AWS C2.20/C2.20M:2016 pdf free download

AWS C2.20/C2.20M:2016 pdf free download.Specification for Thermal Spraying Zinc Anodes on Steel Reinforced Concrete.
8.2.3 Post-Blasting Substrate Condition and Thermal Spraying Period
8.2.3.1 Concrete Surface Temperature and Cleanliness
(1) Measure the concrete surface temperature with a pyrometer. Do not perform any spraying unless the concrete temperature is at least 5°F [3°C] above the dew point.
(2) Spraying shall not be conducted during periods of rain or high winds unless the operation is carried out in a protected area or inside an enclosure. Do not spray on concrete surfaces that are moist or wet.
(3) It may be necessaiy to dry the concrete surface by air blowdown or heating to achieve the bond strength requirements of the contract. The drying method should be validated with the Job Reference Standard per 4.2. Care shall be taken to prevent thermal damage to the concrete surface by any application of heat. The surface temperature shall not be permitted to exceed 212°F [100°C] during heating or drying processes. The concrete surface temperature shall be measured with a contact pyrometer to ensure that the maximum allowable surface temperature is not exceeded.
(4) Maintain surface cleanliness: no oil, grease. dirt, moisture, or loose material on the concrete surface.
8.2.3.2 Holding Period. Thermal spray coatings should he applied as soon as possible after surface preparation to minimize oxidation of exposed steel and contamination of the prepared surfaces. The permissible holding period between start of final blasting for surface preparation and completion of the thermal spray process shall not exceed 2 hours unless agreed upon by the purchaser and system designer. Longer periods may be agreed to by the purchaser and system designer for less aggressive environment. The holding period depends on the moisture content of the concrete, and the temperature-humidity conditions that prevent moisture on the concrete surface and rusting of the rehar. The tensile bond will he reduced by surface moisture, high humidity, and long exposure time prior to coating. In low-humidity environments or in enclosed spaces using dehumidification equipment, it will he possible to prevent or to retard surface moisture and extend the holding period on the concrete and before flash rusting of the exposed rehar.
8.2.3.3 Low Temperature Environments. Thermal spraying in low temperature environments (<40°F [4°C]) must be qualified with statistically valid in-place tensile bond strength tests. The average of the tests should be above the minimum acceptable tensile bond strength. The range of the test strength cannot exceed a 3 sigma variation from the mean (average).AWS C2.20/C2.20M:2016 pdf free download.