Guide to Drafting a Specification for Micropiles-PDF

PDF
Pdf Summary
This 2004 guide from the Deep Foundations Institute and ADSC provides a model specification for high-capacity drilled-and-grouted micropiles used as structural supports. It is primarily written for performance-based specifications, which allow contractors flexibility in design and construction while requiring them to demonstrate that the installed piles meet specified criteria. It also explains open and prescriptive approaches and emphasizes clearly assigning responsibilities among the owner, designer, and contractor.<br /><br />The model addresses micropiles generally 4–12 inches in diameter, with working loads of at least 25 tons, in which steel reinforcement carries most of the applied load. It covers design requirements, allowable loads, corrosion protection, ground conditions, materials, construction submittals, installation records, grouting, splices, and pile-top connections. Project-specific details—including task assignments, loads, tolerances, ground assumptions, and acceptance limits—must be completed by the specification writer.<br /><br />Contractors are expected to have relevant experience and submit sealed designs, construction procedures, material certifications, grout mix designs, and load-testing plans. Installation requirements address drilling, borehole stability, reinforcement placement, grout quality and pressure, and record keeping. The guide outlines optional pre-production verification tests and production proof tests, including loading sequences, movement and creep criteria, and procedures for addressing failures. It also discusses lateral testing and alternative payment methods.<br /><br />Corrosion protection is selected according to loading, ground aggressiveness, and service life, with options including coatings, galvanizing, encapsulation, grout cover, and sacrificial casing thickness. Appendices provide guidance for classifying ground aggressiveness, estimating corrosion allowance, and detailing encapsulation.<br /><br />A supplement adapts the specification for hollow-bar micropiles, including definitions, reinforcement requirements, and grouting provisions for systems drilled and grouted in a single operation. The guide stresses experienced contractors, clear communication, timely submittal review, and careful project-specific editing.
Keywords
micropiles
deep foundations
drilled-and-grouted
performance-based specification
structural supports
corrosion protection
load testing
grouting
steel reinforcement
ADSC