Checking the quality of cement at site is very important because cement is the most important material in the construction side. The Portland cement work like a binder between cement and aggregates. The poor quality of cement effect the strength of the concrete or mortar. So maintaining the proper quality is very important at site.
To check the physical Quality of cement we perform 6 test on cement.
- Cement Color Test.
- Rubbing Test on cement.
- Floating Test on cement.
- Cement Strength Test.
- Shape Test.
- To check the packing date of cement.
CEMENT COLOR TEST:
The color of the Portland cement should be uniform at site. The best and preferable color of cement is Grey and the color look like greenish type shade. The color of cement give us a rough estimate of the cement quality means cement has excess lime or excess clay. If any one cement composition quantity is more according to the design the cement color doesn’t look like perfect in greenish shade.
The rubbing test is the another physical test which perform at site. In this rubbing test we take small amount of cement in our hand and we rub it by using our fingers. If the cement give us a smooth texture while rubbing it means cement is good (Because cement substances size is too small and cement finesse) and if cement give us a rough texture it means cement quality id not good.
In this float test we took a small amount of cement in our hand and throw them into a small water carrying bowl. If cement float on the water the quality of the cement is not good because cement substance are more in weight and they must sink in to the water. If cement sink it indicate the cement quality is good.
The strength test is performed on the crushing machine. In this test we take a cement cube having a dimension 25 mm x 25 mm x 200 mm. The cube is put into the water for at latest 7 days for curing purpose and then we check the strength of the cube. The good cement must resist the load at least 340 N without failure.
In this test we took 100 gram of the cement and we add some amount of water into the cement and make a cement plastic paste. After mating the cement past we put them into the small glass water bowl and note the cement particles while cement is sitting. If the particles are disturbed during sitting. It indicate that cement is not good because cement has a ability to attain the desire strength in water.
By viewing the cement bag packing date we also get the rough idea about the strength of cement because cement will reduce there strength as time passes. The cement is not stored more then 3 months. If Cement was 3 months or more old it should be tested first and then use at the site
Note: These all test are some physical test which we commonly perform at site to check the quality of cement. But the major test should be perform at Testing laboratories.