60 21 00 HydraCement.pdf

Lower Rio Grande Flood Control Project – Interior Floodways Rehabilitation of North Floodway (North and South Levees) and Arroyo Colorado Floodway (North Levee) Hidalgo and Cameron Counties, Texas

HYDRAULIC CEMENT CONCRETE

USIBWC Contract No.: IBM09B0004 Page 60.21.00 - 1

SPECIFICATION 60 21 00

This specification includes requirements for the construction of concrete elements within the Work area, and includes the following:

1.0 General

2.0 Materials & Equipment

3.0 Construction Methods

4.0 Measurement and Payment

PART 1 - GENERAL

1.1 RELATED DOCUMENTS, CONTRACT CLAUSES, & SPECIFICATIONS

The following may not include all related documents, contract clauses, & technical specifications, and does not relieve the Contractor of the responsibility of performing work associated with this specification in accordance with all terms of the Contract herein.

A. Related documents: As described in paragraph 1.2 of SPECIFICATION 01 01 00.

B. Contract: Section I, 52.236-21“Specifications and Drawings for Construction”

C. Technical Specifications: (No Requirements Defined for this Specification)

D. References:

• American Society of Testing and Materials (ASTM) C94 / C94M - 09 Standard Specification for Ready-Mixed Concrete

• ASTM C109 / C109M - 08 Standard Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in. or [50-mm] Cube Specimens)

• ASTM C191 - 08 Standard Test Methods for Time of Setting of Hydraulic Cement by Vicat Needle

• ASTM C685 / C685M - 07 Standard Specification for Concrete Made by Volumetric Batching and Continuous Mixing

• Texas Department of Transportation Department Material Specification (DMS)-4600 Hydraulic Cement, March 2009

• DMS-4610 Fly Ash, March 2009

• DMS 4620 Ground Granulated Blast Furnace Slag, August 2004

• DMS 4630 Silica Fume, August 2004

• DMS-4635 Metakaolin, August 2004

• DMS-4640 Chemical Admixtures for Concrete, March 2008

• DMS 7320 Qualification Procedure for Reinforcing Steel Producing Mills, February 2009

USIBWC Contract No.: IBM09B0004 Page 60.21.00 - 2

• Texas Department of Transportation Department Testing Standard (Tex)-406-A,

• Tex-408-A Organic Impurities in Fine Aggregate for Concrete, August 1999

• Tex-410-A Abrasion of Coarse Aggregate Using the Los Angeles Machine, August 1999

• Tex -411-A Soundness of Aggregate Using Sodium Sulfate or Magnesium Sulfate, October 2004

• Tex-413-A Determining Deleterious Material in Mineral Aggregate, August 1999

• Tex-414-A Air Content of Freshly Mixed Concrete by the Volumetric Method, July 2008

• Tex -415-A Slump of Hydraulic Cement Concrete, July 2008

• Tex-418-A Compressive Strength of Cylindrical Concrete Specimens, July 2008

• Tex-422-A Measuring Temperature of Freshly Mixed Portland Cement Concrete, July

• Tex-426-A Estimating Concrete Strength by the Maturity Method, August 2002

• Tex-447-A Correlating Concrete Strength Tests, July 2008

• Tex-448-A Flexural Strength of Concrete Using Simple Beam Third-Point Loading, July

• Tex-472-A Uniformity of Concrete, July 2008

• Tex-100-E Surveying and Sampling Soils for Highways, August 1999

• Tex-203-F Sand Equivalent Test, August 1999

• Tex-612-J Acid Insoluble Residue for Fine Aggregate, June 2000

• American Concrete Institute (ACI) 211.4R-08: Guide for Selecting Proportions for High- Strength Concrete Using Portland Cement and Other Cementitious Matter

1.2 GENERAL

In general, the Contractor shall furnish hydraulic cement concrete for concrete construction.

PART 2 – MATERIALS & EQUIPMENT

2.1 MATERIALS

A. Cement. The Contractor shall furnish cement conforming to DMS-4600, “Hydraulic Cement.

B. Supplementary Cementing Materials (SCM). The Contractor shall provide SCM conforming as follows:

(1) Fly Ash - conforming to DMS-4610, “Fly Ash.”

(2) Ultra-Fine Fly Ash (UFFA) - conforming to DMS-4610, “Fly Ash.”

USIBWC Contract No.: IBM09B0004 Page 60.21.00 - 3

(3) Ground Granulated Blast-Furnace Slag (GGBFS) - conforming to DMS-4620, “Ground Granulated Blast-Furnace Slag,” Grade 100 or 120.

(4) Silica Fume - conforming to DMS-4630, “Silica Fume.”

(5) Metakaolin - conforming to DMS-4635, “Metakaolin.”

C. Chemical Admixtures. The Contractor shall furnish admixtures conforming to DMS-4640, “Chemical Admixtures for Concrete.” Do not use calcium chloride.

