PWS_SaltwaterConcrete.pdf

Performance Work Statement

Purpose and Scope The Airfields and Pavements Branch (APB) requires pavement structures constructed with a surface layer of Portland cement concrete (PCC) pavement using saltwater as the mixing water.

APB requests a contractor provide materials and construct these structures as described below in the Requirement section.

Requirement Listed below are specific items that will be provided by the APB and items that are to be provided by the contractor.

Work Items Provided by the APB:

1. All subgrade, base preparation and paving surface preparation.

2. Preparation and addition of brine solution to concrete mix trucks at batch plant.

3. Quality control operations:

a. Random sampling and testing will be conducted by the Contracting Engineer at ERDC.

b. Random samples shall be taken at the point of discharge, i.e. transit mix truck, for the determination of air content, slump, temperature, and for the casting of test cylinders and/or beams.

c. Determination of final PCC layer thickness will be performed using rod & level and total station elevation measurement techniques.

Work Items and Materials Provided by the Contractor:

The Contractor shall provide a PCC surface course with dimensions specified in Figure 1, cross section dimensions specified in Figures 2 and 3, complete and in-place, meeting the following requirements:

CONCRETE MIXTURE DESIGN

The concrete mixture shall meet the concrete mix design submittal – Mix Code 5020X652 – from Delta Industries. This concrete mixture was designed to meet the following requirements when using freshwater as the mix water:

a. The concrete mixture shall have a minimum design compressive strength of 5,000 psi at 28 days when tested in accordance with ASTM C39.

b. The concrete mixture shall have a minimum design tensile strength of 650 psi at 28 days when tested in accordance with ASTM C78.

c. The design water-cementitious material ratio shall be 0.41.

d. Size 57 limestone aggregate per ASTM C33 shall be used in the mixture.

e. Target slump shall be 8 ± 1 in.

f. The concrete mixture design shall be submitted for approval by the Engineer at least two weeks prior to placement. No concrete shall be placed without an approved mixture design.

The saltwater will be added to the concrete mixture by creating a brine solution to be added at the time of batching. The brine solution will be prepared and added to the concrete mix trucks at the batch plant by APB. The Government Engineer will coordinate with the batch plant to add the approved amount of brine. The Contractor will pay a clean out fee to the batch plant to remove residual saltwater from the mix trucks, not to exceed $5/cy of concrete.

CONCRETE PLACEMENT

a. The concrete mixture shall be placed using a fixed-form placement method.

b. The concrete mixture shall be placed by a pump-truck.

c. The Contractor shall be responsible for the supply, installation, removal, and disposal of all formwork.

d. Forms shall be structurally sufficient and adequately staked/reinforced.

e. A release agent shall be used to facilitate removal of forms.

f. Dowel bar assemblies shall be placed at the locations indicated in Figure 1. Dowel bar assemblies shall consist of 1.25-in.-diameter epoxy coated dowel bars 18-in.-long, spaced at 12-in. intervals. Dowel bar assemblies shall be sufficiently anchored to maintain vertical (i.e. mid-depth of the slab thickness indicated in Figure 1) and horizontal alignment of the dowel bars during concrete placement. Dowel bar alignment shall be approved by the Engineer prior to concrete placement.

g. Fresh concrete shall be designed using the same admixtures and dosages as Mix Code 5020X652 to meet the slump requirements of 8 ± 1 in. for concrete using freshwater as the mix water. Concrete having slumps less than 4 in. on arrival will be rejected prior to placement.

h. Delivered concrete temperatures must be less than 90°F when tested in accordance with

ASTM C1064.

i. Water in excess of the batch water shall not be added. If the slump is less than specified on arrival to the job site, additional MRWR and/or HRWR shall be used to bring the slump into tolerance for pumping. Water may not be added because the salinity will be affected.

The admixtures must be added into the transit mix truck and mixed thoroughly before placement.

j. Use of a self-powered, vibratory truss screed is required. Roller screeds or manual screeds will not be allowed.

k. Finishing and Curing

a. A textured broom finish is required with no additional water added to the surface.

