5._Cast-in-place_Concrete.pdf

QUUG 11-1016 SOW

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CAST-IN-PLACE CONCRETE

PART 1 - GENERAL

1.1 DESIGN REFERENCES: Provide the design and installation in accordance with the following references. This list is not inclusive and shall be used as a guide that shall be further developed by the Prime Contractor’s A-E hired firm. The publications are referred to in the text by the basic designation only.

UNA NORMA ESPAÑOLA (UNE)

UNE 41.107 1961, “Productos prefabricados elásticos para el relleno de juntas de expansión en pavimento de hormigón.”

UNE-EN 12350-1 2006, “Ensayos de hormigón fresco. Parte 1: Toma de muestras.”

UNE 104.233 1983, “Materiales bituminosos de sellado de juntas de hormigón.”

MINISTERIO DE OBRAS PÚBLICAS, TRANSPORTE Y

MEDIO AMBIENTE (MOPTMA)

MOPT EH-PRE “Instrucción para la fabricación y suministro de hormigón preparado.”

MINISTERIO DE LA PRESIDENCIA

MPR-EHE-08 Instrucción de Hormigón Estructural EHE-08

MINISTERIO DE LA VIVIENDA

CODIGO TECNICO DE LA EDIFICACION (CTE)

SEGURIDAD ESTRUCTURAL (SE)

DB-SE Seguridad Estructural DB-SE-AE Acciones en la Edificación DB-SE-C Cimientos DB-SE-A Acero

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DB-SE-F Fábrica

1.2 MINIMUM CONSTRUCTION SUBMITTALS: As determined during the design phase by the Designer of Record (DOR), additional submittals may be added to this outline list.

1.2.1 Inspection certificate of the concrete batch plant.

1.2.2 Concrete Control Tests Program: Test results shall be issued by an authorized laboratory. Provide a description of the elements to receive concrete, the lots, series and the number of samples to be tested. The same procedure shall apply to the steel to be used on the project.

1.2.3 Results of the Concrete Control Tests: The results of the concrete test of the samples taken in the job site shall be presented with 24 hours following issuance from the laboratory.

1.3 DELIVERY, STORAGE, AND HANDLING: Do not deliver concrete until vapor barrier, forms, reinforcement and embedded items are in place and ready for concrete placement.

Store reinforcement of different sizes and shapes in separate piles or racks raised above the ground to avoid excessive rusting. Protect from contaminants such as grease, oil, and dirt.

Provide for accurate identification after bundles are broken and tags removed.

PART 2 - PRODUCTS

2.1 CONCRETE:

2.1.1 Mix Design: Use in-situ-made concrete only when approved by Contracting Officer.

Design mix in accordance with MPR EHE. Concrete shall have a 28-day compressive strength as specified. Slump shall be between 6 and 9 cm. Water-cement ratio shall not exceed 0,60.

2.1.2 Ready-Mixed Concrete: MOPT EH-PRE, except as modified herein.

2.2 MATERIALS:

2.2.1 Cement: MPR EHE cement CEM I and CEM II/A, as required to achieve compressive strength, without additives for all concrete work.

2.2.2 Water: Water used for mixing and curing the concrete on site shall not contain any deleterious ingredient in such a quantity as to affect the properties of the concrete or the reinforcement protections against corrosion.

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2.2.3 Aggregates: MPR EHE. Obtain all aggregates for exposed concrete from one source. Aggregates shall not contain any substance which may be deleteriously reactive with the alkalis in the cement.

2.2.4 Materials for Curing Concrete: Fabric cloth made from jute or organic emulsion compound of a well known manufacturer which has been in the market for at least five years to prevent premature evaporation of mixing water in the concrete. The compound will be transparent.

2.2.5 Reinforcing Bars: MPR EHE. All bars shall be corrugated bars. Welded wire fabric shall be as per MPR EHE.

2.2.6 Vapor Barrier: Polyethylene sheeting, minimum thickness to be 0.25mm.

2.2.7 Forms: Provide wood, plywood, or steel. Hardwood shall have a phenolic faced for forms used in exposed concrete surfaces. Use plywood or steel forms where a smooth form finish is required. Lumber shall be square edged or tongue-and-groove boards, free of raised grain, knotholes, or other surface defects. Form surfaces shall not contain irregularities.

