301Soil-Cement Construction

301.1General Description

This work includes constructing a base, subbase, or shoulder course composed of soil, or a mixture of soils, and stabilizing with Portland cement. Construct according to these Specifications and conform to the lines, grades, and typical sections shown on the plans or established by the Engineer. Requirements for the mix design, quality control and quality acceptance testing will be controlled by Standard Operating Procedures 29 (SOP 29). The provisions in Section 300 apply to this Item. 301.1.01 Definitions Mixed in Place Construction - This method of construction is used when the Plans and Proposal indicate that the Work will be paid by the square yard (meter). The plans will indicate the method of construction and depth of base unless otherwise directed by the Engineer.

construction. Requirements for the submittal will be controlled by SOP 29.

approves, use materials in the roadbed without additional payment, except for the payment per square yard

or to modify the physical properties of the existing materials, these materials will be paid for as soil-cement material. Central Plant Mixed Construction - This method of construction is used when the plans and proposal indicate that the Work will be paid by the ton (megagram). The plans will indicate the method of construction and depth of base unless otherwise directed by the Engineer.

material. Borrow pits will be sampled under the authority of the District Materials Engineer.

to construction. Requirements for the submittal will be controlled by SOP 29.

use materials in the pit without additional payment, except for the payment per square yard (meter) provided in Subsection 301.5.A, Soil-Cement Material. Accreditations

SOP – Georgia Department of Transportation Standard Operating Procedures 288 288 288 288 288 288 288 288 288

301.1.02 Related References

GDT 19 GDT 20 GDT 21 GDT 59 GDT 65 GDT 67 GDT 86 GSP 16 SOP 29 AASHTO T 134 AASHTO R18 301.1.03 Submittals

Prior to construction, submit a written Construction Work Plan to the Engineer for approval which shall include the following:

289 289 289 289 289 289 289 289 289

For both Mixed in Place and Central Plant Mixed Construction, the Contractor shall submit a mix design package to the Office of Materials and Testing for approval at least three weeks prior to construction. The Mix Design process shall be completed in accordance with GDOT Test Method 65/GDT 65 by an accredited materials laboratory. The sampling, testing, proportioning and documentation shall be completed by an accredited materials laboratory. The Contractor will be responsible for ensuring that appropriate traffic control measures are in place during the sampling operations. The Portland cement used in the design process must be from an approved source listed on GDOT’s Qualified Products List/QPL3 and representative of the same material to be used in construction. (Mixed in Place Construction). In-place samples of the road structure shall be taken at a minimum frequency of 1000 feet (300m) per two lanes; alternating the sample locations to achieve a sample every 500 lane-feet (152m). Additional samples may be needed to represent material changes and/or problem areas. Each sample shall contain at least 20 lbs. (14kg) of proportionally blended material from the roadway. (Central Plant Mixed Construction) The Contractor shall be responsible for locating the source of soil material. The borrow pit is to be sampled in accordance with Georgia Sampling Procedure 16/GSP 16. Borrow pits will be under the authority of the District Materials Engineer. The mix design package shall include the following:

the roadway

301.2Materials

Ensure that materials meet the requirements of the following specifications: Material Specification Soil-Cement Material Subsection 814.2.02 Portland cement (Type I or Type II) Subsection 830.2.01 Water Subsection 880.2.01 Cutback asphalt, RC-30, RC-70, RC-250 or MC-30, MC- 70, MC-250 Subsection 821.2.01 Emulsified Asphalt, EAP, AEP Subsection 822.2.01 Cationic Asphalt, CSS-1h, CRS-2 Subsection 824.2.01 Blotter Material (Sand) Subsection 412.3.05.G.3 301.2.01 Delivery, Storage, and Handling General Provisions 101 through 150. Note: Since the Mix Design is based on source specific materials, any changes to materials, sources, or types will render the design invalid. 290 290 290 290 290 290 290 290 290

301.3Construction Requirements

Mix and place cement-treated base or subbase only when the weather permits the course to be finished without interruption in the time specified. Mix and place materials only when the moisture content of the soil to be used in the mixture meets the limits specified in this Subsection 301.3.05.B.7.c, Moisture Control. Begin mixing only when the air temperature is above 40 °F (4 °C) in the shade and rising. Ensure that the temperature of the soil to be used in the mixture and the subbase or subgrade is above 50 °F (10 °C).