A hard-troweled floor finish is not allowed.

b. Fogging/misting is allowed to prevent shrinkage cracking.

c. A CRD-C 300 curing compound is to be applied to the surface after finishing

(before saw cutting contraction joints) and as soon as the free water has disappeared. The curing compound is to be applied to the free edges as soon as forms are removed. Curing compound should be applied by a pressure sprayer with overlapping coverage in two coats. The second coat should be sprayed at a right angle to the first.

l. Construction and Contraction Joints

a. For purposes of this contract, construction joints are defined as a joint between PCC slabs which are existing or new and exhibit a smooth between-slab interface as a result of forms (e.g., separate paving lanes); contraction joints are defined as a joint between new PCC slabs in the same paving lane used to control cracking due to concrete volume change.

b. All contraction joints MUST undergo initial saw cutting within 6 to 12 hours after placement. If the PCC is chipping, spalling, or tearing during saw cutting, then saw cutting should be stopped until the PCC hardens more. Contraction joints should be sawn to a depth of at least ¼ the slab thickness and a width of 1/8 in. and shall be spaced at 20-feet intervals over the full pavement length as shown in Figure 1.

Additionally, a contraction joint shall be saw cut at the transition (i.e. mid-slab) between the 8 in. and 11 in. PCC thickness (indicated by a dashed line in Figure 1).

Slabs will be replaced at no cost to ERDC if the PCC cracks before saw cutting is completed. A saw-cutting plan must be approved by the ERDC engineer before the PCC is placed.

c. The construction joint between the new and existing 14 in. PCC slabs must be saw cut and sealed. The construction joint should be sawn to the dimensions of the joint sealant reservoir – 5/8 in. wide by 1/1/4 in. deep. A saw-cutting plan must be approved by the ERDC engineer before the PCC is placed.

d. Joint sealant is required for the model for the contraction and construction joints.

A reservoir shall be prepared having dimensions of 5/8 in. wide by 1/1/4 in. deep to receive ¾ in. diameter closed cell foam backer rod and self-leveling silicone joint sealant.

Figure 1. Plan view layout of new PCC pavement

Figure 2. Cross section ‘A-A’ (from Figure 1) of PCC pavement

Figure 3. Cross section ‘B-B’ (from Figure 1) of PCC pavement

Delivery Required Start Date: Two weeks after contract is awarded Required Completion Date: Two week after first day on government site Total Project Time: Four weeks from date of award

Safety It is the responsibility of the contractor to ensure worker safety by informing the workers of any potential hazardous practices. Occupational Safety and Health Administration (OSHA) guidelines must be followed at all times for hazardous practices for handling and placing concrete. Workers are required to be informed of all hazardous materials and practices that may involve exposure to toxic materials in the workplace. Material Safety Data Sheets (MSDS) must be available to all workers at the work site.

Access and General Protection/Security Policy and Procedures: All contractor and all associated sub-contractors employees shall comply with applicable installation, facility and area commander installation/facility access and local security policies and procedures (provided by government representative). The contractor shall also provide all information required for background checks to meet installation/facility access requirements to be accomplished by installation Provost Marshal Office, Director of Emergency Services or Security Office.

Contractor workforce must comply with all personal identity verification requirements (FAR clause 52.204-9, Personal Identity Verification of Contractor Personnel) as directed by DOD, HQDA and/or local policy. In addition to the changes otherwise authorized by the changes clause of this contract, should the Force Protection Condition (FPCON) at any installation or facility change, the Government may require changes in contractor security matters or processes.

For contractors who do not require CAC, but require access to a DoD facility or installation: Contractor and all associated sub-contractors employees shall comply with adjudication standards and procedures using the National Crime Information Center Interstate Identification Index (NCIC-III) and Terrorist Screening Database (TSDB) (Army Directive 2014-05 / AR 190-13), applicable installation, facility and area commander installation/facility access and local security policies and procedures (provided by government representative, as NCIC and TSDB are available), or, at OCONUS locations, in accordance with status of forces agreements and other theater regulations.

Pre-screen candidates using E-Verify Program: The Contractor must pre-screen Candidates using the E-verify Program (http://www.uscis.gov/e-verify) website to meet the established employment eligibility requirements. The Vendor must ensure that the Candidate has two valid forms of Government issued identification prior to enrollment to ensure the correct information is entered into the E-verify system. An initial list of verified/eligible Candidates must be provided to the COR no later than 3 business days after the initial contract award.

Performance Work Statement