The fineness modulus shall not vary by more than 0.20 from the value assumed in selecting proportions for the mortar.
Standard Specifications for Aggregates
ASTM C 33-13: Fine Aggregate for Cement Concrete
AASHTO M 45-15/ASTM C 144-11 specification covers aggregate for use in masonry mortar.
Aggregate for use in masonry mortar shall consist of natural sand or manufactured sand. Manufactured sand is defined in the specifications as the product obtained by crushing stone, gravel, or air-cooled iron blastfurnace slag specially processed to ensure suitable particle shape as well as gradation.
Aggregate shall conform to the grading requirements given in adjoining input table. Separate grading requirements are specified for natural and manufactured sand. Also, aggregate shall not contain more than 50 percent retained between any two consecutive sieves, and no more than 25 percent between the 300-μm (No. 50) and 150-μm (No. 100) sieve.
The amount of deleterious substances shall not exceed the limits given in table below.
|Item||Max. Permissible Mass, %|
|Clay lumps and friable particles||1.0|
|Lightweight particles, floating on liquid having a specific gravity of 2.0||0.5a|
|a - do not apply to blast-furnace slag aggregate.|
Aggregate shall be free of injurious amounts of organic
subjected to the test for organic impurities and producing a color darker than the
standard shall be rejected.
Aggregate failing in the test may be used provided that the discoloration is due principally to the presence of small quantities of coal, lignite, or similar discrete particles.
Aggregate failing in the test may be used provided that, when tested for the effect of organic impurities on strength of mortar by AASHTO T 71, the relative strength at seven days is not less than 95 percent.
Aggregate subjected to five cycles of the soundness test shall have a weighted average loss not greater than 10 percent when sodium sulfate is used or 15 % when magnesium sulfate is used.
Fine aggregate failing to meet the requirements of soundness may be accepted, provided that mortar of comparable properties, made from similar aggregate from the same source, has given satisfactory service when exposed to weathering similar to that to be encountered for a period of more than five years without appreciable disintegration.
|Sieve Size, mm||