D. Water. The Contractor shall furnish mixing and curing water that is free from oils, acids, organic matter, or other deleterious substances. Water from municipal supplies compliance-confirmed by the Texas Department of Health will not require testing. When using water from other sources, the Contractor shall provide test reports showing compliance with Table 1 before use. Water that is a blend of concrete wash water and other acceptable water sources, certified by the concrete producer as complying with the requirements of both Table 1 and Table 2, may be used as mix water. The Contractor shall test the blended water weekly for four (4) weeks for compliance with Table 1 and Table 2 or provide previous test results; then test every month for compliance;

provide water test results upon request.

The Contractor shall not use mix water that has an adverse effect on the air-entraining agent, on any other chemical admixture, or on strength or time of set of the concrete. When using white hydraulic cement, use mixing and curing water free of iron and other impurities that may cause staining or discoloration.

Table 1 Chemical Limits for Mix Water

Contaminant Test Method Maximum

Concentrati on (ppm)

Chloride (Cl) ASTM D 512 Prestressed concrete 500 Bridge decks & superstructure

All other concrete 1,000 Sulfate (SO4) ASTM D 516 1,000

Alkalies (Na2O + 0.658K2O)

ASTM D 4191

ASTM D 4192

Total solids AASHTO T 26 50,000

USIBWC Contract No.: IBM09B0004 Page 60.21.00 - 4

Table 2

Acceptance Criteria for Questionable Water Supplies Property Test Method Limits

Compressive strength, min % control at 7 days ASTM C 1091 90

Time of set, deviation from control, Min. ASTM C 1911 from 60 early to 90 later 1 Base comparisons on fixed proportions and the same volume of test water compared to the control mix using city water or distilled water.

E. Aggregate. The Contractor shall supply aggregates that meet the definitions in Tex-100-E;

provide coarse and fine aggregates from sources listed in the TxDOT’s Concrete Rated Source Quality Catalog (CRSQC). If compliance-confirmed by the COR, the Contractor can provide aggregate from non-listed sources only when tested and results compliance-confirmed by the Government before use. Do not combine compliance-confirmed material with unapproved material.

(1) Coarse Aggregate. The Contractor shall provide coarse aggregate consisting of durable particles of gravel, crushed blast furnace slag, recycled crushed hydraulic cement concrete, crushed stone, or combinations thereof that are free from frozen material and from injurious amounts of salt, alkali, vegetable matter, or other objectionable material, either free or as an adherent coating; provide coarse aggregate of uniform quality throughout; provide coarse aggregate that, when tested in accordance with Tex-413-A, has:

(a) at most 0.25 percent (0.25%) by weight of clay lumps,

(b) at most one percent (1.0%) by weight of shale, and

(c) at most five percent (5.0%) by weight of laminated and friable particles.

Table 3

Coarse Aggregate Gradation Chart Percent Passing on Each Sieve Aggregate

Grade No.1

Nomina l Size 2-1/2" 2" 1-1/2" 1" 3/4" 1/2" 3/8" No. 4 No. 8

1 2" 100 80–100 50–85 20–40 0–5 2 (467) 1–1/2" 100 95–100 35–70 10–30 0–5

3 1–1/2" 100 95–100 60–90 25–60 0–5 4 (57) 1" 100 95–100 25–60 0–10 0–5 5 (67) 3/4" 100 90–100 20–55 0–10 0–5 6 (7) 1/2" 100 90–100 40–70 0–15 0–5

7 3/8" 100 70–95 0–25 8 3/8" 100 95–100 20–65 0–10

1. Corresponding ASTM C 33 gradation shown in parentheses.

Wear must not be more than forty percent (40%) when tested in accordance with

USIBWC Contract No.: IBM09B0004 Page 60.21.00 - 5

Tex-410-A. Unless otherwise shown on the plans, provide coarse aggregate with a 5-cycle magnesium sulfate soundness of not more than eighteen percent (18%) when tested in accordance with Tex-411-A. Crushed recycled hydraulic cement concrete is not subject to the 5-cycle soundness test. The loss by decantation as tested in accordance with Tex-406-A, plus the allowable weight of clay lumps, must not exceed one percent (1.0%) or the value shown on the plans, whichever is smaller. In the case of aggregates made primarily from crushing stone, if the material finer than the No. 200 sieve is established to be the dust of fracture and essentially free from clay or shale as established by Tex-406-A, Part III, the limit may be increased to one and a half percent (1.5%). When crushed limestone coarse aggregate is used in concrete pavements, the decant may exceed one percent (1.0%) but not more than three percent (3.0%) if the material finer than the No. 200 sieve is determined to be at least sixty-seven percent (67%) calcium carbonate in accordance with Tex-406-A, Part III. Unless otherwise specified, provide aggregate conforming to the gradation requirements shown in Table 3 when tested in accordance with Tex-401-A.

