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3501 Lexington Ave - Specs for Reinforced ConcreteX00-7 t GREAT RIVER. ENERGY SPECIFICATION FOR REINFORCED CONCRETE GRE SPECIFICATION SP-3.3 Revised November, 2002 GRE Specification for Reinforced Concrete All concrete work called for in the plans and specifications shall be performed in accordance with the following specifications: 1. EXCAVATION (a) If foundations are to be installed in a station where a layer of crushed rock is existent, then the crushed rock shall be removed from the construction area and stockpiled taking care not to mix any earth with the rock. (b) Foundations shall be excavated to the depths and dimensions specified on the plans. All dirt and loose material shall be removed from the excavation prior to the placing of concrete. (c) The bottom of foundation excavations shall be thoroughly tamped to prevent settlement. If over-excavation should occur, the excess depth shall be filled with concrete or shall be backfilled with crushed rock, which shall be compacted to a 95% Procter density. (d) Excavations shall be free from frost and ice when foundations are poured and the earth temperature shall be at least 40 degrees F. The surfaces of absorptive materials against which concrete is placed shall be moistened to avoid drawing water from the freshly placed concrete. (e) Concrete should not be poured in any excavation containing standing water or mud, however, it is recognized that many areas have a high water table that must be dealt with. Where water is encountered in an excavation, one of the following methods shall be used to assure that an adequate foundation is obtained. (1) In dense clay soils with stable embankments, pumping the hole dry may be sufficient to allow placement of the concrete. (2) In sandy soil where there is constant ingress of water it may be necessary shore up the excavation with removable slip-forms or coat the embankment with Bentonite (drilling mud) and continue pumping until placement of concrete is complete. (3) Another method is to drive well points around the foundation area and to pump for a sufficient time to lower the water table in the immediate area. (4) In extreme cases when the above methods are not workable, the cement may be installed by the Tremi method. This method shall be used only with the approval of the GRE Construction supervisor and the Engineer. The Tremi tube shall extend to the very bottom of the excavation and shall gradually be withdrawn as the concrete level rises. In no case shall the concrete be dropped directly into water. SP-3.3, Revised November, 2002 Page 1 of 10 GRE Specification for Reinforced Concrete 2. PLACING OF FORMS (a) Forms shall conform to grade, lines and dimensions of the concrete as called for on the plans and shall be sufficiently strong to carry the dead weight of the concrete without undue deflection or bulging and sufficiently tight to prevent leakage of mortar. They shall be properly braced and tied together so as to maintain position and shape. (b) Forms used at exposed surfaces shall be lined with plywood that is smooth and free from loose knots or other defects. Joints in forms shall be horizontal or vertical. At all unexposed surfaces and rough work, undressed lumber may be used. Lumber reused in forms shall have nails withdrawn and surfaces to be in contact with concrete thoroughly cleaned before being used again. (c) Form spreaders and ties shall be metal so arranged that when forms are removed no metal shall be within one (1) inch of any surface. All openings left by rods or bolts shall be suitably closed and pointed with cement mortar. No wire ties shall be used. (d) The inside of forms shall be coated with nonstaining mineral oil or approved material. When oil is used, it shall be applied before the reinforcing is placed. (e) All inserts, anchor bolts, etc., as may be required and all recesses shall be built into the construction. Forms shall be inspected and approved by the Engineer before the depositing of concrete is begun. The dimensions of anchor bolts and inserts shall be checked before pouring is begun, and shall be checked again after pouring is complete to assure that they are still in position. 