Frequently Asked Questions
Helpful information
Hot weather conditions
Following the below recommendations will help offset the effects of hot weather conditions and will result in the repair material having the desired characteristics.
- Work in the shade, if possible. Apply early in the morning and late in the evenings to avoid direct sun. Protect the job from wind, if necessary.
- Keep the repair material at a 70-75° F temperature. Keep the repair material in the shade, out of the sun before mixing.
- Use cold water to cool off surfaces where material is to be applied to get those surfaces as close as possible to the temperature of the repair mortar.
- Chill the mixing liquid, if needed. Use ice water, if necessary and appropriate.
- Mix the repair mortar as close to the repair area as possible and place repair material immediately. Keep the time of mixing, placing and finishing to a minimum. Do not over finish the material.
- Protect the material from rapid surface drying and beginning curing after finishing.
- Refer to Hot Weather Concreting in ACI Manual of Concrete Practice for more detailed information.
Cold Weather Conditions
Given below are steps which you can take to minimize the effects of cold weather on the application of repair materials:
- Work in heated enclosure. Raise the temperature of the surface to be repaired to the temperature of the repair mortar. Radiant type heaters are recommended.
- Keep the repair mortar at a temperature of 70-75° F.
- Warm the mixing liquid to raise the temperature of the resulting repair material. Use of warm liquids can also be used to accelerate set times in cold weather.
- Mix the repair material as close as possible to the repair area and place the repair material immediately.
- Delay floating and finishing until the repair material is firm. Finish the material and close the surface only when the repair material has stiffened sufficiently.
- Protect the repair material from rapid surface drying by beginning curing immediately after finishing.
- Maintain heat in the repair area as long as you can, at least 24 hours. Do not direct the heat source at the fresh repair because that will cause rapid surface drying.
- For more detailed information refer to Cold Weather Concreting in the ACI Manual for Concrete Practice.
Surface Preparation
All surfaces must be clean and structurally sound; free of dust, grease, oil, sealers, paints and other contaminates. New concrete to be repaired must be cured 28 days. Pores of the concrete surface must open to allow proper bonding. This type of surface can be achieved by mechanically abrading the surface of the area to be repaired. Remove dust by vacuum or compressed air. Substrate to which repair mortar is to be bonded should be in a saturated surface dry (SSD) condition. For proper methods to abrade, clean and prepare concrete, refer to ASTM Standards D4259-88 (Standard Practices for Abrading Concrete); D4261-83 (Standard Practices for Surface Cleaning Concrete Unit Masonry for Coating), D4258-83 (Standard Practices for Surface Cleaning Concrete for Coating).
Specific surface preparation requirements for each product are included in the Product Literature Sheets.