N.J. Admin. Code § 19:6-2.52

Current through Register Vol. 56, No. 21, November 4, 2024

Section 19:6-2.52 - Compacted concrete piles

(a) A "compacted concrete pile" shall denote a concrete pile formed with an enlarged base in which the concrete in the base is placed in small batches that are compacted prior to attaining an initial set. The concrete in the shaft of the pile shall be placed into a shell as specified in section 51 of this subchapter for cast-in-place concrete piles.

(b) Concrete for compacted concrete piles shall conform to the requirements of this subchapter. Concrete to be compacted shall have a minimum compressible strength at the age of 28 days of 4,000 psi and shall be mixed with sufficient water to permit hydration of the cement, but the slump shall be zero. The concrete shall be placed and compacted before initial set can occur. Non-compacted concrete, if used for the pile shafts, shall conform to the requirements of cast-in-place concrete piles.

(c) Minimum spacing between compacted concrete piles shall be four feet six inches center-to-center except that where the shafts of such piles are cased for their full length, this spacing may be reduced to three feet six inches. Where a question exists as to possible damage to adjacent previously driven piles, these minimums shall be increased.

(d) Rules on installation are:

1. The base shall be formed by ramming concrete in batches of approximately five cubic feet or less, from a drive casing and into the soil. Unless specifically otherwise permitted by the chief engineer, a minimum of 20 blows of at least 140,000 foot pounds per blow shall be required for extrusion of the last five cubic feet of concrete. The total quantity of concrete extruded from the drive casing to form the base shall be equal to or greater than the quantity so extruded in the case of the nearest successful application test pile, except that a compactive effort in excess of 30 blows, each of 140,000 foot pounds, will not be required for extrusion of the last five cubic feet.

2. After the expanded base has been formed, the shaft shall be constructed. Where a cased shaft is to be used, a steel shell shall be inserted into the drive casing and anchored to the expanded base by placing a fresh charge of concrete in the shell and driving it into the base. The shell may then be filled with concrete to cutoff elevation after the removal of the drive casing, in accordance with the provisions relating to cast-in-place concrete piles. Any annular space remaining between the shell and surrounding soil shall be suitably filled to assure proper lateral support of the shaft, unless there is sufficient recovery of the ground to provide the necessary support.

3. The outside diameter of the permanent shaft shall not be more than four inches less than the inside diameter of the drive casing.

4. No concrete shall be placed in the pile shafts until all piles within a radius of 15 feet or within the heave range have been driven.

(e) The enlarged base of the pile shall be formed in, or on, the same type of bearing material as is used to support the nearest applicable load-test and at a similar depth therein. In addition, the enlarged base shall be underlain by a minimum depth of ten feet (measured from the junction of the shaft and base) of soil materials of classes 1-65 to 7-65, except where installation of the base is permitted to be performed with blows of less energy than the 140,000 foot pounds indicated in subsection (d) of this section, the requirement for a ten foot depth of class 1-65 to 7-65 material may be reduced, subject to the approval of the architect or engineer and the approval of the chief engineer.

N.J. Admin. Code § 19:6-2.52