2.2.8 Form Ties and Accessories: The use of wire alone is prohibited. Form ties and accessories shall not reduce the effective cover of the reinforcement.

2.2.9 Expansion/Contraction Joint Filler: UNE 41.107, 1 inch thick, unless otherwise indicated.

2.2.10 Joint Sealants: UNE 104.233.

2.2.11 Polypropylene Fiber: Shall be immersed in a homogeneous manner throughout the whole concrete mass in a proportion of 600 grams per cubic meter of concrete. Concrete tests shall be performed prior to fiber mixture. Fiber shall have the following characteristics:

Density: 0.9 g/cm³

Fiber length 6÷18 mm Fiber diameter 31 microns Elongation breakage 80-140% Melting point 163º-170ºC

PART 3 - EXECUTION

3.1 FORMS: Set forms true to line and grade and make mortar-tight. Before concrete

03 30 00-4 placement, coat the contact surfaces of forms with a coating compound. Do not use mineral oil on formed surfaces to be painted. Prevent concrete damage during form removal. Provide wire ties, supports, and other devices necessary to install and secure the reinforcement. Mass concrete for footings may be placed in excavations shallower than 600 mm without forms, upon inspection and approval of the Contracting Officer. In those cases, excavation width shall be a minimum of 100 mm greater than indicated. After placing concrete, forms shall remain in place for a minimum of 3 days. Prevent concrete damage during form removal.

3.2 PLACING REINFORCEMENT AND MISCELLANEOUS MATERIALS: MPR

EHE. Provide bars, wire fabrics, wire ties, supports, and other devices necessary to install and secure the reinforcement properly. Reinforcement shall not contain rust, scale, oil, grease, clay, and foreign substances that would reduce the bond. Excessive rusting of reinforcement is a basis of rejection. Remove loose rust prior to placing steel. Tack welding is prohibited.

3.2.1 Vapor Barrier: Provide, where indicated in drawings, around foundations. Use the greatest widths and lengths practicable so as to eliminate joints wherever possible. Lap joint minimum of 12 inches. Remove torn, punctured, or damaged vapor barrier material and provide with new vapor barrier.

3.2.2 Spacers: Place reinforcement and secure with galvanized or non- corrodible chairs, spacers, or metal hangers. Use concrete or other non corrodible material for supporting reinforcement on the ground.

3.2.3 Splicing: MPR EHE. Do not make splices at points of maximum stress. Overlap bars 40 diameters minimum. Overlap welded wire fabric the spacing of the cross wires, plus 2 inches.

3.2.4 Cover: MPR EHE, for minimum coverage, unless otherwise indicated.

3.2.5 Construction Joints: Locate joints to least impair strength. Continue reinforcement across joints unless otherwise indicated.

3.2.6 Expansion Joints and Contraction Joints: Provide expansion joints at edges of floor slabs on grade abutting vertical surfaces, and additionally as indicated. Make expansion joints 20 mm wide unless indicated otherwise. Fill expansion joints not exposed to weather with preformed joint filler material. Completely fill joints exposed to weather with joint filler material and joint sealant. Do not extend reinforcement or other embedded metal items bonded to concrete through any expansion joint unless an expansion sleeve is used. Provide contraction joints, either formed or saw cut or cut with a jointing tool, to the indicated depth after the surface has been finished. Sawed joints shall be completed within 4 to 12 hours after concrete placement. Protect joints from intrusion of foreign matter.

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3.2.7 Placing: Place concrete as soon as practicable after the forms and the reinforcement have been inspected and approved. Do not place concrete when weather conditions prevent proper placement and consolidation; or in standing water. Prior to placing concrete, remove dirt, construction debris, water, and ice from within the forms. Deposit concrete as close as practicable to the final position in the forms. Do not exceed a free vertical drop or 3 feet from the point of discharge. Place concrete in one continuous operation from one end of the structure towards the other. Position grade stakes on 10-foot center maximum in each direction when pouring interior slabs and on 20-foot center maximum for exterior slabs.

