Statement of Need_Concrete Final.pdf

STATEMENT OF NEED

Low-Strength Precast Concrete Specimens for Weathering Study of Fiber Reinforced

Polymer Composites Bonded to Concrete

1. BACKGROUND

The Infrastructure Materials Group (IMG)/Materials and Structural Systems Division (MSSD) in the Engineering Laboratory (EL) of the National Institute of Standards and Technology (NIST) studies the durability and service life of polymers, polymer composites, and other engineered materials used in infrastructure applications. Fiber reinforced polymer (FRP) composites are one widely-used repair and strengthening material applied to buildings, bridges, and other infrastructure across the United States.

Currently, outdoor degradation of bonded FRP composites requires further investigation to understand service life, replacement schedules, and inform building design guidelines.

Recently, a preliminary NIST study suggested that FRP bonded to lower-strength concrete exhibited a different failure mode than FRP bonded to higher strength concrete during three-point bending tests. For this reason, and to better represent the range of concrete compressive strengths used in infrastructure applications, incorporation of a low-strength concrete substrate into the FRP/concrete weathering study test matrix is necessary.

2. PURPOSE

The purpose of this acquisition is to procure low-strength (4000 psi – 5000 psi [28 MPa – 34 MPa]) precast concrete specimens according to the product requirements outlined in Section 3, which will be retrofitted by NIST with externally bonded FRP materials and exposed to long-term environmental weathering protocols.

As weathering experiments progress, NIST shall also have the option to exercise the optional requirement outlined in Section 4. The optional requirement, if exercised, will enable NIST to procure more precast concrete specimens having identical concrete formulations and mix procedures within two years following base award.

3. PRODUCT REQUIREMENTS (Base CLIN 0001)

3.1 Types of Precast Concrete Specimens

The contractor shall provide the following precast concrete specimens:

1. Quantity (432) – 4” x 4” x 14” (height x width x length) low-strength (4000 psi – 5000 psi [28 MPa – 34 MPa]) precast concrete rectangular prisms with a cast-in place slit having a width of 1/8” and a depth of 2” (according to ASTM D7958)

2. Quantity (10 per batch of [1]) – 4” diameter and 8” length precast concrete cylinders for compressive testing (according to ASTM C39)

3.2 Concrete Mix Design Parameters and Formulation

1. Aggregates and cement mixes shall be consistently sourced from the same suppliers, including cement, sand, and coarse aggregate. Concrete formulation (including source materials) and mixing procedures shall be consistent for all precast concrete specimens, including any exercised options for increased quantity of precast concrete specimens within two years of base award. Concrete formulation shall be prepared in accordance with ASTM C192.

2. Precast concrete specimens shall be consistently air entrained at 6 % ± 1 % to prevent freeze/thaw damage. Unit weight and air content shall be tested or have been previously tested in-house according to ASTM C138.

3. Precast concrete specimens shall be prepared with an ASTM Type I/II Portland cement according to ASTM C150. White cement shall not be used.

4. Precast concrete specimens shall have a fixed water to cement ratio of 0.5 or as otherwise discussed with the NIST technical point of contact.

5. Precast concrete specimens shall contain coarse aggregate such as a #7 stone in accordance with ASTM C33.

6. Admixture use shall not affect long-term durability of the precast concrete specimens and all admixtures used shall be in accordance with ASTM C494.

Admixture dosage shall be consistent across all batches. Accelerators shall not be used during casting.

7. Precast concrete specimens shall consistently have a compressive strength of at least 4000 psi [28 MPa], but no more than 5000 psi [34 MPa].

The variation in compressive strength of all prisms shall not vary by more than +/- 500 psi [3.4 MPa].

8. Durability of the concrete is critical for this long-term outdoor exposure study since prisms will be retrofitted and placed outdoors for several years. Precast concrete specimens shall meet the following durability requirements:

a. Precast concrete specimens shall use a sand and coarse aggregate with a demonstrated history of not being susceptible to alkali-silica reaction (ASR), either through use in > 3 long-lasting (>5 year) precast concrete projects or with validation using ASTM 1260.

b. Precast concrete specimens shall be warrantied for one year after acceptance, according to Section 5 of this Statement of Need, to withstand harsh environmental conditions that include 300 freeze/thaw cycles, 3,000 hours of high temperature and moisture exposure, and 3,000 hours of sea water immersion. Acceptable durability of precast concrete specimens during the warranty period is defined as precast concrete specimens that do not crack (cracks with >1/8” depth, >1” length), spall (>10 % of surface area), or lose more than 20 % bending or compressive strength after the accelerated weathering cycles described.

Please see additional warranty requirements in Section 5.

c. Precast concrete specimens will also be examined for cracks, casting quality (includes uneven surfaces, poor consolidation, and missing corners), defects, and size requirements at NIST prior to acceptance.

9. Specimens shall be cast, moisture-conditioned with wet burlap, and stored indoors until shipment to NIST occurs.

10. Grab samples (2 kg) of cement, sand, and coarse aggregate used in the concrete formulation shall be provided to NIST before or at the time of prism delivery.

11. Each precast concrete specimen type (Section 3.1) shall be labeled with a unique number or identifier during casting in a corner of the specimen.

Specimens shall be numerically labeled with a numbering system agreed upon with the NIST technical POC so as to not repeat numbering systems used on precast concrete already stored in-house.

Shop drawings of precast concrete specimen dimensions, design parameters, and mix formulation shall be discussed and agreed upon in writing with the NIST Subject Matter Expert (SME) and Contracting Officer’s Representative (COR) at least fourteen days prior to contractor casting of concrete prisms. The contractor is responsible for maintaining accurate records of project activities. The contractor shall provide NIST with accurate records of the following:

1. Materials used in concrete specimen formulation, including admixtures, cement, sand, and aggregates with source information. This includes copies of cement mill sheets and aggregate data.

