Section 552 — Structural Concrete

Description

552.01This work consists of constructing structural concrete in bridges, culverts, and other structures.

Material

552.02Conform to the following Section and Subsections: Coarse aggregate for concrete 703.02 Concrete curing material and additives 711 Fine aggregate for concrete 703.01 Grout 701.04 Hydraulic cement 701.01 Pozzolans 701.03 Penetrating stain for concrete 719.05 Sealants, fillers, and seals 712.01 Structural steel 717.01 Water for cementitious materials 725.01(a)

Construction Requirements

552.03Composition (Mix Design). Design and produce concrete mixtures that conform to the class specified. Submit concrete mix designs for approval at least 36 days before production. Provide a new mix design for approval if ther e is a change in a source of material or when the fineness modulus of the fine aggregate changes by more than 0.20. Table 552-1

Composition of Concrete

Class

of

Concrete Minimum

Compressive

Strength

@ 28 -Days, f 'c, pounds per square inch Maximum

Water -

Cementitious

Material

Ratio Maximum

Coarse

Aggregate Size,

inch(1) Air Content for

Air Entrained

Concrete,

percent A, A(AE) 4500 0.45 1.5 4.0 to 7.0 C, C(AE) 4500 0.45 0.75 4.5 to 7.5 D(AE)(2) 5000 0.40 1.5 4.0 to 7.0 P, P(AE)(3) See plans – 1.0 4.0 to 6.0 S (Seal) – 0.54 1.5 –

(1)Meet size number gradation and requirements from AASHTO M 43 for coarse aggregates. Blending of standard sizes to optimize gradation is allowed.

(2)The maximum water -soluble chloride ion content is 0.1 5 percent by mass of cement. Determine the water -soluble chloride ion content of concrete made with mix ingredients at an age between 28 and 48 days according to ASTM C1218. Submit test results with the concrete mix design for approval.

(3)T he maximum water -soluble chloride ion content is 0.06 percent by mass of cement. Determine the water -soluble chloride ion content of concrete made with mix ingredients at an age between 28 and 48 days according to ASTM C1218. Submit test results with the c oncrete mix design for approval. Table 552-2 Cementitious Material Requirements for Concrete Cementitious Material Maximum Percent of Total

Cementitious Material by

Mass

Fly ash or other pozzolans, AASHTO M 295 25 Slag, AASHTO M 302 50 Silica fume, AASHTO M 307 10 Total fly ash or other pozzolans, slag, & silica fume 50(1) Total fly ash or other pozzolans & silica fume 35(1)

(1)Limit fly ash or other pozzolans to no more than 25 percent of the total mass of cementitious material and limit silica fume to no more than 10 percent of the total mass of cementitious material.

(a)Structural concrete. Design and produce concrete mixtures that conform to Tables 552-1 and 552-2 for the class specified. Determine design strength values according to S ection 4 of ACI 301, Specifications for Concrete Construction. Verify mixture design with trial mixes prepared according to S ection 4 of ACI 301 from proposed sources or with previous concrete production dat a for the mixture design submitted from proposed sources. Submit concrete mix designs on Form FHWA 1608, 552 Structural Concrete Mix Design Submittal . Include the following in each mix design submittal:

(1)Project identification;

(2)Name and address of Contractor and concrete producer;

(3)Mix design designation;

(4)Class of concrete and intended use;

(5)Material proportions;

(6)Name and location of material sources for aggregate, cement, admixtures, and water;

(7)Type of cement and other cementitious material, if used. Fly ash, slag cement , or silica fume may partially replace cement in the mix;

(8)Cement content in pounds per cubic yard of concrete;

(9)Saturated surface dry batch mass of the coarse and fine aggregate in pounds per cubic yard of concrete;

(10)Water content in pounds per cubic yard of concrete;

(11)Water to cementitious material ratio for modified concrete is the ratio of the mass of water to the combined masses of hydraulic cement and cement substitute;

(12)Dosage of admixtures required using the job site material, tri al mixtures, and admixture manufacturer’s recommendations. Do not combine chemical admixtures together in a mix unless they are compatible. Include supporting documentation of compatibility from the manufacturers.

(a)Air-entraining admixtures. Entrained air may be obtained with air -entraining hydraulic cement or air -entraining admixture.

(b)Set accelerating admixtures. Do not use chloride accelerators. Do not use set accelerating admixtures in prestressed concrete applications.

(c)Hydration stabilizing admixtures. Hydration stabilizing admixtures may be used to extend the allowable delivery time for concrete. Base the dosage on the time needed to delay the initial set of the concrete for delivery and discharge on the job. Include the design discharge time limit shown in Table 552-3.

(13)Fine and coarse aggregate quality;

(14)Sieve analysis of fine and coarse aggregate;

(15)Absorption of fine and coarse aggregate;

(16)Bulk specific gravity (dry and saturated surface dry) of fine and coarse aggregate;

(17)Dry rodded density of coarse aggregate in pounds per cubic foot;

(18)Fineness modulus of fine aggregate;

(19)Material certifications for cementitious material, admixtures, and aggregate;

(20)Target values for concrete slump or slump flow, as appropriate, with and without high -range water reducers;

(21)Target values for concrete air content. Include the proposed range of air content for concrete to be incorporated in the work. Describe the methods by which air content will be monitored and controlled;

(22)Concrete density;

(23)Specified design strength and required average strength ( f'cr) for the concrete mixture at 28 days as determined by the process described in Section 4 of ACI 301. This process and associated calculations are outlined on Form FHWA 1608, pages 4 and 5. Pending 28- day st rength results, a mix design may be approved on the basis that 7- day compressive strength results are at least 85 percent of the required average strength ( f' cr) at 28 days;

(24)Compressive strengths test results at 7 and 28 days according to Table 552-10, Note (3);

(25)Material samples, if requested;

(26)Fiber samples, if used;

(27)Integral color admixture, if used. Do not to exceed 10 percent of the weight of the cementitious material; and

(28)Strength -maturity relationships, if used, according to AASHTO T 325.

(b)Internally cured concrete (ICC). Design and produce concrete mixtures that conform to Tables 552-1 and 552-2 for the class of concrete specified. Provide aggregate according to the class specified, except substitute a portion of the normal weight fine aggregate (on a cubic yard basis) for lightweight fine aggregate (LWFA) conforming to AASHTO M 195. Determine th e quantity of LWFA (lb/yd 3) by the following calculations: cementitious factor = cementitious content (lb/yd3) /100 where: cementitious content is the inclusion of portland cement and supplementary cementitious materials in the submitted concrete mixture; 𝑈𝑈𝑊𝑊𝑃𝑃𝑆𝑆 𝑞𝑞𝑃𝑃𝐼𝐼𝑛𝑛𝑓𝑓𝐼𝐼𝑓𝑓𝑞𝑞 =𝑐𝑐𝑀𝑀𝑐𝑐𝑀𝑀𝑛𝑛𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑐𝑐𝑐𝑐𝑠𝑠 𝑓𝑓𝑀𝑀𝑐𝑐𝑀𝑀𝑐𝑐𝑀𝑀 × 7.0 � 𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝 𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑝𝑝𝑝𝑝𝑝𝑝𝑎𝑎𝑎𝑎𝑝𝑝 𝑎𝑎𝑜𝑜 𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿 �1 + �𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝𝑝 𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑝𝑝𝑝𝑝𝑝𝑝𝑎𝑎𝑎𝑎𝑝𝑝 𝑎𝑎𝑜𝑜 𝐿𝐿𝐿𝐿𝐿𝐿𝐿𝐿 100��� ; and Round calculated LWFA quantity to nearest pound per cubic yard. Adjust the concrete mix design normal weight fine aggregate quantity after determining the saturated surface dry (SSD) volume of the LWFA. Subtract the SSD LWFA volume from the original volume of normal weight fine aggregate. Calculate new adjusted SSD weight of normal weight fine aggregate on a pound per cubic yard basis. Determine design strength values according to Section 4 of ACI 301. In addition, design structural concrete mixes according to the following:

(1)ACI 211.1, Standard Practice for Selecting Proportions for Normal, Heavy Weight and Mass Concrete; and

(2)ACI 211.3, Guide for Selecting Proportions of No-Slump Concrete . Submit ICC mix designs according to Subsection 552.03(a) .

