278 ALASKA 2020 SECTION 550
550-1.01 DESCRIPTION . Furnish, place, finish, and cure Portland cement concrete for
manholes, inlets, sidewalk, curb, gutter and other minor structures and incidental construction as shown on the Plans.
550-2.01 MATERIALS. Use materials conforming to Subsection 501- 2.01.
550-2.02 COMPOSITION OF MIXTURE – JOB MI X DESIGN. Provide a Job Mix Design, JMD,
meeting the requirements of Table 550- 1 for each class of concrete included in the Contract. TABLE 550 -1 COMMERCIAL CONCRETE DESIGN REQUIREMENTS Class B W Water -Cement Ratio, lbs/lbs, maximum 0.45 0.50 Total Air Content, % 5.5 – 6.5 4.0 – 6.5 Coarse Aggregate Gradation, AASHTO M 43 No. 57 or 67 No. 7, 8, 57, or 67 Compressive Strength, psi, minimum 4,000 3,000 Alternative sizes of coarse aggregate, as shown in AASHTO M 43, may be used when approved in writing. Calculate the water -cement ratio based on the total weights of all water and all cementitious material. Portland cement, blended hydraulic cement, fly ash, ground granulated blast -furnace slag, and silica fume are cementitious materials. Fly ash, ground granulated blast -furnace slag, silica fume, and combinations of these materials may be used as a substitute for Portland cement provided the quantity meets the limits of Table
550-2 and the total combined quantity of fly ash, ground granulated blast -furnace slag, and silica
fume does not exceed 40 percent of the total cementitious materi al by weight. TABLE 550 -2 SUPPLEMENTARY CEMENT ITIOUS MATERIAL LIMI TS Material Max. Percent Fly Ash 35% Ground Granulated Blast -Furnace Slag 40% Silica Fume 10% Maximum percent includes initial quantities in blended cement plus supplementary cementitious materials.
1.Submittals . Submit a JMD and materials documentation at least 15 days prior to scheduled production.
a.JMD. Submit concrete mixture proportions per cubic yard and test results for the proposed JMD. Submit the following:
1.Weights of cementitious materials
2.Weights of aggregates in saturated surface dry condition
3.Volume or weight range of each admixture.
4.Weight of water
5.Water -cement ratio 279 ALASKA 2020 (6) Percentage of air by volume test results
7.7-day and 28- day compressive strength test results
b.Cementitious Materia ls. Submit the following:
1.Type/Class
2.Brand
3.Producer
4.Plant location
5.Certified test reports confirming the cementitious material meets these specifications.
c.Aggregates . Submit the following:
1.Pit or quarry location(s)
2.Saturated surface dry specific gravities
3.Absorption values
4.Gradations and AASHTO size number
d.Admixtures . Submit the following:
1.Type
2.Manufacturer
3.Manufacturer's product data sheet giving the procedure for admixture use, recommended dosage range, and demonstrating admixture compatibility.
e.Water . Submit the source of supply for water.
2.Approval . Obtain the Engineer’s approval of each mix design prior to use. Approval of the JMD does not constitute acceptance of produced concrete and will not obligate the Department to accept or pay for concrete not meeting the requirements of this Section. CONSTRUCTION REQUIREMENTS
550-3.01 BATCHING, M IXING, AND DELIVERY. Batch concrete according to the approved
JMD. Mix ingredients into a thoroughly intermingled uniform mixture. Hand mixing is not allowed. Do not retemper concrete mixtures except that additional water may be added on- site provided the total amount of water, including that added on site, is within the proportion tolerances of 550- 3.02. Account for the actual volume of concrete remaining in the mix er. Complete all water additions within 30 minutes of the introduction of mixing water to the cementitious materials. If additional water is added, provide additional mixing to ensure a thoroughly intermingled uniform mixture is attained. Discharge the concrete within 1.5 hours of adding the mixing water to the cementitious materials, and within 1.5 hours of adding the cementitious materials to the aggregates. The Engineer may extend the time for placement if provided for in the approved JMD.
550-3.02 EVALU ATION OF MATERIAL FO R ACCEPTANCE. The Engineer may accept
concrete based on conformance with the approved JMD according to this Subsection. Sampling SECTION 5 50 280 ALASKA 2020 and testing is not required for acceptance. However, the Engineer reserves the right to sample, test, eva luate, and reject concrete according to Subsection 501- 3.03.
1.Batch Tickets. Provide a printed ticket with each batch of concrete delivered to the project. Include the following information:
a.Manufacturer plant (batching facility)
b.Department Contract Number
c.Date
d.Batch number
e.Time Batched
f.Truck Number
g.Quantity (volume batched this load)
h.Type of concrete by class and producer’s mix design identification number
i.Weight of every type of cementitious material
j.Weight of each aggregate type
k.Weight or volume of each admixture
l.Weight or volume of water added at the plant
m.Total moisture and absorption percentage for each aggregate
n.Volume or weight of any water added after batching
o.Signature of Contractor’s representative, affirming the accuracy of the information provided.
