- 775 - SECTION 1002 -- PORTLAND CEMENT CONCRETE
1002.01 Description
1.Concrete shall consist of aggregate, Portland cement, water, approved air-entraining and other admixtu res, and pozzolans as required or allowed by these Specifications.
2.All pay items that include t he class of concrete will have the appropriate designation added to the pay item to show the 28-day compressive strength. For exampl e: 47B concrete with a 28-day compressive strength requirement of 3500 psi (25 Mpa) shall be identified as Class 47B-3500 (47B-25). The 7-day compressive strength should be 70% of the 28-day compressive strength.
1002.02 Material Characteristics
1.All materials shall conform to the requirements in Table 1002.01. Table 1002.01 Material Requirements Applicable Materials Section Portland Ce ment ........................................ 1004 Water for Conc rete .................................... 1005 Concrete Aggregate ................................... 1033 Fly Ash ....................................................... 1008 Admixtures ................................................. 1007 Silica Fume ................................................ 1009
a.Concrete mixes will be in accordance of Table 1002.02
2.The Contractor may elect to substitute an acceptable class of concrete shown in Table 1002.03 at no additional cost to the Department. The Engineer shall be notified of an y substitutions before batching the concrete.
3.Type IP, IS and IT Interground/Blended cement shall be used for all classes of concrete except for pavement repair. Type IP, IS and IT Interground/Blended cement shall meet all requirements of ASTM C 595. Pavement repair shall include Type I/II Portland cement for Class PR1 concrete and Type III Portland cement shall be used in Class PR3 concrete.
4.Temperature Requirements: a. The temperature of the mixed concrete shall be not less than 50°F (10 C) immediately after being placed.
b.When the air temperature in the shade and away from artificial heat is less than 35°F (2 C), the Engineer may require the water and/or aggregates to be heated to not less than 70°F (21 C) nor more than 150°F (65C), such that the temperature of t he mixed concrete shall not be less than 50°F (10 C) at the time of placement.
c.Stockpiled aggregates may be heated by the use of dry heat or steam. Aggregates shall not be heated di rectly by gas or oil flame or on sheet metal over fire. Aggregates may be heated in bins with a steam-coil or water-coil system or by other methods which are not detrimental to the aggregates.
1002.02 Portland Cement Concrete
- 776 - d. Heating equipment or met hods which alter or prevent the entrainment of the required amount of air in the concrete shall not be used. The apparatus used shall heat the aggregate uniformly and shall be so arranged as to preclude the possible occurrence of overheated areas which might damage the aggregates.
e.Steam may be used to heat aggregates. When live steam is used in stockpiles, it shall be used in such a manner as to preclude excessive moisture variations within the material. Material containing frost or frozen material shall not be used in the mix. ENGLISH Table 1002.02 Class of Concrete
1.Base Cement Type Total Cementitious Materials Min. lb/cy Total Aggregate Min. lb/cy Max. lb/cy 47B** IP/IT* 564 2850 3150 47B*** 564 2850 3150 47BD 658 2500 3000 47B-HE 752 2500 3000 BX (4) 564 2850 3150 47B-OL**** 564 2850 3200 PR1 I/II 752 2500 2950 PR3 III 799 2500 2950 SF(5) I/II 589 2850 3200 Table 1002.02 (Continued) Class of Concrete
1.Air Content % Min.- Max.
2.Ledge Rock (%) Water/ Cement Ratio Max.
