4108.01 DESCRIPTION.
Fly ash to be substituted for Portland cement in concrete shall comply with AASHTO M 295, either Class F or Class C, except value of available alkalies shall not exceed 1.50% as determined by Materials I.M. 491.17. Sources with fly ash between 1.5% and 2.5% available alkalies may be approved based on satisfactory results of the mortar bar expansion test specified in Materials I.M. 491.17. For Class C fly ash, the pozzolanic activity test with lime will not be required.

When Class F is required, a Class C fly ash with minimum total oxides (SiO₂ +AI₂O₃ + Fe₂O₃) of 66% and minimum SiO₂ of 38% may be used.

Approval of the source of fly ash will be required. This is to be based on fly ash produced when the power plant is using specific materials, equipment, and processes. Any change in materials, equipment, and processes shall void the source approval, and a new approval of the source will be required.

Inspection and acceptance of fly ash will be in accordance with Materials I.M. 491.17.

Ground Granulated Blast Furnace Slag (GGBFS) to be substituted for Portland cement in concrete shall comply with ASTM C 989 Grade 100 or Grade 120. Approval of the source of GGBFS will be required. Inspection and acceptance of GGBFS will be in accordance with Materials I.M. 491.14.