10-49 Section 1024
1024 -1 PORTLAND CEMENT Supply Portland cement that meets AASHTO M 85 for Type I, II or III except that the maximum fineness requirements of AASHTO M 85 do not apply to cement used in precast concrete products. Throughout these specifications Types I and II cement are referred t o as regular Portland cement and Type III as high early strength Portland cement. Certain combinations of cement and aggregate exhibit an adverse alkali -silica reaction. The alkalinity of any cement, expressed as sodium -oxide equivalent, shall not exceed 1.0%. For mix designs that contain non- reactive aggregates and cement with an alkali content less than 0.6%, straight cement or a combination of cement and SCM may be used. The SCM quantity shall not exceed the amount shown in Table 1024- 1. For mixes tha t contain cement with an alkali content between 0.6% and 1.0% and for mixes that contain a reactive aggregate documented by the Department, use a SCM in the amount shown in Table 1024- 1. Obtain the list of reactive aggregates documented by the Department at the Materials and Tests Unit website. TABLE 1024 -1 SUPPLEMENTARY CEMENTITIOUS MATERIAL FOR USE IN PORTLAND CEMENT CONCRETE SCM Substitution Rate (1 lb . SCM per 1 lb . Cement) Class F Fly Ash 20% - 30% Ground Granulated Blast Furnace Slag 35%-50% Microsilica 4%-8% Blended cements meeting AASHTO M 240 may be used with permission of the Engineer. Blended cements consist of either binary blends (e.g. a mixture of hydraulic cement with one other component) or ternary blends (e.g. a mixture of hydraulic cement and two other components). The components permitted for blending with cement are slag, pozzolans, or limestone. The term pozzolan can reference natural pozzolans (e.g. metakaolins), fly ash, or silica fume. The binary blended cements are Type IS (Portland- slag cement), Type IP (Portland -pozzolan cement), and Type IL (Portland- limestone cement). The ternary blended cement is Type IT and represents blends of Portland cement with varying amounts of any two different additives, which are pozzolans, slags or limestone . See AASHTO M 240 for details on the various blend ratios for Type IT blended cement. Type IP or IS blended cement is allowed for the cement -and-fly-ash or cement -and-slag portion of the mix. Type IT may be allowed for the cement -and- supplementary cementitious portion of the mix with the permission of the Engineer. Do not substitute fly ash or slag for a portion of Type IP, IS or IT cement. Use white cement that meets ASTM C150, except that the ferric oxide content is limited to 0.5%. Use Type IP blended cement that meets AASHTO M 240 , except that the pozzolanic content is limited to between 20 and 30% by weight and the constituents shall be interground. Use Type IS blended cement that meets AASHTO M 240 except that the slag content is limited to between 35 % and 50% by weight and the c onstituents are interground. Use Type IT blended cement that meets AASHTO M 240. The Engineer will evaluate the blend of constituents for acceptance in Department work.
10-50 Use Type IL blended cement that meets AASHTO M 240, except the constituents shall be
interground. SCMs can replace a portion of Type IL blended cement and shall be replaced as outlined in Subarticle 1000- 3(I) for Portland cement. Do not use air -entraining Portland cement. Do not mix different types of cement, different brands of cement, or the same brand from different mills nor use them alternately except when authorized in writing by the Engineer. Protect cement from contamination or damage during handling and storage. Do not use cement that is damaged, partially set, lumpy or caked. All cement is sampled and tested by the Department as it arrives on the project or at the batching plant at such frequency as established by the Department. 1024 -2 AGGREGATE Provide aggregate that meets Section 1014. 1024 -3 ADMIXTURES
A.Basis of Acceptance Admixtures from an approved source are accepted without further testing. Only use admixtures that are on the NCDOT APL . Products must be current with the applicable AASHTO Product Evaluation & Audit Solutions workplan to remain on the NCDOT APL .
B.Approved Admixture An approved admixture complies with this subarticle in order to be added to the NCDOT APL . The manufacturer shall submit to the Product Evaluation Program an application and certified reports of tests that show that the admixture meets the applicable specifications . Tests shall be performed by AASHTO’s designated AASHTO Product Evaluation & Audit Solutions laboratory for concrete admixture testing. Admixtures that contain chloride other than calcium chloride as provided herein are not permitted. The manufacturer is required to state in writing that no chloride was added during the manufacture of the admixture. After an admixture is accepted, the manufacturer is required to submit to the Product Evaluation Program on or before February 1 of each year a notarized certification that shows that the material is of the same composition as originally accepted and has not been changed or altered. If an admixture is changed or altered, approval of the source in accordance with the abo ve requirements is necessary before using the admixture. The Engineer has the option to perform tests deemed desirable to verify the manufacturer ’s certification. Failure of the admixture in such tests is cause for discontinuation of its use. Failure of a n admixture to perform satisfactorily under job conditions is cause for rejection of the admixture .
C.Air Entraining Agent Provide air entraining agents that meet AASHTO M 154.
D.Chemical Admixtures
1.Set Retarding Admixtures Use set retarding admixtures that me et AASHTO M 194 for Type D, water reducing and retarding admixtures.
2.Water Reducing Admixtures Use water reducing admixtures that meet AASHTO M 194 for Type A admixtures. Mid-range water reducing admixtures will be considered as high range water reduc ing admixtures if they meet the requirements for Type F water reducing admixtures .
10-51 (3) Calcium Chloride
Provide calcium chloride that meets AASHTO M 144 for Type 2, concentrated flake, pellet or other granular calcium chloride. The Engineer may waive the gradatio n requirement.
4.High -Range Water Reducing Admixtures Use high- range water reducing admixtures that meet AASHTO M 194 for Type F or Type G.
5.Calcium Nitrite Corrosion Inhibitor Use an approved calcium nitrite corrosion inhibitor that contains 30% solids.
E.Other Admixtures Admixtures not otherwise classified will be reviewed on a case- by-case basis by the Materials and Tests Unit. 1024 -4 WATER Ensure that water used to co ndition, wash, or as an integral part of materials is clear and free from injurious amounts of oil, acid, alkali, organic matter, or other deleterious substance. It shall not be salty or brackish. Water used in the production of concrete or grout shall be from wells or public water systems which are suitable for drinking and must meet the criteria listed in Table 1024- 2. Test water from wells at all locations. Test public water supplies from all out of state locations and in the following counties: Beaufort, Bertie, Brunswick, Camden, Carteret, Chowan, Craven, Currituck, Dare, Gates, Hyde, New Hanover, Onslow, Pamlico, Pasquotank, Pender, Perquimans, Tyrell and Washington unless the Engineer waives the testing requirements. Water from a municipal water supply in all other NC counties may be accepted by the Engineer without testing.
Source: North Carolina Standard Specifications for Roads and Structures, 2024 Edition. Pages 465–467 of 857.