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Student Manual Lesson 5- Speedy Moisture Tester

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The Speedy Moisture test is a proven, efficient method of determining the moisturecontent of materials in the field. The results of the Speedy test, combined with thenuclear density gauge are standard accepted practice for determining in-place materialdensity (verification of compaction effort) in the field.

Typically used when nuclear density gauge or material being tested does not permitnuclear moisture content tests.

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FM 5-507 describes in detail the parts of the typical Speedy kitFM 5 507 describes in detail the parts of the typical Speedy kit.

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Similar to left exceptelectronic rather than beam scale.


We will review the Speedy Moisture Test in its’ entirety , starting with Calibration e e e t e Speedy o stu e est ts e t ety , sta t g t Ca b at orequirements through the performance of the test.

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FM 5-507

2.1 Calcium carbide pressure moisture tester: 20 gram or 26 gram. Testers owned bythe FDOT shall be calibrated at least every six (6) months by the District DensityEngineer (DDE), or designee, and at anytime there is reason to suspect malfunction. Acalibration kit shall be used. Testers not owned by the FDOT, but used for requiredtesting, shall also be calibrated every 6 months. Records of calibration shall alwaysaccompany the tester & shall be presented to the department upon request. Thep y p p p qcalibration kits used by the DDE’s, or designees, shall be calibrated by the StateMaterials Office at least once a year.

2.2 Tared scale: Tared scales owned by the FDOT shall be calibrated or verified at leastevery six months, and certified by the DDE, or designee. Tared scales not owned bythe FDOT shall also be calibrated every 6 months. Records of calibration shall alwaysaccompany the tared scales & shall be presented to the department upon request.p y p p p qThe Technician, using the weights required by Section 2.7, shall check tared scales atleast once a day.

Typical FDOT Calibration

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Record

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3.1 Level scale using wedges or sandbag leveling procedures. Scale should bestable at the completion of the leveling procedure.

If using the electronic scale version, it is still very important that the scale be level and“zeroed” or tared properly. As there are several different scale manufacturers, pleasep p y , prefer to the electronic balance user instructions for your model.

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FM 5 507FM 5-507

3.2 Add Reagent to body of tester: For 20-gram testers add 2 scoops, and for 26-gram tester add 3 scoops. Put the 2 steel balls into body of the tester, using caution not to damage body and/or gauge of the tester.

The steel balls are used to assist in breaking down some of the more course grained materials or clayey types of material to ensure proper reaction with the calcium carbide reagent.

THE FDOT PRACTICE CALLS FOR STEEL BALLS TO BE USED WITH ALL TESTS.

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FM 5-507

3.3 Obtain a representative sample of material using an appropriate tool to obtain thesample. A representative sample shall contain material from throughout the testdepth. Place in a moisture-proof container. The sample should be thoroughlymixed, either by shaking the container or by stirring with an appropriate tool.Chopping and stirring may be necessary for some materials in order to assure aproperly mixed sample.p p y p

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FM 5-507FM 5 507

3.4 Weigh Sample: Correct weight is shown when red arrow on beam coincides withmark on the scale. For electronic scales, the correct weight is accomplishedwhen the scale reads 20 grams or 26 grams, according to the type tester beingutilized. The scale should be protected from the wind. The scale pan and testercap should be protected from the sun.

Red Marks

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FM 5-507

3.5 After using cloth to clean cap, making sure that all traces of material fromprevious tests are removed, put sample into cap of tester using a small brush toremove all material from the balance scoop.

3.6 Hold the tester body horizontally to prevent test material and reagent frommixing before instrument is sealed. Insert cap, swing stirrup above cap, andmixing before instrument is sealed. Insert cap, swing stirrup above cap, andtighten top screw.

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3.7 Hold the tester horizontally; put balls into orbit around inside circumference of body. Balls act as ball mill to break down lumps in sample. Mixing time for coarse, variable material such as soils and aggregate - about I minute. Mixing time for heavy clay-type soils - about 3 minutes.

Note: Never shake the tester in such a manner that will cause the steel balls to strike the base of the tester dial.

