752 Page 505752 CHEMICAL ADMIXTURES FOR CONCRETE
The chemical admixtures used for concrete will conform to AASHTO M 194. Chemical admixtures for concrete will be a non-chloride-based material containing less than 1% chloride ion by weight of admixture. Viscosity modifying admixtures (VMA) may be used in self-consolidating concrete (SCC) to attain desired performance. The approval of the Department’s Concrete Engineer is required prior to use of any VMA. Chemical admixtures for dry cast concrete which are not classified in AASHTO M 194 or do not meet the requirements of Section 751 must be approved by the Department’s Concrete Engineer prior to use. 753 Page 506753 FLY ASH 753 FLY ASH Fly ash will be from a base loaded electric generating plant using a single coal source. Plants using a limestone injection process for controlling air pollutants are not acceptable. Fly ash from the start up and shut down of the plant will not be used. A.Class C Fly Ash: Class C fly ash conforming to AASHTO M 295 will only be allowed in grout for pavement jacking, undersealing, controlled density fill, or when specified. B.Class F, Modified Fly Ash: Fly ash used in all other concrete will conform to AASHTO M 295 Class F including the optional requirements in the referenced AASHTO specification except as modified by the following: Loss on Ignition 2.0% Maximum Moisture Content 2.0% Maximum Available Alkalis as Na2O 1.5% Maximum* Note: These modifications will not apply to fly ash used in slurry for pavement jacking or undersealing operations. * Available alkalis up to 2.0% may be used, provided mortar expansion test results at 14 days is less than or equal to that of the control sample. The expansion test will be run in accordance with modified ASTM C441. The control sample will be made using cement that will be used on the project. The test sample will be made using cement and fly ash that will be used on the project. The total of silicon dioxide (SiO 2) plus aluminum oxide (Al2O3) plus iron oxide (Fe 2O3) will be at least 66.0% by dry weight of the total fly ash composition. The silicon dioxide (SiO 2) will be at least 40.0% by dry weight of the total fly ash composition. Number of Tests: Each sample representing 400 tons or less will be tested for the following: 1.Fineness - #325 sieve analysis. 2.Moisture content. 3.Specific gravity. 4.Loss on ignition. 5.Soundness. 6.All other physical tests and chemical determinations will be made on composite samples representing each 3200 tons. This composite sample will be prepared by combining equal parts of 8 consecutive samples, each representing 400 tons. The test data will be furnished to the Engineer in the form of a chemical and physical analysis report. Fly ash delivered without an acceptable Certificate of Compliance will be subject to rejection.