If the work is interrupted for more than two hours after cement has been added, or if rain increases the cement’s moisture content outside the limits specified in Subsection 301.3.05.B.7.c, Moisture Control, remove and replace the affected portion at no additional cost to the Department. 301.3.01 Personnel General Provision 101 – 150 301.3.02 Equipment Use equipment that meets the requirements of Subsection 300.3.02 and this subsection. The Engineer will approve equipment type and condition before construction begins. Provide sufficient equipment in good working condition to do the following:

and capable of metering the spread rate being placed.

materials. The use of disk harrows will not be allowed for the mixed-in-place soil-cement base construction method. Mixer shall be inspected by the Engineer daily and tines with more than 25% wear must be replaced.

should be inspected daily and tines with more than 25 percent wear must be replaced.

301.3.03 Preparation

Subsection 300.3.03.D, Preparing the Subbase if the base, subbase, or shoulders will be composed entirely of new materials, whether mixed-in-place or central plant mixed. In addition to the above requirements, ensure that the subgrade materials used underneath the soil-cement base meets the sulfates and PH requirements of Subsection 814.2.02.A. Place materials only on dry, thawed subgrade or subbase.

graded with a fine grader as outlined in Subsection 300.3.02.H. 291 291 291 291 291 291 291 291 291

301.3.04 Fabrication General Provisions 101 through 150. 301.3.05 Construction

If additional soil is needed on the roadbed, place and spread the soil uniformly to the proper depth to obtain the specified thickness.

Pulverize the roadbed materials as follows:

damaging the underlying subgrade.

and until at least 80 percent of the soil, excluding any stone or gravel, passes through a No. 4 (4.75 mm) sieve.

Immediately before spreading cement, adjust the moisture content of the in-place material so it will stabilize to within 100 to 120 percent of optimum moisture (amount of moisture in the mixture at maximum dry density).

Spread cement as follows:

its equivalent.

amount specified. Furnish a square-yard cloth, scales and personnel for checking the spread rate of cement placed.

affected area within the tolerance specified and recalibrate the mechanical spreader’s spread rate. If the cement content is more than the 10 percent limit in the mixing area, the excess quantity will be deducted from the Contractor’s pay for cement.

compacting and finishing operations specified in Subsection 301.3.05.B.7, Compacting and Finishing can be completed within the required time limits.

does not displace cement.

• Hydration due to rain, before or during mixing operations

• Spreading procedures contrary to the requirements mentioned above

• Displacement by the Contractor’s equipment or other traffic 292292292292292292292292292

Mix the material as follows:

Begin mixing as soon as practical after the cement is spread and continue until a homogeneous and

uniform mixture is produced. If the equipment does not produce a homogeneous and uniform mixture

meeting these specifications, make any necessary changes to meet the Engineer’s requirements.

Perform multiple pass mixing as follows:

1) After spreading the cement, mix it with the material to be treated.

2) Ensure that the material has been adjusted for moisture as stated in

Subsection 301.3.05.B.7.c, Moisture Control.

3) Continue mixing with successive passes until a uniform mixture of cement and soil, or soil-aggregate

is obtained.

4) Immediately after the preliminary mixing of cement and soil or soil-aggregate, add water as needed to

maintain or bring the mixture to within the moisture requirements of

Subsection 301.3.05.B.7.c, Moisture Control.

5) Uniformly mix the additional water to incorporate it into the full depth of the mixture.

Compact and finish according to Subsection 301.3.05.B.7, Compacting and Finishing.

Do the following:

(37.5 mm) sieve.

