Concrete a manmade material widely and greatly used in construction Industry. This concrete is a mixture of adequate proportion of cement, water and aggregate. Hardening (or) strength of this material is obtained by the chemical action between water and cement. As the time increases the stronger it grows (i.e strength of concrete is directly proportion to its age).The durability, strength, versatility and other characteristics of concrete depends upon the properties and proportion of the gradients in the mix.
Strength of concrete is its resistance to rupture on application of load. It is measured by testing the samples for their compression, tension, shear and flexural strength. All these properties shows the strength …show more content…
In case of specific gravity of cement we use kerosene because it does not react with cement. A specific gravity bottle may be employed Le-Chatelier flak may be used.
In case of Specific Gravity Bottle:
• Balance the specific gravity bottle at the dry condition. Take the mass of hollow bottle be W1.
• Add distilled water to the bottle and balance the bottle filled with water. Take the mass be W2.
• Rub the dry specific gravity bottle and fill with kerosene and weigh. Take this mass be W3.
• Discharge some of the kerosene out and introduce a weighed superiority of cement (about 59 g) into the bottle. Bowl the bottle gently in inclined position till no further air bubbles rise in to surface. Fill the bottle to the top with kerosene and weigh it. Take the mass be W4.
• From the above data calculate the specific gravity of cement.
Note: Specific gravity of kerosene
Volume of cement = W5/S.
Volume of bottle = W2-Wl.
Volume of kerosene after cement has been added = W2-Wl-(W5/S)
Wherefrom, mass of kerosene after cement has been added = (W2-W1-(W5/S)/s
Thus (W2-Wl-(W5/S)) s+W5+Wl= …show more content…
The quantity of cement, Steel Fibres, sand and coarse aggregate essential for 30 cubes were weighted. The materials were first dry mixed then with water mixed carefully to get consistent mix. Concrete was transferred into the moulds, after 24 hours concrete cubes were removed from moulds and specimens were kept for curing.
The testing machine may be of any reliable type, of adequate capacity for the tests and capable of applying the load at the rate specified.
Age at test
Tests shall be made at standard ages of the test specimens, the most usual being 7, 14and 28 days. Ages of 13 weeks and one year are suggested if tests at greater ages are required. Where it may be essential to obtain the early strengths, tests may be made at the ages of 24 hours+_1/2 hour and 72 hours¬+_1 hours. However age of 7, 14 and 28 days is considered for this investigation.
Number of specimens
At least three specimens, preferably from different batches, shall be made for testing at each selected age.
• Specimens stored in water shall be tested instantaneously on removal from the water and while they are still in the wet