409.01 409-1 SECTION 409 CHIP SEAL DESCRIPTION
409.01 This work consists of furnishing and applying asphalt emulsion and cover coat material on
an existing surface, per these specifications and in conformity with the lines shown on the plans or established. When rejuvenating agent or emulsified asphalt is used as a fog seal, cover coat material will not be required. MATERIALS
409.02 Asphalt Emulsion . Emulsified asphalt shall be polymerized or latex modified and shall
be rapid set or medium set conforming to the requirements of subsection 702.02(b). Rejuvenating agent shall conform to the requirements of subsection 702.02(f).
409.03 Cover Coat Material . Cover coat material shall meet the requirements of subsection
703.05 for the type specified. The material will be accepted at the spreader.
CONSTRUCTION REQUIREMENTS
409.04 Weather Limitations . Asphalt emulsion shall not be applied on a damp surface, when
either the air or pavement surface temperature is below 70 °F , or when weather conditions would prevent the proper construction of the chip seal.
409.05 Equipment. The following equipment or its equivalent shall be used:
1.Asphalt distributor and equipment shall be capable of uniformly distributing asphalt emulsion at even temperature and uniform pressure on variable widths of surface up to 15 feet at readily determined and controlled rates from 0.05 to 2.0 gallons per squar e yard. The allowable variation from any specified rate shall not exceed plus or minus 0.02 gallon per square yard. The distributor’s spreading capabilities shall be computer controlled or it shall be calibrated to conform to the distributor manufacturer’s procedure before applying the emulsified asphalt. Distributor equipment shall include a tachometer, pressure gauges, accurate volume measuring devices or a calibrated tank, and a thermometer for measuring temperatures of tank contents. Distributors shall be equipped with a power unit for the pump, and full circulation spray bars adjustable laterally and vertically. Distributors shall be equipped with an automatic heater capable of maintaining the asphalt emulsion at the manufacturer’s recommended applicati on temperature or at 140 °F , whichever is higher.
2.A rotary power broom.
3.A minimum of two pneumatic tire rollers that weigh at least 10 tons each.
4.One self -propelled aggregate spreader of approved design supported by at least four wheels equipped with pneumatic tires on two axles. The aggregate spreader shall be capable of applying the larger cover coat material to the surface ahead of the smaller cover coat material and shall have positive controls, so the required quantity of material is deposited uniformly over the full width of the asphalt emulsion. Other types of aggregate spreaders may be used provided they accomplish equivalent results and are approved. 409.06 409-2 409.06 Preparation of Surface. The entire surface that is to receive a chip seal shall be cleaned of loose sand, dust, rock, mud, and all other debris that could prevent proper adhesion of the asphalt coating. The cleaning shall be accomplished by power broom, scraping, blading, or other approved measures. Chip sealing operations shall not be started until the surface is approved.
409.07 Applying Asphalt Emulsion. Asphalt emulsion shall be applied by a pressure
distributor in a uniform, continuous spread and within the temperature range specified. The distributor’s spreading capability shall be computer controlled or calibrated to conform to the distributor manufacturer’s procedure before applying the emulsified asphalt. If streaking occurs, the distributor operation shall be stopped immediately until the cause is determined and corrected. Streaking is alternating, narrow, longitudinal areas of excessive and then insufficient quantities of asphalt emulsion. The quantity of asphalt emulsion per square yard may vary from the rate shown in the Contract, as directed. A strip of building paper , at least 3 feet in width and with a length equal to that of the spray bar of the distributor plus 1 foot shall be used at the beginning of each spread. If the distributor does not have a positive cut - off, the paper shall be used at the end of each spread. The paper shall be removed and disposed of in a satisfactory manner. The dist ributor shall be moving forward at proper application speed at the time the spray bar is opened. Skipped areas and deficiencies shall be corrected. Junctions of spreads shall be carefully made to assure a smooth riding surface. The length of spread of asphalt emulsion shall not be in excess of the area that trucks loaded with cover coat material can immediately cover. The spread of asphalt emulsion shall not be more than 6 inches wider than the width covered by the cover coat material from the spreading device. Under no circumstances shall operations proceed so asphalt emulsion will be allowed to chill, set up, dry, or otherwise impair retention of the cover coat. The distributor shall be parked so that asphalt emulsion will not drip on the surface of the traveled way.