3. PLACING OF STUB ANGLES FOR STEEL TOWERS (a) Stub angles for tower attachment shall be set carefully in the forms prepared for them and maintained at the lines and grades shown on the drawings well within the following maximum tolerances: (1) Anchor elevation difference of 0.12" between adjacent legs on any face of tower, provided the difference in elevation between any two diagonally opposite legs shall not exceed 0.12". (2) The dimension as measured along any face shall be ±0.125" from the plan dimension and the diagonal shall be +0.25" from the dimension shown on the plan. (3) Batter shall conform to the values shown on the drawings. (4) There shall be no twist in the stub angle. (5) Alignment of 1.00" either way from the center line of transmission line. SP-3.3, Revised November, 2002 Page 2 of 10 GRE Specification for Reinforced Concrete (b) Any tower footing which does not satisfy the specified requirements for line, grade, batter and twist shall be rejected. No payment shall be made for any such defective work until the Contractor has completed, to the satisfaction of the Engineer, the necessary corrective work. The Contractor shall bear the full expense of all such work. Stub angles shall be maintained in their proper position and care shall be exercised to avoid jarring them after concrete has been placed around them. 4. REINFORCING STEEL (a) Reinforcing bars conform with the latest revision of ASTM A615 Grade 60 or ASTM A706 (weldable) Grade 60. Deformations on reinforcing bars shall conform to the latest revision of ASTM A615. Welded wire fabric for concrete reinforcement shall comply with the latest revision of ASTM A185. Contractor shall provide certification of reinforcing steel to GRE and the Engineer of Record. (b) The reinforcing steel shall be free from rust, scale, paint, oil or coatings of any character that will prevent its bond with the concrete. Reinforcing steel shall be placed accurately in position shown on drawings, securely tied at all intersections with #18 gauge black annealed wire, and shall be securely held in place during the placing of concrete by spacers, chairs, or other suitable support. Care shall be exercised to see that the clearance from rebars to the surface of concrete structures is maintained in accordance with the plans. If welding is allowed, it shall conform to latest revisions of AWS-D1.4 and ACI - 318 and only on reinforcing steel conforming to the latest revision of ASTM- A706. (c) When splices in reinforcing steel are required, they shall meet the requirements of Chapter 12 of the latest revision of ACI-318 and shall be approved by GRE and the Engineer of Record. (d) Bends for ties and stirrups shall be made around pins having a diameter of at least four times the bar diameter. Bends for other bars shall be made around pins having a diameter of at least six times the bar diameter for bars under one inch and eight times the bar diameter for bars over one inch in diameter. All bars shall be bent cold except that bars over one and one-fourth (1-1/4) inch diameter may be bent hot with the approval of GRE and the Engineer of Record. 5. CEMENT SPECIFICATIONS Portland cement per the latest revision of ASTM C150 shall be used. Unless otherwise designated on the plans, the cement shall be Type IIA-modified cement, air-entrained or Type II-modified cement with an approved GRE air-entraining agent added. In special cases the Engineer of Record or the GRE Field Inspector may specify high early strength, air-entrained, Type IIIA cement. SP-3.3, Revised November, 2002 Page 3 of 10 GRE Specification for Reinforced Concrete 6. FINE AGGREGATE (a) Fine aggregate shall conform to the latest revision of ASTM C33 and shall be clean sand or clean, hard, dense, durable rock fragments, free from dirt, organic matter or other deleterious substance. (b) The fine aggregate shall be well graded from coarse to fine and when tested by means of laboratory sieve shall conform to the following requirements: Passing No. Passing No. Passing No. Passing No. Passing No. 7. COARSE AGGREGATE 3/8" sieve-- 100 percent 4 sieve--95 to 100 percent 16 sieve--50 to 85 percent 50 sieve--5 to 30 percent 100 sieve--0 to 10 percent (a) Coarse aggregate shall conform to the latest revision of ASTM C33 and shall be washed gravel or crushed limestone free from from dirt, organic matter or other deleterious material. (b) Coarse aggregate shall be well graded and be of such a size as to pass through a one-inch screen and be retained on a 1/4 inch screen. Percentage passing laboratory sieves having square openings shall conform to the following requirements: Passing No. 1 1/2" sieve--100 percent Passing 1" sieve--90 to 100 percent Passing 1/2" sieve--25 to 60 percent Passing No. 4 sieve--0 to 10 percent 8. WATER The water used in the concrete mix shall be clean and free from oil, alkalies, acids, salts, organic matter or other substance deleterious to concrete or reinforcement. 