Bonding Agent for Concrete Repair ASTM C1059 Type II
DARAWELD® C is a bonding agent for concrete that complies with the requirements of ASTM C1059 Standard Specification for Latex Agents for Bonding Fresh to Hardened Concrete. DARAWELD® C will improve the bond between new to old or new to new concrete. DARAWELD® C is a dispersion of internally plasticized, high polymer resin in water. Mixed with cement, sand and water, DARAWELD® C forms a strong, highly adhesive bonding grout which will adhere to properly prepared concrete substrates.
DARAWELD® C is intended for bonding new to old or new to new Portland cement concrete in exterior or interior applications. It is used for bonding, patching, or re-surfacing concrete floors, walls, beams, columns, or other structural members. DARAWELD® C will improve the adhesion of pneumatically applied mortar or concrete. DARAWELD® C grouts and mortars have been used in a wide variety of miscellaneous applications. These include bonding construction joints, prevention of cold joints in multiple pours, leveling of floors prior to secondary surfacing, skidproofing existing floors and finishing concrete block walls.
The surface to which DARAWELD® C grout or topping is applied must be clean and sound. Remove oil, grease and similar substances as required. Remove unsound concrete, loose material and foreign matter by scarifying, hydroblasting, or other mechanical means. All concrete, whether new or old, when cleaned, must be thoroughly rinsed with water. A properly prepared surface will be clean and sound, readily and uniformly wettable with water. If the surface condition is questionable, apply a test patch for bond evaluation.
For bonding grout applications, mix equal parts DARAWELD® C and water and then add this to a mixture consisting of:
- 5 parts Portland cement
- 2 parts fine sand
ASTM C144 sand is generally suitable for most applications. For mix designs for specific applications, refer to the DARAWELD® C Job Analyzer. First, blend the cement and sand together. Next, mix the DARAWELD® C and water and add this solution to the cement and sand. Then, mix thoroughly by mechanical means to a thick, creamy consistency.
Additional DARAWELD® C / water may be added in increments until the desired consistency is obtained. The DARAWELD® C bonding grout acts as a glue to bond new concrete to existing concrete. Before applying the bonding grout, the surface of the old concrete should be thoroughly moistened with water. Avoid puddles or standing water in small pits and crevices. Excess water should be removed by mopping or by blowing with compressed air. Use a stif bristle brush or corn broom to apply the DARAWELD® C bonding grout in a layer no more than ⅛ in. thick.
In order to obtain maximum bond strength, the grout must be intimately scrubbed onto the old concrete surface. DARAWELD® C bonding grout has a short working life. DARAWELD® C is non-reemulsifiable, thus if it sets or dries, its bonding benefits are eliminated. Concreting over the bonding grout must occur before the mixture skins over, achieves set or dries out.
For topping applications, mix equal parts DARAWELD® C and water and then add this to the topping mixture. The topping must be applied while the bonding grout is still soft or tacky.
A typical mix for vertical surfaces is:
- 1 part Portland cement
- 3 parts sand
A typical mix for a floor surface topping acceptable for foot or light wheel traffic is:
- 1 part Portland cement
- 2 parts sand
The amount of DARAWELD® C / water solution will depend upon the water requirement of the cement and the amount of water in the sand. Follow the procedure given for the bonding grout in determining the water requirement and for mixing.
For deeper resurfacing, thick patches and overlays, the topping may be proportioned with larger size aggregate consistent with the depth of the overlay.
Care should be taken in finishing very thin overlays. It is difficult to produce a high polished finished surface on thin patches or overlays without impairing the quality of the topping and jeopardizing the strength of the bond.
Excessive steel troweling will cause excessive bleeding with possible self-desiccation and shrinkage.
Excessive working, particularly several hours after wood floating, may break the bond between the DARAWELD® C grout and the old surface before bond strength has fully developed.
In thin resurfacing, wood floating alone, immediately after screeding, will produce maximum bond and minimum shrinkage and therefore is preferred. The surface obtained is often smooth enough for most purposes.
Steel troweling should only be used when necessary. Any steel troweling should be very light, employing a minimum number of passes. Under no circumstances should steel troweling be performed later than two hours after placing.
|Volume, Gals||Coverage, Sq. Ft.|
|DARAWELD® C||Cement||Mason’s Sand||Water||Yield, Cu. Ft.||Yield, Gals.||1/32 in. Thick||1⁄16 in. Thick||⅛ in. Thick|
See DARAWELD® C Job Analyzer for complete instructions
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Last Updated: 2021-02-05