(c)Self-consolidating concrete (SCC). Design and produce SCC mixtures that conform to Section 4 of ACI 301. Provide a maximum water to cementitious material ratio of 0.40. See Table 552-1 for minimum compressive strength requirements and air entrainment. Provide maximum coarse aggregate size less than or equal to 1 inch. Conform to size number gradation and requirements from AASHTO M 43 for coarse aggregates. Blending of standard sizes to optimize gradation is allowed. Design the mix to have slump flow according to ASTM C1611, static se gregation according to ASTM C1610, and passing ability according to ASTM C1621 suitable for the application of SCC. Submit SCC mix designs according to Subsection 552.03(a) .

(d)Integral color admixture. When an integral color admixture is specified, prepare five 2 - by 2- foot test panels. Construct the test panels using the proposed mix design. Determine coloring agent batch amounts by weight. Use variable quantities of coloring agent as approved. Provide additional mixing time according to the manufacturer’s recommendations. Complete a Class 1 finish according to Subsection 552.14(a) . Cure the test panels similar to the structure. Transport the panels to an approved location. Provide at least 2 weeks outside exposure. The CO will select the acceptable test panel. Use the same rate of integral color admixture for the item of work.

552.04Mixing. Use a batching plant, mixer, and agitator conforming to AASHTO M 157. Mix the concrete in a central -mix plant or in truck mixers. Operate equipment according to the manufacturer’s recommendations. Produce concrete of uniform consistency.

(a)Batching tolerances. Batch the concrete according to the approved mix design and Table 552-3. Table 552-3

Batching Tolerances

Material Tolerance,

Percent (±) Cement 1 Water 1 Aggregate 2 Additive 3

(b)Central -mix plant. Dispense liquid admixtures through a controlled flowmeter. Use dispensers with sufficient capacity to measure, at one time, the full quantity of admixture required for each batch. If more than one admixture is used, dispense each with separate equipment. Charge the coarse aggregate, one -third of the water, and all air- entraining admixture into the mixer first, then add remainder of the material. Mix for at least 50 seconds. Start mixing time after all cement and aggregate are in the drum. Add the remaining water during the first quarter of the mixing time. Add 4 seconds to the mixing time if timing starts the instant the skip reaches its maximum raised position. Transfer time in multiple -drum mixers is included in mixing time. Mixing time ends when the discharge chute opens. Remove the contents of an individual mixer before a succeeding batch is charged into the drum. (c) Truck mixer. Do not use mixers with blades worn 1 inch or more below the original manufactured height. Do not use mixers and agitators with accumulated hard concrete or mortar in the mixing drum. Add admixtures to the mix according to the manufacturer’s recommendations. Charge the batch into the drum so a portion of the mixing water enters before the cement. Mix each batch of concrete according to AASHTO M 157.

552.05Delivery. Produce and deliver concrete to allow a continuous placement with no concrete achieving initial set before the remaining concrete being placed adjacent to it. Deliver, handle, and place concrete to minimize rehandling of the concrete and prevent damage to the structure. Do not place concrete that has developed an initial set or exceeds discharge time limits shown in Table 552-4. Do not re -temper concrete by adding water. If a hydration stabilizing admixture is approved for use in the concrete mix, deliver and place the concrete within the approved design discharge time limit. Limit the slump loss to no more than 2 inches during the stabilization period. An approved and compatible hydration activator may be used at the discharge site to ensure proper placement and testing.

(a)Truck mixer and agitator. Use the agitating speed for rotation after mixing. When a truck mixer or truck agitator is used to transport concrete that is completely mixed in a stationary central construction mixer, mix during transportation at the manufacturer’s recommended agitating speed. Do not exceed 100 total revolutions at mixing speed, including both initial mixing and remixing. Do not exceed 300 total revolutions, including both mixing and agitating speed. If the concrete has not obtained an initial set, water and admixtures in the approved mix design may be added one time at the project to obtain the required slump or air content. Limit the total of water in the mix to not exce ed the maximum water to cementitious material ratio of the approved mix design. Remix the concrete and added water or admixtures with 30 revolutions at mixing speed. After the initial introduction of mixing water to cement or cement to aggregates, complete the remixing within the time shown in Table 552-4. After starting the addition of the cement, complete the discharge of the concrete within the time shown in Table 552-4 . Table 552-4 Concrete Remixing and Discharge Time Limits Cement Type(1) Admixtures Remixing

Time Limit,

hour Discharge

Time Limit,

hour

Type I, IA, II, IIA, V, or approved

blended hydraulic cement None 0.75 1.00

Type I, IA, II, IIA, V, or approved

blended hydraulic cement AASHTO M 194, Type B, D, or G 1.25 1.50

Type I, IA, II, IIA, V, or approved

blended hydraulic cement Hydration stabilizer 3.00 Approved design discharge time limit, 3.50 maximum Type III None 0.50 0.75 Type III AASHTO M 194, Type B, D, or G 1.00 1.25

(1)AASHTO M 85 or AASHTO M 240 as applicable.

(b)Non-agitating equipment. Non-agitating equipment may be used to deliver concrete if the concrete discharge is completed within 20 minutes from the starting of the addition of the cement to the mixing drum. Use equipment with smooth, mortar tight, metal containers that can discharge the concrete at a controlled rate without segregation. Provide covers when needed for protection.

552.06Quality Control of Mix. P revent segregation, contamination, or other harmful effects during handling and storage of material. Do not use cement and fly ash containing evidence of moisture contamination. Provide aggregate with uniform moisture content at the time of batching. Submit and follow a QCP according to Section 153 and the following:

(a)Preparatory phase meeting. C onduct a pre -concrete preparatory phase meeting according to Subsection 153.06(a) at least 7 days before the start of structural concrete production operations. Include a representative from the QC testing lab. Be prepared to discuss the following:

(1)Proposed concrete placement schedule;

(2)Approved concrete mix design and determination of batch weights;

(3)Contractor QC, and the minimum frequency schedule for sampling and testing;

(4)Batching, mixing, placing, and curing requirements; and

(5)Subsections 106.03, 106.04, and 106.05.