2.Tolerance. Meet the proportion requirements of the approved JMD within the following proportion tolerances:
a.Total Cementitious Material, weight ±2%
b.Aggregates, weight ±3%
c.Total Water, weight or volume ±4%
d.Admixtures, weight or volume According to approved JMD If the total cementitious material weight is made up of different components, keep the component weights within the following tolerances:
1.Portland Cement ±2%
2.Fly Ash ±5%
3.Ground Granulated Blast -Furnace Slag ±5%
4.Silica Fume ±10% 281 ALASKA 2020 Proportion toleranc e will be calculated using consistent units for M JMD and M A as follows: Where: P = Proportion tolerance, percentage MJMD = Weight or Volume of component per approved JMD MA = Weight or Volume of actual batched component
550-3.03 PLACING CON CRETE. Prepar e foundations according to Section 204 or as specified
for the applicable pay item. Use forms designed and constructed according to Section 512 or as specified for the applicable pay item. Ensure forms, reinforcing steel, and other embedded items are free of concrete splatter and other foreign material. Remove standing water from within the forms. Moisten foundations and forms with water before the concrete is placed. Prevent movement of forms, reinforcing steel, and other embedded items. Ensure the concret e temperature is between 50°F and 90°F when placed. Place and consolidate each layer before the preceding layer takes initial set. Limit layer thickness to the capacity of the vibrators to consolidate and merge the concrete with the previous layer. Do not place concrete that has developed initial set. Place concrete as near as possible to its final position. Prevent segregation of the mix. Do not deposit a large quantity of concrete and run or work the concrete along the forms. Limit the free- fall height of the concrete to less than 5 feet. When pumping concrete use a pump producing a continuous stream of concrete without air pockets.
550-3.04 CONSOLIDATI ON OF CONCRETE. Consolidate fresh concrete within 15 minutes of
placement. Consolidate concrete using mechanical vibrators to make an impervious, dense, homogeneous mass free of voids and rock pockets. Vibrate in a uniform pattern spaced less than 1.5 times the radius of visible effectiveness. Effectively vibrate the full depth of each layer. Do not vibrate concrete that has initially set. Do not hold vibrators against reinforcing steel or use vibrators to flow or spread the concrete into place. Do not allow the concrete to segregate, form pools of mortar, or form laitance on the surface.
550-3.05 FINISHING C ONCRETE SURFACES. After the concrete is consolidated and prior to
the application of curing materials, strike- off unformed concrete surfaces to the required elevation and slope. Finish the surface by floating to remove local irregularities. Leave sufficient mortar to seal the concrete surface. Do not use mortar topping for concrete surfaces. Do not use aluminum finishing equipment. Complete initial floating operations before bleed water or excess moisture is present on the surface and before the concrete de velops initial set. Complete final finishing before final set occurs. Do not use finishing aids or additional water to assist in finishing concrete surfaces. Do not finish concrete surfaces if bleed water is present.
1.Ordinary Finish . Immediately after removing the forms, remove the devices holding the forms in place and passing through the body of the concrete, or cut them back at least 1 inch beneath the concrete surface. Remove fins of mortar and irregularities caused by form joints. Ensure the surface is true and even. Patch cavities greater than ¼ inch. Fill the cavity with stiff mortar composed of one part Portland cement to two parts fine aggregate with only enough water to form a ball when squeezed gently by hand. Clean and wet the cavity before filli ng. Thoroughly tamp the mixture into place. Float the surface of the mortar before initial set to make the surface neat in appearance. Cure the patch according to Subsection 550- 3.06. SECTION 5 50 282 ALASKA 2020 2. Curb, Curb Ramp, and Sidewalk . Broom finish exposed faces of curb, curb ramp, and sidewalk to true surfaces. Broom finish sidewalks perpendicular to the direction of traffic.
550-3.06 CURING CONCRETE. Begin curing immediately after final finishing. Maintain curing for
at least 72 hours. During the curing period, keep the conc rete at a satisfactory moisture content and at a temperature of at least 50°F.
1.Water Curing. Completely cover exposed concrete surfaces with wet burlap or wet cotton mats. Keep mats completely wet during the curing period. Do not allow concrete surfaces to dry or alternate with wetting and drying cycles. If wood forms can remain in place during the curing period, do not loosen forms and keep the forms moist at all times to prevent opening at joints.
2.Membrane Curing . Uniformly apply two coats of liquid membr ane-forming compound, with the second coat at a right angle to the first, until the original color of the concrete is obscured. Apply liquid membrane- forming compound according to the Manufacturer’s instructions. Re- apply liquid membrane- forming compound i f the membrane becomes cracked or damaged.
550-3.07 PROTECTION OF CONCRETE. Protect concrete from damage. Do not apply loads to
the concrete until curing operations are completed and until the concrete has attained sufficient strength to safely carry the applied loads without damage. Forms may be removed after the concrete has cured for at least 24 hours and will not be damaged. Remove and replace concrete damaged by rain, flowing water, frost action, or overheating at no cost to the Department.
