Concrete Cube Compressive Strength
Experiment No : 5 Title : Concrete Cube Compressive Strength (7 days) Introduction : To determine the strength, maximum load can be applied and workability of concrete mixture.
Theory :
Hard concrete test were conducted at the age of 3, 7, 14, 21 and 28 days after curing(but we tested it for 7 days only). The concrete strength increases according to the age,the mixture of its concrete design and the strength increment will continue for sometimes. Nevertheless, for most of the work, the concrete strength on the 28 days is set as standard even though it might be determined at a much earlier or longer period. The increment rate of the concrete strength will depend on the temperature and moisture during hardening process.
Objective : To determine the characteristic strength of the concrete and comparison between group 20 and group 25.
Cubes are properly cured and crushed at the ages of 7 days. 8 cubes are crushed at a time and their mean crushing strength is taken as the compressive strength of concrete.
Apparatus
1. Standard Slump Cone 2. Scoop(trowel) 3. Bullet-nosed rod 4. Rule 5. Slump Plate compressive machine
Procedure
1 .The interior surfaces of the assembled mould is required to be thinly coated with grease oil to prevent adhesion of concrete.
2. Pour the ready mixed concrete with certain mix proportion into the mould in 3 layers and each layer must be tamping 25 times using the compacting steel rod .Fill up the mould until overflow and levelled the surface using the hand float.
3. The concrete will be left for 24 hours setting.
4. The above steps shall be repeated for another 3 more cubes with same mix proportion(group 20) and 4 more cubes from different mix proportion(group 25).
5. Record the date of the mixture for every cube and submerged 2 cubes in the curing tank and the other 2 left it dry outside(ambient temperature) for 7 days.
6. Before placing in the water, the cube must be
Theory :
Hard concrete test were conducted at the age of 3, 7, 14, 21 and 28 days after curing(but we tested it for 7 days only). The concrete strength increases according to the age,the mixture of its concrete design and the strength increment will continue for sometimes. Nevertheless, for most of the work, the concrete strength on the 28 days is set as standard even though it might be determined at a much earlier or longer period. The increment rate of the concrete strength will depend on the temperature and moisture during hardening process.
Objective : To determine the characteristic strength of the concrete and comparison between group 20 and group 25.
Cubes are properly cured and crushed at the ages of 7 days. 8 cubes are crushed at a time and their mean crushing strength is taken as the compressive strength of concrete.
Apparatus
1. Standard Slump Cone 2. Scoop(trowel) 3. Bullet-nosed rod 4. Rule 5. Slump Plate compressive machine
Procedure
1 .The interior surfaces of the assembled mould is required to be thinly coated with grease oil to prevent adhesion of concrete.
2. Pour the ready mixed concrete with certain mix proportion into the mould in 3 layers and each layer must be tamping 25 times using the compacting steel rod .Fill up the mould until overflow and levelled the surface using the hand float.
3. The concrete will be left for 24 hours setting.
4. The above steps shall be repeated for another 3 more cubes with same mix proportion(group 20) and 4 more cubes from different mix proportion(group 25).
5. Record the date of the mixture for every cube and submerged 2 cubes in the curing tank and the other 2 left it dry outside(ambient temperature) for 7 days.
6. Before placing in the water, the cube must be