294 514.4.3 -Acceptance Testing: 514.4.3.1 -Compressive Strength Tests for Acceptance: The compressive strength for acceptance of RCC will be determined by testing cores. The RCC shall be at least 28 days old before the cores are obtained. One four ( 4) inch diameter core shall be obtained, by the Division, for every 1,500 yd2 or fraction thereof of RCC placed and represent that area for acceptance purposes. These cores shall be tested by the Division for compressive strength. The minimum required compressive strength of these cores is 3,500 psi. The Contractor shall repair the core holes using concrete meeting the requirements of Areas of RCC represented by any cores not meeting the minimum compressive strength requirements shall be handled in accordance with Section 105.12. Such areas that are allowed to remain in place shall be paid for at a reduced unit bid price as outlined in Section
601.15.2, with the Design Strength being 3,500 psi
Additionally, as outline d in Section 514.4.2.3, cores may also need to be obtained to determine the compressive strength of any areas which are found to not meet the specified density requirements. It should be noted that lot sizes for density testing (1,000 yd2) and compressive strength acceptance testing (1,500 yd2) are different, and will overlap throughout the project. However, only one price adjustment shall be applied to any area not meeting the specification requirements. If any lot, or portion of a lot, is determined to have compressive strengths below 3,500 psi as outlined in Section 514.4.2.3 and is also found to be deficient in strength as outlined in Section 514.4.3.1, the price adjustment to be applied to that lot, or portion of that lot, shall be the greater of eit her the price adjustments calculated accordingly.
514.4.3.2 -Thickness Tests for Acceptance : The cores obtained in Section 514.4.3.1 shall be measured for thickness, in accordance with AASHTO T 148, prior to being tested for compressive strength. If the thickness of any core is found to be less than the specified design thickness, then an evaluation of the area represented by that core shall be performed by the Engineer in accordance with Section 105.12. If the Engineer allows that area of deficient thickness to remain in place, then that area shall be paid for at a reduced unit bid price as outlined in Table 514.4.3.2.
TABLE 514.4.3.2 Average Value of Pavement Thickness as Represented by Acceptance Core Unit Price as Percent of Contra ct Unit Price 0.1 to 1.0% Less than Specified Thickness 98.0% 1.1 to 2.0 % Less than Specified Thickness 96.0% 2.1 to 3.0% Less than Specified Thickness 94.0% 3.1 to 4.0% Less than Specified Thickness 92.2% 4.1 to 5.0% Less than Specified Thickness 90.3% 5.1 to 6.0% Less than Specified Thickness 88.4% 6.1 to 7.0% Less than Specified Thickness 86.5% More than 7.0% Less than Specified Thickness, with a maximum of 0.70 inches Less than Specified Thickness Remove and Replace
295 514.5-EQUIPMENT AND TOOLS : Construct roller compacted concrete with any combination of equipment that will produce a completed pavement meeting the requirements for mixing, transporting, placing, comp acting, finishing, and curing as provided in this specification.
514.5.1-Field Laboratory: RCC shall be supplied by a plant which has been certified by the Division as meeting all requirements of the governing Specifications and as having the facilities necessary to ascertain and control the quality of the product in accordance therewith. A testing facility or laboratory, meeting the requirements of Section 501.5.1 shall be provided by the Contractor.
514.5.2-Mixing Plant: 514.5.2.1-General: Unless approved measures are taken to delay the setting time of the RCC, the mixing plant shall be located within a thirty -minute haul time from the point of RCC placement. Use only plants capable of producing an RCC pavement mixture in the proportions defined by the final approved mix design and within the specified tolerances. The capacity of the plant must be sufficient to produce a uniform mixture at a rate compatible with the placement equipment. The estimated production rate of the Plant shall be noted i n the Contractor’s Quality Control plan. If the plant is unable to produce material at a rate adequate to prevent unnecessary cold joints and frequent paver stoppages, the Engineer may halt production until such time that a plant of appropriate capacity i s used. The plant shall be inspected and approved by WVDOH District Materials Personnel prior to production of material under these specifications.
