CT Concrete Standard Specifications Chapter 51 & 90 Flashcards
Concrete Washouts must have a sign saying what? With What Dimensions?
CONCRETE WASHOUT ON A 4’x2’ SIGN
Thickness of Polyethylene for temporary concrete washout
10 mils, and free of holes and defects
Portable Temporary Concrete washout bin size
55 gallons
Temporary Concrete Washout Bins size
5 CY
What is required if colored concrete is to be incorporated into the work?
technical data, manufacturer specs working plan for mixing, delivery, placement, finishing and curing
When do we need test panels?
When texture or color is used/notify the architect
Default compressive strength for concrete in structures
3600 PSI @ 28 days
Approximate sack range for structural concrete
7-8.8 sacks
Weight limits for bridges after pour
1000 lbs at 2,400 PSI
4000 lbs at 3250 PSI or 28 days
Nothing over 10,000 until pre-tensioned
Are the bottom of footing elevations final? Who do you coordinate with if not? Its a good time to verify what?
No, they are approximate. Coordinate with SR at the very least. Geotech and Bridge design if you want further consultation or confirmation. Good time to ensure the soil is what was expected.
When the roughened surface is shown, what should the amplitude be?
1/4”
Forms Details (Total of 5)
- Mortar Tight
- True to dimensions, lines, and grades of the structure
- Strong enough to prevent deflection during concrete placement up to 3/32” and/or 1/270 center to center length between joists
- Form exposed surfaces so that similar texture color and appearance is obtained
- use form panels that are 3X6 as least except for smaller members or at the ends
Fillet Dimensions at all sharp corners
3/4” X 3/4”
May remove forms not supporting dead load after how long?
24 hours
When to water form before placing concrete?
Immediately before placing concrete
When can you add water to mix?
Before 1/4 CY is discharged
Except for piles, what is the maximum fall height of concrete?
8 ft
How long before deck for stem and soffit pour?
A minimum of 5 days
Can you vibrate forms or reinforcement for consolidation?
NO
MUST PROVIDE SAFE ACCESS FOR INSPECTORS
The amplitude of roughness between girder tops and deck?
1/4”
Details for Hydrostatic pressure relief holes
3” diameter, 15’ O.C. directly above the footings
Ordinary surface finish (General Definition)
Applies to all surfaces, but might not be the final finish. Basic finishes
Class 1 Surface Finish
Smooth even surface of uniform texture and appearance without bulges, depressions, or imperfections
Class 2 Finish
Special Case where mortar is added to exterior
CoC For Cement must be signed by?
-If sent directly to the job site it must be signed by the cement material supplier
-If mixed and sent to the job site, the CoC must be signed by the concrete manufacturer
If Blended cement is used, show what on ticket?
Show true percentages of supplementary concrete material
Admixtures used?
Must be on authorized material list
What weights should be on weighmaster ticket in concrete delivery?
Actual weights, not theoretical or intended
At what PSI for compressive strength does prequalification start being required?
3600 PSI–> All Structural concrete needs to be prequalified in this case
Where will Contractor QC test results be submitted too?
DIME
QC Summary
Submited Monthly by contractor showing test results, inspection reports, various documentation, and CoC fo structural concrete signed by QC manager
What volume does the compressive strength test represent?
300 CY
Contractor’s responsibilities for QC
-CIP Structures
-Maintain QC Plan
-Provide Inspector
-Provide testing services
-QC inspector AUTHORIZES or REJECTS material
-QC inspectors have no ties to subcontractors/ May be contractors employees
QC manager availability
Must be on site or within 3 hours away
Aggregate QC Test Frequency
Once per day of pouring
Slump Test Frequency
Once Per 100 CY
Uniformity Tests
When Ordered by Engineer
Air Content Tests
Once per 30 CY only applicable in freeze-thaw where concrete is air entrained if not in freeze thaw areas then 100 CY
Temperature check frequency
Once per 100 CY or once a day (whichever is more frequent)
Density Testing Frequency
Once per 100 CY or once a day (whichever is more frequent)
Compressive Strength-How often to check
Once per 100 CY or once a day (whichever is more frequent)
Inspection reports from Contractor’s QC
Must be sent to the Engineer (As inspector I want these)
If 3 subsequent batches fail
STOP (if applicable or reasonable) Revise operations and increase inspection frequency. Must be authorized before resuming.
The Department’s QC does what in relation to collecting concrete cylinders, regardless if contractor is testing as well. Which should be used for making decisions?
-Will still collect cylinders for the compressive strength test. These results will be the ones utilized for making decisions.
If the concrete batch fails any test
REJECT MATERIAL–> Within reason
How OFF can the specific material proportions be in a concrete mix?
-Cumulitive Aggregate ±1 %
-Aggregates Weighed Seperatly ±1.5%
-Cement and SCM weighed in any combo +2% to -1%
-Water ±1.5% of weight or volume
Concrete Temperature upon placing
50-90 degrees Fahrenheit
Hand mixing is allowed up to
1/3 CY
How many revolutions after adding water
30 times
How long before need to discharge all concrete, How many revolutions? (No additive to retard)
1.5 hours and 250 revolutions
Under what circumstances should 90-minute discharge time be reduced?
If concrete temperature goes over 85 degrees
If admixture to retard concrete set time is utilized then what can set time be? Revolution Count? Max Temp?
Concrete temp must not reach 85 degrees
Time limit becomes 2 hours
Revolution limit 300
Slump Range for (Nominal and Maximum) Also, what is nominal and maximum procedures:
-Concrete Structures Over 12 inches in thickness
-Sections 12 inches or less
-CIP Concrete Piles
Nominal and maximum values allow for a buffer zone. If venturing into a nominal zone then correct operations. Do not place if exceeding the maximum.
-Concrete Structure Over 12 inches–> Nominal (1-3”) Max ( 5”)
-Concrete Structures Under 12 inches–> Nominal (1-4”) Max ( 6”)
-CIP Concrete Piles–> Nominal 5-7” Max (8”)
If Type F or G (High Range Water Reducers) admixtures are used , 9” may be used
When can maximum water requirements be exceeded?
- Recieve authorization to increase cementitious material content
- Increase the water and cement material at a ratio that does not exceed 30 lbs of water to 100 lbs of cement per CY.
How long to cure mortar?
3 Days
Water Method for Curing
-7 Day Cure time
-Mist do not allow for running water over surface
-Mats, rugs, carpets, earth, or sand blankets, sheeting material
-Keep surface temp below 140 degrees
The application rate of curing compound
150 sq ft/gal
Curing Compound application method
Machine application only. Hand application for small irregular areas
When to apply curing compound
Before sheen or shrinkage cracks form
Can Curing compound be applied to freestanding water?
NO
If film is damaged on curing compound within 7 days of cure
Come back and reapply
Water Membrane method
using burlene, primarily on bridge decks 72 hours
Form in Place method & What should be done after pour?
7-day curing time. 5 days for over 20” in the least dimension. Reseal forms after pouring to ensure water-tight connections.
Where to find testing frequency for concrete?
Chapter 90 SS and Chapter 6 Construction Manual
