The exhaustive tests are carried out in laboratory to decide precisely the quality of cement. The extreme care should be taken to collect the sample of cement from site. In order to make a representative sample, it is desirable to collect in nearly equal portions as follows: (1) When Cement is Loose: It should be taken from at least 12 [...]
The concrete surfaces are kept wet for a certain period after placing of concrete so as to promote the hardening of cement. It consists of a control of temperature and of the moisture movement from and into the concrete. The term curing of concrete is used to indicate all such procedures and processes. Purposes of Curing: Following are the objects [...]
The manufacture of Portland cement was started in England around 1825. Belgium and Germany started the same in 1855. America started the same in 1872 and India started the same in 1904. The first cement factory was installed in Tamil Nadu in 1904 by South India Industry Limited and then onwards a number of factories manufacturing cement were started. Our [...]
In this article we will discuss about:- 1. Characteristics of Cement 2. Properties of Cement 3. Composition 4. Functions of Ingredients 5. Harmful Constituents 6. Setting Action 7. Site for Factory 8. Packing 9. Ball Mills and Tube Mills 10. Field Tests 11. Storage 12. Uses. Characteristics of Cement: Following are the characteristics of cement: (i) The colour of cement [...]
The entire manufacturing process in a modern plant is now controlled through a microprocessor based programmable logic control system to maintain a consistently uniform quality of cement and a high rate of production. The entire operation of the plant is controlled centrally in a single control room and the plant employs minimum of manpower as compared to previous plants constructed [...]
The following types of cement are used in Construction. 1. Acid-Resistant Cement: Acid-resistant cement is composed of the following: (i) Acid-resistant aggregates such as quartz, quartzites, etc. (ii) Additive such as sodium fluosilicate Na2 SiF6; and (iii) Aqueous solution of sodium silicate or soluble glass. The addition of additive sodium fluosilicate accelerates the hardening process of soluble glass and it [...]
Beams, slabs and columns are the most important components of the concrete structures. Due to the large number of cracks or damages observed in these components of the structures, the repair and rehabilitation of such members assumes greater importance. Techniques of repairs for beams, slabs and columns are discussed below: Repair of Concrete Floor and Slab System: For the change [...]
In this article we will discuss about the tests performed on concrete. Compression Tests: Compression test can be performed on the three types of test specimens, namely cubes, cylinders and prisms. Cubes of standard size of 150 mm are used in India U.K., Germany and many other countries of Europe. Cylinders are the standard specimens in U.S.A. France, Canada, Australia [...]
For repairing concrete works following methods may be adopted: 1. By the Use of Expanding Cement Method 2. By Dry Pack Method 3. By Replacement of Concrete Method 4. By Mortar Replacement Method or Pneumatically Placed Mortar 5. Pre-Packed Concrete. 1. By the Use of Expanding Cement Method: This method is specially useful for hydraulic structures. If small holes or [...]
In this article we will discuss about:- 1. Special Features of Under Water Repair 2. Steps Involved in Under Water Repair of Concrete 3. Modification in Mix Design 4. Placement Methods. Special Features of Under Water Repair: The special features of underwater repairs are as follows: 1. The underwater repairs are more complex and highly costly. Hence the repair operations [...]