(b)Mixing. Provide a supplier representat ive to be responsible for the mixing operations and QC including:

(1)Proper storage and handling of components of the mix;

(2)Proper maintenance and cleanliness of plant, trucks, and other equipment;

(3)Sampling and testing according to Table 552-10 ;

(4)Adjusting the mix proportions to maintain the required water to cementitious material ratio;

(5)Computing batch masses for each day’s production;

(6)Checking of the plant’s calibration; and

(7)Completing batch tickets. Include the following:

(a)Concrete supplier;

(b)Ticket serial number;

(c)Date and truck number;

(d)Contractor;

(e)Structure or location of placement;

(f)Mix-design and concrete class;

(g)Component quantities and concrete total volume;

(h)Moisture corrections for aggregate moisture;

(i)Total water in mix at plant;

(j)Time of batching;

(k)Maximum water that may be added to the mix at the project; and

(l)If a hydration stabilizing admixture is used, the slump at the plant after adding the stabilizer. Provide documentation for Subsections 552.06(b)(3) , (4), (5), and (7) as they are completed.

(c)Delivery and discharge. The QCM is responsible for concrete delivery and discharge including:

(1)Verifying adjustments to the mix comply with the specifications before discharge; and

(2)Completing the batch ticket for each load by recording the apparent water to cementitious material ratio and the time.

552.07Temperature, Weather, and Mass Concrete Cond itions. Maintain the temperature of the concrete mixture immediately before placement between 50 and 90 °F, except for bridge decks between 50 and 80 °F.

(a)Cold weather. Cold weather is defined as a period when the following conditions exist for more than 3 consecutive days:

(1)Average of the highest and the lowest temperatures occurring during the period from midnight to midnight is less than 40 °F; and

(2)Air temperature is not greater than 50 °F for more than one- half of a 24 -hour period. When cold weather is e xpected or has occurred within 7 days of anticipated concrete placement, submit a detailed plan for the producing, transporting, placing, protecting, curing, and temperature monitoring of concrete during cold weather. For each concrete placement and concre te element type, submit a plan for temperature recording device placement. ACI 306, Guide to Cold Weather Concreting may be used for guidance in developing the plan. Include procedures for accommodating abrupt changes in weather conditions. Allow at least 7 days for review and approval of the plan. Do not start placement until the plan is approved. Have material and equ ipment required for protection available at the project before starting cold weather concreting. Remove snow, ice, and frost from the surfaces, including reinforcement and subgrade, against which the concrete is to be placed. Heat surfaces that come into contact with fresh concrete to at least 35 °F and maintain the temperature of these surfaces at 35 °F or above during concrete placement. Place heaters and direct ducts to avoid concrete drying or fire hazards. Vent exhaust flue gases from combustion heating units to the outside of enclosures. Do not damage the mix while heating the concrete components . Do not heat cement or allow the cement to come into contact with aggregates that are hotter than 100 °F. Do not heat aggregates with a direct flame or on she et metal over fire. Do not heat fine aggregate by direct steam. Do not add salts to prevent freezing. Use protection measures for at least 7 days as identified in the cold weather plan to meet the requirements shown in Table 552-5. Provide and place continuously recording surface temperature measuring devices that are accurate within ±2 °F. Provide a datalogging device and collect temperature data every 15 minutes in the first 48 hours and at 1 -hour intervals after that for at leas t 14 days. Verify that data logger and temperature sensors are working before starting cold weather concrete placement. Download and submit data daily. At a minimum, place temperature recording devices at corners and selected surfaces of the concrete place ment. Install temperature recording devices at a depth of 2 inches from the surface of the concrete. For circular cross- sections place at least three surface measuring devices at 120 -degree intervals. Place two temperature measurement devices at the center of the concrete placement. Do not exceed a temperature differential of 60 °F during the protection period as measured from the center of the placement and a point 2 inches from the surface along the shortest line from the geometric center to the nearest surface of the element. Notify the CO if maximum allowable differential is exceeded and adjust protection to reduce temperature differential to below 60 °F. At the end of the protection period, allow the concrete to cool gradually over 24 hours at a rate less than the maximum values shown in Table 552-5. S tart the cooling process when the average wind speed is less than 10 miles per hour as measured 3 feet from the concrete surface. Remove protection when the concrete surface temper ature is within 25 °F of the ambient air temperature. Table 552-5 Cold Weather Concrete Surface Temperatures

Minimum Section Size

Dimension < 12 inches 12 to < 36 inches 36 to 72 inches > 72 inches

Minimum temperature of concrete

during protection period 55 °F 50 °F 45 °F 40 °F

Maximum allowable temperature

drop in a 24 -hour period after end of protection 50 °F 40 °F 30 °F 20 °F

(b)Hot weather. Hot weather is defined as any time during the concrete placement when the ambient air temperature at the work site is above 90 °F. Cool surfaces that come in contact with the mix to below 90 °F by covering with wet burlap or cotton mats, fog spraying with water, covering with protective housing, or by other approved methods. During placement, maintain concrete temperature by using any combination of the following:

(1)Shade the material storage areas or production equipment.

(2)Cool aggregate by sprinkling.

(3)Cool aggregate and water by refrigeration or replacing a portion or all the mix water with flaked or crushed ice to the extent that the ice completely melts during mixing of the concrete.

(c)Evaporation. When placing concrete in bridge decks or other exposed slabs, limit expected evaporation rate to less than 0.1 pound per square foot per hour as determined by Figure 552-1. When necessary, take one or more of the following actions:

(1)Construct windbreaks or enclosures to effectively reduce the wind velocity throughout the area of placement.

(2)Use fog sprayers upwind of the placement operation to effectively increase the relative humidity. (3) Reduce the temperature of the concrete according to Subsection 552.07(b) .

(d)Precipitation. Protect the concrete from precipitation during and after placement. Figure 552-1

Evaporation Rate of Surface Moisture

Source: “Plastic Cracking of Concrete.” Engineering Information, National Ready Mixed Concrete Association/National Sand and Gravel Association, July 1960, 2 pp. Note: Example shown by dashed lines is for an air temperature of 65 °F, relative humidity of 45 percent, concrete temperature of 65 °F, and a wind velocity of 15 miles per hour. This results in a rate of evaporation of 0.13 pounds per square foot per hour.

(e)Mass concrete. Mass concrete is considered any element shown in the plans with a least dimension greater than or equal to 4 feet and having a volume to surface ratio (V/S) greater than 1.5 feet. Provide temperature control of mass concrete to minimize potential cracking and to limit the maximum temperature of concrete during the curing process. Provide temperature control according to ACI 207.1R, Guide to Mass Concrete and ACI 207.4R, Report on Cooling and Insulating Systems for Mass Concrete.

(1)Temperature limit ations. Limit the maximum temperature differential between the geometric center and a point 2 inches from the nearest surface to the requirements shown in Table 552-6. To use this chart: 1. Enter with air temperature, move up to relative humidity. 2. Move right to concrete temperature. 3. Move down to wind velocity. 4. Move left , read approximate rate of evaporation. Table 552-6 Maximum Temperature Differential During Curing Period Curing Period Maximum Temperature Differential Less than 48 hours 40 °F Next 2 to 7 days 50 °F Next 8 to 1 4 days 60 °F Maintain these temperature conditions from time of concrete placement until all interior concrete temperatures are decreasing. Do not allow surface mounted temperature sensors to measure differential temperatures. Do not remove protection until the temperature difference between the geometric center of the mass and forecasted low ambient temperature in the next 48 hours is less than 60 °F. Do not exceed 160 °F for the maximum peak curing temperature.

