Attachment 6 - 31 63 16 Auger Cast Grout Piles.pdf

Ord and Weitzel Gate Reconstruction Arlington National Cemetery Task Order: W91236-14-0028-21

SECTION 31 63 16

AUGER CAST GROUT PILES

11/08

PART 1 GENERAL

1.1 MEASUREMENT AND PAYMENT PROCEDURES

1.1.1 Lump Sum

The contract price for piling will be a principal sum based on 12 inch diameter piles, (including 1 test pile), having a total aggregate length of 176 linear feet and will include 1 pile load tests having a capacity of 15 ton and 1 auger withdrawals.

1.1.1.1 Variations in Pile Quantities

From the results of laboratory tests on soil samples and data obtained as a result of placing and loading the test piles specified herein, the Contracting Officer will determine and will list "calculated" pile tip elevations for all piles. The Contracting Officer reserves the right to increase or decrease the total length of piles to be furnished and installed by changing the pile locations or elevations, requiring the installation of additional piles, or directing the omission of piles from the requirements shown and specified. Should the total pile length installed vary from that specified as the basis for bidding because of added or omitted piles or variations in the pile lengths, the principal sum will be adjusted by the amount bid per linear foot for "Additional Pile Length" or "Omitted Pile Length".

1.1.1.2 Variations in Pile Load Test Quantities

The Contracting Officer reserves the right to increase or decrease the number of pile load tests from that specified for the basis of bidding.

For changes in the number of load tests required, the contract principal sum price will be adjusted by the amount bid for "Each Additional Pile Load Test" or "Each Omitted Pile Load Test."

1.1.1.3 Variations in Auger Withdrawal Quantities

Should the number of auger withdrawals be increased above the specified contract number at the direction of the Contracting Officer, the contract principal sum will be adjusted by the amount bid for "Each Additional Auger Withdrawal."

1.1.1.4 Lump Sum Basis of Payment

The Contractor's furnished price shall include all necessary equipment, tools, material, labor, and supervision required for installing and cutting off the piles (including test piles), for conducting the load tests and for auger withdrawals in order to meet the applicable contract requirements. Payment for piles will be on the basis of the lengths of the piles measured from cut-off elevations to final tip elevations. No additional payment will be made for withdrawn, damaged, or rejected piles, for any portion of a pile remaining above the cut-off elevation, for cutting off piles, nor for any cut off lengths of piles. Payment for load

SECTION 31 63 16 Page 1 tests will be made for each load test satisfactorily performed. Payment for auger withdrawal will be made for each auger withdrawal made at the direction of the Contracting Officer.

1.2 REFERENCES

The publications listed below form a part of this specification to the extent referenced. The publications are referred to within the text by the basic designation only.

ASTM INTERNATIONAL (ASTM)

ASTM C109 (2013; E 2015) Standard Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in. or (50-mm) Cube Specimens)

ASTM C150/C150M (2017) Standard Specification for Portland Cement

ASTM C31 (2012) Standard Practice for Making and Curing Concrete Test Specimens in the Field

ASTM C33/C33M (2016) Standard Specification for Concrete Aggregates

ASTM C39 (2015a) Standard Test Method for Compressive Strength of Cylindrical Concrete Specimens

ASTM C618 (2012a) Standard Specification for Coal Fly Ash and Raw or Calcined Natural Pozzolan for Use in Concrete

ASTM C937 (2016) Grout Fluidifier for Preplaced-Aggregate Concrete

ASTM C939/C939M (2016a) Standard Test Method for Flow of Grout for Preplaced-Aggregate Concrete (Flow Cone Method)

ASTM C942 (2010) Compressive Strength of Grouts for Preplaced-Aggregate Concrete in the Laboratory

ASTM D1143 (2007; R 2013) Piles Under Static Axial Compressive Load

1.3 SYSTEM DESCRIPTION

Submit detail drawings to demonstrate compliance of augering, mixing, and pumping equipment, installation, and installed piles with contract documents. Include with the drawings erection details and reinforcement as specified. Auger cast grout piles are formed by the rotation of a continuous flight hollow-shaft auger into the ground to the tip elevation established by the requirements specified elsewhere in this section.