3.Required Strength Min. psi 47B** 6.5 -9.0 - 0.45 3500 47B*** 6.0 - 8.5 - 0.45 3500 47BD 6.0 - 8.5 30+3 0.42 4000 47B-HE 6.0 - 8.5 30+3 0.40 3500 BX (4) 6.0 - 8.5 - 0.45 3500 47B-OL**** 5.0-7.0 30+3 0.36 4000 PR1 6.0 - 8.5 30+3 0.36 3500 PR3 6.0 - 8.5 30+3 0.45 3500 SF(5) 6.0 - 8.5 50+3 0.36 4000 Portland Cement Concrete 1002.02 - 777 - (1) Each class of concrete shall ident ify the minimum strength requirement, per the contract. For example, where the la st four digits indicate the psi. In the table above, strength of 3,500 psi is indicated for 47B-3500; however, other strengths may be authorized elsewhere in the contract. The classes shown in the chart are typical examples. All classes of concrete shall be air-entrained and a water-reducing admixture shall be used per manufacture’s recommendations. • Class R Combined Aggregate shall use a mid-range water reducer admixture. The dosage shall be at t he manufacture’s recommendation and the Engineer may approve a low-range water reducer admixture.
2.As determined by ASTM C 138 or ASTM C 231. FOR INFORMATION ONLY. The Contract or may develop a Quality Control Program to check the quantity of air content on any given project; such as, checking the air content behind the paver.
3.The Contractor is responsible to adj ust the water/cement ratio so that the concrete supplied achieves the re quired compressive strength without exceeding the maximum water/cement ratio. The minimum water/cement ratio for any slip form concrete pavement is 0.38, unless the Contractor requests approval from the Engineer in writing to change the minimum water/cement ratio to 0.36.
4.For temporary su rfacing, Type I/II cement is allowed.
5.Minimum Portland Cement shall be 564 lbs/cyds and the total Silica Fume added shall be 25 lbs/cyds. (*) Refer to Subsection 1004.02 for material characteristics. Lithium Nitrate may be used in place of Supplemental Cementitious Materials (SCMs), see Section 10 07 of the Standard Specifications. (**) For slip form applications. (***) For hand-pours and substructures applications. (****) When IP using Class N pozzolan, the maximum water/cement ratio is 0.41. Table 1002.03 Table of Acceptable Concrete Class Substitutions Class Specified Acceptable Class for Substitution BX 47B, 47BD or 47B-HE 47B 47BD, or 47B-HE
5.Class PR1 and PR3 Concrete:
a.The calcium chloride for use in PR concrete shall be either:
1.A commercially prepared solution with a concentration of approximately 32% by weight.
2.A Contractor prepared solution made by dissolving 4.5 pounds (0.54 Kg) of Grade 2 or 6.2 pounds (0.74 Kg) of Grade 1 calcium chloride per gallon (liter) of water to provide a solution of approximately 32% by weight.
1002.02 Portland Cement Concrete
- 778 - b. The 7.4 pounds (10.89 Kg) of water in each gallon (liter) of solution shall be considered part of the total water per batch of concrete.
c.The calcium chloride solution shall be added, just prior to placement, at a rate of 0.375 gallons/1 00 pounds of cement (1.4 lb. calcium chloride per 100 lb. cement) [3.13 L/100 Kg of cement (1.4 Kg calcium chloride per 100 Kg cement)].
d.Class A, Flaked or Pellet Calcium Chloride shall be added at a rate not to exceed 2.0% of the weight of the cement for Grade 1, or 1.6% of the weight of the cement for Grade 2. Grade 1 Calcium Chloride purity is between 70 and 90% and Grade 2 Calcium Chloride is between 91 and 100%.
e.Where mixing trucks are used:
1.For Class PR3 concrete , calcium chloride shall be thoroughly mixed into the concrete before placement. The minimum mixing time is 2 minutes.
2.For Class PR1 concrete, calcium chloride shall be added first and then the concrete mixed at least 2 minutes or as required by manufacture. Next, the Type F high range water-reducer admixture is added and the concrete is mixed an additional 5 minutes.
6.Class High Early (HE) Concrete
a.High Early (HE) strength conc rete shall be cured as described in Subsection 603.03, Paragraph 7. T he contractor shall take necessary curing measures so the re quired strength is achieved.
b.High early concrete shall achieve a compressive strength of 3,500 psi (25 MPa) at 48 hours after placement.
c.The 48-hour compressive str engths shall be used to determine pay factor deductions for high early concrete in accordance with Table 603.03.
d.A non-calcium chloride accelerator shall be used when the ambient temperature at the time of the placement of concrete is 70°F or less.
e.When requested by the Cont ractor, the maturity method, as provided in NDOT C 1074, may be used in lieu of the requirements of Subsection 603.03, Paragraph 11.c. and d. to determine the strength of concrete pavement for the purpose of early opening to traffic and acceptance. Requests by the Contractor for use of the maturity method shall be on a project basis and shall be made in writing to the Engineer.
