Published by department of transportation

28-1.03 CONSTRUCTION

28-1.03A General

28-1.03B Subgrade Preparation

1. Free of loose and extraneous material

2. Uniformly moist, but free of standing or flowing water

28-1.03C Placing

Spread, screed, shape, and consolidate concrete base under section 40-1.03F(4) or under section 40-1.03F(5) except where there are confined work areas. If authorized for confined work areas, you may:

1. Spread and shape concrete base using suitable powered finishing machines and supplement with hand work as necessary.

2. Consolidate the base using high-frequency internal vibrators within 15 minutes after depositing the base on the subgrade.

3. Vibrate such that adequate consolidation occurs across the full paving width. Do not use vibrators for extensive weight shifting of the concrete base.
Contraction joints must comply with section 40-1.03B(3).

28-1.04 PAYMENT

The payment quantity for asphaltic emulsion (concrete base) is determined from the gauge reading on the curing seal equipment.

28-2.01 GENERAL

28-2.01A Summary

28-2.01B Definitions

28-2.01C Submittals

28-2.01C(1) General

At least 10 days before field qualification, submit:

1. Aggregate qualification test results

2. Proposed aggregate gradation

3. Mix design, including:

3.1. Proportions

3.2. Types and amounts of chemical admixtures

4. Optional notice of intent to produce LCB qualifying for a transverse contraction joint waiver under section 28-2.03D

28-2.01C(2) Field Qualification

For each field qualification test, submit 6 of the 12 cylinders within 24 to 72 hours after preparing them.

Submit field qualification data and test reports including:

1. Mixing date

2. Mixing equipment and procedures used

3. Batch volume in cubic yards, the minimum is 5 cu yd

4. Type and source of ingredients used

5. Age and strength from compression strength results
The test reports must be signed by the person in responsible charge of the laboratory performing the tests.

28-2.01D Quality Assurance

28-2.01D(1) General

The molds for compressive strength testing under ASTM C31 or ASTM C192 must be 6 by 12 inches.

If the aggregate gradation or sand equivalent test results comply with the contract compliance requirements but not the operating range requirements, you may continue placing LCB for the remainder of the work day. Do not place additional LCB until you demonstrate the LCB to be placed complies with the operating range requirements.

28-2.01D(2) Qualifications

Field qualification tests and calculations must be performed by an ACI certified "Concrete Laboratory Technician, Grade I.

28-2.01D(3) Aggregate Qualification Testing

Qualify the aggregate for each proposed aggregate source and gradation. The qualification tests include (1) a sand equivalent and (2) an average 7-day compressive strength under ASTM C39 of 3 cylinders manufactured under ASTM C192.

For the compressive strength test, the cement content for each cylinder must be 300 lb/cu yd. The 7-day average compressive strength must be at least 610 psi. The cement must be Type II portland cement.

LCB must have from 3 to 4 percent air content during aggregate qualification testing.

28-2.01D(4) Field Qualification Testing

Before placing LCB, you must perform field qualification testing and obtain authorization for each mix design. Retest and obtain authorization for changes to the authorized mix designs.

Notify the Engineer at least 5 business days before field qualification. Perform the field qualification at the job site or an authorized location.

Field qualification testing includes tests for compressive strength, air content, and penetration or slump.

For compressive strength field qualification testing:

1. Prepare 12 cylinders under ASTM C31 from a single batch.

2. Perform 3 tests; each test consists of determining the average compressive strength of 2 cylinders at 7 days under ASTM C39. The average compressive strength for each test must be at least 530 psi

If you submitted a notice to produce LCB qualifying for a transverse contraction joint waiver, manufacture additional specimens and test the LCB for compressive strength at 3 days. Prepare the compressive strength cylinders under ASTM C31 at the same time using the same material and procedures as the 7-day compressive strength cylinders except do not submit 6 additional test cylinders. The average 3-day compressive strength for each test must be not more than 500 psi.

28-2.01D(5) Quality Control

Provide a testing laboratory to perform quality control tests. Maintain sampling and testing equipment in proper working condition.

Test the LCB under the test methods and at the locations and frequencies shown in the following table:

LCB Sampling Location and Testing Frequencies
Quality characteristic	Test method	Sampling location	Minimum sampling and testing frequency
Sand equivalent	ASTM D2419	Source	1 per 500 cubic yards but at least 1 per day of production
Aggregate gradation	ASTM C136
Air content	ASTM C231	Job site
Penetrationa	ASTM C360
Slumpa	ASTM C143
Compressive strength	ASTM C39 b
aTest for either penetration or slump bPrepare cylinders under ASTM C31

28-2.01D(6) Department Acceptance

The Department accepts LCB based on compliance with the requirements shown in the following table:

LCB Requirements for Acceptance
Quality characteristic	Test method	Requirement
Compressive strength (min, psi at 7 days)	ASTM C39 a	530 b
a Cylinders prepared under ASTM C31 b A compressive strength test represents up to (1) 1,000 cu yd or (2) 1 day's production if less than 1,000 cu yd.

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