The owner seems to be blinded by the potential money savings, so he/she does not grasp the future consequences of the mistake he is making . Legally, the architect should be the interpreter of the requirements of the contract documents and the judge of the performance of both the owner and the superintendent. By building code one is required one is required to take a core sample to test the compressive strength of the concrete.
Under 13.4.3, “if procedures for testing ,inspection, or approval under section 13.4.1 and 13.4.2 reveal failure of the portions of the work to comply with requirements established by the contract documents, all cost made necessary by such failure, including those of repeated procedures and compensation for the architect’s services and expenses , shall be at the contractor’s expense.” Meaning that if this is kept under wraps when results of the concrete mixture are found, the expenses to fix the work shall be provided by the contractor.
Also, before things get to this point the architect to cover his bases should have submitted Change Orders and Construction Change Directives to the owner (4.2.8) “ The Architect will prepare a Change of Orders And Construction Change Directives. The Architect will investigate and make determinations and recommendations regarding concealed and unknown conditions as provided in Section 3.7.4” For payment issue the architect can with hold (220.127.116.11)The Architect may also withhold a Certificate for Payment or, because of subsequently discovered evidence, may nullify the whole or a part of a Certificate for Payment previously issued, to such extent as may be necessary in the Architect’s opinion to protect the Owner from loss for which the Contractor is responsible, including loss resulting from acts and omissions described in Section 3.32, because of detective Work not remedied.