(4.75 mm) sieve.

a Pit for at least one day of base construction before operations begin.

Do the following:

Uniformly add cement into the mixture. The cement incorporated, per ton (megagram) of soil, shall be

within ±5 percent of the amount prescribed by the Engineer.

cement specified in the approved Mix Design for the Project on each of the first two tankers supplying

cement to the plant. If these checks are within the specified tolerance, one cement check per day will

be required.

certified scales and the plant computer to ensure the proper percentage of cement is being incorporated

into the mixture between cement checks.

required before returning to a one cement check per day basis. When three consecutive cement checks

fail to meet the specified tolerance, discontinue soil-cement plant production. Correct the problem, and

recalibrate the plant as specified in Subsection 300.3.06.A Monitoring Quality Control before resuming

the work. 293293293293293293293293293

from the Contractor’s pay for cement. When the cement content does not meet the specified tolerance,

the Engineer will evaluate the strength of the affected area after 7 days.

additional cost to the Department, regardless of the percent of compaction. This correction also applies

to the test section described in Subsection 301.3.05.B.7.a, Test Section.

for cement.

Do the following:

homogeneously mixed or does not meet the moisture range specified in Subsection 301.3.05.B.7.c,

Moisture Control, cease plant operations until corrections are made in the plant or to the materials.

Do the following:

water have been charged into the mixer.

over the sides and the end of the bed of each haul vehicle.

Spread the soil-cement mixture as follows:

specified thickness. Spread the mixture the full width of the area to be covered.

material until compaction equipment has made initial passes over the mixture.

lanes at any location, unless longitudinal joints are specified.

Compact the soil-cement base to a maximum thickness of 8 in. (200 mm). Place the full thickness in one

course only and compact as specified in Subsection 301.3.05.B.7, Compacting and Finishing below.

Construct a test section as follows:

1) Use the first section of each constructed soil-cement base course as a test section.

2) Use a test section between 350 ft. (100 m) and 500 ft. (150 m) long for the designated width.

3) Before constructing a test section, submit a Construction Work Plan to the Engineer for approval. The

Construction Work Plan must indicate proposed equipment and compaction procedures.

4) If the Construction Work Plan is approved, the Engineer will evaluate the Work Plan during test

section construction. The Engineer will evaluate compaction, moisture, homogeneity of mixture,

thickness of course, and laminations or compaction planes (scabbing).

5) If the Engineer determines that the Work Plan is not satisfactory, revise the compaction procedure

and augment or replace equipment, as necessary, to complete work according to the specifications. 294294294294294294294294294

Observe the following time limits:

1) Begin compaction within 45 minutes of the time water is added to the soil-cement mixture.

2) Complete compaction within 2 hours.

3) Complete all operations in four hours, from adding cement to finishing the surface.

Control moisture as follows:

1) During compaction, ensure a uniform moisture content of the mixture that is between 100 and 120

percent of the optimum moisture content.

2) If the moisture content exceeds the tolerance at any time, cease operations immediately and make

the adjustments necessary to bring the moisture content within tolerance.

3) Do not use materials that “pump” under construction traffic, regardless of moisture content.

Perform the following additional compaction requirements:

1) Compact the soil-cement base, subbase, or shoulder course to at least 98 percent of the maximum

dry density as determined in this Subsection.

2) Do not perform vibratory compaction on materials more than 1-1/2 hours old, measured from the

time the cement was added to the mixture.

3) Uniformly compact the mixture and then fine-grade the surface to the line, grade, and cross-section

shown on the Plans.

4) Loosened material accumulated during this process is considered waste and is to be removed from

the Project. Do not use additional layers of cement-treated materials in order to conform to cross-

sectional or grade requirements.

5) Use a pneumatic-tired roller to roll the finished surface until the surface is smooth, closely knit, free

from cracks, and in conformance with the proper line, grade, and cross-section.

If the Engineer requires, lightly apply water to the finished surface to aid in sealing the completed

base and preparing the surface for priming.