9. DESIGN OF CONCRETE MIX (a) Mixing. Ready-mix concrete shall be supplied from a single source approved by GRE in accordance with the latest revision of ASTM C94. Placement of each load of concrete shall be completed within 1 1/2 hours of the time water was introduced into the mix at the plant. If the construction site is so distant from the ready-mix plant that this cannot be achieved, then water shall be placed in the mixing drum at the construction site and mixing shall be done there. (See Par. 10.7 of ASTM C94.) Any concrete remaining in the mixer longer than the above limits shall be wasted and not used. No water shall be added at the site to pre-mixed concrete except as permitted by ASTM C94. SP-3.3, Revised November, 2002 Page 4 of 10 GRE Specification for Reinforced Concrete (b) Mix Design. Submit two copies of the mix design to GRE and the Engineer of Record for review 14 days prior to concrete placement. (c) Water-Cement Ratio. The maximum water-cement ratio for concrete exposed to freezing and thawing or deicing chemicals shall be 0.45. The maximum water-cement ratio for other situations shall be 0.5. (d) Minimum Compressive Strength, f'c, shall be 4500 psi at 28 days. When Type I I I or IIIA cement is used, f'c shall be 4500 psi at 7 days. (e) Slump shall be between 2 to 4 inches. (f) Air-Entrainment. Concrete shall have an air content of 5% ±2% as determined by the latest revision of ASTM C173 or ASTM C231. Air-entraining agents used in lieu of air-entraining cement shall be approved by GRE and meet the requirements of ASTM C260 - latest revision. (g) Admixtures. All admixtures shall be approved by GRE and the Engineer of Record and shall conform to ASTM CF494 - latest revision. Calcium chloride or admixtures containing calcium chloride shall not be used in the concrete unless specifically approved by GRE and the Engineer of Record. 10. REPORTS The Contractor shall obtain a report on each truck load of concrete delivered stating the following information: (a) Yardage in load. (b) Minimum compressive strength. (c) Percent of air-entrainment. (d) Water/cement ratio. (e) Admixtures. The Contractor shall supply a copy of this report to GRE and the Engineer of Record. 11. FIELD TESTS (a) Slump Test. The Contractor shall periodically run a slump test in accordance with the latest revision of ASTM C143. The slump shall be between 2 inches and 4 inches. (b) Test Cylinders. The Contractor shall cast one set of three test cylinders for every five piers or 50 cubic yards of concrete or when the material or method of placement is changed, in accordance with the latest revision of ASTM C31 and SP-3.3, Revised November, 2002 Page 5 of 10 GRE Specification for Reinforced Concrete ASTM C172. Test cylinders shall be stored as near to the point of casting as possible. They shall receive the same protection from the weather conditions as is given to the foundation(s) which they represent. Testing shall be completed in accordance to the latest revision of ASTM C31. One cylinder shall be tested at 7 days and one at 28 days for Type IIA or Type II cement. One cylinder shall be tested at 3 days and one at 7 days for Type IIIA or Type III cement. 12. PLACING OF CONCRETE (a) Depositing Concrete. No concrete shall be placed until all form work, installation of parts to be embedded and preparation of surfaces involved in the placing have been approved. No concrete shall be placed in water except with the written permission of the Engineer, and in that event, the method of depositing the concrete shall be prescribed by the Engineer. Concrete shall not be placed in running water and shall not be subjected to the action of running water until after the concrete has hardened to the satisfaction of the Engineer. All surfaces of forms and embedded materials that have become encrusted with dried mortar or grout from concrete previously placed or with ice, mud or other foreign material, shall be cleaned of all such refuse before the surrounding or adjacent concrete is placed. Immediately before placing concrete, all surfaces of foundation upon or against which the concrete is to be placed shall be free from standing water, mud and other foreign matter. The surfaces of concrete which has set and against which new concrete is to be poured, shall be thoroughly cleaned to remove all foreign material and laitance and be saturated with water immediately before placing concrete. Concrete shall be deposited continuously and as rapidly as possible until the unit being poured is complete. The concrete shall not be dropped more than five (5) feet from the end of the chute to the point of deposit unless approved by the Engineer. (b) Vibration and Puddling. Concrete shall be consolidated to the maximum practical density, without segregation, by vibration or puddling so that it is free from pockets of course aggregate and closes against all surfaces and embedded materials. Vibration of concrete in structures shall be by electric or pneumatic-driven, immersion type vibrators operating at speeds of at least 8,000 rpm when immersed in concrete. Vibrators shall be inserted vertically at close enough intervals so that the zones of influence overlap. The vibrators shall be inserted to the full depth of the layer being treated. When concrete is being placed in layers, the tip of the vibrator shall extend approximately four (4) inches into the