2006 New York Code - Mixes.

 
  §  27-605 Mixes. Concrete may be proportioned, batched, and mixed by any
  of the following methods:
    (a) Method I. Mixes with minimum cement content.
    (1) MINIMUM CEMENT CONTENT. The cement content used in the work  shall
  not  be  less than the content given in table 10-3 for the corresponding
  strength of concrete.
                                  TABLE 10-3
                     MINIMUM CEMENT              CONTENT
  ________________________________________________________________________
         Specified Compressive             Minimum Pounds of Cement
         Strength in 28 Days              Per Cubic Yard of Concrete
            (f'c) - psi                        (all aggregates)
  ________________________________________________________________________
             3,000                                 540
             3,500                                 610
             4,000                                 660
             5,000                                 800
           Over 5,000                   Permitted only by reference
                                             standard RS 10-3
          6,000 and over              Permitted only by reference
                                             standard RS 10-3,
                                        "Special Requirements for
                                         High Strength Concrete."
 
    NOTE: Minimum pounds of cement may be reduced up to 8 percent  by  the
          addition of an accepted admixture.
 
    (2)  WATER-CEMENT  OR  STRENGTH-CEMENT RATIO.   Normal weight concrete
  proportioned on the basis of preliminary  tests  shall  be  produced  by
  using a water-cement ratio corresponding to a point on a strength-cement
  or   water-cement   ratio   curve.   Proportioning  of  lightweight  and
  heavyweight concrete, and concrete using an aggregate other than natural
  sand, gravel or stone shall be by using a strength-cement content curve.
  The point on  the  respective  curves  shall  represent  a  strength  of
  concrete  at  the  slump  and  age  called  for  on  the  plans at least
  twenty-five percent higher than the specified strength, f'c. The  cement
  content shall not be less than the content shown in table 10-3.
    (3)  PRELIMINARY TESTS. Preliminary tests of concrete shall be made in
  advance of any concreting  operation  by  a  licensed  concrete  testing
  laboratory   acceptable   to   the  architect  or  engineer  of  record.
  Preliminary tests shall consist of compression strength tests of  molded
  concrete  cylinders made in accordance with reference standards RS 10-17
  and RS 10-21. A curve representing  the  relation  between  the  average
  strength of the concrete at twenty-eight days, or at any other specified
  age  filed  with  the  department,  and the strength-cement ratio or the
  water-cement ratio shall be established for the range of strength values
  at the slump required for the work. The tests  shall  include  at  least
  four  mixes  with  different  strength-cement  ratios or four mixes with
  different water-cement ratios and at least four cylinder  specimens  for
  each  mix. The cylinder strength tests shall be supplemented by tests to
  confirm that the cement and aggregates  conform  to  the  provisions  of
  reference standard RS 10-3.
    (4)  PREVIOUSLY  ACCEPTED  MIXES.  In  lieu  of  the  requirements  of
  paragraph  three  of  this  subdivision,  the  architect   or   engineer
  designated   for  controlled  inspection  may  permit  the  use  of  mix
  proportions of aggregates having the same  specific  gravity,  size  and
  gradation;  cements of the same type and batch weight; admixtures of the
  same type and quantity; and other ingredients the same as  or  equal  to


  those  that  have  been previously submitted with applicable preliminary
  tests which complied with paragraphs one and two  of  this  subdivision,
  and  which  have been accepted by the commissioner within the past year.
  If  any  of  the  mix proportions or ingredients are changed, a separate
  submission for acceptance shall be required.
    (5) QUALITY CONTROL AND  INSPECTION  OF  MATERIALS  AND  OF  BATCHING.
  Where  concrete  materials  are  used for structural elements defined in
  section 27-585 of article one of this subchapter,  quality  control  and
  inspection  shall  be provided at the batch plant by a licensed concrete
  testing laboratory under the supervision of the  architect  or  engineer
  designated   for   controlled   inspection,   in   accordance  with  the
  requirements of table 10-1 and in sufficient scope to:
    a. Determine and record the actual batched weights of the  ingredients
  and the volume of water charged into the mixer;
    b.  Verify  that  such  weights conform to the weights and proportions
  required by the preliminary test mix,  adjusted  for  moisture  content,
  fineness modulus and gradation of aggregates;
    c. Verify conformance of the quality and condition of the materials to
  reference standard RS 10-3;
    d. Verify that the aggregates have the same specific gravity, size and
  gradation;  the cement is the same type and batch weight, the admixtures
  are the same type and quantity; and that any other ingredients  are  the
  same  as  or  equal to those used for the preparation of the preliminary
  test mixes;
    e.  For  all  concrete,  whether  or  not  designated  for  controlled
  inspection, attestation of the results of quality control and inspection
  at  the  batch  plant shall appear on a ticket accompanying each load of
  concrete. The attestation for subparagraphs  a,  b,  c  and  d  of  this
  paragraph   shall   be  executed  by  the    licensed  concrete  testing
  laboratory.
    f. The licensed concrete testing laboratory shall also attest that the
  slump entrained air content and unit weight of the  fresh  concrete,  as
  discharged  from  the  mixer  at the job site, were tested in accordance
  with reference standards RS 10-49, RS 10-51,  RS  10-52,  RS  10-61,  RS
  10-62,  RS  10-63 and RS 10-64, and that all were in compliance with the
  accepted mix design.
    (b) Method II. Proportioning on the basis of field experience.
    (1) PROPORTIONING. For the computation of the  standard  deviation  in
  accordance  with  reference standard RS 10-14, mixes with test data from
  previous  projects,  similarly  proportioned  in  accordance  with   the
  provisions  of  subdivision (a) of this section, and having materials of
  similar density and admixtures and having a slump equal  to  or  greater
  than  that  at  which  the  concrete is to be placed shall be used. Such
  mixes may be accepted subject  to  the  approval  of  the  architect  or
  engineer designated for controlled inspection.
    (2)  STRENGTH.  The  required average strength, fcr, to be used as the
  basis for the selection of mix proportions, shall in  no  case  be  less
  than  fifteen  percent  higher than the specified strength called for on
  the plans.
    (3) BATCHING. The concrete shall be produced either  in  the  concrete
  production  facility  used  to produce the concrete from which the tests
  were made to develop the field experience data referred to in  paragraph
  one  of this subdivision or, subject to the approval of the architect or
  engineer  designated  for  controlled  inspection,   in   any   concrete
  production facility that has data showing a record of standard deviation
  equal  to  or  less  than  that  of  the original facility. All concrete
  proportioned according to field experience shall be produced in a  plant
  with automatic recording equipment for all ingredients.


