Getting Started with Getting Started with Concrete Countertops Concrete Countertops Presented by: Jeffrey Girard, P.E. Presented by: Jeffrey Girard, P.E. Please hold. The seminar will begin shortly. 1 2 Introduction My First Concrete Countertop Jeff Girard CCI • President & founder • Training • Instructor • Technical information • Civil engineer • From-scratch mixes • Started 1999 • Founded 2004 3 Jan 1999 4 My First Concrete Countertop My First Concrete Countertop Aug 1999 5 6 1 My First Concrete Countertop What’s your experience? Poll July 1999 7 8 Your project But first: Your workspace You want to get to all these steps: Need: • Templating • Forming • Space • Reinforcing • Mixing • Power • Casting • Light • Curing • Stripping the forms • Water • Grinding and polishing • Heat • Grouting • Sealing • Installing • Assuming you’ve decided what project to make. 9 10 Workspace Workspace Garage Basement 11 12 2 Second: Your stuff Personal Protection Need: Safety first! • Personal safety protection • Equipment • Materials 13 14 Concrete countertops are countertops… Concrete Countertops Cast-in-place is done on site, right on top of the kitchen cabinets. … that just happen to be made of concrete. 15 16 Concrete Countertops Precast Methods Hand packed Precast is done in your shop, garage or basement. Stiff, zero-slump concrete Variegated, hand-pressed or solid Single-sided molds (2D and 3D) Often all-sand mix concrete 17 18 3 Major steps in precast concrete Precast Methods countertop manufacturing: Wet cast 1. Templating 2. Forming 3. Reinforcing 4. Mixing, casting and curing Vibration 5. Processing Single and double-sided molds (for 3D) 6. Sealing Often aggregate based mix concrete 7. Installing 19 20 Templating Templating Accurately capture important site Shape and dimensions of the information in a physical mock-up. countertops Good templates ensure an accurate fit. 21 22 Templating Templating Location of sink and cooktop openings Fixtures: sinks, faucets, cooktops Bartop overhangs 23 24 4 Templating Templating Cabinet inspection Site conditions Gap, uneven cabinet 25 26 Equipment Equipment Templating and Forming Templating and Forming 27 28 Equipment Equipment Templating and Forming Templating and Forming 29 30 5 Equipment Equipment Templating and Forming Templating 31 32 Materials Forming Forms affect the fit, finish and overall quality. Templating Accurate forms require accurate templates. 33 34 Forming Equipment Melamine boxes. Forming Foam sink knockout has silicone caulking. Glass embedment is glued to form with silicone. Drainboard form is adhered with carpet tape. 35 36 6 Equipment Materials Forming Forming 37 38 Materials Equipment Forming Forming 39 40 Caulking Caulking Only use 100% silicone caulking 41 42 7 Caulking Caulking Wax the form corners first. Only use 100% silicone caulking 43 44 Caulking Caulking Peel off excess after Tool the caulk caulk is cured. 45 46 Curves Embedments Curved edges formed with foam insulation. Embedments are glued to form surface. 47 48 8 Embedments Sinks and Faucets There’s more to forming than just building boxes. 49 50 Sinks and Faucets Forming Faucet and sink layout are critical to function, Good work is noticed once… looks and long-term satisfaction. Poor craftsmanship is never forgotten. 51 52 Forming Tips Reinforcing Proper reinforcing is critical for success. The forms must fit the templates exactly. You’re working upside down. Check, double-check and triple-check your forms against the templates! 53 54 9 Structural Reinforcement Reinforcing Rules Most important in Precast (wet cast, hand Reinforcing is placed close to the packed) tension face. Pieces are moved, handled and transported All countertop slabs are reinforced Moderately important in Cast-in-Place Bartop overhangs also have cantilever Cantilevers still require correct reinforcing reinforcing located near the top surface. Never in the middle of the slab! 55 56 Reinforcing Countertops are not slabs-on-grade Do not make a concrete countertop like a driveway or a sidewalk. Slabs depend on well-compacted subgrade fill to completely support the concrete. Floor slabs cannot span soft spots or open spaces. Slabs usually have only secondary reinforcing for shrinkage and temperature. It won’t perform the way you expect it to. 57 58 Countertops are beams Beam Principles Weight BEAM Beams are structures that span open spaces and are internally self-supporting. Beams contain primary reinforcing to resist all tensile forces developed during service life. 59 60 10 How concrete countertops Reinforcing Placement Tips work: Countertops don’t Flexing creates tensile forces fail by crushing. Reinforcing resists tensile forces Reinforcement and flexural strength are important HERE. This is where countertops crack. Tension forces run in straight lines 61 62 What proper reinforcing can do Reinforcing Placement Tips Cantilevers need reinforcing near the top 500 lbs of sand 8’ x 6” x 1.5” beam No cracks! 