924-1 General.
This Section covers admixtures for specific concrete applications . Admixtures shall comply with applicable ASTM specifications and the requirements of this Section . Admixtures that have been previously qualified for Department use are listed on the Department’s Approved Product List (APL).
924-2 Acceptance of Admixtures.
924-2.1 Approved Product List ( APL): All admixtures must be listed on the
Department’s Approved Product List (APL). Manufacturers seeking evaluation of their products shall submit an application is accordance with Section 6 and include product data sheets, certified independent test data showing the product meets the requirements of this Section, sa fety data sheet (SDS), and a certification of the average solids content and specific gravity. Admixtures shall meet the following requirements : Air-Entraining - ASTM C260 Type A Water-Reducing - ASTM C494 Type C Accelerating - ASTM C494 Type D Water-Reducing and Retarding - ASTM C494 Type E Water-Reducing and Accelerating - ASTM C494 Type F High Range Water Reducing - ASTM C494 Type G High Range Water-Reducing and Retarding - ASTM C494 Type I - Plasticizing - ASTM C1017 Type II - Plasticizing and Retarding - ASTM C1017 Type S Specific Performance - ASTM C494 and the performance requirements of this Section . Corrosion Inhibitors – ASTM G109 and the requirements of this Section. The inclusion of any specific product on the APL, as specified in 6 -1, indicates that the product has been given contingent approval, as evidenced by previous tests and apparent effectiveness under field conditions. Unless otherwise specified, no further testing will be required for any product on the APL unless there is indication in actual field use of inadequate or unreliable results.
924-2.2 Additional Requir ements for Corrosion Inhibitors : Calcium nitrite is a
chemically reacti ve admixture used in concrete to inhibit the corrosion of embedded reinforcing steel and other metallic components. The calcium nitrite supplier shall submit to the Engineer test certificates from an independent laboratory indicating compliance with this S pecification. The test certificate shall include corrosion inhibiting properties per ASTM G109 and results of physical tests included in this section. Calcium nitrite shall be supplied by the same manufacturing source throughout the project. If a single pr imary source of calcium nitrite cannot be maintained throughout the project, new test certificates shall be submitted. The Engineer will determine specification compliance of a new supplier’s product, and evaluate the effectiveness of the new calcium nitri te product before approving the source. The active ingredient shall be calcium nitrite Ca(NO 2)2. The calcium nitrite shall be furnished in solution containing not less than 29% calcium nitrite solids. The concentration of the calcium nitrite solution s hall be verified by FY 2023-24 Return to Table of Contents spectrophotometric analysis or other comparable methods. The nitrite concentration shall be measured in accordance with Standard Methods for the Examination of Water and Waste Water, 18th Edition. A volume of one gallon of calcium nit rite solution shall weigh within the range of 10.40 to 11.92 lb. The calcium nitrite solution shall be added to the concrete mixture at a rate of 4.50 to 4.60 gal/yd3 of concrete. The addition of calcium nitrite to the concrete mix shall not adversely affect the properties of fresh and hardened concrete. Calcium nitrite concrete shall meet the following physical requirements when mixed and tested in accordance with ASTM C494: Table 924-1 Water Content, % of control 95 to 100 Time of setting, allowable deviation from control, h:min: Initial: at least not more than 1:00 earlier nor 1:30 later Final: at least not more than 1:00 earlier nor 1:30 later Compressive Strength, min. % of control: shall be 100 for all ages Flexural strength, min, % of control: shall be 100 for all ages Length change, max Shrinkage (alternative requirements): % of control 135 Increase over control 0.010 Relative durability factor, min 80 The following table lists the corrosion inhibiting test result limits for calcium nitrite concrete tested in accordance with ASTM G109: Table 924-2 Maximum Allowable Test Results of Calcium Nitrite Concrete Measured average macrocell current any time during the test 10 μA Average macrocell current at test completion 2 μA Average visible corrosion measured as percent corroded area of control 85%
924-2.3 Type S (Specific Performance): Trial batches shall use concrete meeting the
requirements of ASTM C494. Additional trial batches may be required. Dosage rate shall be the same for all testing.
924-2.3 1 Workability Retention: Workability retention admixtures are used to
extend workability and slump life without retarding the sett ing time. The dosage rate used shall be capable of maintaining 80% of the initial measured slump after 60 minutes. Perform an initial slump test, hold the trial batch in the mixer for 60 minutes, remix for 30 seconds and perform a second slump test. Workability retention shall be calculated as the percent difference in the initial slump and the slump at 60 minutes.