(2)Temperature control. Control the maximum temperature and temperature differentials in the mass concrete according to the following:

(a)Submittals. Submit a mass concrete placement and curing plan for approval at least 14 days before the scheduled concrete placement for a particular mass concrete element. Include the following information in the plan:

(1)A heat generation analysis for the geometry of each mass concrete element according to ACI 207.2R, Report on Thermal and Volume Change Effects on Cracking of Mass Concrete. Determine the predicted concrete temperature at the center and 2 inches inside of the exterior surface exposed to air for a time period until all concrete temperatures are decreasing and the maximum temperature differential has been reached and starts to decrease, and estimate the protection period. Perform analyses for the anticipated mean weekly ambient or enclosure air temperatures f or the period of the proposed placement, and for temperatures ±10 °F of the mean weekly ambient air temperature;

(2)Models developed for thermal dissipation analyses (such as the Schmidt method according to ACI 207.1R) with the site and element specific input data, output, and results;

(3)Placement and curing methods indicating how temperature controls are to be achieved; and

(4)Proposed changes to the approved concrete mix design.

(b)Temperature monitoring. Provide temperature monitoring devices to record temperature development between the interior and the exterior of the element at points shown in the approved mass concrete placement and curing plan. Monitor at least two independent sets of interior and exterior points for each element to provide redundancy in case of device failure. Locate monitoring points at the geometric center and a point 2 inches to the nearest surface of the element for the exterior point. Use automatic sensing and monitoring devices that record information at a maximum interval of one hour. Provide devices that operate within a temperature range of 0 to 180 °F with an accuracy of ±2 °F. Take readings and record data at intervals less than six hours to ensure that the automatic devices are working properly and that the temperatures are within al lowable limits. Start the intervals of one and six hours immediately after placing is complete and continue until 24 hours after the following:

(1)Maximum temperature differential is reached and starts to drop;

(2)Maximum peak curing temperature is reached and starts to drop; and

(3)Curing is complete and protection is removed. Submit temperature readings to the CO daily. If monitoring indicates the maximum temperature differential or curing temperature will, or has exceeded the temperature requirements, take immedi ate action to retard further increase in temperatures. Make necessary revisions to the approved plan to not exceed the maximum differential and curing temperatures on remaining placements. Submit revisions to the mass concrete placement and curing plan for approval before implementation.

(3)Crack repair. Submit a crack repair plan for approval. Repair mass concrete cracks between 0.010 and 0.060 inch in width according to Section 561. Evaluate mass concrete cracks greater than 0.060 inch in width to determine whether the cracks compromise the structure. Submit findings and proposed corrective work for approval. Do not repair cracks until all concrete cooling operations are completed.

552.08Handling and Placing Concrete. Handle , place, and consolidate concrete by methods that do not cause segregation and will result in dense homogeneous concrete that is free of voids and rock pockets. Construct reinforcing steel according to Section 554. Do not displace reinforcing steel or other material that is to be embedded in the concrete during concrete placement. Do not retemper concrete by adding water to the mix. Use temporary form spreader devices as appropriate. Place concrete continuously between planned construction or expansion joints. Control the delivery rate, placing sequence, and construction methods to ensure fresh concrete is placed and consolidated against previously placed pre -initial set concrete. Do not allow time between the placement of su ccessive batches to exceed 30 minutes. Do not damage previously placed concrete or break the bond between the concrete and reinforcing steel. Keep workers off fresh concrete. Do not support platforms for workers and equipment directly on reinforcing steel. Once the concrete is set, do not disturb the forms or reinforcing bars that project from the concrete until it is of sufficient strength to resist damage. Remove and replace concrete represented by cylinders having a compressive strength less than 90 perc ent of the minimum 28 -day strength ( f' c). Design and construct temporary works according to Section 562. Remove mortar, debris, and foreign material from the forms and reinforcing steel. Do not place concrete until the forms, embedded material, and the adequacy of the foundation material have been inspected. Uniformly moisten the forms and subgrade immediately before concrete is placed against them. Use an approved form release agent to produce a minimum of staining, air holes, and hydration discoloration.

(a)Sequence of placement. For strength determination, use either AASHTO T 22 or T 325.

(1)Substructures. Do not place loads on substructure elements including foundations, bents, piers, or abutments until concrete cylinder tests from the same concrete cured under the same conditions as the substructure element indicate that the concrete has at least 80 percent of its required 28- day compressive strength.

(2)Vertical members. For vertical members less than 15 feet in height, allow the concrete to set for at least 30 minutes before placing integral horizontal members. For vertical members 15 feet or greater in height, allow the concrete to set for at least 12 hours. Do not transfer loads from horizontal members until the concrete has attaine d the specified strength and has been in place at least 7 days. Do not mount friction collars or falsework brackets on vertical memb ers until the concrete has cured for at least 7 days or has attain ed the specified strength.

(3)Superstructures. Strip substructure forms and inspect concrete for defects before placing superstructure concrete. For concrete placed in T -beams or deck girders w ith depths greater than 48 inches, allow 5 days cure time for the stem concrete before placing the top or deck slab. For box girders, do not place the top slab until the stems have 5 days cure time.

(4)Arches. Place concrete for arches in alternate lateral sections to minimize shrinkage stresses. Consider deflections of the arch centering. Place other sections symmetrically with respect to the center of the bridge span. Where wide barrel arches require a longitudinal joint, place concrete on each side of the j oint independently of the centering to avoid relative settlements. Bond the sections together using suitable keys or dowels.

(5)Box culverts. Place the box culvert base slab and allow 24 hours before constructing the remainder of the culvert.

(b)Placing methods. Use equipment of sufficient capacity that is designed and operated to prevent mix segregation and mortar loss. Do not use equipment that causes vibrations that could damage the freshly placed concrete. Do not use equipment with aluminum parts that come in contact with the concrete. Remove set or dried mortar from inside surfaces of placing equipment. Place concrete as close as possible to its final position. Consolidate concrete in horizontal layers greater than 18 inches thick. Do not exceed the vibrator capacity to consolidate and merge the new layer with the previous layer. Do not place concrete at a rate that exceeds the design loading of the forms. Do not drop unconfined concrete more than 5 feet. Concrete may be confined by using a tube fitted with a hopper head or other approved devices that prevent mix segregation and mortar spattering. This does not apply to cast -in-place piling or drilled shaft when concrete placement is completed before initial set occurs in the bottom of the piling. Operate concr ete pumps so that a continuous stream of concrete without air pockets is delivered at the tube discharge.