(2) Fine Aggregate. The Contractor shall provide fine aggregate consisting of clean, hard, durable particles of natural or manufactured sand or a combination thereof with or without mineral filler; provide fine aggregate free from frozen material and from injurious amounts of salt, alkali, vegetable matter, or other objectionable material, and containing no more than one-half percent (0.5%) clay lumps by weight in accordance with Tex-413-A; provide fine aggregate that does not show a color darker than standard when subjected to the color test for organic impurities in accordance with Tex-408-A; unless otherwise shown on the plans, use fine aggregate with an acid insoluble residue of at least sixty percent (60%) by weight when tested in accordance with Tex-612-J in all concrete subject to direct traffic;

and unless otherwise shown on the plans, when necessary, blend the fine aggregate to meet the acid insoluble residue requirement.

When blending, the Contractor shall use the following equation:

Acid Insoluble (%) = {(A1)(P1)+(A2)(P2)}/100 where:

A1 = acid insoluble (%) of aggregate 1 A2 = acid insoluble (%) of aggregate 2 P1 = percent by weight of A1 of the fine aggregate blend P2 = percent by weight of A2 of the fine aggregate blend

The Contractor shall provide fine aggregate or combinations of aggregates, including mineral filler, conforming to the gradation requirements shown in Table 4 when tested in accordance with Tex-401-A unless otherwise specified.

Unless otherwise shown on the plans, the Contractor shall provide fine aggregate with a sand equivalent of at least 80 in accordance with Tex-203-F. For all classes of concrete except Class K, provide fine aggregate with a fineness modulus between 2.30 and 3.10 as determined by Tex-402-A. For Class K concrete, provide a fine aggregate with a fineness modulus between 2.60 to 2.80 unless otherwise shown on the plans.

USIBWC Contract No.: IBM09B0004 Page 60.21.00 - 6

Table 4 Fine Aggregate Gradation Chart (Grade 1)

Sieve Size Percent Passing 3/8 in. 100 No. 4 95–100 No. 8 80–100 No. 16 50–85 No. 30 25–65 No. 50 10–351

No. 100 0–10 No. 200 0–32

1 6–35 when sand equivalent value is greater than 85.

2 0–6 for manufactured sand.

(3) Mineral Filler. The Contractor shall provide mineral filler consisting of stone dust, clean crushed sand, or other compliance-confirmed inert material with one hundred percent (100%) passing the No. 30 sieve and sixty-five to one hundred percent (65% to 100%) passing the No. 200 sieve when tested in accordance with Tex-401-A.

F. Mortar and Grout. When required or shown on the plans, the Contractor shall provide mortar and grout consisting of 1 part hydraulic cement, 2 parts sand, and sufficient water to provide the desired consistency; provide mortar with a consistency such that the mortar can be easily handled and spread by trowel; provide grout of a consistency that will flow into and completely fill all voids.

2.2 EQUIPMENT

A. Concrete Plants and Mixing Equipment. Except for volumetric mixers (auger/mixer), each plant and truck mixer must be currently certified by the National Ready Mixed Concrete Association (NRMCA) or have an inspection report signed and sealed by a licensed professional engineer showing that concrete measuring, mixing, and delivery equipment meets all requirements of ASTM C 94. A new certification or signed and sealed report is required every time a plant is moved. Plants with a licensed engineer’s inspection require re-inspection every two (2) years.

The Contractor shall provide a copy of the certification or the signed and sealed inspection report to the COR. When equipment or facilities fail to meet specification requirements, the Contractor shall remove them from service until corrected.

(1) Scales. Check all scales prior to beginning of operations, after each move, or whenever their accuracy or adequacy is questioned, and at least once every six (6) months. The Contractor shall immediately correct deficiencies, and recalibrate; provide a record of calibration showing scales in compliance with ASTM C 94 requirements. Check batching accuracy of volumetric water batching devices and admixture dispensing devices at least every ninety

(90) days. Perform daily checks as necessary to ensure measuring accuracy.

USIBWC Contract No.: IBM09B0004 Page 60.21.00 - 7

(2) Volumetric Mixers. The Contractor shall provide volumetric mixers with rating plates defining the capacity and the performance of the mixer in accordance with the Volumetric Mixer Manufacturers Bureau or equivalent; provide volumetric mixers that comply with ASTM C 685; provide test data showing mixers meet the uniformity test requirements of Tex-472-A.

(3) Agitators and Truck and Stationary Mixers. Inspect and furnish inspection reports on truck mixers and agitators annually. If an inspection within twelve (12) months is not practical, a two (2)-month grace period (for a maximum of fourteen (14) months between inspections) is permitted. Include in the report the condition of blades and fins and their percent wear from the original manufacturer’s design. The Contractor shall repair mixing equipment exhibiting ten percent (10%) or more wear before use; provide truck mixers and agitators equipped with means to readily verify the number of revolutions of the drum, blades, or paddles.

(4) The Contractor shall provide stationary and truck mixers capable of combining the ingredients of the concrete within the specified time or the number of revolutions specified into a thoroughly mixed and uniform mass and capable of discharging the concrete so that at least five (5) of the six (6) requirements of Tex-472-A are met. To resolve issues of mix uniformity and mixer performance, perform concrete uniformity tests on mixers or agitators in accordance with Tex-472-A. Perform the mixer or agitator uniformity test at the full rated capacity of the equipment and within the maximum mixing time or maximum number of revolutions. The Contractor shall remove from service all equipment that fails the uniformity test. Inspect and maintain mixers and agitators. The Contractor shall keep them reasonably free of concrete buildup, and repair or replace worn or damaged blades or fins.

