5-161 Tension splices in the reinforcement will not be permitted. Fo r splices other than tension splices, the overlap shall be a minimum of 12 inches fo r welded steel wire fabric and as specified in Standard Specification Section 503 for deformed steel bars. The center-to- center wire spacing in wire fabric sheets shall not be less tha n 2 inches, or more than 4 inches, for the circumferential wires, and shall not be more th an eight inches for the longitudinal wires. The center-to-center spacing of the longit udinal distribution steel for either line of reinforcing in the top slab shall not be more th an 15 inches.
534.12 Inserts Refer to Section 712.061.
534.13 Concrete Placement Do not batch or place concrete until all the form(s) for any
continuous placement have been inspected and accepted by the Qu ality Control Inspector (QCI), and the QAI concurs. Test concrete in accordance with the Standards included in Sect ion 712.061. Test the first two loads of concrete for temperature, air entra inment and slump flow for Self-Consolidating Concrete (SCC). If the first load is unacce ptable, test the second load as the first. Continue this process until two consecutive loads a re acceptable. After two consecutive loads are acceptable, the frequency of testing shal l be at the discretion of the QAI. If there is a change in the dosage rate of any admixture or a c hange of more than 5 F in mix temperature, then test the concrete for temperature, air en trainment and slump flow for SCC. Test every load of 1 cubic yard, or less, from a stationary mix er or 2 cubic yards, or less, from a transit mixer for temperature, air entrainment and slump flow for SCC, prior to placing the concrete in the forms. Perform all testing in the presence of the QAI. The QAI will d esignate the loads to be tested. Make cylinders used to determine stripping strength du ring the last 1/3 of the placement. Place the concrete as nearly as possible to its final location. Control the depth of each lift in order to minimize entrapped air voids. The maximum dep th of an unconsolidated lift shall be 18 inches. Vibrate the concrete with internal or inte rnal and external vibrators. Do not use external vibrators, only. Insert internal vibrators ve rtically and penetrate the lower layer of concrete by at least 4 inches. Insert the vibrators i n the concrete to assure that the radii of action of the vibrator s overlap. Hold the vibrators i n position from 5 to 15 seconds; vibration time shall be reduced by 50 percent when placing SCC. Do not use vibrators to move concrete horizontally. Each lift of concrete shall have s ufficient plasticity to be consolidated with subsequent lifts. Do not re-temper the concrete with water after discharging has begun. The Contractor may add High Range, Water Reducing, admixture to the concrete a fter batching if that 5-162 practice conforms to the manufacturer's product data sheet. Di scard concrete that becomes unworkable. Do not use water or water-base d products to aid in finishing fr esh concrete. After the concrete has been placed and finished and before the forms are covered, remove all concrete from projecting reinforcing steel.
534.14 Acceptance and Quality Control Testing of Concrete Ref er to Section 712.061.
534.15 Manufacture of Precast Units The units shall be free of fractures. The ends of the
units shall be normal to the walls and centerline of the unit, within the limits of variation provided, except where beveled ends are specified. The surfaces of the units shall be a smooth steel form or troweled surface finish, unless a form lin er is specified. The ends and interior of the assembled structure shall make a continuous lin e of units with a smooth interior surface. Defects which may cause rejection of precast units include, but are not limited to, the following:
A.Any discontinuity (crack, rock pocket, etc.) of the concrete which could allow moisture to reach the reinforcing steel.
B.Rock pockets or honeycomb over 6 square inches in area or ov er 1 inch deep.
C.Edge or corner breakage exceeding 12 inches in length or 1 i nch in depth.
D.Any other defect that clearly and substantially impacts the quality, durability, or maintainability of the structure, as determined by the Fabricat ion Engineer. The manufacturer of the units shall sequentially number and sho p fit each adjacent unit to ensure that they fit togeth er in the field. This fit up sha ll be witnessed by the QAI. Any non-fitting units shall be corrected or replaced at no cost to the Department. The manufacturer of the units shall keep accurate records of a ggregate gradations, concrete batching, testing, curing, and inspection activities t o verify that forms, reinforcing and unit dimensions conform to t hese requirements. Copies of r eports shall be furnished to the Resident when requested.
534.16 Tolerances Dimensional tolerances shall be in conforma nce with the
following:
A.The internal dimensions shall not vary by more than 1 percen t from the design dimensions or 1-½ inches, whichever is less, with the exception of the cross diagonal dimension which shall not vary by more than one-half inch from the design dimension.
B.The haunch dimensions shall not vary by more than three-quar ters inch from the design dimension.
Source: Maine Standard Specifications for Road and Bridge Construction, 2020 Edition. Pages 453–454 of 817.