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4.3.1 FINE AGGREGATE <br />Fine aggregate for concrete shall consist of clean, hard, durable, <br />uncoated grains of natural sand and shall be free from excessive <br />quantities of deleterious substances, lumps, organic matter and <br />alkali as specified in ASTM C 33. The gradation shall provide a <br />fineness modulus range of 2.30 to 3.10. <br />Sieve Percent Passinq <br />3/8" 100 <br />No. 4 95 - 100 <br />No. 8 80 - 100 <br />No. 16 50 - 85 <br />No. 30 25 - 60 <br />No. 50 10 - 30 <br />No. 100 2 - 10 <br />4.3.2 COURSE AGGREGATE <br />Coarse aggregate for concrete shall consist of crushed stone, <br />gravel, or other approved inert materials of similar characteristics, <br />or combination thereof having hard, strong, durable pieces, free <br />from adherent coatings. Deleterious substances shall not exceed, <br />in accumulations, five percent 15%1 by weight. Gradation shall <br />generally meet the requirements specified in ASTM C 33, Size 57. <br />Gradation for ASTM C 33, Size 57: <br />Sieve Percent Passinq <br />1-1 /2" 100 <br />1/2" 25 - 60 <br />No. 4 0 - 10 <br />No. 8 0 - 5 <br />4.4 ADMIXTURES <br />Air entraining admixtures shall meet the requirements of ASTM C 260 and <br />should be used in all watertight, chemical resistant concrete. Other <br />chemical admixtures shall comply with ASTM C 494. Recommended <br />reference ASTM STP 169. Except as set forth in subparagraphs 2 and 3 <br />below, admixtures shall be used only with prior written authorization of the <br />Engineer. <br />4.4.1 QUANTITY <br />Admixtures shall be used strictly in accordance with the manufac- <br />turer's recommendations. All admixtures shall be added to the <br />concrete mixture with dispersing equipment furnished by the <br />manufacturer. <br />4.4.2 AIR ENTRAINING <br />Air entraining admixtures shall be used to entrain five to seven <br />percent (5-7%) of air by volume in all ordinary structural concrete. <br />SPEC B -CONCRETE <br />PAGE 5 <br />