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Kni ght Piesold CONSULTING ' 28 Class D concrete is a dense medium strength structural concrete. Class H may be substituted for 29 Class D concrete. Additional requirements for Class D concrete are: An approved water reducing 30 admixture shall be incorporated in the mix. Class D concrete shall be made with 19.0 mm ('/< ^ 31 inch) nominal sized coarse aggregate. When placed in a bridge deck, Class D concrete shall 32 contain a minimum of 55 percent AASHTO M 43 size No. 67 coarse aggregate. Approved fly 33 ash may be substituted for portland cement up to a maximum of 20 percent Class C or 30 percent 34 Class F by weight. 35 36 Class DT concrete may be used for deck resurfacing and repairs. Class HT may be substituted - 37 for Class DT concrete. Additional requirements for Class DT concrete are: An approved water ' 38 39 reducing admixture shall be incorporated in the mix. Class DT concrete shall contain a minimum of 50 percent AASHTO M 43 size No. 7 or No. 8 coarse aggregate. Approved fly ash may be 40 substituted for portland cement up to a maximum of 20 percent Class C or 30 percent Class F by 41 42 weight. 43 Class E concrete may be used for fast track pavements needing early strength in order to open a 44 45 pavement to service soon after placement. Additional requirements for Class E concrete are: Type III cement may be used. Class E concrete shall contain a minimum of 55 percent AASHTO 46 M 43 size No. 357 or No. 467 coarse aggregate. If all transverse joints are doweled, then Class E 47 48 concrete shall contain a minimum of 55 percent AASHTO M 43 sizes No. 57, No. 67, No. 357, or No. 467 coarse aggregate. In addition to the compressive strength requirements in Table 601- 49 1 and unless stated otherwise on the plans, Class E concrete shall achieve a field compressive SO strength of 2500 psi within 12 hours. Laboratory trial mix for Class E concrete must produce an 51 average 28 day flexural strength of at least 650 psi. - 52 53 Approved fly ash may be substituted for portland cement up to a maximum of 30 percent Class F 54 by weight. 55 56 Class H concrete is used for bare concrete bridge decks that will not receive a waterproofing 57 membrane. Additional requirements for Class H concrete are: An approved water reducing 58 admixture shall be incorporated in the mix. Class H concrete shall contain a minimum of 55 59 percent AASHTO M 43 size No. 67 coarse aggregate. Class H concrete shall contain 60 cementitious materials in the following ranges: 450 to 500 pounds per cubic yard Type II 61 portland cement, 90 to 125 pounds per cubic yard flyash and 20 to 30 pounds per cubic yard 62 silica fume. The total content of Type II portland cement, flyash and silica fume shall be 580 to 63 640 pounds per cubic yard. Laboratory trial mix for Class H concrete must not exceed 64 permeability of 2000 coulombs at 56 days (ASTM C 1202). Laboratory trial mix for Class H 65 concrete must not exhibit a crack at or before 14 days in the cracking tendency test (AASHTO 66 PP 34). 67 ' 68 Class HT concrete is used as the top layer for bare concrete bridge decks that will not receive a 69 waterproofing membrane. Additional requirements for Class HT concrete are: An approved 70 water reducing admixture shall be incorporated in the mix. Class HT. concrete shall contain a 71 minimum of 50 percent AASHTO M 43 size No. 7 or No. 8 coarse aggregate. Class HT concrete 72 shall contain cementitious materials in~he following t•anges: 450 to 500 pounds per cubic yard 3-31 G \101W0100 OMVtappris\KP1Terhniwl Specifications doc FeKruary 3, 2006