1.Rain Protec tion. Provide materials and equipment on site to protect concrete until final set. During precipitation, or when the Engineer determines precipitation is likely before final set, employ materials and equipment to protect the concrete until final set occurs . Do not expose the concrete to rain or flowing water before final set occurs.
2.Cold Temperature Protection. Protect the concrete during cold weather operations. At least 5 days before placing submit a cold weather concreting plan when air temperatures belo w 40°F are expected during placement or curing. Obtain the Engineer’s approval of the plan and put it into effect before placing any concrete when the air temperature in the shade, away from artificial heat, is below 40° F or, in the opinion of the Engineer , will likely become so during placement or curing. Have in place the materials and equipment required to prevent the concrete from freezing. Before placing concrete, warm forms and reinforcing steel to remove frost, ice, and snow from surfaces that will c ontact fresh concrete. When fresh concrete will contact hardened concrete, warm the surface of the hardened concrete to at least 40 °F. Do not place concrete on a frozen foundation. Maintain concrete curing temperature and moisture. Do not expose concrete s urfaces to air with a temperature greater than 90 °F. At the end of the curing period, remove the protection so the concrete drops in temperature gradually and not more than 30 °F in the first 24 hours. If water curing is used, allow the concrete surface to dry prior to exposure of the concrete to freezing temperatures. Protection may be terminated when the air temperature in the shade rises to 40° F and is expected to remain at least 40° F until the end of the curing period.
3.Hot Temperature Protection. Protect the concrete during hot weather operations. At least 5 days before placing submit a hot weather concreting plan when air temperatures above 90° F are expected during placement or curing. Obtain the Engineer’s approval of the plan and put it into effect bef ore placing any concrete when the air temperature in direct sunlight is above 90°F or in the opinion of the Engineer, will likely become so during placement or curing. 283 ALASKA 2020 Have in place materials and equipment required to prevent the concrete from overheating. Before placing concrete, cool forms and reinforcing steel to less than 90° F. When fresh concrete will contact hardened concrete, cool the surface of the hardened concrete to less than 90° F. Maintain concrete curing temperature and moisture. Keep the concr ete temperature from exceeding 90° F before final set and exceeding 150° F during the curing period. Protection may be terminated when the air temperature in direct sunlight drops to 90 °F and is expected to remain no greater than 90° F until the end of the curing period.
550-3.08 ANCHOR BOLT S, DUCTS, PIPES, AND CONDUITS. When anchor bolts, ducts, pipes,
or conduits will be encased in concrete, secure them in the forms before placing the concrete. When installing anchor bolts in pipe sleeves, pre- cast holes, cored holes, or drilled holes, completely fill the cavity with grout meeting Subsection 701- 2.03.
550-4.01 METHOD OF M EASUREMENT. See Section 109 and the following.
Cubic Yard. The lesser of the actual volume placed or neat line volume of concrete accepted i n place.
550-5.01 BASIS OF PA YMENT. If Items 550.0001.____, 550.0002.____, 550.0003.____, or
550.0004.____ do not appear in the Bid Schedule concrete is subsidiary to other items. Material not appearing in the Bid Schedule and is contained within, embedded, or attached to concrete elements is subsidiary. Repairing unacceptable concrete is subsidiary. Payment will be made under: PAY ITEM Item Number Item Description Unit 550.0001.____ Class B Concrete LS 550.0002.____ Class W Concrete LS 550.0003.____ Class B Concrete CY 550.0004.____ Class W Concrete CY 284 ALASKA 2020 DIVISION 600 –MISCELLANEOUS CONSTRUCTION SECTION 601 METAL FLUME DOWNDRAI NS
601-1.01 DESCRIPTION. Furnish and install tapered inlet assemblies, metal flume downdrains,
and anchor assemblies, at the locations shown on the Plans.
601-2.01 MATERIALS. Fabricate tapered inlets and flume downdrains using any one of the base
metals listed in AASHTO M 36 or AASHTO M 196. Use a minimum sheet thickness of 0.060 inches. Use steel nuts and bolts, galvanized acc ording to AASHTO M 232.
601-3.01 CONSTRUCTIO N REQUIREMENTS. Fabricate downdrains according to the details
and dimensions shown on the Plans. Weld bulkheads and flume pieces to the inlet assembly to form watertight connections. Do not use dissimilar metal at any one installation. Anchor assemblies shown on the Plans may be used with an aluminum installation if the anchor assemblies are electrically insulated. Connect flume downdrain sections together and to the inlet assembly using galvanized bolts as show n on the Plans.
601-4.01 METHOD OF M EASUREMENT. See Section 109, measured along the invert from the
lower end of the inlet assembly, not including flume stub, to the lower end of the flume.
601-5.01 BASIS OF PA YMENT. The contract price includes the inlet, anchor assemblies,
miscellaneous hardware, and excavation for the installation. Payment will be made under: PAY ITEM Item Number Item Description Unit 601.0001.____ Metal Flume Downdrain LF
Source: Alaska Standard Specifications for Highway Construction, 2020 Edition. Pages 306–311 of 584.