Grout is then injected through the auger shaft as the auger is being withdrawn in such a way as to exert removing pressure on the withdrawing earth-filled auger as well as lateral pressure on the soil surrounding the

SECTION 31 63 16 Page 2 grout-filled pile hole. Submit evidence to the Contracting Officer that the Contractor has been engaged in the successful installation of auger cast grout piles for at least 3 years.

1.3.1 Equipment

The minimum inside diameter of the hollow shaft of the augerflight shall be 1-1/4 inches. Provide grout injection equipment with a grout pressure gauge in clear view of the equipment operator. Rate of grout injection and rate of auger withdrawal from the soil shall be so coordinated as to maintain at all times a positive pressure on this gauge which will, in turn, indicate the existence of a "removing pressure" on the bottom of the augerflight. Magnitude of this pressure and performance of other augering and grouting procedures, such as rate of augering, rate of grout injection, and control of grout return around the augerflight, are dependent on soil conditions and equipment capability and shall be at the option of the Contractor, subject to review by the Contracting Officer.

The auger hoisting equipment shall be capable of withdrawing the auger smoothly and at a constant rate.

1.3.2 Subsurface Data

Subsurface soil data logs are in the project geotechnical report.

1.3.3 Grout Pump

Provide a positive displacement grout pump of an approved design. The pump discharge capacity shall be calibrated in strokes per cubic foot or revolutions per cubic foot by a method approved by the Contracting Officer. Remove oil or other rust inhibitors from mixing drums and pressure grout pumps prior to mixing and pumping.

1.4 SUBMITTALS

Government approval is required for submittals with a "G" designation;

submittals not having a "G" designation are for Contractor Quality Control approval. Submit the following in accordance with Section 01 33 00

SUBMITTAL PROCEDURES:

SD-02 Shop Drawings

Auger Cast Grout Piles; G

SD-03 Product Data

Test Piles; G Grout Pump Materials Grout Specimens for Laboratory Tests Grout specimens for Contractor Tests Casings

SD-06 Test Reports

Test Piles; G Loading Test Flow Cone Test

SD-07 Certificates

SECTION 31 63 16 Page 3

Auger Cast Grout Piles

SD-11 Closeout Submittals

Records; G

PART 2 PRODUCTS

2.1 MATERIALS

2.1.1 Grout

Provide grout consisting of a mixture of portland cement, a pozzolanic material when approved, fluidifier, sand, and water proportioned and mixed to produce a grout capable of being pumped with an ultimate compressive strength of 3000 psi at 28 days. Consistency shall not be less than 11 seconds when tested in accordance with paragraph FLOW CONE TEST. Other admixtures shall not be used.

2.1.1.1 Portland Cement

Portland cement shall conform to ASTM C150/C150M.

2.1.1.2 Pozzolan

Pozzolan shall be a fly ash or other approved pozzolanic material conforming to ASTM C618, Class F.

2.1.1.3 Grout Fluidifier

Grout fluidifier shall conform to ASTM C937, except that expansion shall not exceed 4 percent. The fluidifier shall be a compound possessing characteristics which will increase the flowability of the mixture, assist in the dispersal of cement grains, and neutralize the setting shrinkage of the high-strength cement mortar.

2.1.1.4 Water

Water shall be fresh, clean, and free from sewage, oil, acid, alkali, salts, or organic matter.

2.1.1.5 Fine Aggregate

Fine aggregate shall meet the requirements of ASTM C33/C33M. The sand shall consist of hard, dense, durable, uncoated rock particles and be free from injurious amounts of silt, loam, lumps, soft or flaky particles, shale, alkali, organic matter, mica, and other deleterious substances. If washed, a washing method shall be used that will not remove desirable fines, and the sand shall subsequently be permitted to drain until the residual-free moisture is reasonably uniform and stable. The sand shall be well-graded from fine to coarse, with fineness modulus between 1.30 and

3.40. The fineness modulus is defined as the total divided by 100 of the cumulative percentages retained on U.S. Standard Sieve Numbers 16, 30, 50, and 100.