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FM 5-507

3.8 When the needle stops moving read dial, holding the tester horizontally.

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3.9 Convert to Dry Weight: Using dial reading, refer to conversion chart for I or 3 minute readings with steel ball pulverizers to get correct dry-weight percentage.

NOTE: On LIMEROCK use direct dial reading.

Why a Conversion Table?

The dial reading is based upon the total wet weight of the tested material. TheConversion Table is based upon the Dry Weight of the sample.

Therefore, the Conversion table converts the dial reading of % moisture of wet weightto % moisture of dry weight.

N i i d f Li k th l ti d i thNo conversion is used for Limerock, as the larger, more coarse portions are drier thanthe smaller fine particles, and since only fine particles will get into the tester, theresults are more accurate without the chart conversion.

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3.10 Release pressure slowly away from you, empty contents, and examine forlumps. If not completely broken down, increase mixing time with balls by oneminute and rerun test. Clean the tester cap and neoprene ring seal with clothand the tester body with a large brush to insure that a clean tester is availablefor the next test. NOTE: Do not use brush to clean the tester cap.

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A. High Moisture Content

4.1 Some test materials may contain a higher percentage of moisture than allowedfor by the maximum 20% wet-weight (25% dry-weight) figure on the gauge dial.For these materials use the following procedure:

4.1.1 Use only half the standard sample weight. For this purpose use asmall brass weight (half the standard weight) included with thebalance. Hook this weight through the link holding the balance panbalance. Hook this weight through the link holding the balance pancradle - or hang weight on edge of balance pan - and weigh as usual.For electronic scales, weigh 10 grams or 13 grams, according to thetype tester being utilized.

4.1.2 Perform test in normal manner.

4.1.3 Double gauge reading. For example, if gauge reads 15%, calculatet i ht i t t t 15% 2 30% Obt i d i htwet weight moisture content as 15% x 2 = 30%. Obtain dry weight

moisture content from applicable chart.


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B Low Moisture ContentB. Low Moisture Content

4.2 Some test materials may have low moisture content. For these materials use thefollowing procedure:

4.2.1 Increase the sample size from the standard amount. For example,double the sample size.

4 2 2 Perform test in normal manner4.2.2 Perform test in normal manner.

4.2.3 Divide gauge reading by number of batches tested together. If samplewas doubled, divide by 2. A dial reading of 1.8% would be 1.8% dividedby 2 = 0.9% moisture content. Obtain dry weight moisture content fromapplicable chart.


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5 R d ti5. Recommendations

5.1 If the tester is hot from previous testing and/or direct sun, it should be allowed tocool in a shaded area.

5.2 If tester is too cold during the first test (ambient temperature less than 50°F),disregard and retest. Initial test may provide low readings.

5 3 The reagent will lose potential if exposed to air for extended periods Do not fail to5.3 The reagent will lose potential if exposed to air for extended periods. Do not fail toreplace the can lid.

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5 R d ti (C t )5. Recommendations (Cont.)

5.4 The most sensitive part of the tester is the gauge. Dropping the unit may result inthe needle not returning to zero when pressure is released. If the needle does notreturn to zero repair or replacement may be necessary.

5.5 The neoprene washers used to seal the cap to the body should be replaced if aseal cannot be maintained.

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6. SAFE DISPOSAL OF RESIDUE

6.1 The chemical reaction, which occurs in the tester, produces acetylene gas and amild alkali, calcium hydroxide (lime).

6.2 After testing, empty the contents of the tester into a disposable container or bagand when convenient, empty the container onto open ground. When the test isperformed in the field, the contents may be emptied directly onto open ground.

6 3 Spread the residue thinly and allow any unreacted reagent to decompose on6.3 Spread the residue thinly and allow any unreacted reagent to decompose onexposure to air. This must be done well away from buildings, or flammablesubstances.

6.4 Do not empty contents into a waste bin. Keep away from sparks or flame.

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2009 student lesson 5 speedy - ctqp home page level 1/05 - 2009 student lesson... · keep away from...

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