CEMENT TREATED BASE 317.03
311.06 Basis of Payment
The Department will pay for each pay item at the contract unit price per the specified pay unit as follows: Pay Item: Pay Unit:
A.PROCESSING EXISTING BASE AND SURFACE, METHOD A Linear Foot [Meter]
B.PROCESSING EXISTING BASE AND SURFACE, METHOD B Linear Foot [Meter]
C.PROCESSING EXISTING BASE AND SURFACE, METHOD C Linear Foot [Meter]
D.PROCESSING EXISTING BASE AND SURFACE, METHOD D Linear Foot [Meter]
317.01 Description
This work consists of constructing a cement treated base (CTB) using a soil, aggregate, and cement mixture.
317.02 Materials
Provide material in accordance with the following subsections: Material: Subsection: Portland Cement 701.02 Water 701.04 Fly Ash 702.01 Curing Agents 701.07.C Aggregates 703.02 Geotextiles for Bond Breakers 712.1 Provide aggregates that conform to the requirements of Subsection 703.02 , except ensure that the aggregate has an Aggregate Durability Index of at least 30, tested in accordance with AASHTO T 210.
317.03 Equipment
Use equipment for producing and placing the CTB in accordance with Subsection 301.03, “Equipment,” except, only use stationary plants and equipment that combines placement and initial compaction.
317.04 Cement Treated Base
194 317.04 CONSTRUCTION METHODS
A.Mix Design and Proportioning Design CTB mixtures in accordance with OHD L -53. Ensure Portlan d cement is at least 75% of the total cementitious materials in the mix. Submit a CTB mix design to the Engineer at least seven (7) days prior to the beginning of paving. At a minimum, include the following information with each CTB mix design: Project i dentification Name and address of the Contractor and producer A unique mix design name Aggregate sources Gradations for each aggregate source. Sieve sizes shall include the 1 ½ in [37.5 mm], 1 in [25 mm], ½ in [12.5 mm], No. 4 [4.75 mm], No. 40 [425 µm], and the No. 200 [75 µm] Hydraulic cement type and source Types of cement replacement, if used, and sources Types of admixtures and sources, if used Material proportions Combined gradation charts Unit weight Compressive strength at 7 days
B.Mixing Handle and measure materials, batching, and mixing in accordance with Subsection 414.04.C, “Mixing Concrete, ” except only use a central mix plant which has been approved by the Engineer.
C.Placem ent Moisten the surface of the compacted subgrade before spreading the CTB, unless the subgrade has been primed. Finish and compact the CTB to produce a smooth, dense surface that is free of surface compaction planes, cracks, ridges, or loose material. Compact the CTB within two (2) hours of adding water to the aggregate and cement. Follow the recommendations of the mix design. Compact the CTB to at least 95% of the maximum density and test in accordance with OHD L -54. Place the CT B in a single layer. Ensure the compacted thickness is in accordance with the dimensions shown on the plans and in compliance with Subsection 301.04.A, “Tolerances.” After strike off and consolidation, finish the CT B to meet the required elevation and cross section, and to create a smooth surface. Use equipment that automatically controls both grade and line to trim the surface of the CTB. Keep the CTB surface moist during finishing operations, and until the applica tion of the curing agent. Apply a curing agent on the finished CTB surface at the rate of at least 1 gal per 150 ft2 [2 L per 7 m2]. Use butt or sawed longitudinal construction joints; those between the driving lanes shall match the longitudinal joint of overlying pavement. Place other longitudinal joints within 3 ft [1 m] of the longitudinal joint of the overlying pavement and construct transverse construction joints as butt joints. CEMENT TREATED BASE 317.06 Before placing the separator fabric, sweep the CTB surface. Place and secure the separator fabric onto the surface of the CTB in such a manner that the fabric remains free of wrinkles and cracks. Secure the separator fabric with asphalt binder, mechanical fasteners, or other method approved by the Engineer. Overlap the fab ric 8 in [20 cm] both longitudinally and transversely. Limit construction traffic on the CTB to that necessary to apply the separator fabric and overlying pavement. Do not use the CTB layer as a haul road. Allow only concrete delivery trucks necessary to deposit fresh concrete directly in front of the paver. Place overlying pavement on the base after compressive strengths reach at least 600 psi [4,150 kPa] in accordance with OHD L -54. Repair damage to the CTB at no additional cost to the Department.