2. A gradation of the aggregate stock.

3. The dosage and purpose of admixtures.

4. A list of which specimens were prepared within each given batch as well as the date and time of casting for each batch.

5. Specimens shall be numerically labeled with a numbering system agreed upon with the NIST technical POC so as to not repeat numbering systems used on precast concrete already stored in-house.

6. Compressive strength measurements according to ASTM C39 for each cast batch with at least three replicates.

7. Unit weight and air entrainment test results according to ASTM C138.

The contractor shall provide all labor, materials, equipment, project oversight, administration and technical execution of this procurement. The contractor shall provide the products described in Sections 3.1 and 3.2 and, if exercised, Optional Task 1 (CLIN 0002 as described in Section 4 of this document.

4. OPTIONAL REQUIREMENT (Optional CLIN 0002)

The following requirement is optional and may or may not be exercised by the Government. Award of options is at the discretion of the Government in accordance with FAR 52.217-7: Option for Increased Quantity – Separately Priced Line Item. The option may be exercised at time of award in accordance with FAR 52.217-4 or anytime within two years of the effective date of award.

All optional products (i.e., precast concrete specimens) shall have identical concrete formulations, including source materials, identical mix procedures, identical molds, and setting conditions, as the base requirement products. Optional products ordered shall be delivered within 45 days of option exercise.

4.1. Option 1 (CLIN 0002): Delivery of 200 additional precast concrete specimens described in Item 1 plus Item 2 of Section 3.1 and all requirements in Section

3.2. Delivery shall be made within 45 days of option exercise.

5. WARRANTY

Precast concrete specimens shall be warrantied for one year from date of acceptance to withstand harsh environmental conditions that include 300 freeze/thaw cycles, 3,000 hours of high temperature and moisture exposure, and 3,000 hours of sea water immersion.

Acceptable durability of precast concrete specimens is defined as precast concrete specimens that do not crack (cracks with >1/8” depth, >1” length), spall (>10 % of surface area), or lose more than 20 % bending or compressive strength after the accelerated weathering cycles described.

Precast concrete specimens found and documented to not achieve this durability performance criteria within one year of the date of acceptance shall be replaced by the contractor with precast concrete specimens that do reach these criteria at no additional cost to the Government. Precast concrete specimens obtained as optional products must also achieve and maintain this durability performance criteria within one year of the date of optional product acceptance. Replacement products shall be delivered, also at no additional cost to the Government, within 60 days following notification of warranty request.

6. DELIVERY/PERIOD OF PERFORMANCE

Products meeting base requirements (CLIN 0001) shall be delivered within 45 days after contractor receipt of order. However, the award shall have an overall period of performance of three years and two months from date of award. This overall period of performance includes a two-year base period in which options for increased quantity may be exercised, 45 days for the delivery of any optional products ordered, and time for inspection, acceptance and invoice submission. The one-year warranty period associated with all ordered products shall begin following acceptance of products.

Options for increased quantity may be exercised at the Government’s discretion at time of award or any time after the award within the two-year base period of performance.

Delivery for any options exercised shall be completed on a F.O.B Destination basis within 45 days of option exercise.

The minimum period of performance is two years and two months from date of base award and the maximum period of performance, inclusive of any options exercised, is three years and two months from date of base award. The maximum period of performance would occur if an option for increased quantity were exercised on the last day of the two-year base period; thus 45 days for delivery of the optional products, plus time for inspection, acceptance, and invoice submission, plus the one-year warranty, would result in the additional one year and two months).

7. DELIVERY REQUIREMENTS

The contractor shall deliver all ordered products F.O.B Destination to the address below within 45 days after receipt of order. These delivery requirements apply to both base CLIN 0001 and any optional CLINs exercised.

NIST Shipping and Receiving 100 Bureau Drive Building 301 Gaithersburg, MD 20899

F.O.B Destination means that the contractor shall pack and mark the shipment in conformance with carrier requirements, deliver the shipment in good order and condition to the point of delivery specified in the purchase order, be responsible for any loss of and/or damage to the goods occurring before receipt and acceptance of the shipment by the consignee at the delivery point specified in the purchase order; and pay all charges to the specified point of delivery.

Prior to shipment, the Contractor shall request concurrence on delivery method, date and procedures with the NIST SME and COR.

Delivery trucks are to enter the NIST Gaithersburg Campus between 6:00 am and 3:30 pm daily. No deliveries will be allowed after 3:30 pm. Delivery trucks include such vehicles as pick-ups with storage compartments, delivery trucks, delivery vans, and tractor trailers. Trucks arriving to NIST will be directed to the Building 301 Truck Inspection Station. At Building 301, trucks will be registered, inspected, and the drivers will be granted access. Any truck which exits the campus will have to be re-inspected upon re-entry at Building 301. A vehicle dashboard placard will be placed within the truck. Placards change daily.

8. INSPECTION AND ACCEPTANCE

Upon arrival, the precast concrete specimens will first be inspected for cracks, casting quality (includes uneven surfaces, poor consolidation, and missing corners), defects, and size requirements in accordance with Section 3.

The Government will inspect products within fourteen days after receipt. The Government will notify the contractor in writing of acceptance or rejection of products.

The Contractor may invoice after products are accepted.

Initial acceptance is separate from warranty requirements; all products shall be warrantied for one year following their acceptance date in accordance with the requirements of Section 5: Warranty.