MASCO Catalog: Construction Liquid and Powder

Read manufacturers' data sheets for complete specifications, installation procedures, and MSDS precautions. Warning : Chronic health effect possible—inhalation of silica dust may cause lung injury/disease (Silicosis). Take appropriate measures to avoid breathing dust. See page 179-180 for more information. 83 MASONS SUPPLY COMPANY Oregon (800) 537-3407 ♦ Washington (800) 537-6216 ♦ www.MASCO.net Clackamas | Eugene | West Eugene | Hillsboro | Medford | Portland | Salem | Ridgefield | Seattle | Tacoma | Woodinville Proper surface preparation is extremely important to the successful application of any and all repair products. Bond is only as good as the surface to which it is bonded too. Proper preparation of the surface is critical for long term durability. Proper surface preparation of concrete involves 6 basic steps: Contamination Removal: Grease, wax, oil or various sealers will impair proper bond of a repair material. For thinner repairs where the surface preparation technique may involve little removal of the substrate, contamination removal may be necessary. Presence of such contamination may be determined by dropping a small amount of water or diluted muriatic acid onto the substrate and watching whether the droplets are absorbed or a reaction occurs. No reaction indicates that contaminants are present. If oil has penetrated into the concrete surface, it may be detected by raising the temperature of a small area to about 150° F with a heat lamp. Presence of the contamination is indicated if oil appears or the area becomes greasy to the touch. Typically contamination removal would include scrubbing with envirosol available from Masons Supply or some other industrial degreasers. Edge Conditioning: Products being applied in thickness greater than 1/4", or where significant contamination of the concrete exists, requires edge conditioning. Square cutting of the edges using a concrete saw is the most common method. Bulk Removal: Various methods may be employed to remove delaminated or disintegrated concrete down to the level of sound substrate. Chipping is the most common technique. Use of a square tip chisel is recommended. Other methods used include hydro-demolition, scabbling, rotomilling and other mechanical means. Some of these techniques, such as hydro-demolition, may include the final three steps of surface preparation. It is important to select a method that is aggressive enough to get the job done but not so aggressive as to damage the sound concrete. The following methods may be used as preparation for products being applied in thinner sections or where the substrate is not severely damaged. These methods are ranked according to preference: Shot blasting: This is the preferred method for removal of thinner sections of concrete. Follow mechanical cleaning with vacuum cleaning. Sandblasting: Aggressive sandblasting may be used in place of shot blasting for some applications. Use the same procedure as shot blasting, however greater care during clean up will be necessary. Water blasting: High-pressure water blasting using pressures over 8,000 psi may be sufficient for some applications. Thorough rinsing of the substrate to remove wetted laitance is necessary. Water blasting with pressures below 8,000 psi is insufficient for most applications. Undercutting: Where significant corrosion of the reinforcing steel has occurred, undercutting of this reinforcement should take place. Refer to ICRI “Guideline for Repair of Deteriorated Concrete due to Reinforcing Steel Oxidation” for this and the following section. Undercutting a minimum of ¾” behind the rebar is recommended. Cleaning and Repair of Reinforcing Steel: If the exposed reinforcing steel in the patch has corroded it should be cleaned using a sandblaster/water blaster in accordance with commercial blast cleaning standards. In case where the rebar has lost more than 25% of its original cross section, a new rebar piece should be spliced to the old in accordance with ACI 318-83. Significant damage to reinforcement should be reviewed with a licensed professional engineer. Surface Cleaning of Concrete: The final and often the most important step of surface preparation is the surface cleaning of the concrete. All loose particles and dust must be removed prior to placement of the patching material. This is best done with a pressure washer using water at approximately 3,000 psi. The water jet gives the concrete an uncontaminated, bondable surface. Pre-dampening the Substrate: All cementitious materials (with the exception of Set 45) should have the substrate pre-dampened with potable drinking water. A saturated surface dry (SSD) condition is required. Any puddle areas should be brushed away or blown off using oil free compressed air. Bond Slurry Coat: With the exception of Set 45, a bond coat slurry is recommended for achieving better bond with all cementitious products. To make a slurry coat, use a small amount of each batch mixed to a slightly wetter consistency. Thoroughly scrub a bond coat into the substrate with clean, wet, stiff broom or brush immediately ahead of the mortar placement. Do not apply more bond coat than can be covered with mortar before the bond coat dries. The above recommendations are applicable for most applications; however refer to data sheets, installation guidelines, and bag or label instructions for recommendations for each specific product. CONCRETE SURFACE PREP GUIDE Horizontal Concrete Repair