Job Special Provision


Title: Single Machine, One Pass Hot In-Place Recycling and Surfacing *

Name: Hot In-Place Recycling *

ID Number: JSP-04-18

Accountable Division: Construction and Materials

First Effective Bid Opening Date: 12/2007

Last Effective Bid Opening Date: 02/2008

Revision Date: 10/09/2007

Explanatory Notes: * Limited use. Only as approved by Construction and Materials Division
10/09/2007 - Previously MSP-04-11B. Added to the JSP database and provided new naming convention.
3/21/2008 - This provision was removed at the request of Construction and Materials Division and should not be used on any further projects due to proprietary operations described in the provision. Consult Construction and Materials Division for further guidance related to this type of operation.

Units: Dual

File Attachments: JSP0418.doc

Section: 0405 - Placing Reclaimed Bituminous Material

Single Machine, One Pass Hot In-Place Recycling and Surfacing JSP-04-18

1.0 Description. This work shall consist of hot in-place recycling of the existing asphalt surface in a simultaneous, multi-step process of cleaning, heating, milling/scarifying, rejuvenating, spreading and leveling the recycled material, and placement and compaction of virgin hot mix asphalt material over the recycled surface. This work shall be performed with a single machine that heats, scarifies, recycles and spreads virgin hot mix asphalt all in one continuous pass. Additional preheaters may be utilized to achieve specified depth and temperature.

2.0 Material. All material shall be in accordance with Division 1000, Material Details, and specifically as follows:

2.1 The grade and application rate of emulsified asphalt that is added to the recycled material shall be determined by the contractor prior to construction. The emulsified asphalt shall conform to one of the following sets of requirements:

Polymer Modified Asphalt Emulsion
Viscosity, SSF @ 50C100400100400
Storage Stabilityb Test, 24 hour, percent---1----1
Sieve Test, 850 m mesh (No. 20), percent---0.3---0.3
Oil distillate by volume of emulsion, percent
Residue from distillationc, percent
Test on Residue from Distillation
Penetration, 25C, 100 g, 5 seconds
Ductility, 4C, 5 cm/minute, cm
Ashd, percent
Float Test at 60C, sec.
Elastic Recoverye, percent150300300---

a All tests shall be performed in accordance with AASHTO T 59 except as noted.
b In addition to AASHTO T 59, upon examination of the test cylinder, and after standing
undisturbed for 24 hours, the surface shall show no appreciable white, milky colored
substance and shall be a homogeneous brown color throughout.
c AASHTO T 59 shall be modified to maintain a 204 C 5 C maximum temperature for
15 minutes.
d Percent ash shall be determined in accordance with AASHTO T 111, Ash in Bituminous
e Elastic recovery shall be determined as follows. Condition the ductilometer and samples
to be treated at 10 C. Prepare the brass plate, mold and briquet specimen in accordance
with AASHTO T 51. Keep the specimen at the specified test temperature of 10 C for 85 to 95 minutes. Immediately after conditioning, place the specimen in the ductilometer and proceed to elongate the sample to 20 cm at a rate of pull of 5 cm/min. After the 20 cm elongation has been reached, stop the ductilometer and hold the sample in the elongated position for 5 minutes. After 5 minutes, clip the sample approximately in half by means of scissors or other suitable cutting devices. Let the sample remain in the ductilometer in an undisturbed condition for one hour. At the end of this time period, retract the half sample specimen until the two broken ends touch. At this point note the elongation (x) in cm.

Calculate the percent recovery by the following formula:

% Recovery = 20 - X x 100

2.2 The virgin hot mix asphalt shall conform to Section 403 of the standard specifications except the point of sampling of virgin hot mix asphalt will be from the truck transports in accordance with AASHTO T168.

3.0 Equipment Requirements.

3.1 The contractor shall specify, to the engineer, the type of equipment intended for use. The equipment shall be on the project in general operating condition in sufficient time for evaluation by the engineer. The machine shall be a single, self-propelled mobile unit capable of heating, scarifying, rejuvenating, mixing, leveling the recycled material and immediately laying virgin hot mix asphalt over the recycled surface. The contractor shall be required to demonstrate required rate, depth and satisfactory recycling operations on the roadway before being allowed to commence full operations. If the equipment and/or recycling operations fail to meet requirements or provide unsatisfactory results, the contractor shall correct the operation or replace the equipment.

3.2 The machine shall contain a heating unit that shall be of a type specifically designed to heat the surface of the existing asphalt pavement. The unit shall be capable of uniformly heating surface to a temperature high enough to remove excess moisture and allow dislodging of the material to a minimum depth of 1.0 inch (25 mm), without breaking the aggregate particles. Heating shall be accomplished without burning or charring the existing pavement and without producing undesirable pollutants. The heating unit shall be so equipped that the application of heat will be under an enclosed or shielded hood to prevent damage to adjacent vegetation.

3.3 The machine shall contain a milling/scarifying unit that shall be capable of removing existing pavement to a minimum depth of 1.0 inch (25 mm). It shall be capable of loosening the existing pavement to a minimum depth of 1.0 inch (25 mm) without excessive breaking of the aggregate. It shall be equipped with individual height controls, in order to clear manholes and other obstructions in the pavement surface.