6) At any place inaccessible to the roller, secure the required compaction with mechanical tampers

approved by the Engineer. The same compaction requirements stated in the above subsection apply.

Perform the following additional finishing requirements:

1) Use the automatically controlled screed equipment when required by Subsection 300.3.03.H, Fine

Grading Machine of the Specifications. Control fine-grading for this requirement with sensing wires

or a taut string line. Furnish, install, and maintain this operation as a part of this Pay Item. When

automatically controlled screed equipment is not required, fine-grading with motor graders

is permitted.

2) Fine-grade the surface of the cement-stabilized subbase for Portland cement concrete pavement or

the cement-stabilized base for asphaltic concrete pavement.

3) Fine-grade immediately after placement and compaction. Roll the subbase again according to

this subsection.

Form construction joints as follows:

that the material cannot be compacted within the time limit specified in this subsection.

free of loose or shattered material. 295295295295295295295295295

rest at the end of the day’s work, or at the point of interruption.

is impractical to complete the full width during one day’s work. Use the procedure for forming a straight

transverse joint. Ensure that waste material is removed from the compacted base.

Apply bituminous prime to the finished surface of the base course at the end of each day or as soon as the

Engineer determines it is practical. Apply prime only to an entirely moist surface.

If weather delays prime application, apply prime as soon as the surface moisture is adequate. Apply prime

according to Section 412.

Apply a single #89 surface treatment layer over the primed base course.

No traffic or equipment is permitted to operate on the finished base, subbase, or shoulders until the prime has

hardened enough so that it does not pick up under traffic. For the first seven days after priming, traffic is

restricted to lightweight vehicles such as passenger cars and pickup trucks. Vehicles with an average axle

load exceeding 20,000 pounds (9 Mg) will not be allowed on the finished base or subbase at any time.

Correct any failures caused by traffic at no additional cost to the Department.

Maintain the base, subbase, or shoulder course constructed under these specifications until the Engineer

determines that it has sufficiently cured and is ready to be covered with the next base or pavement course.

Make repairs specified in Subsection 300.3.06.B, Repairing Defects whenever defects appear. This preservation

action does not relieve the Contractor of his responsibility to maintain the work until final acceptance as specified

in Section 105.

301.3.06 Quality Acceptance

Test compaction as follows:

material to be compacted according to GDT 19.

compaction, but before the cement sets. Determine in-place density according to GDT 20, GDT 21, or

GDT 59.

Test the finished surface as follows:

• A template, cut true to the required cross-section and set with a spirit level on non-super

elevated sections

• A system of ordinates, measured from a string line

• A surveyor’s level

not exceed 1/4 in. (6 mm) at any point. Rod readings shall not deviate more than 0.02 ft. (6 mm) from the

required readings.

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where the shoulders will be surfaced. Do the following:

necessary to determine the average thickness.

determine the deficient area.

following methods according to these Specifications:

• Apply Asphaltic Concrete 9.5 mm Superpave.

• Remove material to the full depth of the course and reconstruct to the required thickness.

No payment will be made for any 9.5 mm Superpave asphaltic concrete applied to correct deficiencies

nor will payment be made for removing and reconstructing the deficient work.

Average thickness is measured as follows:

mile (kilometer) increment exceeds the allowable 1/2 in. (13 mm) tolerance, payment for the excess

quantity in that increment will be deducted.

(13 mm) tolerance by the surface area of the base, subbase, or shoulder, as applicable.

Do the following:

kPa), as determined from testing the unconfined compressive strength of cores from the completed

course in accordance with GDT 86.

1) Isolate the affected area by securing additional cores 75 ft. (22 meters) in each direction until passing

strengths are achieved.

2) Average all compressive strengths in the affected area to determine the basis for corrective work

according to the table below or the Engineer’s directions. 297297297297297297297297297

The compaction requirement for soil-cement base, subbase, or shoulder course shall be a minimum of

98 percent of the specified theoretical density.