514.5.2.2-Pugmill Plant: Use only pugmill plants of the central plant type with a twin - shaft pugmill mix er, capable of batch or continuous mixing, equipped with synchronized metering devices and feeders to maintain the correct proportions of aggregate, cement, pozzolan, and water. These plants shall meet the requirements of AASHTO M 156. Other pugmill plan t requirements are as follows:
514.5.2.2.1 -Aggregate Storage : If previously blended aggregate is furnished, storage may be in a stockpile from which it is fed directly to a conveyor feeding the mixer. If aggregate is furnished in two size groups, follo w proper stockpiling techniques in accordance with section 501.7 to ensure aggregate separation.
514.5.2.2.2 -Aggregate Feed Rate : Use aggregate bins with a feed rate controlled by a variable speed belt, or an operable gate calibrated to accurately deliver any specified quantity of material. If two aggregate size stockpile sources are used, the feed rate from each bin must be readily adjustable to change aggregate proportions, when required. Feed rate controls must maintain the established proportions o f aggregate from each stockpile bin when the combined aggregate delivery is increased or decreased.
514.5.2.2.3 -Plant Scales: Plant scales, if utilized, for any weigh box or hopper must comply with Section 601.5.2.3.
514.5.2.2.4 -Cement and Pozzolan Material Storage : Supply separate and independent storage silos for Portland cement and pozzolan. At plants with two or more silos in which different types of cement or cementitious materials are stored, ensure that
296 each silo has a sign at each fill inlet to reduce the potential for loading errors. Make the sign from a durable material, with minimum two -inch high by ¼ -inch wide l etters that are raised, indented, or cut. Ensure that the sign clearly identifies the material that is in the silo and may be easily read even when completely coated with dust.
514.5.2.2.5 -Portland Cement and Pozzolan: If using Portland cement and pozzolan (such as fly ash or slag), employ blending equipment acceptable to the WVDOH and demonstrate, with a testing plan, the ability to successfully produce a uniform blended material meeting the mix design requirements. Perform testing on at least a daily basis to ensure both uniformity and proper quantities.
514.5.2.2.6 -Cement and Pozzolan Feed Unit: Provide a satisfactory means of dispensing Portland cement and pozzolan, volumetrically or by weight, to ensure a unifo rm and accurate quantity of cementitious material enters the mixer.
514.5.2.2.7 -Water Control Unit: Use a water control unit capable of measuring the required amount of water for the approved mix by weight or volume. Ensure that the unit is equipped wit h an accurate metering device. Vary the amount of water to be used only with the approval of the Engineer.
514.5.2.2.8 -Gob Hopper: For continuous operating pugmills, provide a gob hopper attached to the end of the final discharge belt to temporarily ho ld the RCC discharge in order to allow the plant to operate continuously.
514.5.2.3-Rotary Drum Mixer: Shall meet the requirements of Section 501.5.3 and shall provide a rotary drum batch mixer capable of producing a homogeneous mixture, uniform in colo r, and having all coarse aggregate coated with mortar. Equip the mixer with batching equipment to meet the following requirements:
514.5.2.3.1 -Weighing Equipment: Measure the amounts of cement, pozzolan, and aggregate entering into each batch of RCC by direct weighing equipment. Use only weighing equipment that is readily adjustable in order to compensate for the moisture content of the aggregate or to change the proportionate batch weights. Include a visible dial or equally suitable device that will accurately register the scale load from zero to full capacity. The cement and pozzolan may be weighed separately or cumulatively in the same hopper on the same scale, provided the cement is weighed first.
514.5.2.3.2 -Weigh Hoppers: Use only bulk cement and pozzolan weigh hoppers that are equipped with vibrators to operate automatically and continuously while weighing hoppers are being dumped. Ensure that the weigh hopper has sufficient capacity to hold not less than 10 percent (10% ) in excess of the cementitious material required for one batch.
