Quantcast Sieve Analysis

 
  
 
Figure  5-3.-Sieve  sizes. Limestone.    Limestone    is    widely    used for     road     surfacing,     in     concrete,     and     for l i m e . Gneiss. Most varieties of gneiss have   good   strength   and   durability   and   make good  road  aggregates. Quartzite. Quartzite is both hard and     durable.     Because     of     these     qualities, it     is     an     excellent     rock     for     construction, although     it     is     often     difficult     to     quarry. Marble.     The     texture     and     color     of marble make it very desirable for dimension    stone,    and    it    can    be    used    for base    course    or    aggregate    material. Sieve Analysis Soil is composed of particles of various    sizes    and    composition.    Figure    5-2 shows    the    major    types    of    soils.    Soil    can be   analyzed   by   size   by   sifting   a   dried   and weighed    sample    through    a    set    of    testing sieves (fig. 5-3) and weighing the material    retained    on    each    screen.    Further testing may be required by the specifications    for    the    product    you    need    to produce. These tests are normally performed    by    the    soil    laboratory    in    the engineering    department    of    the    battalion. Soil     is     classified     according     to     the particle     size,     such     as     coarse     aggregate, fine aggregate, and mineral filler. The maximum size of the aggregate varies, depending upon the construction specifications. Particle size is defined by    passing    a    soil    mass    through    several sieves     with     different     sized     openings     (fig. 5-3). Particles    that    pass    through    a    given sieve    are    said    to    be    passing    that    sieve size.    Particles    that    fail    to    pass    through a    given    sieve    are    said    to    be    retained    on that sieve. The sieve permits particles smaller    than    the    opening    to    fall    through and     retains     the     larger     particles     on     the sieve.    When    you    use    sieves    with    screen openings    of    different    sizes,    the    soil    can be    separated    into    particle    groups    based    on size. A    weighted    sample    of    aggregate    is placed    in    the    top    sieve,    and    the    entire set of sieves (largest on the top, smallest    on    the    bottom)    is    vibrated    either by     hand     or     mechanically.     The     individual weights    are    calculated    as    a    percentage    of the total weight, as shown in the following    example:    Assume    we    take    3,000 grams   of   soil   mass   and   determine   how   much aggregate    passes    each    sieve. Aggregate passing 1/2-inch sieve    and    retained    on 3/8-inch     sieve     =     720     grams     =               24% Aggregate passing 3/8-inch sieve   and   retained   on   No.   4 sieve = 600 grams = 20% Aggregate   passing   No.   4 sieve    and    retained    on No.    10    sieve    =    450    grams    =            15% Aggregate   passing   No.   10 sieve    and    retained    on No.    40    sieve    =    570    grams    =            19% Aggregate   passing   No.   40 sieve    and    retained    on No.    200    sieve    =    420    grams    =            14% Aggregate passing No.    200    sieve    =    240    grams    =                    8% 3,000   grams   =   100% The   above   percentages   are   one   way   of expressing    the    gradation    of    a    sample    of aggregate. 5-5


 


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