D.Weather Limitations Do not mix CTB if the aggregate or subgrade is frozen. Mix and place CTB when the ambient air temperature is at least 40 °F [5 °C] and rising. Protect CTB from freezing for seven (7) days after placement.
E.Tole rances Finish the CTB in accordance with Subsection 301.04.A, “Tolerances.”
F.Acceptance The Engineer will base pay adjustments for strength on a lot by lot basis. A lot w ill normally be defined as 10,000 yd² [8,361 m2] (four sublots of 2,500 yd² [2,090 m2] each). The Contractor will be responsible for making test cylinders and determining compressive strength of the CTB in accordance with OHD L -54. At least one cylinder w ill be made for testing from a random location in each sublot in accordance with OHD L -54. Strength of plant mix CTB shall be between 600 psi [4,150 kPa] and 2,000 psi [13,800 kPa]. The Engineer is responsible for performing compaction tests during placem ent of the CTB using a nuclear density gauge in accordance with OHD L -54. At least one (1) test will be performed from a random location in each sublot in accordance with OHD L -54. The Engineer will reject any load of mixture that is visually unacceptable for reasons of being too wet, excessively segregated, or otherwise obviously deficient. Replace rejected CTB at no additional cost to the Department. When replacing rejected CTB, remove a width of at least one lane and a length of at least 15 ft [4.5 m]. If the removal is within 15 ft [4.5 m] of any transverse joint, remove to the joint.
317.05 Method of Measuremen T
The Resident Engineer will measure the surface area of the completed Cement Treated Base placed at the thickness shown on the Plans.
317.06 Basis of Payment
The Department will pay for each pay item at the contract unit price per the specified pay unit as follows:
317.06 Cement Treated Base
196 Pay Item: Pay Unit: CEMENT TREATED BASE Square Yard [Square Meter] Include the cost of curing agent, separator fabric, and method of fastening in the contract unit price for Cement Treated Base . The Department will use Table 317:1 to calculate the strength pay factor for CTB extents with strengths less than or greater than the s pecified requirements: Table 317:1 Acceptance Pay Factors Strength Pay Factor < 600 psi Remove & Replace 600 psi - 2,000 psi 1 2,000 psi - 4,000 psi 1.00 - ((Actual Strength - 2,000) ÷ 2,000)2 > 4,000 psi Remove & Replace Multiply the contract price by the Strength Pay Factor for the represented CTB extent. Check any outlying concrete cylinder breaks in accordance with ASTM E 178 Table 1, “Upper 10% Significance Level.” The Department will consider the cost of separator fabric a nd method of fastening to be included in the contract unit price for Cement Treated Base . ECONOCRET E BASE 318.04 SECTION 318 ECONOCRETE BASE
318.01 Description
This work consists of the construction of an econocrete base.
318.02 Materials
Provide material in accordance with the following subsections: Material: Subsection: Aggregate 703.02 Portland Cement 701.02 Water 701.04 Air Entraining Agent 701.03 Fly Ash 702.01 Chemical Admixtures 701.03 Curing Agents 701.07
318.03 Equipment
Use equipment for producing and placing the econocrete base in accordance with Subsection 414.03, “Equipment.”
318.04 Construction Methods
Use the absolute volume method for a cubic yard [cubic meter] to design the econocrete base mix proportions. Identify the following in the design: The source of each material, The proportion of each material, The properties of the mixture, and The compressive str ength of the mix at 28 days. Submit the mix design to the Resident Engineer for approval at least 40 days before placing the econocrete base. Ensure the mix design meets the following criteria: The mix requires a cement content of at least 200 lb/yd³ [11 8 kg/m³]. The Contractor may substitute up to 25 percent of the cement content with fly ash at a ratio of 1 lb [1.0 kg] of fly ash per 1 lb [1.0 kg] of cement. Do not use fly ash from November 1 through April 1. The mix produces a maximum slump of 3 in [75 mm]. The mix produces an air content of from 4 to 12 percent.
Source: Oklahoma Standard Specifications for Highway Construction, 2019 Edition. Pages 207–210 of 935.