University of New Mexico
Civil Engineering Department
Civil Engineering Materials Laboratory, CE 305L
SPLITTING TENSILE STRENGTH OF CYLINDRICAL CONCRETE SPECIMENS
ASTM C496
Scope
This ASTM test method covers the determination of the splitting tensile strength of cylindrical concrete specimens. This method consists of applying a diametral compressive force along the length of a cylindrical specimen. This loading induces tensile stresses on the plane containing the applied load. Tensile failure occurs rather than compressive failure. Plywood strips are used so that the load is applied uniformly along the length of the cylinder. The maximum load is divided by appropriate geometrical factors to obtain the splitting tensile strength.
References
ASTM C496 Splitting Tensile Strength of Cylindrical Concrete Specimens
ASTM C39 Compressive Strength of Cylindrical Concrete Specimens
ASTM C78 Flexural Strength of Concrete (Using Simple Beam with Third-Point Loading)
ASTM C192 Making and Curing Concrete Test Specimens in the Laboratory
Apparatus
Compression Testing Machine
Bearing Strips - 2 each, 1/8 in. thick plywood strips, 1 in. wide (the length shall be slightly longer that that of the specimens). The bearing strips are placed between the specimen and the upper and lower bearing blocks of the testing machine (or between the specimen and supplementary bearing bars if used).
Supplementary Bearing Bars - Steel bar 2 in. wide, 3 in. thick, and 12 in. long.
Materials
6” x 12” Moist-cured concrete cylinders
Procedure
Download Procedure for Split Tensile test
Download the Excel form for Split Tensile test
1) Draw diametral lines on each end of the specimen so that they are in the same axial plane.
2) Center one of the plywood strips along the center of the lower bearing block.
3) Place the specimen on the plywood strip and align so that the lines marked on the ends are vertical and centered over the plywood strip.
4) Place the second plywood strip and the bearing bar so that they are lengthwise on the cylinder, centered on the previously marked lines on the ends.
5) Apply the load continuously at a constant rate of 100 to 200 psi/minute of splitting tensile stress until failure occurs (the load rate is 11000 to 22000 lb/minute for 6”diameter by 12” long specimens).
6) Record the maximum load at failure.
7) Calculate the splitting tensile strength as follows:
where P is the maximum load at failure in pounds, and l and d are the length and diameter of the cylindrical specimen, respectively, in inches.
Set up of split tensile test
Specimen after fracture
Top view of fractured specimen
Side view of fractured specimen
Report
1) Report the type of concrete, unit weight, and unconfined compressive strength.
2) Report the splitting tensile strength to the nearest 5 psi.
Questions
1. What is the ratio of the splitting tensile strength to the unconfined compressive strength?
2. How does the splitting tensile strength compare with the strength obtained from the Modulus of Rupture tests (ASTM C78, Flexural Strength of Concrete)? Express as a ratio of the split tensile strength to the MOR.