underlying layer. Vibrators shall not be used to move concrete horizontally. Care shall be exercised to avoid contamination of the concrete through careless use of vibrators or puddling tools. Puddling tools shall be of a type acceptable to the Engineer. SP-3.3, Revised November, 2002 Page 6 of 10 GRE Specification for Reinforced Concrete (c) Construction Joints (1) Construction joints, both vertical and horizontal, shall be made at locations indicated on the plans and where breaks occur in walls necessitated by the sequence of construction, or at such other locations as designated or approved by the Engineer. They shall be so designed and located as least to impair the strength and appearance of the structure. In no case shall vertical joints be made in walls at or near corners. All corners shall be poured monolithically. (2) Keys shall be provided in all joints where required to provide for either sheer or water tightness. Where joints occur at or near points of maximum sheer, such as the base of retaining walls, the width of keys shall be one-half as deep as they are wide. (3) All concrete shall be deposited in forms at such a rate that the forms will be filled at any point with a vertical rise of the concrete surface of not less than two (2) feet per hour. Where necessary, the forms shall be bulk-headed off and construction joints made to provide a form which will be filled at the above specified rate. The location of these construction joints shall be approved by the Engineer. (4) If any concrete is allowed to stand at any elevation below the finish grade top surface, for more than two (2) hours without fresh concrete being applied thereon, the top surface of such concrete shall be considered to be a construction joint, and shall be so constructed in accordance with these specifications, and provided with keys and metal sealing strips if required for shear or water-tightness. (5) At all construction joints the concrete surface shall be thoroughly cleaned and washed free of all laitance and loose materials. (6) Wherever concrete pouring in a wall section is stopped and the wall steel is not carried though, there shall be provided steel dowels to equal wall steel. All dowels must be of sufficient length to provide at least forty (40) diameters of concrete on each side of the joint. (7) Copper dams of at least eight-inch height must be provided in all joints in walls retaining liquids. SP-3.3, Revised November, 2002 Page 7 of 10 GRE Specification for Reinforced Concrete 13. FINISHING (a) Smooth, solid concrete surfaces are required throughout the work. The top surface of the concrete anchors shall be crowned to provide drainage of water with an additional build-up between the inside faces of the leg angles. In general, wood float finish on the concrete is required. When directed by the Engineer, a steel trowel finish may be required, but care shall be taken in the steel troweling not to bring excessive fine material to the surface. Finishing of concrete surfaces shall be performed only by skilled workmen. (b) Transformer, breaker and regulator slabs, building stoops and other surfaces upon which a workman may stand shall be finished with a light broom finish to improve traction under icy conditions. (c) All concrete in structure shall be so finished that it give a solid smooth surface, and any exposed rock or honeycomb shall be sufficient cause for removal and replacement of concrete if so ordered by the Engineer. (d) If the exposed surfaces of walls, slabs, piers and other areas where forms are used are not smooth, they shall be carefully rubbed with carborundum stone and cement mortar after the removal of the forms, if so ordered by the Engineer. (e) Floor Finish. All cement floor constructed in the work shall be finished by means of dust coat finish as follows: (1) Rough concrete shall be brought to proper grade and screeded so as to work the finer particles of cement and sand to the surface. (2) A dry mixture of one (1) cement sack of sand and one (1) cement sack of Portland cement shall be thoroughly mixed to uniform color and when the surface water has disappeared, ninety (90) pounds of this mixture shall be uniformly dusted over each one hundred (100) square feet of surface. (3) The surface shall be floated and troweled twice. The first operation shall not take place until the surface is set sufficiently to retain knee boards and shall be done in such a way as to prevent drawing up too much fine materials. The surface shall receive a second troweling to eliminate all irregularities and leave the floor with a smooth hard finish, free from blemishes and other marks. All floors shall be sloped to floor drain or pit to afford proper drainage. 