7.The yield of the concrete proportions shall be determined by the Producer.
8.All Classes of Concrete with the exception of PR1 and PR3 shall have a Durability Factor not less than 70 and a mass loss not greater than 5% after 300 freeze/thaw cycles when tested in accordance with ASTM C 666. The freeze/thaw testing shall be conducted according to Procedure A.
1002.03 Procedures
1.The Contractor shall identify t he plant that will supply the concrete 14 days before use and be entirely responsib le for its calibration, batching of Portland Cement Concrete 1002.03 - 779 - concrete, aggregate and sampling of cement per Department’s Sampling Guide.
a.The Contractor shall be responsible for the following: (1) Batching concrete. (2) Contractor shall sample aggregate from the conveyor belt or stockpile. Gradations from a split sa mple shall be tested in accordance to Section 1033 and reported to the Engin eer at the frequency required by the Department’s Materials Sampling Guide.
i.Contractor shall retain possession of the split samples on-site at the Contractor’s facility until such a time disposal is approved by the Engineer.
a.At the pre-construction meeting: i. Contractor shall determine the location of testing and report the names of the technician performing the sampling and testing. ii. Engineer will not ify the Contractor of the retrieval of the split samples. (ii) The Contractor shall split the sample, place the Department’s split sample into a cloth bag and immediately seal the split sample with the provided security seal. The cloth sample bag shall be supplied by the Department. (iii) The sampling splitting and placement of the security seal of aggregate samples shall be witnessed by certified Department personnel. (iv) Contractor shall se cure the split sample using a consecutively numbered security seal of 75 pounds breaking strength provided by the Department. The Cont ractor shall use the consecutively numbered security seals to identify and track each Aggregate Class. Samples that are not consecutively numbered will be investigated for custody of the sample and the Engi neer may cease production until it is determined what action will be required.
a.The Contractor shall report the security seal tracking number with the split sample gradation.
b.The following training shall be required for personnel who oversee the batching of the concrete: i . C o n c r e t e T e c h n i c i a n P e r s o n n e l [1] Concrete Plant Technician ii. Portland Cement Sampler [1] NDOT Portland Cement Sampler
2.Portland cement concrete sha ll be supplied by certified Ready Mix Plants that are in compliance with the requirements in the Quality Control Manual , Section 3, -- Certification of Ready Mixed Concrete Production Facilities published by the National Ready Mixed Concrete Association. Refer to the Department’s Material Sampling Guide for the policy on stationary and portable plants.
1002.03 Portland Cement Concrete
- 780 - Table 1002.04 Specific Gravity Correlation Factors Specific Gravity Correction Factor Specific Gravity Correction Factor 2.75 1.050 2.62 1.000 2.70 1.030 2.61 0.997 2.69 1.026 2.60 0.993 2.68 1.022 2.59 0.989 2.67 1.019 2.58 0.985 2.66 1.015 2.57 0.981 2.65 1.012 2.56 0.977 2.64 1.008 2.55 0.974 2.63 1.004 2.50 0.955
3.When the pavement is construct ed under a Quality Control/Quality Assurance specification, the Contra ctor shall have a furnished testing laboratory on the project site. In the event the concrete is obtained from a commercial supplier, the supplier shall have a furnished testing laboratory at the site where the concrete is produced.
4.a. Mix times shall meet t he requirements of ASTM C 94. Mixing time tests shall be repeated whenever the concrete appearance indicates that mixing was inadequate.
b.Batch plants that are trans porting the concrete in non-agitating trucks, the mixing time will not be less than 60 seconds, and for agitating trucks, the mixing time will not be less than 45 seconds.
c.The Certificati on of stationary and por table ready mix plants will conform to the tests that are re quired in the Department’s Materials Sampling Guide.