63 64 Strong Reinforcement Materials Use structural material that is strong, reliable and appropriate in size. 7 day-old concrete 12” bar top overhang 960 lbs of sand No cracks! 9 gauge block ladder wire 65 66 11 Tools and Materials What NOT to use: Stucco mesh /diamond lathe is Reinforcing not appropriate structural reinforcement. Chicken wire and fencing are woefully inadequate . #3 rebar is too large for 1.5” thick slabs. 67 68 Poor Reinforcing: What not to do Poor Reinforcing: What not to do 69 70 Mixing, casting and curing Materials Mixing and Casting 71 72 12 Materials Equipment Mixing and Casting: Specialty materials Mixing and Casting Pigments Superplasticizer VCAS Available from www.concretecountertopinstitute.com73 74 Equipment Equipment Mixing and Casting Mixing and Casting 75 76 Equipment Equipment Mixing and Casting Mixing and Casting 77 78 13 Equipment Concrete 101 Mixing and Casting Aggregates Gravel Sand Cement Water 79 80 Why not just use bagged concrete? What makes a good countertop mix? The right concrete needs to have: Pre-bagged home center concrete: High early strength so you can finish faster. Made for sidewalks, footings Good crack resistance. Aggregate-rich, cement-lean Low shrinkage potential which minimizes curling. Needs excess water for workability Consistency for color duplication and long term 28 days to gain rated strength performance. Low cost. 81 82 Level 1 Mix Level 1 Mix Formula Based on local raw ingredients 53 lbs pea gravel High strength 53 lbs of sand Gray or white cement-based concrete 30 lbs of Type 1 Portland cement Low cost: $1.90/sf @ 1.5” thick 5 lbs of VCAS (pozzolan) 10.5 to 14 lbs of water 5000+ psi in 3 days 7500+ psi in 7 days Makes about 1 cubic foot of concrete 8 sq ft @ 1.5” thick; $1.90/sq ft 6 sq ft @ 2” thick; $2.55/sq ft 83 84 14 Professional Mix VCAS Fully from-scratch VCAS is a pozzolan Allows for total customization and control Ultra-finely ground recycled glass Can make pure-white concrete Based on same materials as Level 1 mix Total control yields consistency and repeatability Requires more precise tools High strength, good performance Enhances workability Low cost: $1.90/sf @ 1.5” thick Boosts long term strength Eliminates efflorescence 85 86 Water Why Not Just Add Water? An important ingredient that must be dosed carefully. It’s easier… It’s cheaper… It’s faster… It is not used like salt and pepper are to “season” the But is it the right thing to do? concrete to “taste”. 87 88 The Role of Water Simply Adding Water: Reduces strength Grape Kool-Aid® Increases porosity Increases shrinkage Alters coloration Decreases freeze-thaw resistance More chance of cracks Produces poorer quality concrete Too much water dilutes strength, color 89 90 15 Improving workability Improving workability without adding water without adding water Superplasticizer Video Use less water to make better concrete Add workability without losing strength 91 92 Precision is essential for quality and consistency Casting Concrete 93 94 Wet Casting Wet Casting Pour adjacent pieces from the same batch for consistency 95 96 16 Wet Casting Wet Casting Complex shapes require complex forms. Wet cast mixes are usually fluid and pourable. Castings are sometimes vibrated for improved surface quality. 97 98 Wet Casting Curing Wet cast concrete has fine detail and great precision. Wet cast concrete has unique surface texture. 99 100 Curing Curing Tomato Seed Needs water to grow Dies if dries out Drying is NOT curing. Curing enables the concrete to gain strength. Cure for 2-3 days before stripping. Wetting the concrete keeps the moisture inside the concrete from evaporating. 101 102 17 Processing Ground versus As-Cast Consists of Grinding, Honing, Grouting, Polishing This choice of finish affects many of the steps: Forming Depends on Ground versus As-Cast Mix design and casting Processing Sealing 103 104 Processing Step 2: Grind Processing Step 1: Flatten (Optional) Rough grinding, initial honing Flattening the back, smoothing the underside. 105 106 Grinding Equipment Heavy milling with turbo cups Grinding Rough, aggressive. Used to expose aggregate. 107 108 18 Processing Step 3: Hone Honing Light material and scratch removal 50 grit – 200 grit Fine finishing, honing 109 110 Equipment Equipment Honing Honing 111 112 Equipment Crème Finish Light Hand Sanding Light Hand Sanding 400 – 800 grit wet/dry sandpaper 113 114 19 Crème Finish Processing Step 4: Grout Light Hand Sanding Filling pinholes and voids. Minimal for as-cast