worked up-grade to the home and garage. The opposite sequence would be used on a site that rises from the home to the street. Photo courtesy of Willamette Graystone

A driveway is a practical feature for every home and is often required by local ordinance. Beyond its basic function, the driveway's up-front spot makes it an obvious place to add color and detail to enhance a property's value and curb appeal. Because they are resting spots for vehicles, all driveways have more robust beds and thicker concrete or paver specifications than patios or other hardscapes. Contractors should look at driveway jobs as a canvas with big possibilities involving color, pattern and texture.

The sections below can serve as a basic guide for two of the most common options?EUR"stamped concrete and paver design. Along with the photos included here, the goal is to give contractors a better idea of the many variations on basic driveway design that are available. The bottom line with driveways is, get creative!

?EUR"Erik Skindrud, regional editor

Tips for Stamping Concrete

By Bob Harris, www.BobHarrisGuides.com

Preparation

A roller is an obvious and time-efficient way to stamp large areas of concrete. The manufacturer of Rock ?EUR~N' Roller says the tool is best used when concrete is semi-wet, unlike the more set consistency that mats are used on. The tool seen here is used for ?EUR~natural stone' borders. Wider rollers create ?EUR~brick' patterns. Photo By Erik Skindrud

Sub-grade

The sub-grade should be well-drained, compacted granular fill and, most importantly, of uniform thickness to aid in consistent setting of the concrete. If the sub-grade is not graded with a uniform thickness, it could result in the concrete setting at different rates, thus not achieving a uniform texture during the stamping process. In hot and windy conditions, the sub-grade and surrounding areas should be saturated with water the day before concrete placement, not the day concrete is delivered.

A worker uses a brush with a long handle to place the final texture on this brushed-concrete driveway. A skilled worker kneeling on pads and plywood created the square joint patterns. Photo By Karl Skindrud

Forming

Forms should be set the same as for any normal concrete installation. However, serious thought should be given to layout and design, taking into consideration the size of the mat, pattern, line of sight, (angle from which it is viewed most often), stamping start point and joint placement on many patterns it is essential that forms be set square. If not, the pattern layout could result in a long or short side and or an odd size shape at some point (this is not as important when using random patterns). When setting the forms, allow sufficient slope so that the stamped concrete drains properly. Cut or drive the stakes flush with the top of the forms so the stakes do not get in the way when the stamps overlap.

"Screeding" refers to scraping and tamping a driveway or hardscape's flat sand bed before laying concrete, bricks or pavers. A variety of screeding machines are available, including this Wildcat Roller by Multivibe. A more traditional technique employs a 2 x 4 in. board, but it's critical to ensure that your board is precisely straight or your project may suffer severe consequences. Photo By Erik Skindrud

Placing and Finishing

Start by placing and finishing small quantities, typically 2 ?EUR" 4 yards. Once confidence has been established in consistently placing these quantities, slightly increase the amount that the crew handles while still producing satisfactory work. The key to a successful final texture is the proper surface preparation of the fresh concrete. Stamp work will require less than perfect finishing because of the texture that is imprinted. However, the build up of proper amount of paste is very important. When the concrete mix is perfect, finishing is at its easiest. Weather conditions, however, can make even good concrete difficult to finish. In rain, keep the surface covered or simply do not pour. In hot and windy conditions, a crust is likely to form. If this happens, cover the surface with plastic in between finishing steps or use an evaporation retardant. Proper surface finishing cannot be done if there is no water at the surface to aid in creating the needed fat cream. Take advantage of early morning and late afternoon finishing.

Companies that do high-volume concrete can find it useful to purchase an industrial power screeder like this Whiteman SuperScreed. Manufacturer Bierschbach Equipment & Supply claims the unit can complete up to 10,000 square feet an hour. Machine widths from 15 to 50 ft. are available. Photo By Erik Skindrud

Release Agent (powder and liquid)

Before applying a powder release agent, stir the contents in the bucket. This will introduce air and make it fluffy, which will aid in obtaining a uniform application. Always condition the stamps with a layer of release brushed into the mat prior to each stamping application. When using liquid release, make sure the bottom of the mat is clean prior to pre-conditioning the bottom of the mats with a light mist of liquid release.