924-2.3 2 Shrinkage Reducing: Shrinkage reducing admixtures are used to
minimize the shrinkage of plastic and hardened concrete. The dosage ra te used shall reduce shrinkage a minimum of 50% after dry curing for 28 days. Shrinkage shall be determined in accordance with ASTM C157, except omit curing period in ASTM C157(10.3). Air storage for FY 2023-24 Return to Table of Contents the 28-day curing period shall be in accordance with ASTM C157(11.1.2). Shrinkage reduction shall be calculated as the percent difference in the control mix length change and the test mix length change.
924-2.3 3 Viscosity Modifying: Viscosity modifying admixtures are used
primarily in flow ing and self -consolidating concrete to maximize the rheology of plastic concrete and reduce segregation. The dosage rate used shall reduce static segregation to a minimum of 10%. A flowing concrete control mix shall be established by adding a compatible hi gh range water-reducing or plasticizing admixture to increase the slump to 10 inches, plus or minus 0.5 inches. To establish the test mix, the control mix shall be reproduced with the addition of the viscosity admixture. The static segregation for both mix es shall be determined in accordance with ASTM C1610. Static segregation shall be calculated as the percent difference of the control mix static segregation to the test mix static segregation.
924-2.3 4 Rheology Modifying: Rheology modifying admixtures a re used to
maximize the rheology of plastic concrete. The dosage rate used shall be based on the manufactures recommendation and may vary for a specific application.
924-3 Retesting.
The approved admixtures are required to be tested for their uniformity and equivalence whenever there is an indication of erratic results. The tests shall be performed in accordance with the following procedure. The admixture shall be checked for comparison between infrared spectrophotometry, pH value, specific gra vity, and solids content. Any marked variation from the original curve, pH value, specific gravity, or solids content will be considered sufficient evidence that the chemistry of the original material has been changed and, therefore, the use of this material will be rejected and the material will be removed from the APL. FY 2023-24 Return to Table of Contents SECTION 925 CURING MATERIALS FOR CONCRETE
925-1 Burlap.
Burlap for curing concrete shall consist either of two layers, each weighing 10 to 18 ounces/10 square feet, or of four layers, each weighing 6 to 7 ounces/10 square feet. Burlap which has been used as a container for sugar shall not be used. Burlap that i s being used for the first time shall be thoroughly washed in order to remove starches used in sizing the material. Burlap shall be furnished in strips of at least 3 feet wide and shall be at least 3 feet longer than the width of surface to be covered.
925-2 Membrane -Forming Curing Compound.
925-2.1 General : Membrane -forming curing compound shall conform to requirements of
ASTM C309 and the following requirements: Table 925-1 Requirement Test Method Test Value Water Loss@72 hours ASTM C156 0.55 kg/m2 Deleterious Reaction with Concrete ASTM C309 None Reflectance ASTM E1347 60% minimum* Drying Time ASTM C309 4 hours maximum Non-Volatile Content ASTM D1644 (Method A) (informational) Density, lbs/gal ASTM D1475 (informational) *Type 2 (White) compounds only. The membrane -forming curing compound shall be of a consistency suitable for spraying at temperatures prevalent at the time of application, and which forms a continuous, uniform film. It shall be free from precipitated matter caused by conditions of storage or temperature. Thoroughly agitate the curing compound in accordance with the manufacturer’s recommendations prior to shipment from manufacturer’s plant and prior to use at job site. Curing compound delivered to the job site shall be in the manufacturer’ s original container and clearly labeled with the following information:
1.manufacturer’s name
2.product name (trade name)
3.type
4.batch or LOT number
5.date of manufacture
925-2.2 Product Acceptance: Acceptance of membrane -forming curing compound shall
be based on the product being listed on the Department ’s Approved Product List ( APL).
925-2.2 1 Approved Product List: Manufacturers seeking evaluation of their
product must submit an application in accordance with Section 6 and include product data sheets, material safety data sheets (SDS) and certified test reports from an independent laboratory showing the product meets the requirements of this Section. Testing in accordance with the FY 2023-24 Return to Table of Contents
Source: Florida Standard Specifications for Road and Bridge Construction, 2024 Edition. Pages 1012–1014 of 1,299.