Coefficient of Thermal Expansion

Coefficient of Thermal Expansion

CTE AFCT2 FixtureEasily and consistently measure the coefficient of thermal expansion of concrete with the AFCT2.  Select the desired test parameters.  Place the preconditioned specimen in a test fixture.  Then place the specimen and the test fixture in the bath.  The computer controls the test and automatically saves temperature, displacement, and time data.  Test up to three specimens simultaneously.   

The system consists of a water-bath, heating/cooling circulator, specimen fixture, interface electronics, temperature measurement instrumentation, and control software.  The control computer may be supplied by the user or purchased as part of the system.  A single USB communication is used to control the system operation.  Model AFCT2 is supplied with a single fixture but is capable of operating up to three fixtures.  Most testing parameters are programmable to allow for alternate testing protocols.

Standard

The AFCT2 performs in compliance with AASHTO T336 and TEX-428-A.

Power: 

AFCT2: 

100-240 VAC, 1 Amp, 60 Hz, 1 ph

Circulator:  

115 VAC (±10%), 16.4 Amps, 60 Hz, 1ph

230 VAC (±10%), 12.5 Amps, 50 Hz, 1ph

Shipping Weight: 

Approximately 136 kg (300 lbs)

Footprint:

Approximately 45" D x 35" W x 35.5" H for the water-bath/circulator system

Allow additional space along the unit for an operator to load specimens.

 Water Bath:

838mm length x 406mm width x 889mm high (33” x 16” x 35”)

Capacity:  68 liters / 18 gallons (holds up to three fixtures)

Circulator:

Temperature Range: 

10° - 50°C (50°-122°F) with a resolution of ±0.1°C

Performance:

Heating: 10° – 50° C ~3.5 hour

Cooling:  50° – 10° C: ~2 hour

Specimen Size:

Diameter: 75mm - 160mm Length1: 178.8mm (7.0”) [168mm – 188mm]

Test specimen lengths other than 177.8 ±2.5mm (7” ±0.1”) require frame standards corresponding to specimen length.

Specimen Fixture:

 Corrosion resistant alloy with submersible LVDT

Verification Specimen:

 304 Stainless Steel, 178.8mm (7") with ASTM E228 CTE

Calibration Specimen:

 Titanium, 178.8mm (7") with ASTM E228 CTE

Input Parameters:

Specimen Length

Temperature Set Points

Equilibrium Requirement (i.e.: 0.00025mm/30 minutes)

Test Stop Criteria (i.e.: 0.3 micro-strain/°C)

Sample Identification

Data Acquisition:

Bath Temperature (4 channel)

Up to 3 Specimen Fixtures

Specimen Temperature (optional)

Data Output:

Formatted Excel® Spreadsheet

Time, Temperature, Change in Length, and CTE Value

Minimum Computer Requirements:

Intel® Pentium® 4 Processor, Microsoft® Windows® 7, 256 MB RAM, 1.2 GB Hard drive space, Microsoft® Excel® 2003

Monitor Resolution:  1024 x 768, 16-bit color

The User Interface:

 A user interfaces with the AFCT2 system on a Windows® based computer system.

 

Test Data Storage:

The AFCT2 system stores the technician’s identity, comments entered regarding a specific test, the serial number of each fixture being used in the test, the correction factor for each fixture being used, the frame calibration standard serial number used to calibrate each fixture, the frame calibration standard’s CTE, the frame calibration date, the frame verification date, the identification of each specimen being tested, the height (length) of each specimen being tested, the date of each measurement, the time of each measurement, the temperature set point for each measurement, the temperature, the LVDT displacement for each LVDT,  on the Windows® system that runs it.  These files can be moved to different computers by standard means of file sharing.

 

Test Data Viewing:

 The AFCT2 provides for data to be viewed in the form of a CTE Report or as raw data in Microsoft® Excel®.

 The CTE Report workbook also allows a user to determine and see the thermal expansion coefficient based on the temperature transition slope of the Texas DOT method TEX-428-A.

 

Test Data Printing:

 Test data and reports can be printed through the normal print functions of the computer being used.

 

Multiple Test Specimens:

The Pine AFCT2 has the capacity to determine the coefficient of thermal expansion of three (3) concrete specimens at one time.  The purchase of an AFCT2 unit includes the frame required to measure a single concrete specimen.  Additional test frames may be purchased from Pine.

