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Pavement material strength tester using the method

Pavement material strength tester and other supporting fixture can be conducted a number of experiments, such as the compressive strength of cement and lime stabilized soil, splitting tensile strength, elastic modulus test, asphalt concrete and the Marshall test, subgrade soil and a variety of pavement materials bearing ratio (CBR) test.
1. Marshall stability test of pavement material strength tester
(1) measurement of the height of the specimen
Use vernier caliper to measure the height of the specimen, at least four of the average circumference as specimen height, accurate to 1mm.
(2) determination of the density of the specimen
The quality of the test piece in the air, and then it is said to be in the air quality (such as the wax seal method), which is accurate to 0.1g.
Among them: Dm - /cm3 G
W - quality of G in air
W1 - G in water quality
W2 - wax specimens in air quality G
W3 wax specimens in water quality G
Gp - the proportion of wax
Gw 1g density (/cm3)
(3) determination of the stability of the specimen
A. will determine the density of the test specimen and the Marshall test, the pressure head, placed at a temperature of 60 degrees 1 degrees oil asphalt constant temperature water tank to maintain at least 30~45 minutes.
B. the upper and the lower pressure head from the sink out to wipe clean inside, in under the indenter guide rods coated with a little butter and then test piece out set under pressure head, cover the upper pressure head, and then loaded on loading equipment.
C. flow value measuring device mounted on the guide rod, the guide sleeve head gently pressed on, while the flow gauge to zero value.
Put appropriate D. in the head of the ball on the tee, pressure head and alignment test force ring, then the force on the zero ring dial indicator.
E. will range from 0 to 30 kn force measuring ring mounted on the test apparatus and adjusting the speed of loading to 50 mm / min and start the tester. When the load reaches its maximum moment, reading test force ring dial indicator and flow value flow meter readings.
Note: the time of the test piece to the maximum load value is removed from the constant temperature water tank, and no more than 30s.
2, pavement material strength test instrument in the bearing ratio test
(1) the water swelling capacity determination
A. test pieces made, remove the test parts of the top surface of the broken filter paper, put a piece of paper and the placed attached to the adjusting rod of the perforated plate, add enough load plate in the plate, the surface pressure is equal to the pressure of the material layer on the pavement.
B. will try cylinder and the porous floor together into the tank, then drain) and tie will die taut, dial indicator is installed and read the initial reading.
C. to sink drain, free water into the top and bottom, immerse themselves in water during the water surface in the groove should be keep in the specimen on the top surface about 250mm above, usually specimen need to soak for 96 hours.
D. in 96 hours at the end of the specimen, read the dial indicator readings, with the following formula and expansion:
From the tank remove specimens, poured specimens of the top surface of the water, standing for 15 minutes, and then unload the additional load of the perforated plate, a bottom plate and a filter paper and weighed, calculating test of temperature and density changes.
(2) penetration test of pavement material strength tester
A. will be the end of the water test specimen on the test instrument on the lifting table, placed in a predetermined number of loading plate penetration rod.
B. 4500g first applied load on the penetration rod, then the force and deformation of the measuring indicator pointer to zero.
C. in the test apparatus installation range for measurement ring of 0-50 kn, adjust the loading speed is 1mm / min and start testing instrument, force measuring ring dial indicator of some entire readings (e.g., 20, 40, 60 records...) When the quantity of penetration, and the need to pay attention to, the penetration rate was 2.5 mm, can have more than 5 readings. The first reading of the test force ring indicator should be about 0.3mm.
Test results of calculation and drawing the pressure (pressure) - penetration curve, the unit pressure as abscissa, penetration as ordinate, draw the curve.
The penetration of 2.5 mm unit pressure (kPa) and the standard pressure ratio as the material of bearing ratio, so the carrying ratio = unit pressure / a 0.7 x 100%. At the same time, calculate penetration to 5.0mm of bearing ratio.
Such as penetration to 5.0mm bearing ratio greater than 2.5mm bearing ratio test shall be repeated. If the result is still the case, the use of 5.0mm bearing ratio.
3, the resilience modulus test of pavement material strength tester
A. measuring force ring is installed on the test instrument for measuring range of 0~50kN.
B. the bottom surface of the specimen and the test tube is placed on the platform of the test instrument.
C. will dial indicator bracket fixed in test tube on both sides of the screw hole, the bearing plate on the specimen surface central position, and with the tester penetration bar is.
D. will be an indicator and header on the supporting rod, and a dial indicator measuring head is placed in the bracket on both sides of the bearing plate
E. the predetermined maximum pressure divided into 4 to 6 copies, as the pressure of each stage of the loading, the first level load is applied (such as 1 / 5 of the predetermined pressure, when the load of 60 s, records of the dial indicator readings, also lifted the load, let specimen deformation recovery to 30s, recording dial indicator readings.
F. applying the two-stage loading (to a predetermined maximum load of 2 / 5), load 1min, records of the dial indicator readings, and lifted the load and unloading after 30s record dial indicator readings, and the third level load is applied, so step by step until the finish a final test.

G. test results:

Springback deformation at first stage load I

I= loading - unloading reading reading, mm

The unit pressure of P as the abscissa (Xiang You), the rebound deformation as the ordinate (down), draw the curve of relationship between P and I. If there is a concave phenomenon in the beginning, the first point and the second point can be combined into a straight line, and then the line and the vertical coordinate are extended.

Press type calculation of resilient modulus E:

I - the rebound deformation of P corresponding to the unit pressure mm

Mu - Poisson's ratio, the subgrade soil is 0.35, 0.25 for pavement material.

4, indirect tensile strength test (split test)

A. will have a day and night in the water to remove the specimen from the water, with a soft cotton cloth to the surface of the test piece of visible free water, said the test piece quality.

B. use vernier caliper to measure the specimen height (H1) to 0.1mm.

C. in the tester of the lifting platform is provided with a pressing bar sample placement on the layering (layering) and in the top surface of the specimen also put a layering (layering and specimen of the contact line must is specimens of average, and perpendicular to the lifting platform).

The maximum pressure P (kN) of the D. (1mm/min) was recorded at the time of the test.

E. from the specimen to take a representative sample (after breaking) to determine its water content.

F. test results:

D - the diameter of MM

L - the height of the specimen after immersion mm

5, pavement material strength tester in the unconfined compressive strength test

A. will have been immersed in a day and night to remove the specimen from the water, with a soft cloth to the surface of the test piece of free water, and said the quality of the specimen.

B. with vernier caliper test piece height h, accurate to 0.1mm.

C. will measure the range of 0~100kN to the ring, installed on the tester.

D. will try to put on the test apparatus of the lifting platform, start the machine, and the rate of 1mm/min, record the maximum pressure of the test pieces of kN.

E. from the specimen to take a representative sample (after breaking), determine its water content.

F. test results:

D - the diameter of MM