SECTION 302 – AGGREGATE BASE COURSE
302.01 Description
This Section describes the requirements for constructing aggregate base courses.
302.02 Materials
302.02.01 Materials
Provide materials as specified: Dense-Graded Aggregate................................ ................................ ................................ .............................. 901.10 Soil Aggregate (I-5) ................................ ................................ ................................ ................................ ..... 901.11 Where I-5 soil aggregate is specified, the Contractor may substitute DGA with the approval of the RE.
302.02.02 Equipment
Provide equipment as specified: Pneumatic-Tired Compactor ................................ ................................ ................................ ........................ 1002.01 Dynamic Compactor ................................ ................................ ................................ ................................ ... 1002.02 Steel-Wheel Roller ................................ ................................ ................................ ................................ ...... 1002.03 Padfoot Roller ................................ ................................ ................................ ................................ ............. 1002.04
302.03 Construction
302.03.01 Soil Aggregate Base Course and Dense-Graded Aggregate Base Course
A.Preparing Subgrade or Subbase. Before placing base course on subgrade or subbase, prepare surfaces as specified in 301.03.01.
B.Density Control Strip. Obtain RE approval of the underlying surface before constructing the density control strip. Before constructing the aggregate base course, construct a density control strip using the same type of material from the same source as the aggregate base course. Construct additional density control strips if a change is made in the type or source of material, if a significant change occurs in the composition of the material from the same source, or if a change is made in the type of comp action equipment used, as determined by the ME. Provide at least 400 square yards for each density control strip. Construct a density control strip for each thickness specified for the aggregate base course. Ensure that the moisture content for the test strip material is within 2 percent of its optimum moisture content according to AASHTO T 99, Method C, including replacement option. Place and spread aggregate base course as specified in 301.03.01.B. Place the base course and compact within a tolerance of 1/2 inch of the required elevation. Ensure that no compacted lift exceeds a thickness of 8 inches. For base courses greater than 8 inches thick, construct the base course in 2 or more lifts of approximately equal thickness. Compact the density control strip using the same type and weight of equipment that will be used for compaction of the aggregate base course. Compact the density control strip with a minimum of 2 passes of the compaction equipment. A pass is defined as 1 passage of each compacting element in use of the compaction equipment over the entire surface of the course. After each pass of the compaction equipment transverses the density control strip, the ME will make 3 density determinations according to AASHTO T 310. Continue compacting until no appreciable increase in density is obtained by additional passes. After the Contractor completes compaction of the control strip, the ME will take at least 10 density tests at random locations to determine the average in -place dry density of the density c ontrol strip. If the average density of the material in the density control strip is equal to or greater than 95 percent of its maximum density, as determined according to AASHTO T 99, Method C, including replacement option, then use the value of this ave rage as the reference maximum density for courses of the same materials and thicknesses. Establish a density control strip satisfying the 95 percent density requirement, according to AASHTO T 99, Method C, before constructing additional base courses. If this density level in the density control strip is not achieved, the RE will reject the compaction equipment, its method of use, or both. If approved by the RE, the density control strips may remain in place and become a portion of the completed base course. The RE will check elevations, as specified in 202.03.03.D, of the roadbed base course to ensure that base course elevations are within ±1/2 inch.
C.Aggregate Base Course Placement. Construct the aggregate base course in the same manner as the approved density control strip. If less than 500 contiguous square yards of aggregate base course is being constructed, place and spread the aggregate base course as specified in 301.03.01.B. Place the base course and compact within a tolerance of 1/2 inch of the required elevation. Compact the base course areas as specified in 203.03.02.B.4 and ensure that no compacted lift exceeds a thickness of 8 inches. For base courses greater than 8 inches thick, construct the base course in 2 or more lifts of approximately equal thickness.
D.Thickness Requirements. The RE will measure thickness, by test holes or by calculating the difference in elevations between the base course and the underlying layer. Refill test holes with base course material and recompact using the directed method as specified in 203.03.02.B.3. If the total thickness of base course differs from specified thickness by more than 1/2 inch, correct deficient areas as follows:
1.Scarify the base course to a depth of 3 to 4 inches.
2.Ensure that remaining material is contaminant free.
3.Add or remove base course material to obtain the required grade while the existing surface is in a loose, scarified condition.
4.Compact using the same method used for the density control strip.
E.Compaction Acceptance Testing. The ME will divide the base course into lots of approximately 5,000 square yards or 1,000 cubic yards. The ME will test each lot of completed base course for compliance. Th e ME will determine the 5 locations for density tests using a table of random numbers. The ME will make 1 density determination at each of the selected locations. To determine acceptability, use the following procedure:
1.Formula. Calculate Q using the following formula: Q = Average Lot Density − 0.95 of the Reference Maximum Density Range of Lot Density Where average lot density is the average dry density of 5 randomly selected locations in the lot and the range of lot density is the absolute difference between the lowest and highest dry density values recorded at these same 5 locations. The reference maximum density is determined by the method specified in 302.03.01.B.
2.Criteria. Q must be equal to or greater than 0.36. If a lot is unacceptable, rework, or recompact the lot.
302.04 Measurement and Payment
The Department will measure and make payment for Items as follows:
Referenced in this section
Sections that cite this one
Aggregate Base Course in other states
Get an email when 302 changes
New Jersey revises spec sections through supplementals and new editions. We check this one every week and email you the day it changes. Free, no account.
Source: Standard Specifications for Road and Bridge Construction, 2019 (rev. 2022-12-21) Edition. Pages 177–178 of 651. View official source ↗