Item 406 Prestressed Concrete Structures

36問 • 1年前

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For pre-tensioning work-samples, at least a ____ long shall be furnished of each size of wire or strand proposed

For post-tensioning work-samples, a ____ long shall be furnished for wire requiring heading

For wires not requiring heading, sufficient length to make up one parallel-lay cable of ____ long consisting of the same number of wires as the cable to be furnished

1.5m

For strand to be furnished with fittings, _____ long shall be between near ends of fittings

1.5m

If anchorage assemblies are not attached to reinforcement samples, _____ anchorage assemblies shall be furnished, completed with distribution plates of each size and type to be used

The pressure gauge, if used, shall have an accurate reading dial at least _____ in diameter

154mm

The range of the load cell shall be such that the lower ____ of the manufacturer's rated capacity will not be used in determining the jacking stress

10%

Vents shall be _____ minimum diameter standard pipe

12.7mm

Ends of vents shall be removed _____ below the roadway surface after grouting has been completed

25.4mm

When acceptable prestressing steel for post-tensioning is installed in ducts after completion of concrete curing, and if stressing and grouting are completed within ___ calendar days after the installation of the prestressing steel

Prestressing steel, installed, tensioned and grouted in this manner, all within ___ calendar days shall be subject to all the requirements in this Item pertaining to corrosion protection and rejection because of rust

No bond stress shall be transferred to the concrete, nor end anchorages released until the concrete has attained a compressive strength, as shown by cylinder tests, of at least _____ unless otherwise specified

28 MPa

_______ after placing concrete and after the concrete has undergone initial set, the first application of steam or radiant heat shall be made unless retarders are used

2-4 hours

The waiting period before application of steam or radiant heat shall be increased to between ________

4-6 hours

During the waiting period, the temperature within the curing chamber shall not be less than _____ and live steam or radiant heat may be used to maintain the curing chamber at the proper minimum temperature

10°C

The steam shall be at ____ relative humidity to prevent loss of moisture and to provide moisture for proper hydration of the cement

100%

During application of the steam, or of radiant heat, the ambient air temperature shall increase at a rate not to exceed _____ per hour until the curing temperature is reached

4.41°C

The maximum curing temperature within the enclosure shall not exceed _____

71.1°C

Tensioning of the prestressing reinforcement shall not be commenced until tests on concrete cylinders, manufactured of the same concrete and cured under the same conditions, indicate that the concrete of the particular member to be prestressed has attained compressive strength of at least ______ unless otherwise specified

28 MPa

Cast-in-place concrete shall not be post-tensioned until at least _____ after the last concrete has been placed in the member to be post-tensioned and until the compressive strength of said placed concrete has reached the strength specified for the concrete at the time of stressing

10 days

The falsework under the bottom slab supporting the superstructure shall not be released until a minimum of _____ have elapsed after grouting of the post-tension tendons nor until all other conditions of the Specifications have been met

48 hours

The water content shall be not more than _____ per sack of cement

19L

Grouting equipment shall be capable of grouting at a pressure of at least _______

0.6894 MPa

Grouting equipment shall be furnished with a pressure gauge having a full-scale reading of not more than _______

2.07 MPa

Standby flushing equipment capable of developing a pumping pressure of ______ and of sufficient capacity to flush out any partially grouted ducts shall be provided

1.72 MPa

All grout shall pass through a screen with a ______ maximum clear opening prior to being introduced into the grout pump

2mm

Approximately _______ after the concrete pour, the metal conduits shall be flushed out with water and then blown out with compressed oil free air

24 hours

Grout shall be pumped through the duct and continuously wasted at the outlet until no visible slugs of water or air are ejected and the efflux time of ejected grout is not less than _______

11 seconds

After all vents and openings shall then be closed and the grouting pressure at the injection end shall be raised to a minimum of _______ and held for a minimum of ______

0.6894 MPa, 10 seconds

From 2 to 4 grams of the unpolished variety, about __________ of each sack of cement used in the grout

1 to 2 teaspoons

The aluminum powder shall be blended with pumicite or other inert powder in the proportion of _____ powder to _______ pumicite (or other inert powder) by weight

1 part, 50 parts

After all ingredients are added, the batch shall be mixed for ________

3 minutes

Batches of grout shall be placed within _______ after mixing

45 minutes

Prestressed concrete girders shall not be shipped until indicate that the concrete of the particular girder has attained a compressive strength equal to the specified design compressive strength of the concrete in the girder and has attained a minimum age of ______

14 days

The width of the deci soffit shall be within _____

± 25mm

The width of gap between individual beams shall not exceed ______ the nominal gap

twice

Project Engineer EXAM

Vaantoote · 62問 · 2年前

Project Engineer EXAM