Aggregates Aggregates Introduction Aggregates are the inert materials that are mixed in fixed proportion with cementing material to produce concrete These act as fillers or volume increasing components on the one hand and are responsible for strength hardness and durability of the concrete on the other hand Most of the aggregates used are naturally e or curing aggregates such as coarsed rock, gravel and coarse sand Artificial and processed aggregates may be broken break or crushed air-cooled blast furnace slag These aggregate are bound together by means of cement Properties of good aggregates Following are the desirable properties for requirement of a a good aggregates It should be chemically inert the aggregate should be sufficiently strong to withstand the stress developed due to the wheel loads of the traffic It shoul...
Types of cement Beside the ordinary Portland cement or number of other type of cement are also manufactured by varying the ratio of the raw material or by adding some additional materials In additional to ordinary cement the following are the other important varieties of cement available in the market Quick setting cement Rapid hardening cement High alumina cement Blast furnace cement Low heat cement White cement Coloured cement Sulphate cement Expanding cement Pozzolana cement Hydrophobic cement Waterproofing cement Acid resistant cement Each of the above variety of cement will now be discussed in brief Quick setting cement It is produced by adding a small percentage of aluminium sulfate and by finally grinding the cement It contain very little or no retarding substance like gypsum The setting action of the cement starts within a 5 minutes after addition of water and cement becomes hard in...