5.The Contractor shall furnish the Engineer a weekly concrete placement schedule that is updated as necessary. The Engineer may observe any or all of the procedures and shall have access to all reported data during production and placement. Any inconsistencies shall be reported to the job superintendent and not ed in the Engineer's diary.
6.Batch tickets shall be prepared as described in the National Ready Mixed Concrete Association's Quality Control Manual . The Contractor shall keep all gradations and batch ticke ts until final acceptance by the Department. Projects that have less than 200 cubic yards of concrete placed will be allowed to have hand written tickets. For projects greater than 200 cubic yards, hand written tickets will be at the Engineer’s discretion. The concrete batch tickets shall show batch weights, aggregate moisture (shall be tested daily and moisture probes are allowed), admixtures used, water, and mix design calculations. A copy of the batch ticket shall be given to the Engineer upon delivery of concrete.
7.Aggregates from different sour ces shall be sto ckpiled separately. Aggregates produced by pumping from di fferent pits in the Platte River Valley shall be considered to be from the same source. Aggregate production and quality of concrete are subject to the approval of the Department. Portland Cement Concrete 1002.03 - 781 - 8. Coarse aggregate and aggregate from a dry pit shall be uniformly saturated with water before it is used. The wetting shall begin 24 hours before concrete mixing to allow complete saturation.
9.Cementitious Materials:
a.Cementitious materials sha ll be stored separately according to material type, class, and source. Simi lar materials from different sources shall not be mixed or stored together or used alternately in the same concrete placement without permission of the Engineer.
b.When the same scale is used to weigh more than one cementitious material, the weight of the Portland cement shall be determined first.
c.Cementitious materials s hall be stored in watertight bins.
10.Concrete mixers shall have a 1/4 inch (6 mm) diameter drilled hole at the midpoint of each blade locate d at the point(s) recommended by the manufacturer.
11.Concrete transported in tr uck mixers or agitators shall be discharged within 90 minutes after t he introduction of the cement to the aggregate. In hot weather, or under other conditions contributing to stiffening of the concrete, a shorter time may be specified by the Engineer.
12.Concrete transported in non- agitating trucks (i.e., dump trucks) shall be discharged within 30 minutes afte r the introduction of the cement to the aggregate. In hot weather, or under other conditions contributing to stiffening of the concrete, a shorter ti me may be specified by the Engineer.
13.Water: a. The quantity of water shall be determined by the Contractor. The minimum quantity of water should be used which will produce the required workability. Any additional water used to rinse the charging hopper and fins after the batching of concrete is allowed. This water must be estimated and recorded on the batch ticket.
b.If the water/cement ratio is varied by more than 1%, an air test shall be performed and cylinders made to determine if the concrete is acceptable.
c.Water added to any mix must pass through an approved and adjustable water-measuring device.
14.Additional Water: a. If additional mixing water is added, a minimum of 20 revolutions of the truck mixer drum at mixing speed shall be required.
b.In no case shall the total am ount of water in the batch exceed that allowed in Table 1002.02.
c.No water may be added after discharge has begun. 15. Mobile mixers:
a.Mobile mixers shall be self -contained and continuously mix the concrete.
b.The mixer shall be self-propelled and shall be capable of carrying unmixed, dry bulk cement, aggregate, and water.
1002.03 Portland Cement Concrete
- 782 - c. The mixer shall measure the volume of cement added to the mix. A recording meter visible at all ti mes and equipped with a ticket printout shall indicate this quantity.
d.Water flow into the mixing chamber shall be automatically controlled. Water flow shall be indicated by flow meter and shall be readily adjustable to provide for minor variations in aggregate moisture.
e.The Contractor shall calibr ate the aggregate gates once each year. However, the cement meter must be calibrated at each project site. The Engineer shall be given advance not ice of the calibration tests so they can be observed.
