The Table of Contents for this section is available.
(A) General:
Portland cement shall meet the requirements of AASHTO M85 for portland cement Types I, II, and III, except that the maximum fineness requirements of AASHTO M85 will not apply to cement used in precast concrete products. Throughout these specifications Types I and II cement will be referred to as regular portland cement and Type III as high early strength portland cement.
The alkali content of cement, expressed as sodium oxide equivalent, shall not exceed 0.4%, except that cement with a higher alkali content not to exceed 1.0% may be used with Class F fly ash, ground granulated blast furnace slag, or other NCDOT approved pozzolans in the following amounts:
Class F Fly 20% by weight of required cement content, with 1.2 lbs.Class F fly ash per lb. cement replaced.
Ground Granulated 35% - 50% by weight of required
Blast Furnace Slag cement content, with 1 lb.slag per lb. cement replaced.
Type IP or IS blended cements may be used for the cement-and-fly-ash or cement-and-slag portion of the mix.
White cement shall meet the requirements of ASTM C150, except that the ferric oxide content of the white cement shall not exceed 0.5 percent.
Type IP blended cement shall meet the requirements of AASHTO M240 except that the pozzolanic content shall be between 17 and 23 percent by weight and the
constituents shall be interground.
Type IS blended cement shall meet the requirements of AASHTO M240 except that the slag content shall be between 35 and 50 percent by weight and the constituents shall be interground.
Air-entraining portland cement shall not be used.
Different types of cement different brands of cement, or the same brand from different mills shall not be mixed nor shall they be used alternately except when authorized in writing by the Engineer.
Cement shall be fully protected from contamination or damage during handling and storage. Cement which has been damaged, which is partially set, or which is lumpy or caked shall not be used.
(B) Cement for Class S Concrete:
Portland cement shall meet the requirements of AASHTO M85 for Type II cement. The requirements of Table 1 of AASHTO M85 shall be revised to delete the restriction on the maximum amount of tricalcium silicate. The optional chemical requirements of Table 1A shall apply except that the sum of the tricalcium silicate and the tricalcium aluminate shall not exceed 68 percent. The Contractor shall provide a certification showing the chemical and physical analysis for each 500 tons of cement.
(C) Basis of Acceptance, Cast-in-Place Construction:
The Contractor shall furnish the Engineer 5 copies of a Type 5 Materials Certification in accordance with Article 1063 from each supplier furnishing portland cement concrete. The Certification shall state that the portland cement used on the project meets the requirements of Article 10241 of the Standard Specifications. Upon receipt of this certification the cement may be used prior to testing by the Department.
All cement will be sampled and tested by the Department as it arrives on the project at such frequency as may be established by the Department.
(D) Basis of Acceptance, Precast Concrete Products:
All cement will be sampled and tested by the Department as it arrives at the precasting plant at such frequency as may be established by the Department.
All aggregate to be used in portland cement concrete shall meet the requirements of Section 1014.
(A) Basis of Acceptance:
Admixtures from an approved source will be accepted without prior testing. Admixtures which are not from an approved source shall not be used until the admixture has been sampled and tested by the Department and found to be acceptable, or until the proposed source has been approved by the Department.
(B) Approved Sources:
An approved source will be considered to be any manufacturer of admixtures who complies with the requirements of this subarticle.
The manufacturer shall submit to the Materials and Tests Unit certified test reports of tests performed in a recognized laboratory which show that the admixture meets all the requirements of the applicable specifications. A recognized laboratory is any laboratory regularly inspected by the Cement and Concrete Reference Laboratory of the National Bureau of Standards.
Admixtures containing chloride other than calcium chloride as provided herein will not be permitted. The manufacturer shall state in writing that no chloride was added during its manufacture.
After an admixture has been accepted, the manufacturer shall submit to the Materials and Tests Unit on or prior to February 1 of each calendar year a notarized certification showing that the material is of the same composition as that originally accepted and has not been in any way changed or altered. If an admixture is changed or altered, approval of the source in accordance with the above requirements will be necessary before the admixture can be used.
The Engineer may at any time make any or all tests which he deems desirable to verify the manufacturer's certification. Failure of the admixture in such tests shall be cause for discontinuing use of the admixture. Failure of an admixture to perform satisfactorily under job conditions shall be cause for rejection of the source.
The Engineer will maintain on file a list of approved sources.
(C) Air Entraining Agent:
Air entraining agents shall meet the requirements of AASHTO M154.
(D) Chemical Admixtures:
(1) Set Retarding Admixtures:
Set retarding admixtures shall meet the requirements of AASHTO M194 for Type D - water reducing and retarding admixtures.
(2) Water Reducing Admixtures
Water reducing admixtures shall meet the requirements of AASHTO M194 for Type A Admixtures.
(3) Calcium Chloride:
Calcium chloride shall meet the requirements of AASHTO M144 for Type 2, concentrated flake, pellet, or other granular calcium chloride. The Engineer may waive the gradation requirement.
(E) OTHER ADMIXTURES
Admixtures not otherwise classified will be reviewed on a case-by-case basis. Any policy regarding such admixtures may be obtained from the Materials and Tests Unit.
Water shall be clean and practically free from oil, salt, acid, alkali, organic matter, or other substances injurious to the finished product. It shall not contain more than 100 ppm chlorides nor more than 500 ppm dissolved solids, and it shall have a pH in the range of 4.5 to 8.5.
Water from a city water supply may be accepted without being tested. Water from other sources will be tested unless the requirement for testing is waived by the Engineer.
When water is to be tested, the tests will be performed in accordance with AASHTO T26. Comparison tests for time of setting and mortar strength will be performed. Other tests covered by AASHTO T26 will be performed at the discretion of the Engineer. Any test results which indicate undesirable characteristics will be sufficient cause for rejection of the water.
Fly ash shall meet the requirements of ASTM C618 for Class F or Class C except that the loss on ignition shall not exceed 4%. Table 1A, Supplementary Optional Chemical Requirement of ASTM C618, shall apply to Class F fly ash. Fly ash shall also meet the optional physical requirements for uniformity as shown in Table 2A of ASTM C618.
Class C fly ash shall not be used in portland cement concrete if the alkali content of the cement exceeds 0.4%.
The Contractor shall furnish the Engineer 5 copies of a Type 4 Materials Certification in accordance with Article 10630 from each supplier furnishing fly ash. The laboratory which performs the tests included in the certification shall be regularly inspected by the Cement and Concrete Reference Laboratory for fly ash testing and shall authorize CCRL to submit a copy of the inspection reports directly to the Materials and Tests Unit of the Department. The Certification shall state that the fly ash used on the project meets the requirements of Article 10245. Upon receipt of this certification the fly ash may be used prior to testing by the Department.
All fly ash will be sampled and tested by the Department as it arrives on the project at such frequency as may be established by the Department.
1024-6 GROUND GRANULATED BLAST FURNACE SLAG.
Blast furnace slag shall meet the requirements of AASHTO M302, Grade 100.
The Contractor shall furnish the Engineer 5 copies of a Type
5 Certification in accordance with Article 1063 from
each supplier furnishing slag. The Certification shall state
that the blast furnace slag used in the concrete meets the requirements
of Article 9246. Upon receipt of this Certification
the slag may be used prior to testing by the Department. All
slag will be sampled and tested by the Department as it arrives
on the project at such frequency as may be established by the
Department.