The Contractor shall ensure all mixers have a plate affixed showing manufacturer’s recommended operating speed and rated capacity for mixing and agitating.

B. Hauling Equipment. The Contractor shall provide hauling equipment capable of maintaining the mixed concrete in a thoroughly mixed and uniform mass and of discharging the concrete with a satisfactory degree of uniformity. When using non-agitating equipment for transporting concrete, the Contractor shall provide equipment with smooth, mortar-tight metal containers equipped with gates that prevent accidental discharge of the concrete.

C. Testing Equipment. Unless otherwise shown on the plans or specified, in accordance with the pertinent test procedure, the Contractor shall furnish and maintain:

(1) test molds,

(2) curing facilities,

(3) maturity meters if used, and

(4) wheelbarrow or other container acceptable for the sampling of the concrete.

The Contractor shall provide strength-testing equipment in accordance with the Contract controlling test unless shown otherwise.

USIBWC Contract No.: IBM09B0004 Page 60.21.00 - 8

PART 3 – CONSTRUCTION METHODS

3.1 CLASSIFICATION AND MIX DESIGN

The Contractor shall furnish mix designs using ACI 211, “Standard Practice for Selecting Proportions for Normal, Heavyweight, and Mass Concrete,” or other compliance-confirmed procedures for the classes of concrete required in accordance with Table 5. Do not exceed the maximum water-to-cementitious-material ratio. A higher-strength class of concrete with equal or lower water-to-cementitious-material ratio may be substituted for the specified class of concrete. To account for production variability and ensure minimum compressive strength requirements are met, over-design the mix in accordance with Table 6.

A. Cementitious Materials. The Contractor shall use cementitious materials from pre-qualified sources; otherwise, request sampling and testing for compliance-confirmation before use. Unless otherwise specified or compliance-confirmed, limit cementitious material content to no more than seven hundred (700) pounds per cubic yard. When supplementary cementing materials are used, “cement” is defined as “cement plus supplementary cementing material.” Use Type III cement only in pre-cast concrete or when specified or permitted. For monolithic placements, use cement of the same type and from the same source. When sulfate-resistant concrete is required, use mix design Options 1, 2, 3, or 4 given in “Mix Design Options” using Type I/II, II, V, IP, or IS cement. Do not use Class C fly ash in sulfate-resistant concrete. Do not use supplementary cementing materials when white hydraulic cement is specified.

B. Aggregates. The Contractor shall limit the use of recycled crushed hydraulic cement concrete as a coarse or fine aggregate to Class A, B, D, E, and P concrete; limit recycled crushed concrete fine aggregate to a maximum of twenty percent (20%) of the fine aggregate; when white hydraulic cement is specified, use light-colored aggregates.

C. Chemical Admixtures. The Contractor shall use only pre-compliance-confirmed concrete chemical admixtures from the list of pre-qualified concrete admixtures maintained by TxDOT;

submit non-pre-compliance-confirmed admixtures test reports to the COR for compliance-confirmation. The Contractor shall not use high-range water-reducing admixtures (Type F or G) or accelerating admixtures (Type C or E) in bridge deck concrete.

D. Air Entrainment. The Contractor shall air-entrain all concrete except for Class B in accordance with Table 7 unless otherwise shown on the plans; use moderate exposure values unless otherwise specified. If the air content is more than 1-1/2 percentage points below or 3 percentage points above the required air, the load of concrete will be rejected. If the air content is more than 1-1/2 but less than 3 percentage points above the required air, the concrete may be accepted based on strength tests.

E. Slump. Unless otherwise specified, the mix shall provide concrete slump in accordance with Table 8 using the lowest slump possible that can be placed and finished efficiently without segregation or honeycombing. Concrete that exceeds the maximum acceptable placement slump at time of delivery will be rejected. When compliance-confirmed, the slump of a given concrete mix may be increased above the values shown in Table 8 using chemical admixtures, provided that the admixture-treated concrete has the same or lower water–cement or water–cementitious-material ratio and does not exhibit segregation or excessive bleeding. The Contractor shall

USIBWC Contract No.: IBM09B0004 Page 60.21.00 - 9 request compliance-confirmation for the mix design sufficiently in advance for proper evaluation by the Government.

Table 5

Concrete Classes

Class of Concrete

Design Strength, Min.

