Decorative Concrete...

Concrete - strong, durable, flexible, the most versatile building material in the world, and gray. All of these descriptive words of concrete are true, but not complete. Concrete is indeed strong and versatile, but it no longer needs to be gray. Architects, landscape designers, and homeowners are reveling in the news that the color of concrete driveways, patios, decks, sidewalks, porches and more can match any decor. Colored and stamped concrete provides all of the wonderful assets of concrete and lets imaginations go wild.

The rise in popularity of colored and stamped concrete may be attributed to three key factors - the continuing evolution of stamping tools, the development of a wide variety of colors, and people becoming aware of the possibilities.. Colored and stamped concrete has also become more popular at the commercial level, to the extent that the NNECPA needed to add a commercial decorative category to their design awards recently.

Stamping Concrete

If one thinks of a concrete slab, still in its plastic state, like cookie dough rolled out and ready to cut, it is easy to understand how skilled contractors stamp concrete. There are three basic types of systems, but the end results are similar, driveways looking like brick pavers, decks that appear to be slate, walkways that appear to be tile.

The roller system works very similar to a rolling pin imprinted with a pattern that is rolled across the concrete. Plastic forms can also be pressed into the concrete which cut outlines similar to brick and cobblestone patterns. The stamping mat forms, gaining quickly in popularity, not only imprint the outline of the patterns, but also provide the texture and "imperfections" to the surface of the concrete, creating a very realistic surface that can imitate slate, stone, wood, and a myriad of other surfaces.

Coloring Concrete

There are two primary ways to color concrete for colored and stamped work. The integral method mixes the coloring agent throughout all of the concrete, usually mixing it in the ready mix truck. Generally the integral method is best for colors that are more muted in nature. Just like adding food coloring to the dough, the effect can be dramatic, but it is difficult to get the more vibrant colors.

The dry shake-on method of coloring concrete applies the color after the concrete is placed, but before it is stamped. The coloring agent is troweled into the surface, and usually colors the top ¼ inch of the slab. These colors tend to be more vibrant than the integral method, similar to sprinkling colored sugar on your favorite cut-out cookies. In addition, since the dry shake-on method usually contains additional cement, this coloring system helps create a very durable and strong surface.

When the stamping mats are used to create the impression, a release agent is used to prevent the concrete from sticking to the stamp (like flour with a cookie cutter). In addition to its practical use, the release agent can also be colored. This will color the impressions and "imperfections" of the design, adding depth and character to the final project. This is frequently how the "grout" color is added on a cobblestone pattern.

Advantages

While colored and stamped concrete driveways will cost more than a traditional concrete driveway, it usually costs the same or less than the cobblestone, slate, or other material it resembles. In addition, you get the durability and low-maintenance advantages of a concrete driveway. There isn’t the same problem with frost heave that the alternate materials face.

Staining Concrete

Chemical Stains penetrate the concrete surface to create beautiful color tones in existing concrete. Stains react directly with the concrete’s minerals and produce uneven, mottled, and variegated color effects.

Chemical stains can be used for both interior and exterior applications and are often used on concrete that had already been colored integrally or with the dry shake method.

A traditional concrete driveway is a wonderful investment, but a stained, colored or stamped driveway, patio, or walkway may provide that elegant, dramatic look to your new home. For more information on decorative concrete, contact the Northern New England Concrete Promotion Association.

Recommended Stamped Concrete Specifications...

SECTION 03330 

These specifications are intended as a guide they should be modified and approved for your particular project. 

PART ONE - GENERAL 

1.1 SECTION INCLUDES 

A. Furnish and install interior stamped, colored concrete floor slabs. 

1.2 RELATED SECTIONS 

A. Section 01030: Alternates. 

B. Section 07210: Building Insulation. 

1.3 QUALITY ASSURANCE 

A. The interior stamped concrete floor for the project shall be done by a company which is ACI flatwork certified, with a minimum of three years experience in the placement and stamping of colored concrete for interior finished floors. 

1. Qualified Contractors: 

Contact NNECPA for a list of qualified contractors in your area.