If any compaction test falls below 98 percent, core and retest the represented area for compressive strength

determination after 7 days. If the strength is 300 psi (2070 kPa) or greater, no correction will be required. If the

strength is less than 300 psi (2070 kPa), isolate the affected area by obtaining additional cores.

Average all compressive strengths in the affected area to determine the basis for corrective work, according

to the following table.

Compressive Strength Corrective Work

Ensure that a corrected area requiring asphaltic concrete is at least 150 ft. (45 m) long.

Perform corrective work requiring asphaltic concrete or reconstruction at no additional cost to

the Department.

301.3.07 Contractor Warranty and Maintenance

General Provisions 101 through 150.

301.4Measurement

Soil-cement material is measured by the cubic yard (meter), loose volume, as specified in Section 109, during

mixed-in-place construction if it is necessary to add materials to the roadbed or to build up the base, subbase, or

shoulders with new material.

Soil-cement stabilized base, subbase, and shoulder course are measured as follows:

width is specified on the plans.

ton (megagram).

The actual weight is determined by weighing each loaded vehicle on a required motor truck scale as the material

is hauled to the roadway. The actual weight will be the pay weight; no deduction will be made for the weight of

the cement.

300 psi (2070 kPa) or greater None

200 psi (11380 kPa) to 299 psi (2062 kPa) 6 in. & 8 in. (150 mm & 200 mm) base - add 135 lbs./yd² (75

kg/m²) asphaltic concrete

Less than 200 psi (1379 kPa) Reconstruct the affected area 298298298298298298298298298

Portland cement is measured by the ton (megagram).

Bituminous prime is not measured for separate payment. Include the cost of furnishing and applying bituminous

prime according to the provisions of Section 412 in the Unit Price Bid for each individual base item.

Unsuitable materials that have been removed are measured and paid for according to the Earthwork Item in the

Contract.

301.4.01 Limits

General Provisions 101 through 150.

301.5Payment

Where in-place mixing is done, and when it is necessary to add other materials to those in the roadbed or to build

up the base, subbase, and shoulders entirely with new materials, the added soil-cement material, in place and

accepted, will be paid at the Contract Price per cubic yard (meter). Payment will be full compensation for soil-

cement material; mixing in the pit; loading, hauling, and unloading; and spreading

Where specified, soil-cement stabilized base, subbase, and shoulder course, in place and accepted, will be paid

at the Contract Price per square yard (meter). Payment will be full compensation for roadbed preparation, mixing

on the road, shaping, pulverizing, watering, compaction, defect repair, and maintenance.

Where specified, pre-mixed soil-cement stabilized base, subbase, and shoulder course, in place and accepted,

will be paid at the Contract Price per ton (megagram) or square yard (meter).

Payment will be full compensation for roadbed preparation; all materials except Portland cement; loading, hauling,

and unloading; mixing; spreading; watering; rolling and shaping; and maintenance.

Portland cement will be paid at the Contract Price per ton (megagram). Payment is full compensation for

furnishing, hauling, and applying the material. Only Portland cement incorporated in the finished course will be

paid; no payment will be made for cement used to correct defects due to the Contractor’s negligence, faulty

equipment, or plant calibration error. 299299299299299299299299299

Payment will be made under:

Item No. 301 Soil-cement material—including material and haul per cubic yard (meter)

Item No. 301 Soil-cement stabilized base, subbase, and shoulder

course ___in. (mm)

per square yard (meter)

Item No. 301 Pre-mixed soil-cement stabilized base, subbase, and

shoulder course—including material and haul

per ton (megagram) or per square yard

(meter)

Item No. 301 Pre-mixed soil-cement stabilized base and shoulder

course—including material and haul

per ton (megagram) or per square yard

(meter)

Item No. 301 Portland cement per ton (megagram)

301.5.01 Adjustments

General Provisions 101 through 150.. 300 300 300 300 300 300 300 300 300