28-day f′c (psi)

Maximum

W/C Ratio1

Coarse Aggreg ate Grades

2,3

General Usage4

A 3,000 0.60 1–4, 8 Inlets, manholes, curb, gutter, curb & gutter, conc. retards, sidewalks, driveways, backup walls, anchors

B 2,000 0.60 2–7 Riprap, small signs, and anchors

C5 3,600 0.45 1–6

Drilled shafts, bridge substructure, bridge railing, culverts except top slab of direct traffic culverts, head-walls, wing walls, approach slabs, concrete traffic barrier (cast-in-place)

D 1,500 0.60 2–7 Riprap E 3,000 0.50 2–5 Seal concrete

F5 Note 6 0.45 2–5 Railroad structures; occasionally for bridge piers, columns, or bents

H5 Note 6 0.45 3–6 Prestressed concrete beams, boxes, piling, and concrete traffic barrier (precast)

S5 4,000 0.45 2–5 Bridge slabs, top slabs of direct traffic culverts

DC5 5,500 0.40 6 Dense conc. overlay CO5 4,600 0.40 6 Conc. overlay

LMC5 4,000 0.40 6–8 Latex-modified concrete overlay

SS5 Note 7 0.45 4–6 Slurry displacement shafts, underwater drilled shafts

K5 Note 6 0.45 Note 6 Note 6 HES Note 6 0.45 Note 6 Note 6

1 Maximum water-cement or water-cementitious ratio by weight.

2 Unless otherwise permitted, do not use Grade 1 coarse aggregate except in massive foundations with 4-in.

minimum clear spacing between reinforcing steel bars. Do not use Grade 1 aggregate in drilled shafts.

3 Unless otherwise compliance-confirmed, use Grade 8 aggregate in extruded curbs.

4 For information only.

5 Structural concrete classes.

6 As shown on the plans or specified.

7 Cementitious material content shall be minimum 658 lb/cy of concrete.

USIBWC Contract No.: IBM09B0004 Page 60.21.00 - 10

Table 6 Over Design to Meet Compressive Strength Requirements1

Standard Deviation, psi No. of Tests2,3 300 400 500 600 700

15 470 620 850 1,120 1,390 20 430 580 760 1,010 1,260

30 or more 400 530 670 900 1,130 1 When designing the mix, add the tabulated amounts to the minimum design strength in Table 5.

2 Number of tests of a concrete mixture used to estimate the standard deviation of a concrete production facility. Test of another mix within 1,000 psi of the specified strength may be used.

3 If less than 15 prior tests are available, the overdesign should be 1,000 psi for specified strength less than 3,000 psi, 1,200 psi for specified strengths from 3,000 to 5,000 psi and 1,400 psi for specified strengths greater than 5,000 psi.

Table 7 Air Entrainment

Nominal Maximum % Air1 Aggregate Size, in. Moderate Exposure Severe Exposure 3/8 (Grades 7 & 8) 6 7-1/2

1/2 (Grade 6) 5-1/2 7 3/4 (Grade 5) 5 6 1 (Grade 4) 4-1/2 6

1-1/2 (Grades 2 & 3) 4-1/2 5-1/2 2 (Grade 1) 4 5

1 For specified concrete strengths above 5,000 psi a reduction of 1 percentage point is permitted.

USIBWC Contract No.: IBM09B0004 Page 60.21.00 - 11

Table 8 Slump Requirements

Concrete Designation

Recommended Design and

Placement Slump (in)

Maximum Acceptable

Placement Slump (in)

Thin walled section (9 in. or less) 4 6-1/2

Approach slabs, concrete overlays, caps, columns, piers, wall sections (over 9 in.) 3 5

Bridge slabs 4 5-1/2 Prestressed concrete members1 4 6-1/2 Concrete traffic barrier, concrete bridge railing 4 6-1/2

Dense concrete overlay 3/4 2 Latex-modified conc. for bridge deck overlays 3 7-1/2

Concrete placed underwater 6 8-1/2 Concrete pavement (slip-formed) 1-1/2 3 Concrete pavement (formed) 4 6-1/2 Riprap, curb, gutter, slip-formed, and extruded concrete

As compliance-confirmed

As compliance-confirmed

1 If a high-range water reducer (HRWR) is used, maximum acceptable placement slump will be 9 in.

F. Mix Design Options. For structural concrete identified in Table 5 and any other class of concrete designed using more than five hundred twenty (520) pounds of cementitious material per cubic yard, the Contractor shall use one of the mix design Options 1–8 shown below. For concrete classes not identified as structural concrete and designed using less than five hundred twenty

(520) pounds of cementitious material per cubic yard, the Contractor shall use one of the mix design Options 1–8 shown in Table 5, except that Class C fly ash may be used instead of Class F fly ash for Options 1, 3, and 4 unless sulfate-resistant concrete is required.

