GENERAL
Concrete shall be cured by one or a combination of the methods given in ACI 308, Chapter 2.
Sea water shall not be used for curing concrete.
Concrete shall be cured by one or a combination of the methods given in ACI 308, Chapter 2.
Sea water shall not be used for curing concrete.
Concrete shall be shaded from the wind and sun for a minimum
of seven days after placement.
The following curing periods shall apply Concrete floors and stair treads with monolithic or steel trowel finish 10 days. Roof slabs of job-placed concrete 7 days. All other concrete work 5 days.
The following curing periods shall apply Concrete floors and stair treads with monolithic or steel trowel finish 10 days. Roof slabs of job-placed concrete 7 days. All other concrete work 5 days.
MEMBRANE CURING
Immediately after completion of required surface treatment
of concrete, surface of concrete shall be covered by membrane curing compound.
Where forms are left in place for entire period for which
curing is specified foregoing, use of curing compound may be omitted, provided
that forms will be wet down with water, where forms are stripped before
completion of specified curing period, curing compound shall be to such
surfaces immediately after completion of specified surface treatment.
Approximately a square meter per liter curing compound shall
be applied unless otherwise instructed by manufacturer.
Smoking, open flame or fires shall not be permitted while
material is being applied. Adequate ventilation shall be provided. Workmen
shall be equipped with respirators if required.
Prior to initial use of any specified compounds, arrange with manufacturer for manufacturer's technical representative to visit the project site and give instructions on correct use of material.
CURING COMPOUNDS CONTAIN VOLATILE THINNERS
Prior to initial use of any specified compounds, arrange with manufacturer for manufacturer's technical representative to visit the project site and give instructions on correct use of material.
CURING COMPOUNDS CONTAIN VOLATILE THINNERS
Do not permit smoking, open flame or fires while materials
is being applied. Provide adequate ventilation. Equip workmen with respirators
if required.
TREMIE CONCRETE
MATERIAL
To the requirements specified for Grades 25 and 40 concrete unless otherwise indicated, except use 10 % additional cement in mix and limit slump to 140 mm maximum.
To the requirements specified for Grades 25 and 40 concrete unless otherwise indicated, except use 10 % additional cement in mix and limit slump to 140 mm maximum.
TREMIE EQUIPMENT
Pipe or tube with minimum diameter of 250 mm shall be
utilized installed in sections with flanged and gasket couplings and hopper at
top.
Tremie shall be support so as to permit free movement of
discharge and over entire top surface of work and so as to tremie to be rapidly
towered, when necessary, to choke off or retard of concrete.
PLACING
Concrete shall be deposited by carefully placing concrete in its final position by means of tremie. The concrete shall not be disturbed after it is deposited.
Concrete shall be deposited by carefully placing concrete in its final position by means of tremie. The concrete shall not be disturbed after it is deposited.
Special care shall be taken to maintain still water at point
of deposit tremie shall not be placed concrete in running water.
Carefully regulate consistency of concrete and use special
care to prevent segregation of materials.
Concrete shall be placed in continuous horizontal layers, with thickness of each layer generally not exceeding 300 mm. Carefully regulate method of depositing concrete as to produce approximately horizontal surfaces on each layer.
Concrete shall be placed in continuous horizontal layers, with thickness of each layer generally not exceeding 300 mm. Carefully regulate method of depositing concrete as to produce approximately horizontal surfaces on each layer.
Tremie hopper completely shall be full of concrete during
entire placing operation in order to maintain sufficient head. Keep flow
continuous, and in no case interrupt, until placing of concrete is completed.
CONCRETE FILLS FOR EQUIPMENT BASES
Hollow bases of equipment with concrete unless otherwise
indicated on the contract drawings, after bedplates have been grouted. Concrete
fill shall conform to requirements for class of concrete specified for the
work, except maximum size of coarse aggregate shall be 19 mm.
REPAIR OF CONCRETE
Repair of concrete shall be made in accordance with USBR,
Chapter 7, "Repair and Maintenance of Concrete".
Imperfections in formed concrete shall be repaired as soon
as practicable after removal of forms.
Cure repairs in accordance with Section “curing“ above.
Cure repairs in accordance with Section “curing“ above.
CAST-IN-PLACE ELECTRICAL DUCTRUNS
Cast in place electrical ductruns shall conform to the
requirements of applicable Electrical specification and to requirements for
class of concrete specified for the work.