409.08 Application of Cover Coat Material. Immediately following the application of the
asphalt emulsion, cover coat material shall be spread in quantities as designated. The spreading rate may vary from the rate shown in the Contract when approved. Spreading shall be accomplished so the tires of the trucks or aggregate spreader do not contact the uncovered and newly applied asphalt emulsion. The cover coat material shall be moistened with a sufficient amount of water to reduce the dust coating of the aggregate before spreading. The cover coat material shall not contain free moisture as evidenced by drain down in the delivery truck bed. Immediately after the cover coat material is spread, deficient areas shall be covered with additional material. Rolling shall begin immediately behind the spreader and shall continue until three complete coverages are obtained. Rolling shall be completed t he same day the asphalt emulsion and cover coat materials are applied. The completed roadway surface shall be lightly broomed the following morning to remove any excess material, without removing any embedded material. The Contractor shall conduct additional brooming if so directed. 409.09 409-3 A fog seal shall be applied to the surface of the completed chip seal at the rate of 0.11 plus or minus 0.04 gallon per square yard of diluted emulsion when directed. The fog seal shall have a 3:2 emulsion to water dilution rate. The application rate and the dilution rate may be changed by the Engineer. METHOD OF MEASUREMENT
409.09 Chip seal will be measured by the number of tons, cubic yards, or square yards of the
designated type of cover coat aggregate. BASIS OF PAYMENT
409.10 The accepted quantities of chip seal will be paid for at the contract price per ton,
cubic yard, or square yard for cover coat material. Payment will be made under: Pay Item Pay Unit Cover Coat Material (Type ) Ton Cover Coat Material (Type ) (Lightweight) Cubic Yard Cover Coat Material (Type __) Square Yard Asphalt emulsion, including the asphalt emulsion used for fog seal, will be measured and paid for per Section 411. 409.10 409-4 THIS PAGE INTENTIONALLY LEFT BLANK 411.01 411-1 SECTION 411 ASPHALT MATERIALS DESCRIPTION
411.01 This work consists of furnishing asphalt materials of all types and the application of
these materials per these specifications and details shown on the plans. MATERIALS
411.02 All asphalt materials shall conform to the requirements of Section 702.
The type and grade of asphalt material will be specified in the Contract. The grade may be changed one step by the Engineer at no change in unit price except as provided for under subsection 104.02. Emulsion used for seal coat will be identified as rapid setting or medium setting emulsion and conform to the requirements of subsection 702.02. CONSTRUCTION REQUIREMENTS
411.03 Asphalt materials shall be fortified when required by the Contract with an additive of an
approved type. Additive shall be uniformly blended with asphalt materials at the refinery, or through an approved in -line blender as specified in the Contract. Asphaltic application methods that result in the discoloration of concrete structures, concrete curbs, and concrete gutters will not be permitted. Coatings shall be applied so as to cause the least inconvenience to traffic and to permit one- way traffic. Traffic will be permitted to travel on fresh asphalt material when it can be accomplished without pickup or tracking of the asphalt material. Asphaltic materials used as fuel or lubricant shall be stored separately. Emulsified asphalt for tack coat shall be diluted before use as shown in the Contract or as directed. METHOD OF MEASUREMENT
411.04 Asphalt cement will be measured by the ton by one of the following methods as
determined by the Engineer:
1.The pay quantity of asphalt cement will be determined by multiplying the total accepted tons of paving mix by the weighted average of all asphalt content percentages obtained from the field acceptance tests for that item, or
2.The pay quantity of asphalt cement will be determined from the invoices for the asphalt cement delivered to the job corrected by tank stabs. Emulsified asphalt and liquid asphaltic materials will be measured by the gallon. The pay quantity for emulsified asphalt shall be the number of gallons before dilution with water.
Source: Colorado Standard Specifications for Road and Bridge Construction, 2023 Edition. Pages 373–376 of 943.