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Part-IQ1 Short Answer Type Questions (Answer All-10)a) Mention the test adopted to test the properties of cement in laboratories? |
| Answer» <p>The physical tests which are generally performed to determinethe acceptability of cements are –</p><p>Fineness Test</p><p>2. Consistency Test3. Setting time Test4. Soundness Test5. Strength Test6. Heat of Hydration Test7. Specific Gravity Test1. Fineness TestFineness is the mean size of cement grain. Fineness test is done to measure the mean size of cement grain.The finer the cement the surface area for hydration will be large and it increases the strength of cement. But the fineness varies in different types of cement.Following three methods are applied to test the fineness of cementSieve methodAir Permeability methodSedimentation method2.Consistency TestThis test is done to estimate the required water quantity to form a normal consistency cement paste. It is defined as the percentage of water required for the cement paste.3.Setting Time TestCement has two types of setting time, one is initial setting time and another is final setting.Initial setting time is the state of cement mortar or concrete when it starts to become stiffen and unworkable.Final setting time is the state when cement mortar or concrete has become fully unworkable.Two methods are used to find the initial and final setting time of cementVicat needle method, andGillmore needle method4.Soundness TestSoundness of cement means it doesn’t undergo large volume change after setting. Large changes in volume produce cracks, disintegration and distortion, ultimately leading to failure. So it is very important to test the soundness of cement.To test the soundness two methods can be applied.Le-chatelier methodAutoclave method5.Strength TestCement has two types of strength – compressive strength and tensile strength.To know the compressive strength and tensile strength of cement following tests are performed –Cement mortar cube test (for compressive strength)Briqutte test (for tensile strength)Split tensile test (for tensile strength)6.Heat of Hydration TestCement produce large amount of heat during hydration process. When large amount of concrete volume is poured the inner temperature is greater than outer surface of concrete. Because outer surface is exposed to weather. Thus surface shrinks rapidly than the inner and tends to produce cracks. That is why it is important to test the heat of hydration of cement.Following test is performed to know the heat of hydration of cementCalorimeter method7.Specific Gravity testSpecific gravity of cement is a comparison of weight of a cement volume to the weight of same volume of water.Le-chaterlier flask is used to test the specific gravity of cement.</p> | |