Spectech – Cold Weather Grouting and Repair
Read Spectech’s latest magazine issue on Cold Weather Grouting and Repair:
Cold temperatures delay set time and strength development of cementitious grout. Cementitious grout, like concrete, must be allowed to attain a “green strength” before being subjected to freezing temperatures. The following guidelines may help compensate for cold temperature placement.
Materials should be pre-conditioned/stored as necessary so that the mixed grout is between 40 F and 80 F (4 C and 27 C). Due to the mass of palletized (bagged) material, up to 24-48 hours of pre-conditioning may be required. Store grout in an indoor or a tarped and heated area when required.
All surfaces in contact with grout should be pre-conditioned and maintained at a temperature between 35oF and 90oF (2oC and 32oC) for 8-24 hours. Presoaking concrete with hot water (90oF) may aid in raising concrete surface temperatures. Mixing grout with warm or hot water should also be considered. Ensure water used for presoaking does not freeze on concrete surfaces. Remove any frost from the surface.
Read original here:
Heating shall be accomplished by indirect exposure – do not blow heat directly on to newly placed grout surfaces. Heated enclosures should be windproof and weatherproof as much as possible. Combustion heaters must be vented and shall not be permitted to heat and dry the concrete locally. Caution: Exhaust gases may contaminate or cause carbonation within the enclosed environment.
Grout temperature shall be maintained above 35 F (2 C) until the grout reaches 1000 psi (6.9 MPa) or the required strength. For SpecChem Grouts placed at temperatures of 35oF, protection from freezing must be afforded 24 hours.
Once the grout has attained 1000 psi in compressive strength, gradually allow the temperature of grout to drop to ambient temperature to avoid thermal shock.
This time lapse video shows the construction of a grout shaft in Dering Yard.
The grout shaft was sunk to a depth of 17m. It is one five shafts required to ensure that nearby properties are protected from ground settlement (small movements of the ground) during our tunnelling works for the new Crossrail Bond Street station platforms.
All the work within Dering Yard was performed through the Medici passage, a narrow vehicle width passage with restricted height from New Bond Street. Access to several properties and emergency fire escape routes, as well as a public right of way, had to be maintained through this passage at all times while this work was carried out.