FINE AGGREGATE
COARSE AGGREGATE
Coarse aggregate is a material that will pass the 3-inch screen and will be retained on the No. 4 sieve. As with fine aggregate, for increased workability and economy as reflected by these of less cement, the coarse aggregate should have abounded shape. Even though the definition seems to limit the size of coarse aggregate, other considerations must be accounted for. When properly proportioned and mixed with cement, these two groups yield an almost void less stone that is strong and durable. In strength and durability, aggregate must be equal to or better than the hardened cement to withstand the designed loads and the effects of weathering. It can be readily seen that the coarser the aggregate, the more economical the mix. Larger pieces offer less surface area of the particles than an equivalent volume of small pieces. Use of the largest permissible maximum size of coarse aggregate permits a reduction in cement and water requirements. One restriction usually assigned to coarse aggregates its maximum size. Larger pieces can interlock and form arches or obstructions within a concrete form. That allows the area below to become a void, or at best, to become filled with finer particles of sand and cement only. That results in either a weakened area or cement-sand concentration that does not leave the proper proportion to coat the rest of the aggregate. The maximum size of coarse aggregate must be no larger than the sizes given in table 13-1. The capacity of the mixing equipment may also limit the maximum aggregate size.
20 March 2012 at 07:16
fine aggregate is a sieve text that aggregate that can pass through the sieve which diameter is 5mm while for coarse aggregate cont pass though??
this statement is true??
20 March 2012 at 07:23
yup~~thx for your comment..