2.1.1.6 Aggregate

Aggregate shall meet the requirements of ASTM C33/C33M, for fine

SECTION 31 63 16 Page 4 aggregate, except as to grading. The sand shall consist of hard, dense, durable, uncoated rock fragments and shall be free from injurious amounts of silt, lumps, loam, soft, or flaky particles, shale, alkali, organic matter, mica, and other deleterious substances. If washed, the method shall not remove other desirable fines, and the sand shall be permitted to drain until the residual free moisture is reasonably uniform and stable.

Sand grading shall be reasonably consistent and shall conform to the following requirements as delivered to the grout mixer:

U.S. Standard Sieve Number Cumulative Percent by Weight Passing

Cumulative Percent by Weight Retained

8 100 0

16 95-100 0-5

30 55-80 20-45

50 30-55 45-70

100 10-30 70-90

200 0-10 90-100

The sand shall have a fineness modulus of not less than 1.30 nor more than

2.10. Sand grading shown above may be modified with the approval of the Contracting Officer. Mortar test specimens made with the modified sand shall exhibit compressive strength equal to or greater than that exhibited by similar specimens made with sand meeting grading and other requirements shown above.

2.1.2 Reinforcement

Materials, assembly, and placement of reinforcement shall conform to the requirements of Section 03 30 00.00 10 CAST-IN-PLACE CONCRETE.

2.1.3 Casings

Submit a description of the materials to be used and the proposed methods of operations. Casings shall be approved steel as soil warrants.

Cylinder casings shall be of sufficient strength and rigidity to withstand all installation stresses, to prevent distortion caused by placing adjacent piles, and to prevent collapse due to soil or hydrostatic pressure.

PART 3 EXECUTION

3.1 GROUT VOLUME

The volume of grout per linear foot of pile shall be not less than the volume of grout per foot of test piles. All volume measurements shall be made in the presence of the Contracting Officer's representative.

3.2 INSTALLATION

Install piles after rough grading at pile locations have been completed.

The ground surface at each pile location at the time of augering and grouting shall be at least 12 inches higher than the required pile cutoff

SECTION 31 63 16 Page 5 elevation, unless a steel casing will be used, and the augered hole shall be completely filled with grout. All materials shall be fed to the mixer accurately measured by weight, except water that may be measured by volume. The order of placing the materials shall be as follows: (1) water, (2) fluidifier, and (3) other solids in order of increasing particle size. Time of mixing shall not be less than 1 minute.

3.2.1 Casings Placement

Casings shall be approved by the Contracting Officer and shall be left in place and filled with grout. The casing shall be rotated by the auger drive unit or weighted to the required depth. After the casing is in place, the casing and hole shall be cleared of water, sediment, and debris prior to pouring the grout.

3.2.2 Drilling

Except where auger withdrawal is required or directed by the Contracting Officer, each pile hole shall be drilled and filled with grout in an uninterrupted operation. Drill each pile hole to the required tip elevation. Should the required tip elevation shown on the drawings differ from the calculated tip elevation, an adjustment in the contract requirements will be made. Advance the auger at a continuous rate which prevents removal of excess soil. Stop rotation of auger after reaching the required pile tip elevation.

3.2.3 Grouting and Auger Removal

At the start of pumping grout, raise the auger from 6 to 12 inches and after grout pressure builds up, indicating discharge of grout, redrill auger to the required tip elevation, and fill pile hole with grout without interruption. When the auger is withdrawn to check the soil profile, it shall be reinserted in the pile hole to the required tip elevation and the pile hole then filled with grout without interruption. Coordinate rate of grout injection and rate of auger removal from the soil in such a manner as to maintain a positive pressure on the grout pressure gauge. The gauge indicates the existence of a removing pressure on the bottom of the augerflight. If the auger jumps upward during withdrawal, or if the grouting process is interrupted, or if there is decreased grouting pressure, reinsert it to the original tip elevation and decrease the rate of withdrawal to prevent further jumping. The auger may rotate very slowly during withdrawal. However, counterclockwise rotation is not permitted.