 Part Number

 Part Description

 ACCTE07

 Water Bath Temperature Probe (thru S/N 103201) mini-jack

 ACCTE09

 Submersible Transducer, ±5 mm stroke

 ACCTE16

 Water Bath Temperature Probe (S/N 111801 and up)

 AFCTS02F                               

 CTE Frame with Transducer (specimen fixture)

 Note:  The water bath has capacity for three frames and the operating system is designed to handle data from three specimens at one time.  The system allows for one, two, or three tests to completed simultaneously.

AFCTX01

 Specimen Temperature Data Acquisition Module (includes one EXT44034 specimen probe with 90" leads)

EXT44034

 Specimen Temperature Probe

RAHTDT

 Digital Thermometer:  -50° to 150°C, 0.001°C resolution, ±0.05°C accuracy

RCWP3

 Computer to operate the AFTC2.  Computer specifications are as follows:  Intel® Pentium® 4 Processor, Microsoft® Windows® 7, 19” Flat Panel Display, Keyboard, Mouse, Read/write CD, Ethernet network module, Microsoft® Office basic edition.

ACCTF27K

 Replacement Anode Kit (3)

 

Call +1.724.458.6393

 

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Verification:  

  • Verification is used to maintain the traceability of a system and to determine when to recalibrate. If the machine response is in conformance, no correction is required and the system is considered calibrated.
  • Verify the transducer displacement calibration every 3 months.
  • Verify the Frame Correction Factor every 1 month.
  • Verify the lengths of the calibration and verification specimens annually.
  • Verify the system temperatures every month when the Frame Correction Factor is being verified. 

Calibration:

Important Note:  If a measurement system (force, angle, height) is shown to be correct when verified, it is considered fully calibrated. It is preferable to not update a stable system’s calibration data if it is correct so that system stability can be observed over time.

Traceability:

  • The coefficient of thermal expansion of the titanium calibration specimen is traceable.  It is used to calibrate the transducer displacement (stroke) and the Frame Correction Factor.
  • The coefficient of thermal expansion of the 304 stainless steel verification specimen is traceable. It is used to verify the transducer displacement (stroke) and the Frame Correction Factor.
  • The temperature of the system, in the water bath and at the circulator, is calibrated using a traceable thermometer.

Part Number       

Part Description 

AFCTC05S3C       

 304 Stainless Steel Verification Standard, 7" with ASTM E228 CTE  

 AFCTC08TIC 

 Titanium Calibration Standard, 7.1"/7.0"/6.9" with ASTM E228 CTE   

 RAHTDT 

 Digital Thermometer:  -50º to 150º C, 0.001ºC resolution, ±0.05ºC accuracy   

 

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Cleaning:

A clean machine is vital to getting accurate test results.

Maintenance:

The transducer

  • Clean the spring loaded shaft with isopropyl alcohol and a cotton swab on a weekly basis.
  • Polish the shaft with a Scotch-Brite™ Ultra Fine Abrasive Pad to remove any scaling.
  • Use a fine wire brush to ensure the vent hole on the transducer is clear.
  • Work the probe on the transducer in and out to ensure smooth operation.
  • Warning:  Do not use WD-40™ or other penetrating solvents on the transducer shaft.

Specimen Contact Points

Polish the three specimen support buttons and the transducer ball tip with a Scotch-Brite™ Ultra Fine Abrasive Pad to remove any scaling.

Water Bath

  • Change the water every 2-3 weeks to minimize the buildup of scale deposits.
  • Add Simple Green™ cleaner to the water bath on a yearly basis and circulate it to minimize calcium scaling in the circulator.
  • Remove any obstructions caught on the circulator screen before each use.

Lubrication:

Apply synthetic grease to the transducer's shaft after it is cleaned each week.

What does one need to consider in choosing a location for this machine?

  • Select a sturdy, level, preferably concrete and ground level floor.
  • A nearby floor drain would be useful.
  • Stay away from other test machines that apply cyclical or impact loading.
  • Allow sufficient space around the machine to load and unload specimens from the water bath.

Does the length of the concrete specimen matter?

  • The specification requires a specimen length of 175 mm to 180 mm.
  • The frame correction factor should be recalculated using a calibration specimen of appropriate length if specimen length are outside this range.
Pine Test Equipment

Pine Test Equipment, Inc.
101 Industrial Drive
Grove City, PA 16127

Phone: (724) 458-6393
Fax: (724) 458-6418
E-mail: Contact Us

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