14. PROTECTION AND CURING (a) Protection: Concrete when deposited shall have a temperature of not less than 40 degrees Fahrenheit and not more than 80 degrees Fahrenheit. In freezing weather, suitable means shall be provided for maintaining concrete at a temperature of at least 50 degrees Fahrenheit for five days or more after SP-3.3, Revised November, 2002 Page 8 of 10 GRE Specification for Reinforced Concrete placing, or until the concrete has thoroughly hardened. The methods of heating the materials and protecting the concrete shall be approved by the Engineer. After concrete has been deposited it shall be kept wet for a period of at least 72 hours. (b) Curing: All exposed concrete shall be properly cured for seven days by moist curing using wetted burlap, covering with Kraft paper or polyethylene sheets to prevent evaporation, or by spray application of a liquid membrane-forming compound conforming to ASTM Designation C309-58, Type 1. The membrane shall be applied according to the manufacturers recommendations. Surface defects shall be filled prior to application of membrane curing compound. The application shall be made with spraying equipment capable of applying a smooth, even-textured coat and compressed air line shall be trapped to prevent moisture or oil from getting into the compound. All concrete surfaces on which membrane compound has been applied shall be adequately protected for the duration of the curing period from any cause which would disrupt the continuity of the curing membrane. No membrane curing compound shall be used on surfaces of construction joints or on surfaces requiring subsequent bonding. (c) Removal of Forms: Forms shall not be disturbed until the concrete has hardened sufficiently to support any loads that may be imposed upon the concrete. When stripping forms, metal wedges or tools shall not be used to pry panels loose. If wedging is necessary, it shall be done with wood wedges lightly rapped to break adhesion. 15. TOLERANCES FOR CONCRETE CONSTRUCTION (a) General: The intent of this paragraph is to establish tolerances that are consistent with modern construction practice, yet governed by the effect that permissible deviations will have upon the structural action or operational function of the structure. Deviations from the established lines, grades and dimensions will be permitted to the extent set forth herein: Provided, that GRE reserves the right to diminish the tolerances set forth herein if such tolerances impair the structural action or operational function of a structure. Where tolerances are not stated in the specifications or drawings for any individual structure or feature thereof, permissible deviations will be interpreted conformably to the provisions of this paragraph. Notations on the drawings, included in these specifications, or specific maximum or minimum tolerances in connection with any dimension shall be considered as supplemental to the tolerances specified herein. The Contractor shall be responsible for setting and maintaining concrete forms sufficiently within the tolerances specified herein. Concrete work that exceeds the tolerances limits specified herein shall be remedied or removed and replaced at the expense of and by the Contractor. SP-3.3, Revised November, 2002 Page 9 of 10 GRE Specification for Reinforced Concrete (b) Tolerances for reinforced-concrete structures -- (1) Variation in the thickness of slabs Minus ........................ 1/4 inch Plus ....................... 1 /2 inch (2) Footings -- Variation of dimensions in plan Minus ........................ 1/2 inch Plus ....................... 1 inch (3) Misplacement of eccentricity Two percent of the footing width in the direction of misplacement but not more than...... 1 inch (c) Tolerances for placing reinforcement steel -- (1) Variation of protective covering With cover of 2 and 1/2 inches or less ...... 1/4 inch With cover over 2 and 1/2 inches .............. 1/2 inch (2) Variation from indicated spacing ............... 1 inch 16. CLEANUP AND RESTORATION OF GRADE (a) After forms have been removed, the Contractor shall backfill around the completed foundations to restore original grade lines, or if grading work is being done, to the proposed grade lines. The material excavated from the footing shall be used for backfill, if suitable, otherwise material conforming to GRE Specification GS40 (or MNDOT C1. #5 road base material) shall be furnished for backfilling. (b) The backfill shall be installed in lifts not to exceed 8 inches and shall be thoroughly tamped to prevent settlement. (c) All excess excavation material shall be removed from the site or spread out in an area designated by the GRE Construction supervisor. (d) If surface rock was existent at the construction site, the Contractor shall restore it to the depth and grade lines existing. Any rock that has become mixed with earth shall be disposed of and matching new rock installed in its place. SP-3.3, Revised November, 2002 Page 10 of 10