3.2.8 Vibration: Furnish a spare vibrator on the job site whenever concrete is placed.

Consolidate concrete slabs greater than 4 inches in depth with high frequency, internal, mechanical vibrating equipment supplemented by hand spading and tamping. Consolidate concrete slabs 4 inches or less in depth by wood straight edge. Operate vibrators with vibratory element submerged in the concrete with a minimum frequency of not less than 6000 impulses per minute when submerged. Do not use vibrators to transport the concrete in the forms. Insert and withdraw vibrators approximately 18 inches apart. Penetrate the previously placed lift with the vibrator when more than one lift is required. Place concrete in 18-inch maximum vertical lifts.

External vibrators shall be used on the exterior surface of the forms when internal vibrators do not provide adequate consolidation of the concrete.

3.2.9 Setting Miscellaneous Material: Place and secure pipe sleeves, drains and other such items in position before concrete placement. Temporarily fill voids in sleeves and drains with readily removable material to prevent the entry of concrete.

3.3 MEASURING, MIXING, TRANSPORTING, AND PLACING CONCRETE: MPR

EHE. Provide mandatory batch ticket information for each load of ready mix concrete. For "in situ" mixed concrete begin mixing within 30 minutes after the cement has been added to the aggregates. Place concrete within 90 minutes of either addition of mixing water to cement and aggregates or addition of cement to aggregates if the air temperature is less than 30 degrees C.

Reduce mixing time to 60 minutes if the air temperature is greater than 30 degrees C. Additional water may be added, provided that both the specified maximum slump and water-cement ratio are not exceeded. Prior to placing concrete, remove dirt, construction debris and water from within the forms. Consolidate concrete slabs greater than 10 cm depth with high frequency, internal, mechanical vibrating equipment supplemented by hand spading and tamping.

Consolidate concrete slabs 10 cm or less in depth by tamping, spading, and settling with a heavy levelling straight edge.

3.3.1 Cold Weather: Provide and maintain 10 degrees C minimum concrete temperature.

Do not place concrete when the ambient temperature is below 5 degrees C. Cover concrete and provide with a source of heat sufficient to maintain 10 degrees c minimum while curing.

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3.3.2 Hot Weather: Concrete temperature from initial mixing through final cure shall not exceed 32 degrees C. Use suitable means to control concrete temperature to prevent rapid drying of newly placed concrete. Shade the fresh concrete and start curing as soon as the surface of the fresh concrete is sufficiently hard to permit curing without damage.

3.4 SURFACE FINISHES: Slope floors uniformly. After trowelling is completed protect surface for curing.

3.4.1 Defects: Repair formed surfaces by removing minor honeycombs, pits greater than 1 mm5 surface area or 3 mm maximum depth, or otherwise defective areas. Provide edges perpendicular to the surface and patch with nonshrink grout. Patch tie holes and defects when the forms are removed. Concrete with extensive honeycomb will be rejected, unless correction of defects is approved. Obtain approval of corrective action prior to repair. Exposed surfaces shall be uniform in appearance and finished to a smooth form finish, unless otherwise specified.

3.4.2 Not Against Forms: Surfaces not otherwise specified shall be finished with wood floats to even surfaces. Finish shall match adjacent finishes.

3.4.3 Formed Surfaces:

3.4.3.1 As-Cast Rough Form: Provide as-cast rough form for surfaces not exposed to public view. Remove fins and other projections exceeding 0.25 inch in height; level abrupt irregularities.

3.4.3.2 As-Cast Smooth Form: Provide as-cast smooth form for surfaces exposed to public view. Form facing material shall produce a smooth, uniform texture on the concrete.

Remove fins and other projections.

3.5 FLOOR, SLAB AND PAVEMENT FINISHES AND MISCELLANEOUS

CONSTRUCTION: Slope floors uniformly. Provide floor slabs with a steel trowelled finish.