Concrete artist Rae Kozai of Chandler, Ariz. completes masking for a concrete staining demo at January's World of Concrete show. The fluffy material sitting on the surface at left is pet bedding sold for hamsters and other small mammals. Kozai likes the material's absorbent qualities for creating a textured effect with acid stain. It's probably best to take a class or work with an expert before attempting advanced techniques like this.Photo By Erik Skindrud

Stamping

At the concrete's optimum degree of plasticity for texturing, great force should not be necessary to press the mat into the concrete. Since timing is of the utmost importance in texturing, this process should begin without delay. There will be adjustments to timing depending on the degree of texture from mat to mat. For example, fine grooves and light textures are stamped later in the process; where as deep grooves with heavy texture would be stamped much sooner. Using a leapfrog method, mats should be advanced shortly after they are tamped (the longer the mat stays on the surface of the fresh concrete, after it has been tamped, the more likely moisture will bleed and suction to the bottom of the mat).

Artist Julie Thompson of Designing Concrete uses a variety of staining and texture techniques to add color and interest to what could otherwise be a two-dimensional art form. Thompson is also known for her use of wasp and jointing tools to engrave text, logos and patterns in concrete. Photo By Erik Skindrud

Curing

Curing can only be done by covering with plastic, building paper or straw, if using a powdered release agent. Avoid covering too soon so that you do not leave marks. The curing material is left in place until the release agent is washed off of the surface. When temperatures are cooler and damp, you may need to delay washing and sealing for several days to make sure the surface paste has reached the proper strength. Conversely, as the temperature increases, you can start the cleaning of your release agent much sooner. Work done with liquid release can be cured the same day, but be careful if the intent is to chemically stain at a later date. If this is the case, do not use a liquid membrane type-curing compound for it would need to be stripped prior to staining.

Julio Hallack uses a foam brush to apply a copper-toned stain to a concrete surface. Note the protective gloves; this acid stain product is corrosive and can severely irritate eyes, nose and throat. Workers should wear eye protection and follow label instructions to the letter. Photo By Erik Skindrud

Wash and Seal

The best way to wash off the desired amount of powder release agent is with a floor maintenance machine (buffer) with a medium to soft brush attachment and water, assuming the surface is hard enough. This method will remove the release from the same area where traffic would attack the high points of the surface. If powder release removal is done with a pressure washer or by simply applying a detergent and brushing, there will be a slight amount of release residue present, which may promote weak bonding between the sealer and the concrete surface.

Bob Harris is founder and president of the Decorative Concrete Institute in Douglasville, Ga.

Contractor and artisan Ralph Gasser of Redding, Calif. specializes in fanciful designs like this overlay work. His reputation for custom designs has brought him work in Disneyland and Disney World, among other high-profile spots. Gasser recently won a decorative concrete award for a 6,000-sq. ft. multicolored, dyed and saw-cut job at the Brenden Theater in Modesto, Calif. Photo By Erik Skindrud

Paver Installation Tips

From Rob Burak, P. Eng., Director of Engineering, icpi.org

For residential driveways, a consideration for ensuring long-term performance is the laying pattern. This is the reason why the industry has recommended herringbone patterns; no joint is longer than one-and-a-half pavers. Many popular random patterns have entered the market and these patterns can be used on residential driveways. When installed, there should be discontinuity in the bond lines. This helps reduce potential for horizontal movement of the pavers from wheel loads. If running bond patterns are used in a residential driveway, bond lines should run perpendicular to the wheel travel direction.

A more varied pattern is created using pavers with different shapes and colors. This permeable paver design is set on sand adjacent to a xeriscape (drought tolerant) garden. Photo By Erik Skindrud

Establishing Layout and Pattern

The most important part of paver installation is establishing a starting point for paving. There is almost always a garage at the end of the driveway, so the paver bond lines should run perpendicular to the concrete slab at the garage front. For a simple installation with a straight sight line to the street, a string line pulled to driveway end to the street becomes the line for creating a 90?? reference line for the pattern to follow.

