501.21ADVERSE WEATHER CONDITIONS :

501.19.2 1

501.19.2 1 -When a thickness measurement, which represents a sampling unit, has a

value of 0.922T or less, the area of deficient thickness in that sampling unit will be delineated by taking exploratory cores at approximately twenty ( 20) foot intervals, parallel to the centerline, in each direction from the measurement taken in subsection 501.19.2, until a core is obtained, in both directions, which is greater than 0.922T in ch thickness (length). Areas thus defined shall be removed and replaced at no additional cost to the Division. These exploratory cores will not be used in the analysis of the remainder of the unit. The balance of the sampling unit will be treated as a separate sampling unit. One additional core will be obtained from another random location in that sampling unit and shall represent the thickness of the remainder of that sampling unit. The thickness of the sampling unit represented by this core, when greater than 0.922T, will b e included in the measurements specified in subsection 501.23.1.1.

501.19.3 Refilling of Cores: As soon as directions are issued by the Engineer, the

Contractor shall refill and properly cure all test holes at no additional cost to the Division.

501.20 Pavement Widening :

When called for on the Plans or directed by the Engineer to widen an existing pavement by means of strips of portland cement concrete, on one or both sides, the cons truction methods and materials shall be as specified for regular portland cement concrete pavement, except as modified.

501.21 Adverse Weather Conditions :

501.21.1 Cold Weather Concreting: When the component materials are not artificially

heated and the temperature of the plastic concrete becomes less than 55 F, the provisions for cold weather concreting shall apply. The concrete shall have a temperature of at least 50 F but not more than 85F. This temperature shall be maintained by heating the water or aggregate, or both, as necessary. Heating methods which alter or prevent the entrainment of the required amount of air in the concrete shall not be used. The equipment shall be capable of heating materials uniformly. Aggregates or water shall not be heated to a temperature exceeding 150F. Stockpiled aggregate may be heated by the use of dry heat or steam. Aggregates shall not be heated directly by gas or oil flame or on sheet metal o ver fire. Binned aggregates may be heated by steam -coil or water -coil heating. The use of live steam on or through binned aggregates will not be permitted. If the Contractor is placing concrete or plans to place concrete during cold weather conditions, the Contractor shall advise the Division of their plans for curing and protecting the concrete. The Division may, at any time, require the Contractor to provide additional 256 protection to cause the provisions of this Specification to be met. When concrete is being placed and the air temperature is expected to fall below 35 F, a sufficient supply of suitable blanketing material shall be provided. Any time the air temperature is expected to reach the freezing point during the day of placement or the followi ng night, the material so provided shall be spread over the pavement to a sufficient thickness to prevent freezing of the concrete. The material shall be covered or otherwise secured to insure that it will remain in place for the duration of the curing pe riod. No concrete shall be placed on a frozen subgrade. Materials containing frost or lumps of frozen material shall not be used.

501.21.2 Hot Weather Concreting: The Contractor will be required to state, at the pre -

construction conference, their pl an of action when the temperature of plastic concrete reaches 90F. When a shaded thermometer in the vicinity of the production plant reaches 85 F, thermometer readings of the temperature of the plastic concrete shall be taken at least once per hour. When the temperature of the plastic concrete reaches 85 F, the elapsed time between the introduction of the mixing water to the cement -aggregates and discharge of the mix shall not exceed 45 minutes. At this temperature or above, particular attent ion shall be paid to the Specification provisions concerning the sprinkling and wetting of subgrade and forms, the maintenance of coarse aggregate stock in saturated surface -dry condition, and the prompt start of concrete curing operations. When the temp erature of the plastic concrete reaches 90 F, immediate steps shall be taken to cool either mixing water or aggregates, or both, in order to maintain a plastic concrete temperature of 90 F, or less. Crushed or flaked ice may be used to cool the mixing wate r. Crushed or flaked ice may also be introduced into the mixing drum when the concrete is batched and mixed in a truck mixer. The ice will be considered as part of the mix water in the mix proportions. The mixing operation shall not be considered comple te until all ice in the drum has melted. In no event shall concrete be placed when its temperature in the plastic state, at the completion of mixing, exceeds 90 F.

501.22 Method of Measurement :

The quantity of concrete pavement to be paid for will be the number of square yards complete in place and accepted. The width for measurement will be the width of the pavement shown on t he typical cross section of the Plans and additional widening where called for or as otherwise directed in writing by the Engineer. The length will be measured on the surface along the centerline of each roadway ramp. When Item 501009 -* is specified in t he project plans, the quantity of concrete overlay placement to be paid for will be the number of square yards complete in place and accepted. The width for measurement will be the width of the pavement or overlay shown on the typical cross section of the Plans and additional widening where called for or as otherwise directed in writing by the Engineer. The length will be measured on the surface along the centerline of each roadway and each roadway ramp.