(c)Consolidation. Provide sufficient hand -held internal concrete vibrators or mechanical vibrator gangs suitable for the conditions of concrete placement. Use vibrators conforming to Table 552-7. Provide rubber-coated vibrators when epoxy- coated reinforcement is used. Provide a spare vibrator on site in case of breakdown. Use external form vibrators only if the forms have been designed for external vibration and if internal vibration is not possible. Table 552-7

Hand- held Vibratory Requirements

Head Diameter, inch Frequency,

vibrations/minute Radius of Action, inch ¾ to 1½ 9000 to 15,000 3 to 6 1¼ to 2½ 8500 to 12,500 5 to 10 2 to 3½ 8000 to 12,000 7 to 14 Consolidate concrete by mechanical vibration immediately after placement. Manipulate vibrators to thoroughly work the concrete around reinforcement, embedded fixtures, corners, and angles in the forms. Do not cause segregation. Do not consolidate concrete placed under water. Supplement vibration with spading, as necessary, to ensure smooth surfaces and dense concrete along form surfaces, in corners, and at locations impossible to reach with the vibrators. Vibrate the concrete at the point of deposit and at uniformly spaced points not farther apart than one and one -half times the radius over which the vibration is visibly effective. Insert vibrators so that the affected vibrated areas overlap. Do not use vibrators to move concrete. Insert vibrators vertically and slowly withdraw from the concrete. Vibrate with sufficient duration and intensity to thoroughly consolidate the concrete, but not to cause segregation. Do not vibrate at one point long enough to cause localized areas of grout to form. Do not vibrate reinforcement. Mechanical vibration or consolidation is not required for SCC.

(d)Underwater placement. Underwater placement of concrete is allowed only for concrete mixtures designed for underwater placement according t o Subsection 552.03. Use tremies, concrete pumps, or other approved methods for placement.

(1)Tremies. Use watertight tremies, with a diameter sufficient to ensure that aggregate -induced blockages will not occur . Use multiple tremies as required. Make tremies that can be rapidly lowered to slow or stop the flow of concrete. Seal the discharge end and fill the tremie tube with concrete at the start of concrete placement. Keep the tremie tube full of concrete to the bottom during placement. If water enters the tube, withdraw the tremie and reseal the discharge end. Maintain continuous concrete flow until the placement is completed.

(2)Concrete pumps. Use pumps with a device at the end of the discharge tube to seal out water while the tube is first being filled with concrete. When concrete flow is started, keep the end of the discharge tube full of concrete and below the surface of the deposited concrete until placement has been completed. Place underwater concrete continuously from start to finish in a dense mass. Place each succeeding layer of concrete before the preceding layer has taken initial set using more than one tremie or pump if necessary. Keep the concrete surface as horizontal as practical. Do not disturb after placement. Maintain still water at the point of deposit. Dewater after test specimens cured under similar conditions indicate that the concrete has sufficient strength to resist the expected loads. Remove laitance or other unsatisfactory material from the exposed conc rete.

(e)Concrete railings and parapets. Use smooth, tight -fitting, rigid forms. Neatly miter corners. Place concrete railings and parapets after the falsework for the supporting span is released. Remove forms without damaging the concrete. Finish corners to be true, clean -cut, and without cracks, spalls, or other defects.

552.09Construction Joints. Place construction joints at locations shown in the plans. Obtain approval for additional construction joints. Extend reinforcing steel uninterrupted through construction joints. Embed lap splices or mechanical splices within the concrete. Do not use dowels. At horizontal construction joints, place gauge strips inside the forms along exposed faces to produce straight joint lines. When the joint is between fresh and newly hardened concrete, rough float the first placement to thoroughly consolidate the surface and leave the surface in a roughened condition. Clean the joint surface of laitance, curing compound, and other foreign material. Use an abrasive blast or other approved methods to expose the aggregate on the joint surface. Re -tighten forms where the joint overlaps the first placement. Immediately before placing new concrete, flush the joint surface with water and allow it to dry to a su rface dry condition. When the joint is between existing concrete and a new placement, abrasive blast clean or use other approved methods to remove laitance and foreign material, to expose clean aggregate, and to roughen the joint surface. Before concrete p lacement, apply approved bonding products to the joint surface according to the manufacturer’s recommendations.

552.10Expansion and Contraction Joints.

(a)Open joints. Form open joints with a wooden strip, metal plate, or other approved material. Remove the joint forming material without chipping or breaking the corners of the concrete. Do not extend reinforcement across an open joint.

(b)Filled joints. Cut pre -molded expansion joint filler to the shape and size of the surface being jointed. Secure the joint filler on one surface of the joint using galvanized nails or other approved means. Splice according to the manufacturer’s recommendations. After form removal, remove and neatly cut concrete or mortar that has sealed across the joint. Fill joint gaps ⅛ inch or wider with approved filler. Place necessary dowels, load transfer devices, and other devices as shown in the plans or as directed.

(c)Steel joints. Fabricate plates, angles, or other structural shapes accurately to conform to the concrete surface. Submit proposed joint opening to ensure optimal joint operation for the ambient temperature at the time of placement for approval. Securely fasten the joints to keep them in the correct position. Maintain an unobstructed joint opening during concrete placement.

(d)Comp ression joint seals. Use one -piece compression joint seals for transverse joints and the longest practical length for longitudinal joints. Clean and dry joints and remove spalls and irregularities. Apply a lubricant adhesive as a covering film to both side s of the seal immediately before installation. Compress the seal and place it in the joint according to the manufacturer’ s recommendations. Ensure the seal is in full contact with the joint walls throughout its length. Remove and discard seals that are twi sted, curled, nicked, or improperly formed. Remove and reinstall joint seals that elongate more than 5 percent of their original length when compressed. Remove excess lubricant- adhesive before it dries.

(e)Elastomeric expansion joint seal. Install the joint according to the manufacturer’s recommendations and as shown in the plans. (f) Asphaltic plug joint. Install the joint according to the manufacturer’s recommendations and as shown in the plans.

552.11Watertight Integrity Test. After completion of each expansi on joint within the limits of the bridge, perform a watertight integrity test on the top surface to detect leakage. Notify the CO 5 working days before performing watertight integrity test. For each joint, perform the watertight integrity test and inspection in the presence of the CO. Cover the entire joint system with either water ponded to a depth of at least 1 inch or continuously flowing water directly over full plan area of joint for at least 4 hours. Inspect the underside of the joints for evidence of dripping water or moisture for the duration of water application and for 2 hours after water supply is removed. The joint system is considered watertight when no free dripping water or moisture on underdeck surfaces beneath and adjacent to the joint is observed. Before performing the test, submit a detailed procedure for the watertight integrity test for approval. Submit photographic documentation performing the watertight integrity test. Include date, time, and location of joint inspections. If the joint system leaks, locate the place of leakage and perform repair measures necessary to stop the leakage according to the manufacturer ’s recommendations. After repair measures to eliminate leakage are taken, perform a subsequent water integrity test subject to the same conditions as the original test until watertight integrity results show no dripping water or moisture. Subsequent tests carry the same responsibility as the original test.

552.12Finishing Plastic Concrete. Strike off concrete surfaces that are not placed against forms. Float finish the concrete surface. Remove laitance or thin grout. Carefully tool non- chamfered edges with an edger. Leave edges of joint filler exposed. Protect the surface from precipitation damage. Provide at least two non-s agging and non- vibrating work bridges that can support the workers and equipment during placement, finishing, and curing operations. Place the work bridges at a reasonable height above the concrete surface to not impede worker performance and not touch the finished or fresh concrete surface.