(1) Option 1 - Replace twenty to thirty-five percent (20% to 35%) of the cement with Class F fly ash;

(2) Option 2 - Replace thirty-five to fifty percent (35% to 50%) of the cement with GGBFS;

(3) Option 3 - Replace thirty-five to fifty percent (35% to 50%) of the cement with a combination of Class F fly ash, GGBFS, or silica fume; however, no more than thirty-five percent (35%) may be fly ash, and no more than ten percent (10%) may be silica fume;

(4) Option 4 - Use Type IP or Type IS cement; (up to ten percent (10%) of a Type IP or Type IS cement may be replaced with Class F fly ash, GGBFS, or silica fume);

(5) Option 5 - Replace thirty-five to fifty percent (35% to 50%) of the cement with a combination of Class C fly ash and at least six percent (6%) of silica fume, UFFA, or

USIBWC Contract No.: IBM09B0004 Page 60.21.00 - 12 metakaolin; however, no more than thirty-five percent (35%) may be Class C fly ash, and no more than ten percent (10%) may be silica fume;

(6) Option 6 - Use a lithium nitrate admixture at a minimum dosage of 0.55 gallon of thirty percent (30%) lithium nitrate solution per pound of alkalis present in the hydraulic cement;

(7) Option 7 - When using hydraulic cement only, ensure that the total alkali contribution from the cement in the concrete does not exceed four (4) pounds per cubic yard of concrete when calculated as follows:

cementin equivalent ΟNa %yd. cu.per cement lb.yd.cu.peralkalilb. 2×

In the above calculation, use the maximum cement alkali content reported on the cement mill certificate.

(8) Option 8 - For any deviations from Options 1–7, perform the following:

(a) Test both coarse and fine aggregate separately in accordance with ASTM C 1260, using four hundred forty (440) grams of the proposed cementitious material in the same proportions of hydraulic cement to supplementary cementing material to be used in the mix.

(b) Before use of the mix, provide the certified test report signed and sealed by a licensed professional engineer demonstrating that the ASTM C 1260 test result for each aggregate does not exceed 0.10 percent (0.10%) expansion.

3.2 TRIAL BATCHES

The Contractor shall perform all preliminary trial batches and testing necessary to substantiate the proposed mix designs, and provide documentation including mix design, material proportions, and test results substantiating that the mix design conforms to specification requirements; make all final trial batches using the proposed ingredients in a mixer that is representative of the mixers to be used on the job; make the batch size at least fifty percent (50%) of the mixer’s rated capacity; perform fresh concrete tests for air and slump, and make, cure, and test strength specimens for compliance with specification requirements; test at least three (3) sets of design strength specimens with two (2) specimens per set in accordance with Tex-418-A or Tex-448-A for each test age. Before placing, provide the Government the option of witnessing final trial batches, including the testing of the concrete. If not provided this option, the COR may require additional trial batches, including testing, before the concrete is placed. Establish 7-day compressive strength target values using the following formula for each concrete mix to be used:

strengthbatch trialavg.day -28 strengthbatch trialavg.day -7strengthdesignMinimumvalueTarget ×=

When there are changes in aggregates or in type, brand, or source of cement, SCM, or chemical admixtures, reevaluate the mix as a new mix design. A change in vendor does not necessarily constitute a change in materials or source. When only the brand or source of cement is changed and there is a prior record of satisfactory performance of the cement with the ingredients, new trial batches may be waived by the Government.

USIBWC Contract No.: IBM09B0004 Page 60.21.00 - 13

When the maturity method is specified or permitted, establish the strength–maturity relationship in accordance with Tex-426-A. When using the maturity method any changes in any of the ingredients, including changes in proportions, will require the development of a new strength–maturity relationship for the mix.

3.3 STORAGE OF MATERIALS

A. Cement, Supplementary Cementing Materials, and Mineral Filler. The Contractor shall store all cement, supplementary cementing materials, and mineral filler in weatherproof enclosures that will protect them from dampness or absorption of moisture. When permitted, small quantities of sacked cement may be stored in the open, on a raised platform, and under waterproof covering for up to forty-eight (48) hours.

B. Aggregates. The Contractor shall handle and store concrete aggregates in a manner that prevents contamination with foreign materials. If the aggregates are stored on the ground, clear the sites for the stockpiles of all vegetation, level the sites, and do not use the bottom six (6)-inch layer of aggregate without cleaning the aggregate before use. When conditions require the use of two (2) or more grades of coarse aggregates, maintain separate stockpiles and prevent intermixing.

Where space is limited, separate the stockpiles using physical barriers. Store aggregates from different sources in different stockpiles unless the COR authorizes pre-blending of the aggregates.

Minimize segregation in stockpiles. Remix and test stockpiles when segregation is apparent.

Sprinkle stockpiles to control moisture and temperature as necessary. Maintain reasonably uniform moisture content in aggregate stockpiles.

C. Admixtures. The Contractor shall store admixtures in accordance with manufacturer’s recommendations and prevent admixtures from freezing.

3.4 MEASUREMENT OF MATERIALS

Except for volumetric mixers, the Contractor shall measure concrete materials by weight; measure mixing water, consisting of water added to the batch, ice added to the batch, water occurring as surface moisture on the aggregates, and water introduced in the form of admixtures, by volume or weight; measure ice by weight; measure cement and supplementary cementing materials in a weigh hopper and on a separate scale from those used for other materials; measure the cement first when measuring the cumulative weight; measure concrete chemical admixtures in powdered form by weight; measure concrete chemical admixtures in liquid form by weight or volume; measure batch materials within the tolerances of Table 9.