After trowelling and moist curing are completed, apply a liquid chemical sealer-hardener compound on interior floor slabs that do not receive floor covering.

3.5.1 Finish: Place, consolidate, and immediately strike off concrete to obtain proper contour, grade, and elevation before bleedwater appears. Permit concrete attain a set sufficient for floating and supporting the weight of the finisher and equipment. If bleedwater is present prior to floating the surface, drag the excess water off or remove by absorption with porous materials. Do not use dry cement to absorb bleedwater.

3.5.1.1 Broomed: Provide for exterior walks unless otherwise indicated. Provide a

03 30 00-7 floated finish, then finish with a flexible bristle broom. Permit surface to harden sufficiently to retain the scoring or ridges. Broom transverse to traffic or at right angles to the slope of the slab.

3.6 CURING AND PROTECTION: Begin curing immediately following form removal.

Protect concrete from injurious action by sun, rain, flowing water, frost, mechanical injury, tire marks and oil stains. Do not allow concrete to dry out from time of placement until the expiration of the specified curing period. Do not use membrane forming compound on surfaces where appearance would be objectionable, on any surface to be painted, where coverings are to be bonded to the concrete, or on concrete to which other concrete is to be bonded. If forms are removed prior to the expiration of the curing period, provide another curing procedure specified herein for the remaining portion of the curing period. Provide moist curing for those areas non receiving liquid chemical sealer-hardener.

3.6.1 Moist Curing: Provide for the removal of water without erosion or damage to the structure. Use one or several of the hereafter explained methods as per the Contracting Officer's instructions.

3.6.1.1 Fog Spraying or Sprinkling: Provide uniform and continuous application of water throughout the curing period. For temperatures between 40 and 50 degrees F, increase the curing period by 50 percent.

3.6.1.2 Pervious Sheeting: Completely cover surface and edges of the concrete with two thicknesses of wet sheeting. Overlap sheeting 6 inches over adjacent sheeting.

Sheeting shall be at least as long as the width of the surface to be cured. During application, do not drag the sheeting over the finished concrete nor over sheeting already placed. Wet sheeting thoroughly and keep continuously wet throughout the curing period.

3.6.1.3 Impervious Sheeting: Wet the entire exposed surface of the concrete thoroughly with a fine spray of water and cover with impervious sheeting throughout the curing period. Lay sheeting directly on the concrete surface and overlap edges 12 inches minimum.

Provide sheeting not less than 18 inches wider than the concrete surface to be cured. Secure edges and transverse laps to form closed joints. Repair torn or damaged sheeting or provide new sheeting. Cover or wrap columns, walls, and other vertical structural elements from the top down with impervious sheeting, overlap and continuously tape sheeting joints, and introduce sufficient water to soak the entire surface prior to completely enclosing.

3.6.2 Liquid Membrane-Forming Compound Curing: Seal or cover joint openings prior to application of the curing compound. Prevent curing compound from entering the joint. Provide and maintain compound on the concrete surface throughout the curing period.

3.6.2.1 Application: Unless the manufacturer recommends otherwise, apply

03 30 00-8 compound immediately after the surface loses its water sheen and has a dull appearance, and before joints are sawed. Mechanically agitate curing compound thoroughly during use. Use approved power-spraying equipment to uniformly apply two coats of compound in a continuous operation. The total coverage for the two coats shall be 200 square feet maximum per gallon of undiluted compound unless otherwise recommended by the manufacturer's written instructions.

The compound shall form a uniform, continuous, coherent film that will not check crack, or peel.

3.6.2.2 Protection of Treated Surfaces: Prohibit foot and vehicular traffic and other sources of abrasion for not less than 72 hours after compound application. Maintain continuity of the coating for the entire curing period and immediately repair any damage.

3.6.3 Curing Period: Not less than 7 days for all concrete.

3.6.3.1 Additional Curing: Double the required curing period if either one or the average of both test cylinders indicate less than 90 percent of the strength specified.

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