(a)Striking off and floating. For bridge decks or top slabs of structures serving as finished pavements, use an approved power -driven finishing machine equipped with a screed that oscillates in a transverse direction. A power- screed or roller- screed is not allowed. Use hand -finishing methods for irregular areas if approved. Strike off surfaces. Do not support rails within the limits of the concrete placement without approval. Set rails or headers on non -yielding supports so the finishing equipment operates without interruption over entire surface being finished. Extend rails beyond both ends of the scheduled concrete placement a sufficient distance to enable finishing machine to finish the concrete being placed. Set rails the entire length of continuous girder structures before placing deck concrete. Adjust rails, headers, and strike -off equipment to the required profile and cross -section allowing for anticipated settlement, camber, and deflection of falsework. At least 1 day before starting delivery and placement of concrete, operate the finishing machine over the entire area to be finished to check for excessive rail deflections, deck thickness, reinforcing steel cover, and to verify proper operation of equipment. Make nec essary corrections before concrete placement starts. After placing the concrete, operate finishing machine over the concrete as needed to obtain the required profile and cross -section. Always keep a slight roll of excess concrete in front of the cutting ed ge of the screed. Maintain this excess of concrete to the end of the pour or form and then remove and waste it. Adjust rails or headers as necessary to correct for unanticipated settlement or deflection. Remove rail supports embedded in the concrete to at least 2 inches below the finished surface. Clean the voids of dust and debris using compressed air or other means. Apply approved bonding material in the voids. Fill the voids with fresh concrete of the same type and property as previously placed. Finish t he surface with a float, roller, or other approved devices as necessary to remove local irregularities. Remove excess water, laitance, and foreign material brought to the surface using a squeegee or straightedge drawn from the center of the slab towards ea ch edge. Do not apply water to the surface of the concrete during finishing operations.

(b)Straightedge measurement. Check horizontal surfaces with a 10- foot metal straightedge. Check the entire surface parallel to the centerline of the bridge. Overlap the straightedge at least one -half of the length of the previous straightedge placement. Correct deviations more than ⅛ inch from the testing edge of the straightedge. For deck surfaces that are to receive an overlay, correct deviations more than ¼ inch.

(c)Texturi ng. Finish after floating or at a time when finishing operations will not displace aggregate. Produce a skid- resistant surface texture on driving surfaces by grooving. Use one of the following or a combination for other surfaces as required.

(1)Grooved finish . Use a float having a single row of fins. Space fins ½ to ¾ inch on centers. Make the grooves ⅟ 16 to 3⁄16 inch wide and ⅛ to 3⁄16 inch deep. Groove perpendicular to the centerline without tearing the concrete surface or loosening surface aggregate. On bridge decks, discontinue grooving 12 inches from curb face and provide a longitudinal troweled finish on the surface of gutters.

(2)Sidewalk finish. Strike off the surface using a strike board and then float the surface. Use an edging tool on edges and expansion joints. Broom the surface using a broom with stiff bristles, broom perpendicular to the centerline from edge to edge with adjacent strokes slightly overlapped. Produce regular corrugations not over ⅛ inch in depth without tearing the concrete. Correct porous spots, irregularities, depressions, small pockets, and rough spots while the concrete is plastic. Groove contraction joints at the required interval using an approved grooving tool.

(3)Troweled and brushed finish. Use a steel trowel to produce a slick, s mooth surface free of bleed water. Brush the surface with a fine brush using parallel strokes.

(4)Exposed aggregate finish. Strike off the surface using a strike board and then float the surface. Use an edging tool on transverse and longitudinal joints that a re against forms or existing pavement. Do not edge transverse joints in a continuous lane pour or longitudinal joints in a continuous dual lane pour. Broom the surface as soon as the concrete hardens sufficiently to prevent particles of gravel from being d islodged. Use approved stiff brushes. Exercise care to prevent marring the surface and cracking or chipping of slab edges or joints. Apply a light spray of retardant to the unfinished surface to facilitate this work, if approved. Broom transversely across the pavement. Pull the loosened semi -stiff mortar off the pavement. Remove the mortar from adjacent pavements. Then broom parallel to the pavement centerline. Continue this operation until coarse aggregate is exposed. Other methods of aggregate exposure, such as using a water spray attachment on a special exposed aggregate broom, will be allowed if satisfactory results are demonstrated. After curing according to Subs ection 552.13(b) or (c), wash the su rface with water and brush to remove laitance and cement from the exposed coarse aggregate.

(d)Surface underneath bearings. Finish bearing surfaces to within ⅛ inch of plan elevation. If a masonry plate is to be set directly on the concrete or on filler material less than ⅛ inch thick, finish the surface with a float to an elevation slightly above plan elevation. Grind the surface as necessary to provide a full and even bearing after the concrete has set. If a masonry plate is to be set on filler material between ⅛ and ½ inch thick, finish the surface with a steel trowel. Finish or grind the surface so that it does not vary from a straightedge in any direction by more than ¼ inch. If a masonry plate is to be set on filler material greater than ½ inch thick or when an elastomeric bearing pad is to be used; finish the surface to a plane surface free of ridges.

(e)Surface underneath waterproofing membrane deck seal. Finish to a smooth sur face, free of ridges and other projections.

552.13Curing Concrete. Start curing immediately after the free surface water has evaporated and the finishing is complete. If the surface of the concrete starts to dry before the selected cure method can be implemented, keep concrete surface moist using a fog spray without damaging the surface. Keep surfaces to be rubbed moist after forms are removed. Cure immediately following the first rub. Cure the top surfaces of bridge decks using the liquid membrane curing compound method combined with the water method. Apply liquid membrane curing compound immediately after finishing. Apply the water cure within 4 hours after finishing. Cure concrete uninterrupted for at leas t 7 days. If pozzolans more than 10 percent by mass of the hydraulic cement are used in the mix, cure uninterrupted for at least 10 days.

(a)Forms in -place method. For formed surfaces, leave the forms in -place without loosening. If forms are removed during the curing period to facilitate rubbing, only strip forms from those areas able to be rubbed during the same shift. During rubbing, keep the surface of the exposed concrete moist. After the rubbing is complete, continue curing process using the water method for the remainder of the curing period.

(b)Water method. Keep the concrete surface continuously wet by ponding, spraying, or covering with material that is kept continuously and thoroughly wet. Covering material may consist of cotton mats, multiple layers of burlap, or other approved material that does not discolor or otherwise damage the concrete. Cover the covering material with a waterproof sheet material that prevents moisture loss from the concrete. Use the widest sheets practical. Lap adjacent sheets at least 6 inches, and tightly seal seams with pressure sensitive tape, mastic, glue, or other approved methods. Secure material so that wind does not displace it. Immediately repair sheets that are broken or damaged.

(c)Liquid membrane curing compound method. Do not use the liquid membrane method on surfaces to receive a rubbed finish. Use on construction joint surfaces is allowed only if the compound is removed by sandblasting before placement of concrete against the joint. Only use Type 2, white -pigmented liquid membrane on the top surfaces of bridge decks or on surfaces not exposed to view in the completed work. Use Type 1- D, clear curing compounds, on other surfaces and on colored concrete. Mix membrane curing solutions containing pigments before use. Continue to agitate during application. Use equipment that can produce a fine spray. Apply the curing compound at a minimum rate of 1 gallon per 150 square feet in one or two uniform applications. If the solution is applied in two applications, follow the first a pplication with the second application within 30 minutes, and apply at right angles to the first application. Immediately apply a new coat over the damaged areas if the membrane is damaged by precipitation or other means during the curing period.