When measuring cementitious materials at less than thirty percent (30%) of scale capacity, ensure that the quantity measured is accurate to not less than the required amount and not more than four percent (4%) in excess. When measuring aggregates in a cumulative weigh batcher at less than thirty percent (30%) of the scale capacity, ensure that the cumulative quantity is measured accurate to ±0.3% of scale capacity or ±3% of the required cumulative weight, whichever is less. For volumetric mixers, base tolerances on volume–weight relationship established by calibration, and measure the various ingredients within the tolerances of Table 10. Correct batch weight measurements for moisture. When compliance-confirmed, under special circumstances, measure cement in bags of standard weight. Weighing of sacked cement is

USIBWC Contract No.: IBM09B0004 Page 60.21.00 - 14 not required. Do not use fractional bags except for small hand-mixed batches of approximately five (5) cubic feet or less and when an compliance-confirmed method of volumetric or weight measurement is used.

Table 9

Measurement Tolerances – Non-Volumetric Mixers

Material Tolerance

Cement, wt. ±1 Mineral admixture, wt. ±1 Cement + SCM (cumulative weighing), wt. ±1 Water, wt. or volume ±3 Fine aggregate, wt. ±2 Coarse aggregate, wt. ±2 Fine + coarse aggregate (cumulative weighing), wt. ±1 Chemical admixtures, wt. or volume ±3

Table 10 Measurement Tolerances – Volumetric Mixers

Material Tolerance Cement, wt. % 0 to +4 SCM, wt. % 0 to +4 Fine aggregate, wt. % ±2 Coarse aggregate, wt. % ±2 Admixtures, wt. or volume % ±3 Water, wt. or volume % ±1

3.5 MIXING AND DELIVERING CONCRETE

The Contractor shallmix and deliver concrete by means of one of the following operations: central-mixed, shrink-mixed, truck-mixed, volumetric mixer-mixed, or hand-mixed.

The Contractor shall operate mixers and agitators within the limits of the rated capacity and speed of rotation for mixing and agitation as designated by the manufacturer of the equipment. For shrink-mixed and truck-mixed concrete, when there is a reason to suspect the uniformity of concrete delivered using a truck mixer or truck agitator, conduct slump tests of two (2) individual samples taken after discharging approximately fifteen and eighty-five percent (15% and 85%) of the load as a quick check of the probable degree of uniformity; take the two (2) samples within an elapsed time of at most fifteen (15) minutes. If the slumps of the two (2) samples differ by more than the values shown in Table 11, investigate the causes and take corrective actions including adjusting the batching sequence at the plant and the mixing time and number of revolutions. Delivery vehicles that fail to meet the mixing uniformity requirements must not be used until the condition is corrected.

USIBWC Contract No.: IBM09B0004 Page 60.21.00 - 15

Table 11 Slump Tolerance1

Average Slump Slump Tolerance2 4 in. or less 1.0 in.

4 to 6 in. 1.5 in.

1 Do not apply these tolerances to the required slumps in Table 8.

2 Maximum permissible difference in results of test of samples from 2 locations in the concrete batch.

Re-tempering or adding concrete chemical admixtures is only permitted at the job site when concrete is delivered in a truck mixer. Do not add water after the introduction of mixing water at the batch plant except on arrival at the job site, with compliance-confirmation, to adjust the slump of the concrete. When this water is added, do not exceed the mix design water–cementitious-material ratio. Turn the drum or blades at least thirty (30) additional revolutions at mixing speed to ensure thorough and uniform mixing of the concrete. Do not add water or chemical admixtures to the batch after any concrete has been discharged. Maintain concrete delivery and placement rates sufficient to prevent cold joints. Before unloading, furnish the delivery ticket for the batch of concrete. When the concrete contains silica fume, adjust mixing times and batching operations as necessary to ensure the material is completely and uniformly dispersed in the mix. The dispersion of the silica fume within the mix will be verified by using cylinders made from trial batches. If uniform dispersion is not achieved, make necessary changes to the batching operations until uniform and complete dispersion of the silica fume is achieved.

A. Central-Mixed Concrete. The Contractor shall provide concrete that is mixed completely in a stationary mixer; mix concrete for a period of one minute for one cubic yard and fifteen seconds for each additional cubic yard of rated capacity of the mixer unless mixer performance test data demonstrate that shorter mixing times can be used to obtain a uniform mix in accordance with Tex-472-A; count the mixing time from the time all the solid materials are in the drum; charge the mixer so that some water will enter before the cement and aggregate; ensure that all water is in the drum by the end of the first one-quarter (1/4) of the specified mixing time; adjust the mixing time if necessary to achieve a uniform mix. Concrete mixed completely in a stationary mixer must be delivered to the project in a truck mixer, truck agitator, or non-agitating delivery vehicle.

When a truck mixer or truck agitator is used for transporting concrete, use the manufacturer’s designated agitating speed for any turning during transportation. Non-agitating delivery vehicles must be clean and free of built-up concrete with adequate means to control concrete discharge.

Deliver the concrete to the project in a thoroughly mixed and uniform mass, and discharge the concrete with a satisfactory degree of uniformity. Resolve questions regarding the uniformity of the concrete by testing in accordance with Tex-472-A.