514.5.2.3.3 -Water Metering: Measure the amount of water entering each batch of RCC by weight or volume. Use only equipment capable of measuring the water to within a tolerance of plus or minus one percent (1%) and equipped with an accurate gauge or dial measuring device. Vary the amount of water to be used only with the approval of the Engineer. During batching, admit water to the mixer only through the water measuring device and then on ly at the time of charging.
297 514.5.2.3.4 -Mixing Time: Use only drum mixers equipped with an accurate clock or timing device, capable of being locked, for visibly indicating the time of mixing after all the materials, including the water, are in the mixer .
514.5.2.3.5 -Recharging: Discharge all material in the drum before recharging. Ensure that the volume of mixed material per batch does not exceed the manufacturer’s rated capacity of the mixer.
514.5.3-Paver: Place RCC with a high -density asphalt -type paver subject to approval by the Engineer. Use only pavers equipped with compacting devices capable of producing an RCC pavement with a minimum of 90 percent (90%) of the maximum density in accordance with AASH TO T 180, Method D prior to any additional compaction. Ensure that the paver is of suitable weight and stability to spread and finish the RCC material, without segregation, to the required thickness, smoothness, surface texture, cross -section, and grade.
514.5.4-Compactors: Use self -propelled steel drum vibratory rollers having a minimum static weight of 10 tons for primary compaction. For final compaction, use either a steel drum roller, operated in a static mode, or a rubber -tired roller of equal or greater weight. Only use walk -behind vibratory rollers or plate tampers for compacting areas inaccessible to large rollers.
514.5.5-Haul Trucks: Use trucks for hauling the RCC material from the plant to the paver with covers available to protect the material from inclement weather and excessive evaporation. To ensure adequate and continuous supply of RCC material to the paver, have a sufficient number of trucks. If the number of trucks is inadequate to prevent frequent starts and stops of the paver, cease production until additional trucks are obtained.
514.5.6-Water Trucks: Keep at least one water truck, or other similar equipment, on -site and available for use throughout the paving and curing process. Equip such equipment with a spreader pipe containing fog spray nozzles capable of evenly applying a fine spray of water to the surface of the RCC without damaging the final surface.
514.5.7-Inspection of Equipment: Before start -up, the Contractor’s equipment will be carefully ins pected. Should any of the equipment fail to operate properly, cease work until the deficiencies are corrected.
514.5.8-Access for Inspection and Calibration: Provide the Engineer or WVDOH District Materials Inspector access at all times for any plant, equipment, or machinery to be used in order to check calibration, scales, controls, or operating adjustments.
514.6-PREPARATION OF GRADE AND CONDITIONING OF SUBGRADE OR BASE : Before the RCC processing begins, prepare the subgrade in accordance with Section 228 of the Specifications.
514.7-HANDLING, MEASURING, AND BATCHING MATERIALS : Handling, measuring, and batching of materials shall be in accordance with Section 501.7, except that volumetric batching shall not be permitted.
298 514.8-MIXING RCC : 514.8.1-Mixing Process: Use the same mixture for the entire project unless otherwise stated in the project documents. If, during production, the source of Portland cement, pozzolan, or aggregates is changed, then suspend production and submit a new mix design to the Engineer for approval. Do not exceed the manufacturer's rated capacity for dry concrete mixtures in the mixing chamber. Keep the sides of the mixer and mixer blades free of hardened RCC or other buildups. Routinely check mixer blades for wear and replace if wear is sufficient to cause inadequate mixing.
514.8.2-Mixing Time: Use a mixing time adequate to ensure a thorough and complete mixing of all materials. Do notal low the mixing time, after all materials including water are in the mixer, to be less than 1½ minutes for one cubic yard and 20 seconds for each additional cubic yard.
514.8.2.1-Mixing Time for Truck Mixers: When truck mixers are used to mix RCC, the mixer capacity shall be limited to 5 cubic yards per batch and mixing time shall be a minimum of 3 minutes. If the condition of the blades in the drum of any truck mixer, used for mixing RCC, is such that the adequacy of mixing after 3 minutes is questionabl e, or if there is any other reason to question the adequacy of the mixing, uniformity testing, in accordance with AASHTO M 157, for mass per cubic foot and coarse aggregate content, shall be performed on that truck prior to using it during production. If that truck mixer cannot produce a uniform RCC mix after 3 minutes of mixing, then the required mixing time shall be increased to the mixing time which is shown to produce a uniform mix.
