Last month, the Department of Buildings (DOB) released Bulletin 2021-003 with the intent to avoid non-conforming concrete placement within New York City.
In December of 2019 during the construction of a high-rise building, localized failures in the form of severe cracking of several reinforced concrete column elements were observed. An investigation of the cause concluded that the failures were due to the use of non-conforming concrete. The origin of the non-conforming concrete was traced to grout slurry used as a priming agent to lubricate the boom and hoses associated with the concrete pump truck. The grout was pumped in advance of the specified design concrete mix and should
have been discarded into grout boxes. Instead, the grout was pumped and cast into various structural elements contrary to the approved construction documents. The investigation determined that inadequate special inspections and undersized grout boxes may have played a role in the decision to place the grout in the structural elements.
View the Department of Buildings, Bulletin Highlights here.
View the Technical/Buildings Bulletin 2021-003 here.
DUTIES OF THE CONSTRUCTION SAFETY MANAGER RELATIVE TO THE PUMPING AND LUBRICATING GROUT Section BC 3310.9.1 requires that on concrete projects with 2,000 cubic yards or more, the concrete contractor designates a concrete safety manager (CSM). This individual is responsible to confirm proper procedures are being followed during concrete operations, including, but not limited to, required special inspectors be present during concrete placement, pumping crews have participated in preplanning meetings, and that requisite grout discharge boxes are available.
Refer to the Concrete Safety Manager Inspections Checklist
Sign up for our Concrete Safety courses:
PURPOSE: Clarify the role of the Special Inspector during concrete placement
SUBJECT(S): Grout box, Grout, Special Inspectors, Concrete placement, Concrete mix, Construction Safety Manager