552.14Fi nishing Formed and Deck Concrete Surfaces. Before finishing, remove and replace or repair rock pockets or honeycombed concrete, as approved. Refinish concrete surfaces exposed to view that have become streaked or unsightly according to the appropriate cla ss. Finish sound, formed concrete surfaces as follows:

(a)Class 1 – Ordinary surface finish. Finish the following surfaces with a Class 1, ordinary surface finish:

(1)Under surfaces of slab spans, box girders, filled spandrel arch spans, and the roadway deck slab between superstructure girders;

(2)Interior vertical surface or T -girders of superstructures; and

(3)Surfaces to be buried and culvert surfaces above finished ground that are not visible from the traveled way or a walkway. Start finishing as soon as the forms are removed. Remove fins and irregular projections from surfaces that are exposed or will be waterproofed. Remove bulges and offsets with carborundum stones or discs. Remove localized, poorly -bonded rock pockets or honeycombe d concrete, and replace with sound concrete or packed mortar in an approved manner. Fill holes using a mortar composed of cement and fine sand from the approved mix design and mixed in the same proportions as the concrete being finished. Float to an even, uniform finish. A bonding agent may be used with approval. Clean and point form tie cavities, holes, broken corners and edges, and other defects. Saturate the area with water. Finish the area with mortar that is less than 1 -hour old. After the mortar is set, rub it if required, and continue curing. Match exposed surfaces to surrounding concrete. Carefully tool and remove free mortar and concrete from construction and expansion joints. Leave joint filler exposed for its full length with clean, true edges. Rub or grind bearing surfaces on piers and abutments to the specified elevation and slope. If the final finished surface is not true and uniform, rub the surface according to Subs ection 552.14(b) .

(b)Class 2 – Rubbed finish. Finish the following surfaces with a Class 2, rubbed finish:

(1)Surfaces of bridge superstructures, except those surfaces designated to receive another finish;

(2)Surfaces of bridge piers, piles, columns and abutments, and retaining walls above finished ground and to at least 12 inches below finished ground;

(3)Surfaces of open spandrel arch rings, spandrel columns, and abutment towers;

(4)Surfaces of pedestrian undercrossings, except floors and surfaces to be covered with earth;

(5)Surfaces of culvert headwalls and endwalls that are above the finished ground and visible from the traveled way or walkway;

(6)Inside surfaces of culvert barrels higher than 48 inches that are visible from the traveled way. Finish for a distance inside the barrel at least equal to the height of th e culvert; and

(7)Surfaces of railings. Finish according to Subsection 552.14(a) . Thoroughly wash the surface of the concrete with water. Apply mortar composed of cement and fine sand from the approved mix design and mixed in the s ame proportions as the concrete being finished. Apply mortar that can be finished in the same day . Rub the mortar with burlap or a piece of carpet as soon as it takes initial set. If the mortar has attain ed final set, then rub the surface with a carborundu m stone and water until form marks, projections, and irregularities are removed. Grinding is not allowed. Fog-spray water over the finish as soon as the mortar has attain ed final set. Keep the surface damp for at least 2 days. Leave a uniform surface witho ut unsound patches, paste, powder, and objectionable marks. Continue to apply a Class 2 rubbed finish until the entire surface has a smooth texture and uniform color. (c) Class 3 – Tooled finish. Finish according to Subsection 552.14(a) . Do not use mortar blocks or wires to set reinforcing steel near the formed surface of areas to receive a tooled finish. Let the concrete set for 14 days or longer if necessary to prevent the aggregate particles from being picked out of the surface. P roduce a tooled finish using pneumatic power tools. Chip away the surface mortar and break the aggregate particles to expose a grouping of broken aggregate particles in a matrix of mortar. Produce a tooled finish on a small test area for approval before pr oceeding. Adjust the work procedures to produce a satisfactory finish and use the same procedures to finish the designated area.

(d)Class 4 – Sandblasted finish. Finish according to Subs ection 552.14(a) . Let the concrete cure for at least 1 4 days. Protect adjacent surfaces that are not to be sandblasted. Sandblast a small test area for approval before proceeding. Use hard, sharp sand to produce an even fine -grained surface in which the mortar is cut away leaving the aggregate exposed. Do not remove mortar beyond one -third the diameter of the coarse aggregate.

(e)Class 5 – Wire brushed or scrubbed finish. Finish according to Subs ection 552.14(a) . Start as soon as the forms are removed. Scrub the surface with stiff wire or fiber brushes using a solution of muriatic acid. Mix the solution in the proportion of 1 part acid to 4 parts water. Scrub until the cement film or surface is completely removed and the aggregate particles are exposed. Leave an evenly pebbled texture having the appearance of fine granite to coarse conglomerate depending upon the size and grading of aggregate. Wash the entire surface with water containing a small quantity of ammoni a.

(f)Class 6 – Penetrating stain. Build at least three 2 - by 2- foot concrete color sample panels with varying shades of color. Use concrete fr om the approved mix design. After the test panels have had at least 2 weeks of outside exposure, the CO will select a test panel to serve as a guide for the colored finish. Preserve the approved color sample panel. Color designated surfaces to match the color of the approved sample. Complete the designated finish. Do not apply the stain finish until concrete placement f or the structure is complete. Remove dust, foreign matter, form oil, grease, and curing compound with a 5 percent solution of trisodium phosphate and rinse the concrete surface with clean water. Use paper, cloth, or other means to protect surfaces not to be stain finished. Apply the finish to a dry concrete surface when the surface temperature is 40 °F or higher and the air temperature in the shade is anticipated to be 40 °F or higher during the 24 hours following application. Apply the stain finish according to the manufacturer’s recommendations. Spray, brush, or roll on the first coat of penetrating sealer and stain base. Spray, brush, or roll on the finish coat after the first coat has thoroughly dried. Apply finish to provide a uniform, permanent stain, without runs and sags to the surfaces. Remove stain from areas not intended to be covered by the finish using an approved method.

(g)Class 7 – Grooved finish. Texture the riding surfaces by mechanical grooving. Cut grooves into the hardened concrete us ing a mechanical water -cooled diamond edge blade saw device which produces straight, uniformly spaced grooves at ¾- inch intervals. Provide a groove width of ⅛ inch ±0.02 inch and a groove depth of ⅛ inch plus ⅟ 16 inch or minus zero inch. Apply grooved fini sh after defects to riding surfaces have been corrected.