1.4 REFERENCES 

A. "Manual of Standard Practice" of the Concrete Reinforcing Steel Institute. 

B. ACI 318-83 - Building Code Requirements for Reinforced Concrete. 

C. ACI 302 - Guide for Concrete Floor and Slab Construction. 

D. ACI 305R-77 (R1982) - Hot Weather Concreting. 

E. ACI 306R-78 - Cold Weather Concreting. 

F. ASTM A-185-90a - Steel Welded Wire Fabric, Plain, For Concrete Reinforcement. 

G. ASTM A-615-90 - Deformed and Plain Billet-Steel Bars for Concrete Reinforcement. 

H. ASTM C-31-90 - Making and Curing Concrete Test Specimens in the Field. 

I. ASTM C-33-90 - Concrete Aggregates. 

J. ASTM C-94-90 - Ready-Mixed Concrete. 

K. ASTM C-143-90 - Slump of Portland Cement Concrete. 

L. ASTM C-150-89 - Portland Cement. 

M. ASTM C-172-90 - Sampling Freshly Mixed Concrete. 

N. ASTM C-173-78 - Air Content of Freshly Mixed Concrete by the Volumetric Method. 

O. ASTM C-231-89 - Air Content of Freshly Mixed Concrete by the Pressure Method. 

P. ASTM C-260-86 - Air-Entraining Admixtures for Concrete. 

Q. ASTM C-309-89 - Liquid Membrane-Forming Compounds for Curing Concrete. 

R. ASTM C-494-86 - Chemical Admixtures for Concrete. 

S. ASTM D-994-71 - Performed Expansion Joint Filler for Concrete (Bituminous Type). 

T. MCTCB - Maine Concrete Testing Certification Board. 

1.5 SUBMITTALS 

A. Submittals shall be in accordance with 01340. 

B. Submit concrete mix design(s), concrete tests, and manufacturer's descriptive literature for materials specified. 

C. Submit Shop Drawings showing control joint layout for slabs. 

D. Submit a copy of current MCTCB certification card belonging to the preparer of on-site concrete samples. 

1.6 SAMPLE 

A. Prepare an 8' x 10' x 4" sample of a finished colored stamped concrete floor. 

PART TWO - PRODUCTS 

2.1 MATERIALS 

A. Steel Reinforcement: Deformed bars complying with the requirements of ASTM A-615, Grade 60, unless otherwise indicated, and of domestic manufacture. Mesh reinforcement shall conform to the requirements of ASTM A-185. 

B. Metal Accessories: Shall include all spacers, chairs, ties, and other devices for properly spacing, supporting, and fastening reinforcement in place. 

C. Cement: Portland cement of North American manufacture conforming to the requirements of ASTM C-150, Type I or II. Use only one brand of cement throughout the project, one concrete plant when using integral color. 

D. Concrete Aggregates: Shall conform to the requirements of ASTM C-33. 

1. Fine Aggregate: Sand shall consist of hard, tough, and preferably siliceous material, clean, free from mineral or other coatings, soft particles, clay, loam, or other deleterious matter. 

2. Coarse Aggregate: Crushed stone or gravel, having clean, hard, durable, uncoated particles, free from deleterious matter. The 1-1/2" aggregate shall conform to gradation #467 and the 3/4" aggregate to the size #67 in Table II of ASTM C-33. The 3/4" aggregate shall be used for structural slabs, lintel beams, and any other location where 3/4 of the clear space between reinforcing bars or between bars and the forms require this size aggregate. 

E. Admixtures: 

1. Water Reducing Admixture: "Eucon 75" by The Euclid Chemical Company, Polyheed Non-Chloride by Master Builders, WRDA with Hycol by Grace Construction Products, or Platocrete 160" by Sika Chemical Corporation. The admixture shall conform to ASTM C-494, Type A, and not contain more chloride ions than are present in municipal drinking water. 

2. Non-Corrosive, Non-Chloride Accelerator: "Accelguard80" by The Euclid Chemical Company, or approved equal. The admixture shall conform to ASTM C-494, Type C or E, and not contain more chloride ions than are present in municipal drinking water. The admixture manufacturer must have long-term non-corrosive test data from an independent testing laboratory (or at least a year's duration) using an acceptable accelerated corrosion test method such as that using electrical potential measures. 

3. Air Entraining Admixture: Conform to ASTM C-260, "Darex AEA" as manufactured by The Construction Products Division of W.R. Grace & Company, or approved equal. 

4. Prohibited Admixture: Calcium chloride, thiocyanates or admixture containing more than 0.05% chloride ions are not permitted. 

5. Certification: Written conformance to the above mentioned requirements and the chloride ion content of the admixture will be required from the admixture manufacturer prior to mix design review by the Architect. 

F. Curing Paper: Water, reinforced appear; "Orange Label Sisalkraft," as manufactured by the American Sisalkraft 
Corporation, "Scuf-Champ,: as manufactured by Ludlow Papers, "Flor-Cur W/S," as manufactured by Glas-Kraft, or approved equal. 

G. Moisture Barrier: "J" Pro Vapor Shield, Super Sampson SS4 or Tu Tuff 4. 

H. Color Hardener: L.M. Scofield Company Lithochrome color hardener. Hardener shall be Brick Red color. 

I. Concrete Colorant: L.M. Scofield Company Chromix admixture color shall be Quarry Red. 

J. Release Agent: L.M. Scofield Company Lithochrome antiquing release. Color shall be Santa Barbara Brown. 

K. Floor Slab Sealer: ProSoCo Inc., SLX 100 penetrating sealer. 

L. Texture Mat: Brickform, Inc., Texture Tool, or approved equal; new brick basket weave pattern. 

M. Concrete Stain: L.M. Scofield Company, lithochrome chemical stain, Padre Brown, natural. 

N. Truncated Dome Stamp: Cobblecrete ADA concrete texturing tool. 

2.2 MIXES 

A. Grade and Strength: 

1. Concrete Requirements: Exterior Sidewalk 

Minimum Compressive Strength 4000psi - 28 Days 

1 inch Aggregate Size 

Minimum Cement Content 564 lbs/yd 

Slabs-On-Grade 

2. All concrete shall contain the specified water reducing admixture or the specified high range water reducing admixture (superplasticizer. Add admixtures in dosage recommended by the admixture manufacturer. All concrete required to be air-entrained shall contain an approved air entraining admixture. 

3. Prior to starting construction, submit proposed mix design, accompanied by complete standard deviation analysis or trail batch data. No change in source of materials or mix shall be made without Architect's approval. 

B. The concrete mix designs shall be proportioned in accordance with Section 4.3 "Proportioning on the Basis of Field Experience or 4.4 Trial Mixture" of ACI 318-83. The proportions of ingredients shall be such as to produce a mixture which will work readily into the corners and angles of the forms and around reinforcement by the methods of placing and consolidation employed on the work, but without permitting the materials to segregate or excessive free water to collect on the surface. 

C. The approved air-entraining admixture shall be used in concrete exposed to weather to obtain proper percentages of air-entrainment as follows: 6% plus/minus 1%.