3.2.4 Pile Butts

Unless a permanent steel casing is provided as specified in paragraph entitled "Casings," place a steel sleeve at top of pile to form the pile butt. For pile cutoff above ground surface, the steel sleeve shall extend from the pile cutoff elevation to a point not less than one foot below the ground surface. For pile cutoff at or below ground surface, the steel sleeve shall extend from the ground surface to a point not less than one foot below the pile cutoff elevation. Pump excess grout to displace as much potential laitance as possible. Remove pile butt to required cutoff elevation or to sound grout, whichever is lower.

3.2.5 Placement Tolerances

Locate piles where indicated. The maximum permissible variation of the center of each pile from the required location is 2 inches at the ground

SECTION 31 63 16 Page 6 surface. No pile shall be out of required axial alignment by more than 2 percent. Periodically check the required axial alignment of each pile during the drilling operation and after reaching required tip elevation with not less than 5 feet of the augerflight extending above ground surface. Abandon piles which are damaged, mislocated, or out of alignment beyond the maximum tolerance and provide additional piles where directed.

3.2.6 Cutoff

Removal of pile butts above the indicated cutoff elevation may be accomplished by dipping the grout from the pile, while grout is fluid, but not less than one hour after installation. At the option of the Contractor, and as approved prior to pile installation, grout may be allowed to harden at its initial top elevation and then carefully trimmed off to the indicated cutoff elevation with hand operated chipping guns.

3.2.7 Disposal of Excavated Material

Do not leave any piles partially completed overnight. Completely grout and protect piles at the termination of each day's operation. Dispose of excavated material, resulting from augering, off Government property.

3.3 FLOW CONE TEST

The quantity of water used shall produce a grout having a consistency of not less than 21 seconds when tested with a flow cone in accordance with ASTM C939/C939M. The flow cone shall be modified by removal of the 1/2 inch orifice allowing grout to pass through the 3/4 inch hole in bottom of cone. Conduct tests at the beginning of grout injection and at subsequent intervals to ensure specification requirements are met.

3.4 GROUT SPECIMENS FOR LABORATORY TESTS

Conduct grout tests in accordance with ASTM C109 or ASTM C942 in a laboratory, approved by the Contracting Officer. Prepare test specimens by pouring grout into 2 by 2 by 2 inch cube molds. Not less than 9 cubes shall be cast during each 8-hour shift. Three cubes shall be tested at 7 days; 3 at 28 days; and 3 at 90 days.

3.5 GROUT SPECIMENS FOR CONTRACTOR TESTS

Conduct grout tests in accordance with ASTM C31 and ASTM C39. Prepare test specimens of grout by pouring grout into 6 by 12 inch cylinder molds. Provide molds with a top cover plate so designed as to restrain grout expansion and to permit escape of air and water. Not less than one set of cylinders shall be collected during the placing of each group of 15 piles or fraction thereof. One set shall consist of six cylinders of which three cylinders shall be tested in 7 days and three cylinders at 28 days. Any set of cylinders of which one or more cylinders test at 10 percent or more below the required strength shall be cause for rejection of the pile group.

3.6 TEST PILES

Submit a complete and accurate record of all auger cast grout piles (both test piles and production piles), indicating the pile location, diameter, length, elevation of tip and top of pile, and the quantity and strength of grout material actually pumped in each pile hole.

