specifications - FAACO - Federal Aviation Administration Contract ...

FTWIC-2235June, 2009water-cement ratio shall not be exceeded. No additional compensation shall bemade for additional cement.4. If fly ash is to be used in place of cement, no more than 20 percent of the cementmay be replaced. The amount of fly ash used in place of the cement shall be 20percent greater than the amount of cement removed.D. CONCRETE STRENGTH:The concrete mix shall be designed with the intention of producing concrete which hascompressive or flexural strength equal to or greater than the following, when tested inaccordance with ASTM C-39 and ASTM C-293.E. TRIAL MIXES:MinimumCompressive Strength(lbs. per sq. in.)7 Day 28 DayMinimumFlexural Strength(lbs. per sq. in.)4 Day 7 DayClass ofConcreteA 3,000 4,000 450 550B 3,000 4,000 450 550C 3,000 4,000 450 550D 4,000 6,000 480 600E 1,320 2,000 - -F - 1,000 - -G 3,000 4,000 450 5501. Laboratory samples shall be taken in accordance with the trial mix designs forlaboratory testing purposes.2. The fresh concrete shall be tested for Slump (ASTM C-143) and Air Content(ASTM C-173 and ASTM C-231). Strength test specimens shall be made, curedand tested for seven (7) and twenty-eight (28) day strength in accordance withASTM C-192, ASTM C-39, and ASTM C-293.3. Suitable facilities shall be provided for readily obtaining representative samplesof aggregate from each of the weigh batchers for test purposes and for obtainingrepresentative samples of concrete for uniformity tests. The necessary platforms,tools, and equipment for obtaining samples shall be furnished. Aggregates shallbe tested in accordance with ASTM C-289.4. The proportions of materials entering into the trial mix shall be laboratory testedprior to concrete placing. The cement contents specified are minimum values. Ifadditional quantities are required to obtain the specified strengths, supply thecement at no additional cost to the Government.5. A trial mix shall be designed by an independent testing laboratory, retained andpaid by the Contractor and approved by the Owner. The testing laboratory shallsubmit verification that the materials and proportions of the trial concrete mixdesign meet the specifications. The laboratory trial concrete mix design shall besubmitted to the Contracting Officer before the 7-day strength tests are made.03300-3