Use cores to determine acceptance of concrete pavement thickness. To determine the total deduction, add the deductions for primary units and the cost of all secondary cores, including those taken outside secondary unit areas. The personnel who measure core thickness prepare the coring records, which include information about core location (include sketches) and measured thickness. The request will have the effect of increasing, not necessarily doubling the number of cores. vUnderstand the various types of equipment used to form joints. An equipment crossing and a bridge within the limits of the day’s run caused “skips” in the length paved totaling 460 feet (from Station 21+20 to Station 25+80). The average of the thickness variations in the preceding table is -0.045 feet. Discuss any adjustment in their construction operations as a result of predicted weather. If the average thickness deficiency is more than 0.01 foot, continue with the following steps. Note these areas in daily reports with stationing and offset information. When sufficient rain may fall to damage fresh pavement, stop pavement placement or verify that other steps, such as covering, are taken to prevent damage. Areas not meeting coefficient of friction requirements must be corrected by grooving or grinding in conformance with Section 42, “Groove and Grind Concrete,” of the. Benchmark evaluation of pavement for cracking, faulting, spalling, and raveling. At the start of each day’s work, check that the specified date stamp is used to mark the new pavement. This average was rounded to -0.05 foot, and used for the thickness variation for Core 7 in the primary unit. 1. For information on producing and transporting concrete, refer to Section 4-90, “Concrete,” of this manual. Such adjustments do not result in abrupt changes in grade or adversely affect smoothness. Use judgment regarding which of these areas warrant thickness coring. Verify that the contractor performs initial texturing with a broom or burlap drag to produce striations parallel to the centerline. vLearn about the three joint types normally specified for a concrete pavement. Watch for improper proportions or inadequate mixing as concrete is placed. When it is a construction joint AND the pavement is . Determine the lateral location of the first core by selecting a value from the lateral column shown in Table 4-40.1, "Calculation Factors to Locate Cores," and measuring that distance from the right-hand edge (when looking ahead) of the lane selected. Divide the net length of the primary unit by the number of primary cores to be taken in that unit. A good location is one convenient to a water source and removed from any traffic. The secondary unit area was later removed, reworked, and replaced. Following is an example illustrating the procedure for measuring the pavement for thickness and calculating deductions for thickness deficiencies. To obtain the deficiency adjustment in dollars per square yard, use the table in Section 40-1.01D(8)(c)(iv), “Thickness,” of the. Beam Fabrication: For the beam fabrication, use the following information as described in ASTM C31 (Sections 6 and 9): Minimum Cross-Sectional Dimension of Beams. Refer to Section 36-3, “Pavement Smoothness,” of the. Where air entraining admixtures are required by the project’s pavement climate region, in accordance with Section 40-1.02B(4), “Air Entrainment,” of the. When slip-form pavers are used, inspect the grade on which the paver will ride to determine if the grade is smooth enough to prevent abrupt vertical changes in the finished surface. All values in the table are to be used successively for each primary unit throughout the project after the value for the first core in the unit is selected at random. Whenever early tests are performed, advise the contractor that such areas are subject to retesting. Maintain good communication between field personnel inspecting the placing portion of the paving operation and plant inspection personnel, so that problems related to mixing or hauling may be addressed and corrected effectively. Also, be sure the contractor does the vibrating at the locations and in the frequencies and amplitudes specified. Generally it is made of epoxy coated steel. To verify compliance with the requirements for protecting pavement, examine all equipment that will be placed on previously completed pavement. Select any factor from the longitudinal factors shown in Table 4-40.1, “Calculation Factors to Locate Cores,” and multiply the factor by the primary coring interval. Refer to Section 84-8, “Rumble Strips,” of the. 4.5m to accommodate the effect of differential settlement of pavement foundation. On slipform pavers, tie bars are inserted on slab edges that will become longitudinal joints (see Figure 2 and 3) and, if two lanes at once are being paved, pushed into a mid-slab area (similar to dowel bar insertion) that will later be cut as a longitudinal joint (see Figure 4 and 5). Refer to Section 6-202, “Responsibilities for Acceptance of Manufactured or Fabricated Materials and Products,” of this manual for additional information. However, in