16.Hand mixing will be allowed only on small jobs or in the case of an emergency. When hand mixing is allowed, it shall be done on a watertight platform.
1002.04 Acceptance Requirements
1.Class 47B Concrete Mix Design Submittal: a. The Contractor shall s ubmit the Concrete Mix Design Worksheet consisting of design mix prop ortions, testing of mix design from a minimum of 4 cubic yards and aggregate data for 47B class of concrete being placed on the project.
1.All testing must be performed by a qualified laboratory found on the Department’s Material an d Research website, under the Nebraska Qualified Consultant & LPA Laboratories and submitted to the Engineer.
2.The Concrete Mix Design shall be submitted to the Engineer 4 weeks prior to any concrete being placed on the project.
3.The Concrete Mix Design shall not be paid for directly by the Department and shall be subsidiary to items which direct payment is made.
4.Concrete shall not be placed on the project before the Concrete Mix Design Worksheet has been reviewed and approved by the Engineer.
b.The Contractor shall s ubmit the Concrete Mix Design Worksheet to the Engineer. Email su bmissions are preferred but will be accepted by fax or postal mail.
1.Contractor’s Mix Design Worksheet can be found on the Materials and Research website. The submitted Mix Design Worksheet shall include the following: • Contractor Name • P r o j e c t N u m b e r • D a t e • Location of ready mix or central mix plant • Date submitted • Signature of C ontractor representative
2.Material Source Information. Portland Cement Concrete 1002.04 - 783 - • Cement Manufacturer • Type of Interground/Blended Cement • Type of Admixtures • Aggregate Pit and Quarry location (3) Specific Gravity of each individual aggregate source.
4.Sand Equivalent for dry pit sand-gravel aggregate. (5) Combined Aggregate percent passing as described on Table 1033.03C.
6.Contractor’s Target combined aggregate gradation percent passing.
i.The Contractor’s required worksheet can be found on the Materials and Research website.
7.Testing of Mix Design: (i) The mix design shall show the weights of all ingredients including Interground/Ble nded cements, aggregates, water, admixtures types and water cement ratio. • Temperature of conc rete at time of sampling, ASTM C 1064. • The air content of plastic concrete, ASTM C 231. • Weight per cubic foot, Yield, ASTM C 138. The relative Yield shall be a minimum of 97%. • Compressive strength shall be performed with a minimum of three averaged specimens at 7-day and 28-day, ASTM C 39. The minimum 28-day compressive strength shall be 3500 psi.
8.Traditional 47B Mix Design is defined as an IP(25) cement, 70% Class B Aggregate and 30% Class E Aggregate may be exempt from the concrete testing descr ibed in Paragraph 1.(b)(7). All other requirements shall be included in the Concrete Mix Design Report.
c.The PCC Engineer will notify the Contractor of the mix design approval for Class 47B Concrete. Approval of the mix design does not alleviate the Contractor of the responsibility of the in-place concrete. The Contractor may adjust admixtures, wate r cement ratio, vibrator frequency, etc., as needed in accordance to the specifications.
d.The Contractor shall submit a new concrete mix design worksheet meeting the above requirements when a change occurs in the source, type, or proportions of cements or aggregates; unless otherwise approved by the Engineer.
2.The quantity of water to be used shall be determined by the Contractor. It shall not be varied without the Engineer's consent.
3.If the concrete mixture is excessively wet causing segregation, excessive bleeding, excessively dry or any other undesirable condition, the concrete shall be rejected. At the option of the Engi neer, slump tests may be performed to determine the consistency.
1002.04 Portland Cement Concrete
- 784 - 4. Concrete which has developed initial set before it is consolidated and finished shall be rejected.
5.a. If false set is encountered, the batching operation shall be stopped until the problem is resolved.
b.Each batch must be mixed or agitated for at least 3 additional minutes after observing the false set and the concrete must be of satisfactory consistency.
6.Compressive strength tests shall be made in accordance with ASTM C 39.
