Soil Testing Equipment

Referent and Standards Product for Soil Testing Equipment

Standard Test Procedures Manual - WET TRACK ABRASION TEST


1.1. Description of Test

This method covers measurement of the wearing qualities of slurry seal, hot sand asphaltmix and sulphur mixes under wet abrasion conditions.


2.1. Equipment Required

Balance 5000 g ± 1 g.
Sieves - Canadian Metric Standard square mesh of size numbers as required by the specifications for the materials being tested. Oven - thermostatically controlled at 60oC ± 1o.
Model C-100 Hobart mixer or equivalent. Metal tray 264 mm by 267 mm by 57 mm deep fitted with four vertical pins near the corners for holding template, sample and distilled water. Template 6 mm thick by 241 mm square with a centre hole 216 mm in diameter complete with four holes in corners to match pins in container tray. 22 to 27 kg grade asphalt roll roofing paper, 240 mm square with four holes to fit pins in metal tray. Water bath thermostatically controlled at 25o C ± 1o.

Abrasive head weighing 2.27 kg coupled to the Hobart mixer with approximately 14 mm free up and down movement in the shaft sleeve. A section of 300 psi reinforced rubber hose 14 mm ID by 31 mm OD and 127 mm in length shall be mounted horizontally on the abrasive head as shown in ASTM Method D3910. Plywood base 305 mm square for transporting and drying of sample in template in the oven.

Suitable prop block and spacers for supporting platform assembly in position during testing. Mixing pan, soft brush, spatula, graduated cylinder, 1800 ml beaker and distilled water. Squeegee or straight edge 305 mm in length. Fumehood, hot plate. Hydraulic press. Steel plate 255 mm square and a 215 mm diameter steel disk, both about 10 mm thick to hold sample while forming in press.


3.1. Sample Preparation

3.1.1. Slurry

Air dry aggregate similar to stockpile average to be used on job. Riffle carefully and complete sieve analysis as per STP 206-1. Place template on roofing paper and tack coat opening with SS1 emulsion. Quarter sufficient amount of dry aggregate required. Weigh approximately 80 gm of aggregate into mixing bowl making sure it is uniformly distributed. Add the predetermined amount of water and mix until particles are uniformly wetted. Finally, add the predetermined amount of emulsion and mix for a period of not less than 1 minute and not more than 3 minutes.

Note: the required water and emulsion content are determined by the consistency test method described in ASTM method paragraph 5.1. A flow of 2 to 3 cm is normally required. Immediately pour sample into template containing smooth roofing paper. Squeegee or straight edge slurry level with the top of the template with minimum amount of manipulation and scrape off excess material and discard

Place specimen in oven at 60o C and dry to constant weight. This usually requires a minimum of 15 hours. Remove sample from oven and allow to cool at room temperature and remove template and weigh. After weighing, place sample in 25o C water bath for 60 to 75 minutes before doing abrasion test.

3.1.2. Hot Sand Asphalt Mix

Dry aggregate and adjust gradation with filler as necessary. Heat aggregate and asphalt cement to desired temperature required and mix at the asphalt content required by the engineer (usually 8 to 12%). Cut square of roofing paper, place on steel plate. Apply tack coat of asphalt to roofing paper and place two template molds on top. Spread 800 g of mix in mold and strike off level with straight edge. Place steel disk over centre of template and place in hydraulic press under 4545 kg for 5 minutes. Weigh mold, mix and paper. Place in oven at 60o C for 4 1/2 hours.
After removing specimen from oven, place in water bath at 25o C for 1 1/2 hours.

3.1.3. Sulphur Mixes

Dry aggregate and riffle sample to approximately 800 g required for testing. Select grade of asphalt cement and heat to approximately 135o C. Heat aggregate and asphalt to 135o C and mix at required asphalt content (usually 8%). Add pelletized sulphur to asphalt mixture based on weight of total mix. This usually requires 16-17% sulphur when the asphalt used is 8 to 8.5 percent range.

Mix well under fume hood until the mixture becomes sloppy. Do not allow the temperature to exceed 150o C as the sulphur will combine with hydrogen to give off sulphur oxide gas. Cut square of roofing paper and place on steel plate. Apply tack coat of asphalt to roofing paper and place two mold plates on top. Spread sulphur mix in mold and strike off level with straight edge. Allow to cool at room temperature for 24 hours and weigh. After curing, place in water bath for 1 1/2 hours

3.2. Test Procedure
Remove specimen, template and roofing paper from water bath and place in metal tray with four pins to secure sample in bottom of tray. Cover sample with 6 mm distilled water at room temperature. Secure metal tray on the Hobart mixer by means of clamps provided and attach the rubber hose abrasion head. Elevate the platform until the rubber hose contacts the surface of sample. This usually requires sufficient pressure for the pin to be at the midpoint of the slotted sleeve. Use prop block to support platform assembly during testing. Operate mixer for exactly 5 minutes ± 2 seconds, at low speed. Remove sample from metal tray and wash off debris using soft brush. Place washed sample at 60o C in oven and dry to constant weight. Remove from oven and allow to cool at room temperature and weigh.


4.1. Collection of Test Results

Record original sample weight after molding and drying to constant weight.

4.2. Calculations

Weigh sample after abrasion and dry to constant weight. Original sample weight minus final abraded weight multiplied by 32.9 expresses the loss in grams per meter square.
(W1 - W2) x 32.9 = g/m2

4.3. Reporting Results

Report the loss in g/m2.


5.1. References
A.S.T.M. D3910
Saskatchewan Highway Technical Report #29.

5.2. General

Slurry showing a loss of more than 800 g/m2 is not acceptable. For asphalt mixes, a loss of 400 g/m2 should not be exceeded. For sulphur mixes no values are available. When pouring sample into template, care should be taken to mix the material uniformly to avoid segregation. Rotate hose after completion of each test and replace if badly worn.

Source : Saskatchewan Highways and Transportation