addition to onsite inspection, mix design authorization and plant inspection are part of the resident engineer’s responsibility. To meet these conditions, specimens made for the purpose of determining when the pavement may be open to traffic must be removed from the molds 44-52 hours after molding. Note that this stress reduction is very limited under construction joints. While the required width applies to both upper and lower surfaces, the bottom width can be greater than specified to reduce edge slump. With the district materials engineer, arrange to measure the coefficient of friction (California Test 342, “Surface Skid Resistance with the California Portable Skid Test”). Using -0.05 foot for the Core 7 thickness deficiency, the engineer calculated the average thickness deficiency (cores 1 through 7) for the primary area to be -0.016 foot. When deficiencies are not resolved or continue to occur, suspend the contractor’s pavement operations until the contractor provides satisfactory assurances and written documentation of their corrective plans. Make sure the contractor sprays the concrete with a mist of water until the concrete has set before placing the membrane. Warping joints relieve part of warping stresses 3. These joints It is used to hold the faces of the abutting slab. Note that for continuously reinforced concrete pavements, there is specified acceptance criteria for coefficient of thermal expansion at field qualification; otherwise this is provided for information only. Observe the operation of equipment on existing pavements to make sure no cracking or other damage occurs. Note that tests performed before the concrete is 7 days old are not valid for acceptance. Require the contractor to supply sufficient sand or earth for burying the beams. To determine the average thickness deficiency, if any, for the primary unit, average the thickness variations of all primary cores. • Tie bars : deformed rebars or connectors used for holding faces of rigid slabs in contact to maintain aggregate interlock. After measuring and recording pavement thickness, retain the cores until final agreement is reached on payment for the concrete pavement, usually after the contractor returns the proposed final estimate. As necessary, verify contractor’s analysis by performing an independent simulation using high performance concrete paving software. Test areas with visibly smoother texture as completely as necessary to verify compliance or delineate areas that must be corrected. Notify the contractor in writing of the date and place where coring will be performed. When these tie bars are used to connect two lanes, or a lane and shoulder, the tie bar may be mechanically inserted by the paving machine into the fresh concrete ahead of the float, or it may be held in position by support devices. To determine the limits of secondary units, locate cores in approximately the center of each adjacent panel. However, you may use values higher than the required minimum to indicate compliance even if you made measurements lower than 40 degrees Fahrenheit. Telltale signs of the unacceptable practice include the following: Areas still soft and wet in the finished surface while the surrounding area has turned firm and lost its watery sheen. This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU. Continue taking a secondary core in adjacent panels, expanding as necessary, until the deficient area is bounded by panels with deficient thickness of 0.05 foot or less. However, if the contractor requests additional thickness measurements before the performance of any of the primary coring, you may shorten the length of the coring interval for the primary unit accordingly. Tie Bars provide in mid-depth of the concrete slab ( as shown in the figure ). Source: Hilti, Inc. 2017 Tie Bars are deformed steel bars or epoxy coated steel bars. When a curing compound will be used, discuss the labeling and packaging requirements for acceptance of the compound with the contractor. A single core was then taken to determine thickness variation and found to be -0.01 foot. In fact, longitudinal joints are normally designed at a regular spacing e.g. California Test 523, “Method of Test for Flexural Strength of Concrete (Modulus of Rupture),” follows ASTM C31, “Standard Practice for Making and Curing Concrete Test Specimens in the Field,” for making and curing concrete test specimens. Portions of the concrete slab ( as shown in the longitudinal location each... Materials and Products, ” of the forms complies with specifications adjustment on the average the... Effect of differential settlement of pavement for cracking, faulting, spalling and! For locating the primary unit either plastic or wet burlap secondary area measurements the. Were taken at a regular spacing e.g transportation by wrapping the specimens from freezing with suitable cushioning material to measurable! Core should be protected from corrosion cushioning material to prevent the opening of the are. Than sawed, be sure transverse contact joints are constructed and tie design! 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