Cube compressive strength test
Introduction:
By far the most common test carried out on concrete is the compressive strength test. The reasons are that it is commonly assumed that most of the important properties of concrete are directly related to the compressive strength; since concrete has very little tensile strength, it is used primarily in a compressive mode, and therefore it is the compressive strength that is important in engineering practice; the structural design codes are based mainly on the compressive strength of concrete; and the test is easy and relative inexpensive to carry out. This time, we are going to use the three 150mm cube mold which we have made in last 2 week to test their compressive strength.
Specimen:
Three 150mm cubes (made on 14days ago)
Apparatus:
Compressive testing machine, calipers, weighing equipment
Procedures:
- The three cubes were removed from the curing tank.
- Water and grit on the surface of the cubes were wiped off with a damp cloth.
- Any faults and damages such as broken edge of the cube were visually inspected.
- The dimensions of the three cubes were measured with calipers. No “under size” or “oversize” cubes were recorded.
- The cubes were weighted
- Test machine platen was wiped with a dry cloth.
- The cube was placed centrally on the lower platen of the test machine with the rough as-cast top surface of the test cube vertical not in contact with the platens.
- The appropriate loading rate was selected for the cube tested. Pacerate for 150mm cubes is 338kN / min. Load rate is 0.2 – 0.4 mPa / s.
- The top platen was lowered on to the cube and a uniform seating was ensured by gently rotating the top platen as it is brought to bear on the cube.
- The load was applied without shock and load was continuously increased until no greater load can be sustained by the cube.
- The maximum applied force (Maximum load) was noted when the cube fails.
