Amend 002 Concrete Durability QA.pdf

Questions & Answers Solicitation No. NIST-RFQ-23-7300579

Corrosion and Concrete Durability Expertise and Testing Services for the Champlain Towers South Investigation

1. ASTM C1356 is referenced as one of the analysis procedures. ASTM C1356 is the “Standard Test Method for Quantitative Determination of Phases in Portland Cement Clinker….” As the proposed statement of work is focused on hardened concrete and not clinker, please confirm that this standard is correct.

Point counting shall be conducted per ASTM C1356. This means the grid, counts, and uncertainty estimation should be conducted per this standard. Per the ASTM standards, adjacent points shall not sample the same feature. The features of interest in the point counting are aggregates, voids, cement, and hardened cement paste. The specimen shall be imaged per the procedures in ASTM C457 at spatial resolution of 2 µm/pixel to 4 µm /pixel.

Modifications to this procedure may be permitted subject to approval by the NIST

COR.

2. In reference to question 1 above, Figure 4.1 indicated that ASTM C856 (petrography) is one of the analysis methods of selected pucks, but is not referenced as a Task 4 procedure. Please confirm the use of ASTM C856. Perhaps ASTM C856 should replace ASTM C1356?

Petrography per ASTM C856 is not required on pucks. The SOW, specifically Figure 4.1, is revised to reflect this An updated image is provided as a response to Question 5.

3. Similar to question 2 above, Figure 4.1 references SEM/EDS, XRF/XRD, FTIR/Raman analysis but with no reference in Task 4. Please confirm what materials and/or constituents these procedures are seeking to identify and quantify.

SEM/EDS, XRF, XRD, FTIR and Raman are not required. The SOW, specifically Figure 4.1, is revised to reflect this. An updated image is provided as a response to Question 5.

4. Type A cores may vary in length from 14.5 inches to 17.5 inches. If only 14.5 inches, please confirm if puck dimensions can be less than the 2” specified.

The exact core length is expected to vary depending on the sample and the extraction process. The general procedure required is to section the cores into approximately equal lengths. The contractor shall be responsible for cutting the cores into equal-length pucks and testing the pucks as specified in the SOW.

Pucks less than 2 inches are acceptable with concurrence from the NIST COR.

The dimensions and mass of each puck shall be recorded after cutting.

5. Figure 4.1 does not provide puck dimensions for the 9 inch cores. Please provide.

Please find the updated figures for the 16 inch cores and the 9 inch core shown in Figure 4.1 below and in the revised SOW. Unless otherwise specified, the 16 inch cores shall be cut into 8 equal length pucks and tested as shown in Figure 4.1(a). The 9 inch cores shall be cut into 4 equal length pucks as shown in Figure 4.1(b). The total number of pucks and associated tests are listed in Table 4.1.

(a) Type A Core (b) Type A Core – 9 in length

(c) Type B Core (d) Type C Core

Figure 4.1: Schematic Diagrams of samples to be obtained from cores extracted from evidentiary building debris.

6. Please confirm the number of puck specimens to be tested in Task 4. If there are a total of 5 pucks/slices removed from 15 cores at 16” length, that results in 75 pucks., not 125. Or are pucks from the 9” cores also included? If so, how are they numbered?

Yes, the 9 in cores are included. Please see the following breakdown in tabular form. 16 in cores will produce 8 pucks and 9 in cores will produce 4 pucks. Table

4.1 summarizes the total number of pucks expected.

Table 4.1: Summary of the expected number of Type A cores and the total number of pucks to be tested.

For ASTM C1585-20, ASTM C1792-14, ASTM C642-21, ASTM C1356-07(2020) tests, and an agreed-upon bulk resistivity test:

Expected Number of Cores Pucks/core Total Pucks

16 in Cores 15 5 75 9 in Cores 25 2 50

Total 125 For ASTM C1202-19 tests:

Expected Number of Cores Pucks/core Total Pucks

16 in Cores 15 3 45 9 in Cores 25 2 50

Total 95

NIST will label the cores sent to the contractor. The contractor shall section the pucks and label them by an agreed upon labeling scheme. The labeling scheme shall convey information regarding the core from which it was extracted and its location.

7. Page 4 of the SOW notes that 15 Type B and C cores will be utilized. Task 4.4 indicates 14 total cores. Please confirm value.

NIST confirms that the the correct number of total cores for Task 4.4. is 14. The SOW has been revised to eliminate the error on page 4 indicating 15 cores.

8. Section A-A of Figure 4.2 indicates a ¾” clear spacing between the #4 bars and the bottom of the slab. Typical cover for concrete mixes with ¾” nominal aggregate would be at least 1-1/8”. Please confirm proper clear spacing.

The clear spacing between the #4 bars and the bottom of the slab shall be ¾ in.

Also, the SOW has been revised to rename Figure 4.2 as Figure 5.1.

