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'ION 2. SAND.
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<br /> All sand shall be clean, hard, durable, uncoated stone particles free from organic
<br /> matter and lumps of clay.
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<br /> (a) CONCRETE SAND. Sand for all cement and concrete work shall contain, not
<br /> more than three (3) per cent, by weight, of mica; not more than four (4) per cent by weight
<br /> removable by the eintriation test; not more than six (6) per cent, by weight, shall pass a
<br /> sieve having one hundred (100) Meshes per linear inch; not less than ninety-five (95)
<br /> per cent, by weight, shall pass a screen having four (4) meshes per linear inch; at least
<br /> fifty (~)) per cent, but not more than eighty-five ($3) per cent, by weight, shall be retained
<br /> on a sieve having thirty (30) meshes per linear inch.
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<br /> When thc sand is mixed with Portland Cement in the proportion of one (1) part of
<br /> cement to three (3) parts of sand, by weight, according to the standard methods-of making
<br /> 1:3 mortar briquettes, the resulting briquettes at the ages of both seven (7) and twenty-
<br /> eight (28) days, when compared with briquettes mixed at the same time in the same
<br /> proportions and consistently using the same cement, but with Standard Ottawa Testing
<br /> Sand, shall show a tensile strength ratio of one hundred (100) per cent Sand showing
<br /> a tensile strength of less than one hundred (100) per cent, but not less than eighty-five
<br /> (83) per cent, will be accepted for use subject to the use of additional cement The addit-
<br /> ional proportion of cement required shall be determined by laboratory tests and shall be
<br /> the percentage required to increase the strength ratio to one hundred (100) per cent
<br /> In the absence of the above laboratory tests, and at the option of the Superintendent
<br /> of Streets only, a field test may be made as follows:
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<br /> Fill an ordinary glass fruit jar two-thirds (2-$) or three-fourths (3-4) full of the
<br /> sample of sand, then add sufficient water to thoroughly wash the sand by vigorous shaking;
<br /> the shaking to be done for three (3) minutes, and by holding the jar in a vertical position,
<br /> after which it shall be allowed to settle. The indicated sediment appearing on the top
<br /> of the well defined minute grains of sand shall not measure more than ten (10) per cent
<br /> of the total after settling for one (1) hour, nor more than five (3) per cent after settling
<br /> for a period of twenty-four (24) hours.
<br /> (c) CUSHION SAND. Sand for cushion under concret~ work on adobe and other
<br /> swelling soils, shall contain not more than ten (10) per cent by weight, of clay and silt
<br /> and shall all pass a screen having one-half (~) inch round openings.
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<br />SRCTION 3. BRO~rgN STONE OR' GRAVEL.
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<br /> (a) BROKEN STONE. Broken stone shall be quarried rock, free from loam, clay
<br /> and organic matter, and shall have a specific gravity of not less than two and sixty-i~ve
<br /> hundreths (2.65). It shall be uniform in quality and shall contain not more than five (5)
<br /> per cent, by weight, of pieces having rounded surfaces.
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<br /> (b) GRAVEL. Gravel shall ocnsist of clean, water-worn pebbles, crushed boulders,
<br /> or both, and shall be free from organic matter, shale, disintegrated or soft stone, clay,
<br /> or other deelterious substance.
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<br /> · (C) CLASSIFICATION. The maximum length of any one particle o{ gravel or
<br /> ~ broken stone passing a screen or ring~ shall not be greater than fifty (~0) per cent in
<br /> excess oi the m~ximum dimension specified as follows:
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<br /> Not more than i~ve ($} per cent by wei~ht~ of ~at~ thin, or elongated pieces or partlcles
<br /> ot stone, will be permitted in any class or size of broken stone or gravel· Pieces or
<br /> particles of stone whose greatest thickness does not equal or excell twenty (20) per cent
<br /> of its greatest length wlil be considered as fiat, thin or elongated.
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<br /> The gravel, broken stone or both shall consist of sizes ranging from a minimum o{
<br /> not more than five (3} per cent, by weight, passing a screen having one-fourth (~) inch
<br /> round openings, to a maximum size that shall pass a screen having two (2) inch round
<br /> openings, and shall contain sizes of which not more than ninety-five (95) per cent, by weight,
<br /> will pass a screen having one and one-half (1~) inch round openings and not less than
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