B. Shrink-Mixed Concrete. The Contractor shall provide concrete that is first partially mixed in a stationary mixer and then mixed completely in a truck mixer. Partially mix for the minimum time required to intermingle the ingredients in the stationary mixer, and then transfer to a truck mixer and mix the concrete at the manufacturer’s designated mixing speed for an adequate amount of time to produce thoroughly mixed concrete. Deliver the concrete to the project in a thoroughly mixed and uniform mass, and discharge the concrete with a satisfactory degree of uniformity.

C. Truck-Mixed Concrete. The Contractor shall mix the concrete in a truck mixer from seventy to

USIBWC Contract No.: IBM09B0004 Page 60.21.00 - 16 one hundred (70 to 100) revolutions at the mixing speed designated by the manufacturer to produce a uniform concrete mix. Deliver the concrete to the project in a thoroughly mixed and uniform mass and discharge the concrete with a satisfactory degree of uniformity. Additional mixing at the job site at the mixing speed designated by the manufacturer is allowed as long as concrete is discharged before the drum has revolved a total of three hundred (300) revolutions after the introduction of the mixing water to the cement and the aggregates.

D. Volumetric Mixer-Mixed Concrete. Unless otherwise specified or permitted, the Contractor shall perform all mixing operations in accordance with manufacturer’s recommended procedures.

Provide an accurate method of measuring all ingredients by volume, and calibrate equipment to assure correct measurement of materials within the specified tolerances.

E. Hand-Mixed Concrete. When permitted, for small placements of less than two (2) cubic yards, the Contractor shall mix up to a 2-sack batch of concrete by hand methods or in a small motor-driven mixer. For such placements, proportion the mix by volume or weight.

3.6 PLACING, FINISHING, AND CURING CONCRETE

The Contractor shall place, finish, and cure concrete in accordance with the pertinent Items.

3.7 SAMPLING AND TESTING OF CONCRETE

Unless otherwise specified, all fresh and hardened concrete is subject to testing as follows:

A. Sampling Fresh Concrete. The Contractor shall provide all material to be tested. Fresh concrete will be sampled for testing at the discharge end if using belt conveyors or pumps. When it is impractical to sample at the discharge end, a sample will be taken at the time of discharge from the delivery equipment and correlation testing will be performed and documented to ensure specification requirements are met at the discharge end.

B. Testing of Fresh Concrete.

(1) Air Content. Tex-414-A or Tex-416-A.

(2) Slump. Tex-415-A.

(3) Temperature. Tex-422-A.

(4) Making and Curing Strength Specimens. Tex-447-A.

C. Testing of Hardened Concrete. Only compressive strength testing will be used unless otherwise specified or shown on the plans.

(1) Compressive Strength. Tex-418-A.

(2) Flexural Strength. Tex-448-A.

(3) Maturity. Tex-426-a.

D. Certification of Testing Personnel. Contractor personnel performing testing must be either ACI-certified or qualified by a recognized equivalent written and performance testing program for the tests being performed. Personnel performing these tests are subject to Government compliance-confirmation. Use of a commercial laboratory is permitted. All personnel performing testing using the maturity method must be qualified by a training program recognized by the Government

USIBWC Contract No.: IBM09B0004 Page 60.21.00 - 17 before using this method on the job.

E. Adequacy and Acceptance of Concrete. For any concrete that fails to meet the required strengths as outlined below, investigate the quality of the materials, the concrete production operations, and other possible problem areas to determine the cause. Take necessary actions to correct the problem including redesign of the concrete mix. The Government may suspend all concrete operations under the pertinent Items if the Contractor is unable to identify, document, and correct the cause of the low strengths in a timely manner. Resume concrete operations only after obtaining compliance-confirmation for any proposed corrective actions.

(1) Structural Concrete. For concrete classes identified as structural concrete in Table 5, make and test 7-day and 28-day specimens. Acceptance will be based on the design strength given in Table 5.

(2) The adequacy of the concrete will be evaluated by comparing 7-day test results to the target value established in accordance with “Trial Batches.”

(3) All Other Concrete. For concrete classes not identified as structural concrete in Table 5, make and test 7-day specimens. Acceptance will be based on the 7-day target value established in accordance with “Trial Batches.”

F. Test Sample Handling. Unless otherwise shown on the plans, the Contractor shall remove forms and deliver test specimens to curing facilities, in accordance with pertinent test procedures; the Contractor shall clean and prepare forms for reuse.

G. Test Reporting Frequency. Test results will be made immediately available to the COR upon request. The Contractor shall provide a certified hard-copy of each test report to the COR within 24-hours of each test result or as requested by the COR.

PART 4 – MEASUREMENT AND PAYMENT

The Work performed by the Contractor under this specification shall not be paid for directly, but shall be considered subsidiary to the various Bid Items under this Contract.

- END OF SPECIFICATION -

USIBWC Contract No.: IBM09B0004 Page 60.21.00 - 18

This Page Intentionally Blank