9. Will Optional Task 8 be exercised/awarded before the contractor mobilizes for Task 3?

No, NIST does not expect to exercise Optional Task 8 before Task 3 begins.

Please price optional tasks independently from the other tasks and please consider this answer when proposing a travel ceiling.

10. How many on-site days at the NIST Structural Testing Contractors site should be planned for Task 5.3?

The contractor shall plan for the number of on-site days necessary to set up and train the structural test contractor on operating the accelerated corrosion equipment. Virtual meetings may be used to provide training and support online, if necessary. NIST estimates 2 to 4 days necessary for this task; however the Contractor shall propose the approach it believes most appropriate.

11. In reference to Task 5.4, can NIST please provide some clarification as to the possible minimum and maximum length of the bars that they expect to be evaluated?

Rebar lengths are expected to be between 6 inches and 12 inches.

12. Regarding Task 4.3 – Water Absorption and Drying Rate Measurements on Type A Cores:

a. Figure 4.1 (a) Type A shows how the pucks are to be sectioned from Type A cores. In addition, it also shows collection of a Thin section for

Carbonation and indicates that the slice should be recovered after all ASTM tests. ASTM C856 Petrography is also listed. In the scope of work carbonation testing and petrography on Type A cores is not mentioned.

Please clarify if Figure 4.1 is only to be used for sectioning the cores into 8 pucks and other test information provided on it is to be ignored.

Figure 4.1 has been updated in the SOW to be consistent with the text and is shown as a response to Quesetion 5. ASTM C856 petrography is not required on Type A cores. Please refer to Table 4.1 for the expected number of pucks to be tested per the specified ASTM tests.

b. Similarly in Figures 4.1 (b) and (c) list ASTM C856, MicroXRF (Micro X- Ray Fluorescence), and Thin sections. Are these to be performed? If MicroXRF is to be performed, what elements are we looking for?

Figure 4.1 has been updated in the SOW to be consistent with the text and is shown as a response to Quesetion 5. ASTM C856, Micro XRF, and thin sections, and carbonation are not required as part of this SOW.

13. May Contractors use commercial list pricing as part of price quotations, without a breakdown of associated costs, if commercial list pricing is appropriate for some aspects of a quote?

Contractors may include commercial list pricing as part of their price quotations where it is applicable. However, the price quotation shall make clear which portions of quoted pricing are commercial list prices and which are not. Non-commercial-list-prices must include a breakdown of associated costs. A copy of the contractor’s commercial price list shall be included in any quotation that includes commercial list pricing.

14. What format should price quotations be provided in?

Please see the “Instructions to Quoters” section of the solicitation, copied below:

Per the solicitation “Instructions to Quoters” section, price quotations shall be submitted in Microsoft Excel or search Adobe PDF format. All figures must be rounded to the nearest hundredth.

Price quotations shall be submitted on a firm fixed price basis with summary price information in accordance with the contract line item numbering structure identified in the solicitation (copied below).

CLIN Description Total Price

Corrosion and Concrete Durability Expertise and Testing Services for Champlain Tower South Investigation in accordance with the attached Statement of Work

Firm Fixed Price

Travel and Other Direct Costs

Not-to-Exceed

Optional Task 8: Extend Corrosion Potential and Corrosion Rate Mapping by 15 Specimens

Optional Task 9: Second Round of Cores for Concrete Transport Properties

TOTAL

Quotations shall be valid for 60 days after solicitation close.

To assist the Government in evaluating firm fixed price quotations, the Quoter shall provide a breakdown of the proposed labor and materials costs per task identified in the Statement of Work. The proposed labor breakdown shall include proposed labor categories and estimated hours per labor category.

Quoters shall also include a proposed fixed price payment schedule based on requirement milestones/deliverables in relation to the deliverables table in the Statement of Work. Quoters may propose alternate payment schedules.

15. Statement of Work Table 4.1 contains the following language:

“*Cement shall be procured by NIST and stored at the PEF in Miami, FL. The Contractor shall be responsible for shipping the cement from the PEF to the Contractor’s location.

**Coarse aggregate shall be ASTM C33 crushed limestone obtained from designated south Florida quarries with nominal maximum aggregate size = ¾ in.

To be provided by NIST.

*** Fine aggregate shall be concrete sand meeting the requirements of ASTM for quality and grading. To be provided by NIST.”

Does this mean that Contractor quotes need to include the cost of shipping materials to the contractor? Or does this mean Contractor quotes simply needs to provide information as to where the Government should send materials and how to package it?

The Contractor shall bear the costs of shipping all materials mentioned and shall include such costs in its firm fixed price quote. The contractor shall coordinate material transport(s) from the storage location in Miami to its facility.

16. Is there a NIST ceiling for price quotations?

No, the solicitation does not set a ceiling for price quotations. It is the responsibility of the contractor to quote its best pricing to perform the required tasks.

-- No additional questions were received in relation to this solicitation --