3.4 The machine shall contain an emulsified asphalt application system that shall automatically add emulsified asphalt to the scarified material at a uniform rate as shown on the plans or as directed by the engineer. The system shall equipped with a means to verify the quantity of emulsion. The application rate shall be synchronized with the forward speed of the machine to maintain the application rate with an allowable variation from the specified rate not to exceed 0.02 gallon per square yard (0.1 L/m2). The emulsified asphalt storage unit shall be thermostatically controlled to maintain the emulsified asphalt at a constant temperature specified by the supplier.

3.5 The machine shall contain a recycling unit that shall be capable of thoroughly mixing the scarified material with emulsified asphalt, producing a uniform, consistent final product.

3.6 The machine shall contain a spreading and leveling unit. It shall be capable of spreading and leveling the blended, mixed, recycled material uniformly over the width being processed to the grade and cross slope as shown on the plans. The unit shall be equipped with a leveling blade and augers capable of moving recycled material in a transverse direction to the center of the windrow. The unit shall also be equipped with a screed, which shall partially compact the recycled mix before placement of the top layer of virgin hot mix asphalt.

3.7 The machine shall contain a virgin hot mix asphalt unit that shall consist of a receiving hopper and conveying system to collect and transport virgin hot mix asphalt to the finishing unit.

3.8 The machine shall contain a finishing unit that shall be equipped with automatic grade controls. It shall be capable of spreading and leveling the virgin hot mix asphalt uniformly over the width being processed to the grade and cross slope as shown on the plans. The unit shall be capable of performing the functions of a bituminous paver as described in Section 403.9 of the Standard Specifications.

4.0 Construction Requirements.

4.1 The existing pavement surface to be recycled shall be cleaned of all dirt, fabric, oils or any other objectionable materials before beginning the hot in-place surface repaving.

4.2 The existing pavement surface shall be evenly heated, milled/scarified and reworked to a minimum depth of 1.0 inches (25 mm), and to the width shown on the plans. The surface of the existing pavement shall be heated with continuously moving heaters to allow the pavement to be scarified to a minimum depth of 1.0 inches (25 mm) in a single pass, hold the surface temperature of the existing pavement below 475 F (246 C), and produce recycled mix at a temperature of not less than 225 F (107 C). The heating operation shall extend at least 2.0 inches (50 mm) beyond the width of scarification on both sides. On the second pass, the recycling shall overlap the previously recycled mat by at least 2.0 inches (50 mm). The heated pavement shall be immediately scarified by scarifying teeth spaced so that they provide complete coverage of the surface without leaving ridges and mounted so that they can be controlled from the operator’s platform. The depth of scarification shall be a minimum of 1.0 inch (25 mm) from the bottom of the rut. Immediately following the milling/scarifying process, the emulsified asphalt shall be uniformly applied to the milled/scarified material. The contractor shall determine the actual amount and grade of emulsified asphalt to be added in order to address field conditions and to optimize the properties of the existing pavement. This shall be done prior to construction and be accomplished by determining the properties of the asphalt in the existing mat. A copy of the mix design shall be submitted to the Materials Field Office for approval 7 days prior to construction.

4.3 The recycled mix shall be uniformly spread and leveled without segregation, to the width, grade and cross slope as specified on the plans. After partial compaction of the recycled mixture by means of the recycling screed, a new layer of virgin hot mix asphalt is to be placed on top of the recycled material by means of a vibratory screed in one continuous operation while the temperature of the recycled mix is maintained at a minimum of 225 F (107 C). The mat shall be thoroughly and uniformly compacted in accordance with Section 403.15 of the Standard Specifications. Joint compaction shall be in accordance with Section 403.16 of the Standard Specifications.

4.4 Hot in-place recycling shall not take place when the roadway surface is wet, frozen or if the weather conditions prevent proper handling, finishing and compacting of the bituminous mixture.

5.0 Method of Measurement.

5.1 Final measurement of the completed hot in-place recycling will not be made except for authorized changes during construction, or where appreciable errors are found in the contract quantity. Where required, measurement of hot in-place recycling, complete in place, will be made to the nearest square yard (m2). The revision or correction will be computed and added to or deducted from the contract quantity.

5.2 Measurement of emulsified asphalt to the nearest 10 gallons (50 L) will be made as specified in Section 1015 of the Standard Specifications. If water is added to the emulsified asphalt, the quantity to be paid for will be determined prior to the addition of water.

5.3 Measurement of the virgin hot mix asphalt will be in accordance with Section 403.22 of the Standard Specifications.

6.0 Basis of Payment.

6.1 Hot in-place recycling will be paid for at the contract unit price per square yard (m2), complete in place, and will be considered full compensation for all material, testing, labor, tools, equipment and appurtenances necessary to complete the work, including cleaning of existing pavement, heating, scarifying, mixing and relaying recycled material.

6.2 The accepted quantity of emulsified asphalt will be paid for at the contract unit price. No direct payment will be made for water added to the emulsified asphalt.

6.3 Payment for the virgin hot mix asphalt will be in accordance with Section 403.23 of the Standard Specifications.