514.8.3-Plant Calibration: Prior to commencement of RCC production , carry out a complete and comprehensive calibration of the plant in accordance with Section 501.5.2. Provide all scales, containers, and other items necessary to complete the calibration. After completion of the initial calibration, calibrate the plant periodically as directed by the Engineer. Plants listed on WVDOH approved list at the time of RCC production are exempt from this requirement, although the WVDOH reserves the right to require additional calibration if variation in mixture quantities are s uspected.
514.8.4-Daily Reports: Supply daily plant records of production and quantities of materials used that day to the Engineer. These records may be used as a check on plant calibration.
514.8.5-Transportation: Transport the RCC pavement material from the plant to the areas to be paved in dump trucks equipped with retractable protective covers for protection from rain or excessive evaporation. Ensure that the trucks are dumped clean with no buildup or hanging of RCC material in the corners. Have the dump trucks deposit the RCC material directly into the hopper of the paver or into a secondary material distribution system that deposits the material into the paver hopper. Dump truck delivery must be timed and s cheduled so that RCC material is spread and compacted within the specified time limits.
514.9-PLACING RCC : 514.9.1-Subbase Condition: Prior to RCC placement, ensure that the surface of the subbase is clean and free of foreign material, ponded water, and frost. Ensure that the subbase is uniformly moist at the time of RCC placement. If sprinkling of water is required to remoisten
299 certain areas, ensure that the method of sprinkling will not form mud or pools of freestanding water. Correct soft or yielding subbase areas prior to placement of RCC as specified in Section 6.1 above.
514.9.2-Adverse Weather Conditions: 514.9.2.1-Cold Weather Precautions: Employ cold weather precautions as detailed in Section 601.9.1 of the Specifications. Stop placement operations when the air temperature falls below 40°F and is declining. Start operations only if the air temperature rises above 35°F and is elevating. If the air temperature is expected to fall below 40°F at some time during construction, and if the Contractor plans to place RCC during that time, the Contractor shall advise the Division of his plans for cold weather curing and protecting the RCC. The Division may, at any time, require the Contractor to provide additional protection to cause the provisions of this specification to be met.
514.9.2.2-Hot Weather Precautions : Employ hot weather precautions as detailed in Section 601.9.2 of t he Specification. During periods of hot weather or windy conditions, take special precautions to minimize moisture loss due to evaporation. Cooling of aggregate stockpiles by shading or the use of a fine mist may be required. Protective covers may be req uired on dump trucks. Keep the surface of the newly placed RCC pavement continuously moist. The Engineer may decrease the allowable time, specified in Section 514. 10.1, between mixing and the completion of compaction when the ambient temperature exceeds 90°F or during windy conditions. In no event shall RCC be placed when its temperature at any time after the completion of mixing exceeds 90°F.
514.9.2.3-Rain Limitations: Conduct no placement of RCC pavement during rain conditions sufficient to be detrimental to the finished product. Placement may continue during light rain or mists provided the surface of the RCC pavement is not eroded or damaged in any way. Use dump truck covers during these periods. The WVDOH may terminate paving at any time w hen, in the WVDOH judgment, the rain is detrimental to the finished product.
514.9.3-Paver Requirements : Place all RCC with an approved paver as specified in Section 514.5.3, and also meeting the requirements of this Section.
514.9.3.1-Filling the Pa ver: Do not allow the quantity of RCC material in the paver to approach empty between loads. Maintain the material above the auger at all times during paving.
514.9.3.2-Stopping the Paver : Ensure that the paver proceeds in a steady, continuous operation with minimal starts and stops, except to begin a new lane. Maximum paver speed during laydown is ten (10) feet per minute. Higher paver speeds may be allowed at the discretion of the WVD OH if the higher speeds may be obtained without distress to the final product or cause additional starts and stops.