7.Concrete shall be sampled as described in the Department’s Materials Sampling Guide. Samples shall be taken at the point of placement, never before the discharge from the last conveyance.
8.Aggregate Acceptance, Veri fication, Sampling and Testing:
a.The aggregate will be acce pted based on the Contractor’s testing results except as noted below.
b.The aggregate verification sampling and testing by the Department will be randomly selected and tested according to sublot sizes in Table 1002.05. Table 1002.05 Aggregate Class Lot Sublot E and F 3000 tons 1000 tons A, B and C 6000 tons 2000 tons R 6000 tons 2000 tons
c.The results of Contractor sp lit sample will be verified by the Department’s verification tests. Any samples outside of the tolerances as specified according to the Materials Sampling Guide, Section 28 under the Acceptable Tolerance Limits for Independent Assurance will result in an Independent Assurance (IA) review of testing and may result in the Department test results being applied.
d.On any given Lot, if the results of the gradation from the verification test are within Department ’s specification, the Contractor’s results will be used for the entire lot. On any given Lot, if the gradations results from the verification test are outside Department’s specification, further investigation will be initiated by the Engineer for that sublot. Any or all of the remaining Department sublot samples may be tested and the Department sublot test results may be applied to the respective sublot and the acceptance will apply.
e.When verification tests are within testing tolerance but results show a consistent pattern of deviation from the split sample results, the Engineer will exercise one or more of the following: - Cease production. - Request additional verification testing. - Initiate a co mplete IA review. Portland Cement Concrete 1002.04 - 785 - f. Independent Assurance (IA) Review of Testing:
1.The Contractor shall allow the Department personnel access to the Contractors’ laboratory to conduct IA review of the technician testing procedures and apparatus. Any deficiencies discovered in the Contractor’s testing procedures will be reported to the Contractor and corrected by the Contractor.
2.During the IA review, the Department personnel and the Contractor shall split a sample for t he purpose of IA testing. The samples selected will be tested in the Department’s Branch Laboratory. Any IA test results found to be outside of defined testing tolerances as stated in Paragraph 8.c. of Subsecti on 1002.04 will be reported to the Contractor. The Contractor shall immediately correct any deficiencies found during the IA review.
3.If the project personnel and the Contractor cannot reach agreement on the accuracy of the te st results, the Department Central Laboratory will be asked to resolve the dispute, which will be final. All dispute resolutions will be in accordance with the Quality Assurance Program requirements in the Depart ment’s Materials Sampling Guide. - 786 - SECTION 1003 -- FLOWABLE FILL
1003.01 Description
1.Flowable fill shall be a mixture of cement, fly ash, fine sand, water, and air having a consistency which will flow under a very low head.
1003.02 Material Characteristics
1.The approximate quantities of eac h material per cubic yard (cubic meter) of mixed material shall be as shown in Table 1003.01. Table 1003.01 Flowable Fill Composition Cement (Type I or II) 50 pounds/cu. yd. (30 kg/m3) Fly ash 200 pounds/cu. yd. (120 kg/m3) Fine sand 2,700 pounds/cu. yd. (1600 kg/m3) Water (approx.) 420 pounds/cu. yd. (250 kg/m3) Air content (approx.) 10%
2.Actual quantities shall be adjusted to provide a yield of 1 cubic yard (cubic meter) with the materials used.
3.Approximate compressive strength should be 85 to 175 psi (0.6 to 1.2 MPa).
4.Fine sand shall be an evenly graded material having not less than 95% passing the No. 4 sieve (4.75 mm) and not more than 5% passing the No. 200 (75 m) sieve.
5.Mixing and handling of the material shall be in accordance with
1003.03 Acceptance Requirements
1.Flowable fill is accepted bas ed on it meeting the requirements in this Section.
2.Cement must be on the Depar tment’s Approved Products List.
3.Fly ash meeting requirements in Section 1008 can be either Class “C” or Class “F”.
Source: Nebraska Standard Specifications for Highway Construction, 2017 Edition. Pages 809–819 of 1,048.