Specification for Ultra-High-Performance-Concrete:

Materials.
Materials shall conform to Subsection, Division, and the following:

Material UHPC:
Provide Ultra-High-Performance Concrete (UHPC) where indicated on the Plans, all components supplied by one manufacturer. Materials commonly used in UHPC are:

Fine aggregate
Cementitious material
Superplasticizer
Accelerator
Steel Fibers
Volumizing/Shrinkage reducing admixture (joints over 9” depth)

UHPC material requirements at 28 days, unless otherwise noted, are as follows:

Minimum Compressive Strength (ASTM C39):
High Heat-Treated* ——————————————————————————-25 ksi
Medium Heat-Treated 12 hours** ————————————————————-12 ksi

Not Heat-Treated 14 days*** ——————————————————————-21 ksi
Prism Flexural Tensile toughness (ASTM C1018; 12 in. span) ————————-I30 ≥ 48
Long-Term Shrinkage (ASTM C157; initial reading after set) ————————-≤ 766 microstrain
Chloride Ion Penetrability (ASTM C1202) ————————————————–≤ 250 coulombs
Chloride Ion Penetrability (AASHTO T259; ½ in. depth) ——————————-< 0.07 oz/ft3
Scaling Resistance (ASTM C672) ————————————————————–y < 3
Abrasion Resistance (ASTM C944 2x weight; ground surface) ———————–< 0.025 oz. lost
Freeze-Thaw Resistance (ASTM C666A; 600 cycles) ————————————-RDM > 96%
Alkali-Silica Reaction (ASTM C1260; tested for 28 days) ——————————-Innocuous
* High Heat-Treated – According to the manufacturer’s recommendation, the temperature not to exceed 250ºF.
** Medium Heat Treated temperatures not to exceed 120ºF
*** Not Heat Treated temperature not to exceed 70ºF

Submit the results of all the tests above, conducted by an AASHTO accredited testing lab, to the Engineer along with the installation drawings. Provide to the Engineer a list of bridge projects in which the proposed UHPC material has been used as a link slab joint. The Engineer reserves the right to reject a proposed UHPC material which lacks a proven track record in link slab joint in bridge applications.

Storage:

Assure the proper storage of premix, fibers, and additives as required by the supplier’s specifications to protect materials against loss of physical and mechanical properties.

Material Prequalification Testing:

Complete the testing of the UHPC a minimum of one month before placement of the link slab UHPC joint. The testing sequence will include the submission of a plan for casting and testing procedures to the Engineer for review and approval followed by casting and testing according to the approved plan.

Include the following in casting and testing procedures:

(A)   A minimum of 12 test cylinders, 3 x 6 inches.
(B)   Maintain the temperature during curing as per heat treatment temperature limits established in this
specification. Test 2 cylinders at each testing interval. Testing intervals are at 10 hours, 12 hours, 14 hours, and
24 hours. Measure the compressive strength by ASTM C39. Only a concrete mix design that passes these tests
may be used to form the joint.
(C)   Pullout Test: Cast 6 additional cylinders, 12-inch diameter x 7½ inch deep. Place one 32-inch-long galvanized
reinforcing bar cast in the center of the circular face. Set the axis of the bar perpendicular to the formed surface.
In three (3) of the cylinders embed one #6 bar 5 inches deep and in the other three (3) cylinders embed one #4
bar embedded 3 inches deep. Keep these cylinders wet for four days and then the test specimens for pull-out
testing. The pull-out tests will be performed as soon as practical after the corresponding compressive strength
samples reach 12 ksi. Acceptance criteria for pullout testing are when there is a complete tensile failure of the
reinforcing bar, prior to pullout from the concrete or failure of the concrete.
(D)   Maturity Testing:

(1) Equipment for maturity testing: Use a Maturity Meter and thermocouples that can:

          • Provide a maturity value based on the Equivalent Age or Temperature Time Method as
            detailed in ASTM C 1074-11.
          • Continuously log and store maturity data.
          • Accurate to within +/- 1° F when the meter is calibrated as per the manufacturer’s
            instructions.
          • Take readings every half hour for the first 48 hours and every hour after that at a minimum.
          • Print data and/or download it into a spreadsheet.

(2) Methodology for Maturity Testing:

The procedure for utilizing the maturity method to determine in-place UHPC strengths
includes three steps: development of the strength-maturity relationship, monitoring the
maturity of the placement, and regular validation of the strength maturity relationship.
Any changes in the mix design, its components, or proportions will require that a new
strength-maturity relationship be developed.

Complete development of the strength-maturity relationship a minimum of two months
prior to construction. Continue data collection for the strength-maturity relationship after
acceptance of the maturity value until the strength reaches 21 ksi.

Submit a procedure for developing the strength-maturity relationship to the Engineer for
review and approval. Include all necessary information for the development of the
strength maturity relationship. All necessary testing included in the procedure shall be
conducted by an AASHTO accredited testing lab.

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