    (4) QUALITY CONTROL AND INSPECTION OF MATERIALS AND OF BATCHING.  When
  the  concrete  is batched in a plant where automatic recording equipment
  documents  the  batched  weights  or  volumes  of  cement,   aggregates,
  admixtures and water, no inspection of the materials or of the batching,
  nor   any   attestation   by  a  licensed  concrete  testing  laboratory
  responsible to the  architect  or  engineer  designated  for  controlled
  inspection, shall be required. A concrete producer shall:
    a.  Verify  that  such  weights  conform  to  the required weights and
  proportions, and to the  strength-cement  ratio  or  water-cement  ratio
  required  by  the proportioning established pursuant to paragraph one of
  this subdivision, adjusted for moisture content,  fineness  modules  and
  gradation of aggregates.
    b. Verify conformance of the quality and condition of the materials to
  reference standard RS 10-3.
    c.  Attest,  on  a  ticket  accompanying  each  load, to the specified
  strength  of  the  concrete,  the  actual  weights  or  volume  of   the
  ingredients, and the weight or volume of water charged into the mixer at
  the  batch  plant  or  to  be  added  at  the job site. A statement that
  subparagraph b of this paragraph has been complied with  shall  also  be
  included.
    d.   If   at  any  time  the  automatic  recording  equipment  becomes
  inoperative, the concrete production facility may be permitted, but only
  with the approval of the architect or engineer designated for controlled
  inspection, to batch and mix concrete for a period not to  exceed  three
  consecutive  working days. During such a period, the concrete production
  facility shall engage a concrete batch plant inspector from  a  licensed
  concrete  testing laboratory to observe and record the actual weights of
  the cement, aggregates, admixtures and other ingredients, and the weight
  or volume of water charged into the mixers. If the  automatic  recording
  equipment  is  inoperative  for  a  period longer than three consecutive
  working days the concrete production facility shall  not  batch  or  mix
  concrete  and  the  architect  or  engineer  designated  for  controlled
  inspection shall notify the commissioner in writing that such  equipment
  is inoperative.
 
  (c)  Method  III.  Average  Concrete.  (1) in lieu of making preliminary
  tests, average concrete limited to the concrete strengths shown in table
  10-3A below may be used, and the cement content shall not be  less  than
  the   value  given  in  table  10-3A  for  the  corresponding  specified
  compressive strengths, nor shall the total  volume  of  water  (moisture
  plus added water) exceed that specified therein, provided that the total
  yardage  placed  does  not  exceed  fifty  cubic yards and the levels of
  calculated stress do not exceed seventy percent of the  basic  allowable
  stresses.
 
                                 TABLE 10-3A
  ________________________________________________________________________
  Specified                 Minimum  pounds of        Maximum permissible
  compressive strength in   cement per cubic yard of  total volume of
  twenty-eight days (f'c)   concrete                  water, U.S. gallons
  pounds per square inch                              per cubic yard of
                                                      concrete
  ________________________________________________________________________
          2000                        520                     40
          2500                        560                     41
          3000                        610                     42
  ________________________________________________________________________


    2) Each load of concrete shall be certified by the producer to the
  owner, whether produced at a ready mixed plant or site mixed, as to the
  total quantity of concrete, concrete strength and actual quantities per
  cubic yard of each material, including water, contained therein. A copy
  of such certificate shall be available to the department during the
  progress of the work and for two years thereafter.