SECTION 31 63 16 Page 7

3.6.1 Placement

Provide test piles of the required type placed in the manner specified elsewhere in this section for all piling. The Government will use test pile and load test data in addition to test reports on soil samples to determine "calculated" pile tip elevations. Piles immediately adjacent to the test pile shall be placed after placing test pile and prior to load testing. Test piles that are located within the tolerances indicated for all piles and provide a safe design capacity as determined by the results of a satisfactory load test may be used in the finished work. Test loads shall not be applied to the piles until the grout has obtained a minimum strength of 3000 psi. Report immediately any unusual conditions encountered during pile installation to the Contracting Officer.

3.6.2 Depth

For all test piles, the auger shall be withdrawn after reaching the "calculated" tip elevation and before grout is pumped. The Contracting Officer will be present to check the soil conditions and will have the right to increase the test pile length if soil conditions warrant. In such cases, the Contracting Officer may require additional auger withdrawals after drilling to the lower tip elevation. Such additional auger withdrawals shall be included in the total number of auger withdrawals made. The pile hole shall not be filled with grout until the Contracting Officer has approved the final tip elevation.

3.6.3 Loading Test

Perform load tests in accordance with ASTM D1143, cyclic loading method.

The load tests at locations shown or directed shall be made on test piles placed to the tip elevation used for establishing lengths of piles for bidding, except as otherwise directed by the Contracting Officer. Perform loading, testing, and recording of data under the direct supervision of a registered professional engineer. The analysis of the load test data shall be done by the registered professional engineer. The registered professional engineer will be provided and paid by the Government. The installation of contract piles shall not proceed within each area of substantially different subsoil conditions until a satisfactory load test has been performed in that area. Submit results of all tests performed.

3.6.4 Acceptance

Load test piles to twice the design working load of 15 tons, unless failure occurs first. The safe design capacity of a test pile, as determined from the results of load tests, shall be the lesser of the two values computed according to the following:

a. One-half the load that causes a net settlement after rebound of not more than 0.01 inch per ton of total test load.

b. One-half the load that causes a gross settlement of not more than 1 inch provided that the load settlement curve shows no sign of failure.

3.6.5 Tolerances

Locate test piles as shown on drawings or as otherwise directed by the Contracting Officer. Install piles from the ground surface existing after general excavation work has been completed. The maximum variation of the center of any pile from the required location shall be 2 inches at the

SECTION 31 63 16 Page 8 ground surface, and no pile shall be out of plumb more than 2 percent.

Piles damaged, mislocated, or out of alignment beyond the maximum tolerance shall be abandoned and additional piles shall be placed as directed.

3.7 SOIL PROFILE

At 1 pile holes, in addition to the test piles, the auger shall be withdrawn from the ground before the grout is pumped to check the soil profiles. Drill soil probes within a radius of 20 feet of their associated test pile. The Contracting Officer will be present to verify the soil condition at the "calculated" pile tip elevation and has the right to increase the soil probe length or require additional soil probes, if soil conditions warrant. After soil conditions have been inspected and approved by the Contracting Officer, install test piles. Soil probes that are located within the tolerances indicated for piles shall be filled with grout and may be used in the finished work, if approved by the Contracting Officer and if satisfactorily load tested.

3.8 PROTECTION OF PILES

The sequence of pile installation shall be such that adjacent piles show no evidence of disturbance. This evidence would actually appear as a drop in the grout surface. The load applied to the soil by the drilling equipment shall be far enough away from the pile being drilled to avoid compressing or shearing of the soil which may in turn displace or squeeze-off the grout column. No piles shall be placed within 5 feet of adjacent piles until the grout in the piles has set for 24 hours, or 12 hours for pile distance between 6 and 5 feet, unless otherwise directed by the Contracting Officer.

3.9 RECORDS

Keep complete and accurate records of all auger cast grout piles.

Indicate the pile location, diameter, length, elevation of tip and top of pile, quantity of grout material actually pumped in each pile hole, and the rated load capacity of the pile. Determine grout quantity by recording grout pump displacement or by other approved means. Record and report immediately any unusual conditions encountered during pile installation. Submit specified records upon completion of work.

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SECTION 31 63 16 Page 9