-7.04 PAYMENT Not Used 53 SHOTCRETE 53-1 GENERAL 53-1.01 GENERAL

52-7.04 PAYMENT

53-1.01 GENERAL

53-1.01A Summary

Reinforcement must comply with section 52.

53-1.01B Definitions

53-1.01C Submittals

53-1.01D Quality Assurance

53-1.02 MATERIALS

For the dry-mix process:

1. Thoroughly mix 1 part cementitious material to not more than 4.5 parts fine aggregate in a dry state before charging into the machine. Measurement must be either by volume or weight.

2. Fine aggregate must contain not more than 6 percent moisture by weight.

1. Shotcrete must contain at least 632 pounds of cementitious material per cubic yard.

2. You may substitute a maximum of 30 percent pea gravel for the fine aggregate. The maximum size of pea gravel must be such that 100 percent passes the 1/2-inch screen and at least 90 percent passes the 3/8-inch screen.

3. You may add admixtures complying with section 90-1.02E.

53-1.03 CONSTRUCTION

53-1.03A General

53-1.03B Preparing Foundations

Thoroughly compact foundations. Foundations must contain enough moisture to provide a firm foundation and to prevent absorption of water from the shotcrete. Foundations must be free of surface water.

Use ground or gauging wires if necessary to establish thickness, surface planes, and finish lines.

53-1.03C Placing Shotcrete

Direct the nozzle in a way that minimizes rebound of the shotcrete.

Maintain a uniform velocity of the material as it leaves the nozzle and at a rate determined for the job site conditions.

For dry-mix shotcrete:

1. Maintain a constant pressure of at least 45 psi in the placing machine if the hose length is 100 feet or less. Increase the pressure at least 5 psi for each additional 50 feet of hose or fraction thereof.

2. Maintain uniform water pressure at the nozzle of at least 15 psi greater than the air pressure at the machine.

3. Do not use aggregate and cementitious materials that have been mixed for more than 45 minutes.
For wet-mix shotcrete:

1. Transport shotcrete under section 90-1.02G(3)

2. Limit placing to 8-foot lifts measured along the slope

3. Place gauging wires at approximately 7-foot centers

4. Do not use materials that have been mixed for more than 90 minutes
You may reuse rebound as fine aggregate in quantities not to exceed 20 percent of the total fine aggregate requirements.

53-1.03D Finishing Shotcrete

Remove and replace loose areas of shotcrete.

Cure shotcrete for at least 72 hours by spraying with water, by a moist earth blanket, or by any of the methods specified in section 90-1.03B.

If you add a coloring agent to the shotcrete and you use the curing compound method for curing the shotcrete, use curing compound no. 6.

Protect shotcrete under section 90-1.03C.

53-1.04 PAYMENT

The Department does not pay for shotcrete placed outside the dimensions shown or to fill low areas of foundations.

53-2.01 GENERAL

53-2.01A Summary

53-2.01B Definitions

53-2.01C Submittals

1. QC plan that includes:

1.1. Number and qualifications of nozzlemen available to place shotcrete, number of nozzlemen on the job site at any time during shotcrete placement, description of their work schedule, and procedures for avoiding fatigue of any nozzleman

1.2. Proposed method of placing shotcrete, including application rates, details of proposed construction joints and their locations, and methods for achieving the required thickness and surface finish

1.3. Procedures for curing shotcrete surfaces

1.4. Description of any required debris containment system

2. Preconstruction test panels and test results

3. Production test cores and test results

53-2.01D Quality Assurance

53-2.01D(1) General

Reserved

53-2.01D(2) Qualifications

Each nozzleman must have at least 3,000 hours of ex`perience as a nozzleman on projects with a similar application.

53-2.01D(3) Preconstruction Test Panels

Obtain authorization of the QC plan before constructing test panels.

Construct 1 unreinforced test panel and 1 reinforced test panel for each proposed mix design. Use nozzlemen, application crew, equipment, materials, mix designs, and procedures proposed for the work.

Cure the test panels under conditions similar to those in the work.

