specified bearing value as determined by the applicable formula indicated in subsection 600A.04. Subsequent test piles to be load tested shall be driven to the specified bearing values as determined by the applicable formula modified by the results of prior test loads and foundation data. It is the intent of these specifications that test piles to be load tested shall fail between 2 and 3 times the specified bearing value except for piles driven to refusal, rock or a specified tip elevation. The ground at each test pile shall be excavated to the elevation of the bottom of the footing before the pile is driven. The hammer used shall conform to the requirements under subsection 600A.13. If it becomes necessary to obtain a desired test elevation, piles may be driven in conjunction with water jets or pre-drilled holes. Piles shall not be jetted in areas of unstable embankments or whenever any improvements could become endangered. Whenever pre-drilled holes are required, their diameters shall not be greater than the piling diameters.

600A.03 Load Tests. When called for in the bid schedule, load tests shall be made where shown on the plans or in the special provisions. When diesel or other types of hammers requiring calibration are to be used, the Contractor shall make load tests even though no load tests are called for in the bid schedule, except that load tests will not be required when the hammer is to be used only for driving piles to refusal, rock or a fixed tip elevation or the hammer is of a type and model that has been previously calibrated for similar type, size and length of pile, and foundation material. Calibration data must have been obtained from sources acceptable to the Engineer.

Load tests shall be made by methods approved by the Engineer. The Contractor shall submit to the Engineer for approval detailed plans of the loading apparatus he intends to use. The apparatus shall be so constructed as to allow the various increments of the load to be placed gradually without causing vibration to the test piles. If the approved method requires the use of tension (anchor) piles, such tension piles shall be of the same type and diameter as the permanent piles and shall be driven in the location of permanent piles. Pipe and shell piles whose walls are not of adequate strength to sustain the test loading when empty, shall have the required reinforcement and concrete placed before loading. Loads for the load tests shall not be applied until the concrete has attained a minimum compressive strength of 95 percent of the design 28-day compressive strength as indicated by test cylinders made and tested in accordance with AASHO T 23 and T 22, respectively. If he so elects, the Contractor may

use high early strength cement, type III or IIIA, in the concrete of the load test pile and the tension piles.

Suitable approved apparatus for determining accurately the load on the pile and the settlement of the pile under each increment of load shall be supplied by the Contractor. The apparatus shall have a working capacity of three times the design load shown on the plans for the pile being tested. Reference points for measuring pile settlement shall be sufficiently removed from the test pile to preclude all possibility of disturbance. All pile load settlements shall be measured by adequate devices, such as gauges, and shall be checked by means of an engineer's level. Increments of deflection will be read just after each load increment is applied and at 15-minute intervals thereafter. The safe allowable load will be considered as 50 percent of the load which, after 48 hours of continuous application, has caused not more than 4 inch of permanent settlement, measured at the top of the pile. The test load shall be twice the design load shown on the plans. The first increment of load to be applied to the test pile shall be the pile design load. The load on the pile shall be increased to twice the design load by applying additional loads in three equal increments. A minimum period of 2 hours shall intervene between the application of each increment, except that no increment shall be added until a settlement of less than 0.005 of an inch is observed for a 15-minute interval under the previously applied increment. If there is a question as to whether the test pile will support the test load, the load increments shall be reduced by 50 percent, at the direction of the Engineer, in order that a more closely controlled failure curve may be plotted. The full test load shall remain on the test pile not less than 48 hours. The full test load shall then be removed and the permanent settlement read. Loading shall then continue beyond the double design load in 10-ton increments until the pile fails or the capacity of the loading apparatus is reached, whichever is the lesser. The pile may be considered to have failed when the total settlement under load exceeds 1 inch or the permanent settlement exceeds 14 inch.

After the completion of loading tests, the load used shall be removed and the piles, including tension piles, utilized in the structure if found by the Engineer to be satisfactory for such use. Test piles not loaded shall be utilized similarly. If any pile, after serving its purpose as a test or tension pile, is found unsatisfactory for utilization in the structure, it shall be removed if so ordered by the Engineer or shall be cut off below the gound line or footings, whichever is applicable. 600A.04 Timber Pile Bearing Values by Formula. When load tests are called for in the bid schedule, and when diesel

or other hammers to be calibrated are used, the minimum number of hammer blows per unit of pile penetration needed to obtain the specified bearing value of piles will be determined by load tests as provided in subsections 600A.02 and 600A.03. In the absence of load tests, the safe bearing value of each timber pile will be determined by whichever of the following approximate formulas is applicable.

For single-acting steam or air hammers and for diesel ham

mers having unrestricted rebound of ram, P=

2WH S+0.1

For double-acting steam or air hammers and diesel ham

P-safe load per pile in pounds.