552.15Concrete Anchorage Devices. Use chemical, grouted, or cast -in-place concrete anchorage devices for attaching equipment or fixtures to concrete. Provide the following for approval:

(a)Concrete anchorage device sample ;

(b)Manufacturer’s installation instructions; and

(c)Material data and certifications. Fabricate metal parts of the anchorage devices from stainless steel or from steel protected with a corrosion resistant metallic coating that does not rea ct chemically with concrete. Provide anchorage devices complete with hardware. For chemical or grouted anchors, conduct a system approval test on one anchor on the project, not to be incorporated in the work. Conduct a static load test according to ASTM E488. Demonstrate that the anchorage device can withstand a sustained direct tension test load according to Table 552-8 for at least 48 hours with movement no more than ⅟ 32 inch. Demonstrate that when loaded to failure the anchor de vice demonstrates a ductile failure of the anchor steel, not a failure of the chemical, grout, or concrete. Table 552-8

Sustained Load Test Values

Anchorage Device

Stud Size, inch Tension Test

Load, pound

¾ 5000 ⅝ 4100 ½ 3200 ⅜ 2100 Install concrete anchorage devices according to the manufacturer’s recommendations and so that the attached equipment or fixtures bear firmly against the concrete. Torque installed nuts to the values shown in Table 552-9 unless otherwise specified in the manufacturer’s recommendations. Set bearing anchor bolts according to Subsection 564.09 . In the presence of the CO, proof load a random sample of at least 10 percent of the anchors to 90 percent of the yield stress of the steel. If an anchor fails, reset the failed anchor and proof load the reset anchor and 100 percent of remaining anchors. The proof load may be applied by torquing against a load indicator washer, applying a direct tension lo ad to the anchor, or another approved method. After proof loading, release the load on the anchor and retighten the nuts to the torque shown in Table 552 -9 or according to the manufacturer’s recommendations. Table 552-9

Torque for Anchorage Devices

Anchorage Device

Stud Diameter, inch Torque,

foot- pound ¾ 125 ⅝ 90 ½ 60 ⅜ 35

552.16Loads on New Concrete Structures. Do not allow traffic on concrete approach slabs and bridge decks until concrete has attained the design compressive strength and has been in place 14 days or longer. Construction loads less than 4000 pounds may be placed on the approach slab or deck 7 days after the concrete is placed and the concrete in the entire span has attained a compressive strength of at least 70 percent of the specified design strength. For precast concrete multi -beam sections, do not allow vehicles on any span until the grout has attained a strength of 3000 pounds per square inch and tie rods have been tight ened. For post -tensioned concrete structures, do not allow vehicles over 4500 pounds on any span until the prestressing steel for that span is tensioned, grouted, and cured; the grout has obtained a strength of 3000 pounds per square inch; and the tie rods are tightened. Vehicles weighing less than 4500 pounds may be allowed on a span if the mass of the vehicle was included in the falsework design.

552.17Geocomposite Sheet Drain System and Weep Hole System. Place geocomposite sheet drain system and weep h ole system according to Section 605.

552.18Acceptance. See Table 552- 10 for sampling, testing, and acceptance requirements. Material for concrete will be evaluated under Subsections 106.02 and 106.03. Provide production certifications with each shipment of cementitious material. The concrete mixture’s slump, air content, density, and temperature will be evaluated under Subsections 106.02 and 106.04. Concrete compressive strength will be evaluated under Subsection 106.05. The lower specification limit is the minimum required compressive strength at 28 days ( f'c) specified. Construction of concrete structures will be evaluated under Subsections 106.02 and 106.04. Concrete crack repair will be evaluated under Section 561. Geocomposite sheet drain system s and weep hole system s will be evaluated under Section 605. Reinforcing steel will be evaluated under Section 554. Temporary works will be evaluated under Section 562.

Measurement

552.19Measure the Section 552 pay items listed in the bid schedule according to Subs ection 109.02 and the following as applicable: When measuring structural concrete by the cubic yard, measure in the structure. Do not measure the volume of concrete required, outside the neat lines of a footing, to pour against rock as shown in the plans. Do not measure concrete for precast and prestressed concrete structural members.

Payment

552.20The accepted quantities will be paid at the contract price per unit of measurement for the Section 552 pay items listed in the bid schedule, except the structural concrete contract price will be adjusted according to Subs ection 106.05. Payment will be full comp ensation for the work prescribed in this Section. See Subs ection 109.05. Payment for structural concrete will be made at a price determined by multiplying the contract price by the compressive strength pay factor. Table 552-10 Sampling, Testing, and Acceptance Requirements

Material or

Product

(Subsection) Type of

Acceptance

(Subsection) Characteristic Category Test Methods

Specifications Sampling

Frequency Point of

Sampling Split

Sample Reporting

Time Remarks

Source

Aggregate

(fine & coarse) Measured & tested for conformance (106.04 & 105) Quality − Subsections

703.01&

703.021 per material type Source of material Yes Before producing −

Mix Design

Concrete

composition Measured & tested for conformance (106.04) All − Subsection

552.031 per mix design Source of material If requested Before producing −

Production

Produced

aggregate (fine & coarse) Process control (153.03 ) Gradation − AASHTO T 27 & T 11 1 per day Flowing aggregate stream (bin, belt, discharge conveyor belt, or stockpile) Yes Before batching −

Fineness

modulus − AASHTO T 27 − " " " − Moisture test − AASHTO T 255 − " " " − Table 552- 10 (continued) Sampling, Testing, and Acceptance Requirements

Material or

Product

(Subsection) Type of

Acceptance

(Subsection) Characteristic Category Test Methods

Specifications Sampling

Frequency Point of

Sampling Split

Sample Reporting

Time Remarks

Production (continued)

Concrete

(552.03 )(1) Process control (153.03 ) Density − AASHTO T 121 1 per load after 0.25 yd3 minimum is discharged(4) Point of discharge at truck No Upon completing tests − Air content − AASHTO T 152 or T 196 " " " " − Slump(5) − AASHTO T 119 " " " " − Slump flow(6) − ASTM C1611 " " " " For SCC mixes only Temperature − ASTM C1064 " " " " −

Concrete

(552.03 )(1) Measured & tested for conformance (106.04 ) Density − AASHTO T 121 1 per load after 0.25 yd3 minimum is discharged(4) Discharge at point of placement No Upon completing tests − Air content − AASHTO T 152 or T 196 " " " " − Slump(5) − AASHTO T 119 " " " " − Slump flow(6) − ASTM C1611 " " " " For SCC mixes only Temperature − ASTM C1064 " " " " − Table 552- 10 (continued) Sampling, Testing, and Acceptance Requirements

Material or

Product

(Subsection) Type of

Acceptance

(Subsection) Characteristic Category Test Methods

Specifications Sampling

Frequency Point of

Sampling Split

Sample Reporting

Time Remarks

Production (continued)

Concrete

(552.03 )(1) Statistical (106.05) Compressive Strength(2),(3) (28-day) II AASHTO R 100 & T 22 1 set per 30 yd3 but not less than 1 per day & at least 5 sets total Discharge stream at point of placement Yes 28 days Deliver verification cylinders to the CO or designated laboratory for scheduled testing

(1)Sample according to AASHTO R 60, except composite samples are not required.

(2)Cast at least four compressive strength test cylinders for 6 - by 12 -inch specimens or six compressive strength cylinders for 4- by 8- inch specimens and transport the cylinders to the job site curing facility.

(3)A single compressive strength test result is the average result from two 6 - by 12 -inch o r three 4 - by 8-inch cylinders cast from the same load.

(4)If three successive samples are tested and compliance with the specifications is indicated, screening tests may be reduced to an approved frequency. Resume testing frequency if a test shows a fail ing temperature, air content, or slump, or if directed.

(5)If a hydration stabilizer is used, limit slump loss to 2 inches as compared to slump recorded at the batch plant.

(6)Use ASTM C1611 instead of AASHTO T 119 for SCC mixes.