For the unreinforced test panel:

1. Determine the size of the test panel

2. Obtain 3-inch-diameter cores from the test panel

3. Discard cores that show evidence of improper coring

4. Identify each core that is to be tested

5. Test cores for compressive strength

6. Label and submit the test panel and a copy of the test results within 5 days of testing

7. Include the mix design and ambient temperature in the submittal
For the reinforced test panel:

1. Construct a square test panel that has the same (1) thickness, (2) bar size and quantity of bar reinforcement or other obstructions, and (3) positioning of bar reinforcement or obstructions as the most heavily reinforced section of shotcrete to be placed

2. Minimum length of each side must equal 3 times the thickness of the most heavily reinforced section of shotcrete to be placed but not less than 30 inches

3. Break the test panel in the presence of the Engineer after a minimum 7-day cure into pieces no larger than 10 inches in the greatest dimension

4. Surfaces of the broken pieces must be dense and free of laminations and sand pockets and must show that the bar reinforcement or other obstructions are completely encased
Obtain and test cores for compressive strength under section 53-2.01D(4)(a).

Instead of constructing a separate unreinforced test panel, you may obtain cores from the reinforced test panel to determine the compressive strength. If you choose this option, do not break the test panel until it has cured for at least 14 days.

Dispose of test panels.

53-2.01D(4) Quality Control

53-2.01D(4)(a) General

Obtain cores for compressive strength testing under ASTM C1604/C1604M. Discard cores that contain bar reinforcement or other obstructions or show evidence of improper coring. Test cores for compressive strength at 28 days under ASTM C1604/C1604M at an authorized laboratory. The compressive strength is the average strength of at least 3 cores that are free from bar reinforcement or other obstructions.

Notify the Engineer at least 24 hours before performing any coring or testing.

53-2.01D(4)(b) Field Quality Control

Obtain at least four 3-inch-diameter test cores from each 50 cu yd, or portion thereof, of shotcrete placed each day. Three cores must be free from reinforcement or obstructions. One core must include reinforcement. The Engineer determines each core location.

Cores must be both visually inspected and tested for compressive strength. The Engineer performs the visual inspection and you must perform compressive strength testing.

Identify each core, including a description of the core location and mix design, and submit the cores immediately after coring.

The Engineer will perform the visual inspection and return the cores to you for compressive strength testing within 48 hours.

53-2.01D(5) Department Acceptance

53-2.01D(5)(a) General

The Department accepts shotcrete based on test cores for visual inspection and compressive strength.

53-2.01D(5)(b) Visual Inspection

Each test core must be dense and be free of laminations and sand pockets. Any core with reinforcement must show reinforcement or other obstructions are completely encased.

Shotcrete represented by an unacceptable core will be rejected unless you submit evidence that the quality of the shotcrete placed in the work is acceptable.

53-2.01D(5)(c) Compressive Strength

If the compressive strength of the shotcrete is below the specified compressive strength:

1. Make corrections to the mix design or fabrication procedures and obtain authorization before you place additional shotcrete.

2. Shotcrete represented by the cores is subject to one of the following:

2.1 If the compressive strength is at least 95 percent of the specified strength, $10/cu yd is deducted from the payment for structural shotcrete.

2.2 If the compressive strength is below 95 percent of the specified strength but is at least 85 percent of the specified strength, $15/cu yd is deducted from the payment for structural shotcrete.

2.3 If the compressive strength is below 85 percent of the specified strength, the shotcrete must be removed.

If the compressive strength is below the specified strength but is at least 85 percent of the specified strength, the deductions specified above apply unless you obtain and submit evidence that the strength of the concrete placed in the work is greater than or equal to the specified strength and this evidence is accepted by the Engineer.

If the compressive strength is below 85 percent of the specified compressive strength, the noncompliant concrete represented by the test must be removed unless you obtain and submit evidence that the strength of the concrete placed in the work is at least 85 percent of the specified compressive strength and this evidence is accepted by the Engineer.

If the evidence consists of tests made on cores taken from the work, obtain and test the cores under ASTM C1604/C1604M.

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