W=weight of the striking part of the hammer in pounds. H-height of fall in feet for gravity, steam, and air hamhammers, and;

= observed average height of fall, in feet, of blows used
to determine penetration for diesel hammers with
unrestricted rebound of ram.

S average penetration per blow in inches for the last 5
to 10 blows of a gravity hammer or the last 10 to
20 blows of a steam, air, or diesel hammer.
E-the manufacturer's rating for foot-pounds of energy
developed by double-acting steam or air hammers
and;

= 90 percent of the average equivalent energy in foot-
pounds as determined by a guage attached to the
pile hammer and recorded during the period when
the average penetration per blow is recorded for
diesel hammers having enclosed rams. Hammers of
this type shall be equipped with a guage and appli-
cable charts supplied which will evaluate the
equivalent energy being produced under any driv-
ing condition.

The above formulas are applicable only when:

(1) The hammer has a free fall.

(2) The head of the pile is free from broomed or crushed wood fiber or other serious impairment.

(3) The penetration is at a reasonably quick and uniform rate.

(4) There is no measurable bounce after the blow.

(5) The weight of pile is no more than the weight of hammer used, if hammer is of the gravity type.

(6) A follower is not used.

If there is a measurable bounce, twice the height of bounce shall be deducted from H to determine its value in the formula.

The bearing power as determined by the appropriate formula in the foregoing list will be considered effective only when it is less than the crushing strength of the pile. Other recognized formulas for determining pile bearing power may be used whenever fully detailed in the special provisions.

In all cases when bearing power is determined by a formula, timber piles shall be driven if possible until the computed safe bearing power of each is not less than 20 tons.

600A.05 Concrete and Steel Pile Bearing Values. The formulas specified above for timber piling may be used in determining a rough approximation for the bearing power of precast and cast-in-place concrete piles and of structural steel piles.

In all cases when the bearing power of concrete and steel piles is determined by formula, the piles shall be driven, if possible, until the safe bearing power of each is computed to be not less than 30 tons.

600A.06. Safe Loads. When the safe bearing power of any pile is found by test, or computation, to be less than the design load, longer piles or additional piles shall be driven as ordered in writing by the Engineer.

600A.07 Jetted Piles. The safe bearing power of jetted piles will be determined by actual tests or by the appropriate method and formulas given above. No jet shall be used during the test blows.

Materials

600A.08 Materials. Materials for piling shall conform to the requirements of the following subsections:

Construction Requirements

600A.09 Precast Concrete Piles. Precast concrete piles shall be of the design or designs shown on the plans. They shall be constructed of portland cement concrete in accordance with the requirements of section 601. Prestressed concrete piles shall be prestressed as stipulated in section 601A. The piles shall be cast separately or, if alternate piles are cast in a tier, the intermediate piles shall not be cast until 4 days after the adjacent piles have been poured. Piles cast in tiers shall be separated by tar paper or other suitable separating materials. The concrete in each pile shall be placed continuously. The completed piles shall be free from stone pockets, honeycombs, or other defects, and shall be straight and true to the form specified. The forms shall be true to line and built of metal, plywood, or dressed lumber. A 1-inch chamfer strip shall be used in all corners. Forms shall be watertight and shall not be removed until at least 24 hours after the concrete is placed. Every exposed surface of a pile shall be given ordinary finish.

Piles shall be cured and finished in accordance with the requirements of sections 601 or 601A.

When testing equipment is available, test cylinders will be made in accordance with AASHO T 23 and tested for compressive strength in accordance with AASHO T 22. Piles shall not be moved until the tests indicate a compressive strength of 80 percent of the design 28-day compressive strength and they shall not be transported or driven until the tests indicate a compressive strength of the design 28-day compressive strength.

When testing equipment is not available, piles shall not be moved until they have set for at least 14 days, after casting, at a minimum temperature of 60° F. or 21 days at a minimum temperature of 40° F. They shall not be transported or driven until they have set at least 21 days at a minimum temperature of 60° F. or 28 days at a minimum temperature of 40° F. If high-early-strength cement is used, piles shall not be moved, transported, or driven prior to 7 days after casting.

When concrete piles are lifted or moved, they shall be supported at the points shown on the plans or, if not so shown, they shall be supported at the quarter points.

Whenever required by the plans or whenever directed by the Engineer, pre-drilled holes shall be provided to facilitate pile-driving operations. Diameter of holes shall not be greater than the diameter of the piles.

600A.10 Cast-in-Place Concrete Piles:

(a) General.-Cast-in-place concrete piles shall be of the