Applying a release agent (in this case a dry powder) is essential to ensuring the easy release of the concrete mold from the surface. The worker at left is sifting the release agent. The worker at center is using a hand tamper to push the mold into the moist and pliable surface. Photo By Pacific concrete images

Laying the First Pavers

Since most driveways are sloped away from the house, paving starts at the street (or curb). Pavers should always be installed up a grade to prevent horizontal shifting during installation and to maintain consistent joint widths and parallel bond lines. In addition, whenever possible, it is always best to create access for materials from the street for better job site flow of materials. In the case where the driveway slopes down from the road to the garage, the paver installation should begin at the garage and move up slope.

This scheme shows how concrete, brick and natural stone can be combined to add color, texture and interest. Remember that driveways require thicker brick and stone than patios to resist the weight of automobiles and other vehicles. Photo By Erik Skindrud

Cutting Pavers

Practically all jobs will involve cutting. There are three tools for cutting pavers: the mechanical splitter, the powered table saw and the hand-held gas-powered quick saw. Many contractors prefer to cut pavers in place with a handheld quick saw. Although this saw can be very fast, there are safety and dust concerns. Table saws can accommodate dust control equipment and are safer. They should be brought as close as possible to the edge receiving the cut pavers. These saws are mounted on wheels with the dust collection system. Mechanical splitters are beneficial for cutting a tumbled paver since they create a rough cut edge that resembles their tumbled surface. Pavers are marked in place by a variety of markers including soap stone or chalk.

Steve Logsdon of Crosby, Texas, demonstrates proper technique with a rigid mold stamp tool. (The mold replicates a Vermont slate pattern.) An 18-square-foot mold like this can complete about 1,000-1,200 square feet of surface per day. A trained crew of three should allow about five days to complete a 10,000-square-foot job, Logsdon said. Photo By Erik Skindrud

Compacting the Pavers

Pavers are fully compacted twice on the job site. First, the bond lines are adjusted for consistency and alignment, the surface swept clean and compacted without joint sand to create an initial interlock. This happens by bedding sand migrating up the bottom of the joints during compaction. ICPI recommends using a vibratory compactor. It should weigh between 165 and 240 lbs. Begin by compacting the area perimeter and work toward the pavement center. For the first two passes, overlap the passes with the compactor by a minimum of 6 in. Then compact the pavers with perpendicular passes for uniform compaction.

All pavers should receive two passes of the plate compactor prior to filling the joints with joint sand. After compaction is complete, spread and sweep dry joint sand and compact the pavers again, being sure to add sand until the joints are completely full. Sweeping dry sand ensures that it won't hang up in the joints and reduce interlock. It also speeds joint filling and saves labor hours.

A permeable paver driveway is especially welcome in the rainy Pacific Northwest. (The job seen here is at Valley Covenant Church in Eugene, Ore.) These Aqua-loc pavers are installed directly on a sand bed; once completed, contractors use push brooms to sweep dry joint sand into the gaps. This step locks the pavers into position with a flexible bond that lets water percolate through the gaps. Photo courtesy of Willamette Graystone

What You'll Need

It's best to start simple when adding driveway construction to your business. Many manufacturers offer step-by-step instructions. Having the tools you need on hand will help ensure that the job flows smoothly. (This list details items needed for paver installation.)

?EUR? Tape measure
?EUR? Spray paint to mark project area
?EUR? Shovel
?EUR? Wheelbarrow
?EUR? Hand tamper
?EUR? Wooden stakes and transit or string level to mark grade
?EUR? Mallet
?EUR? Knife or heavy scissors (for cutting geotextile layer)
?EUR? Hard-tooth rake
?EUR? Hand saw (to cut edge restraint)
?EUR? 4-foot hand level
?EUR? Screed guides (1-inch iron pipe)
?EUR? Screed board (2?--4 long enough to span screed guides)
?EUR? Masonry trowel
?EUR? Mason's string line
?EUR? Wide-blade mason's chisel
?EUR? Stiff-bristle push broom
Source:?EUR"Willow Creek Paving Stones

A worker removes a flexible mold from the concrete surface after tamping. Using the same, skilled crew from start to finish will ensure uniform results on a job. Experience teaches, among other things, that a limited amount of time and pressure prevents the mold from sticking from the somewhat-tacky surface. Photo courtesy of pacific concrete images Photo courtesy of pacific concrete images