for Highway Construction Page 299 of 715 SECTION 501 – STRUCTURES
501.01 Description.
Construct structures .
501.02 Materials.
Not specified.
501.03 Construction Requirements.
A.General. Before placing concrete , obtain approval for the excavation depth and the foundation materials .
B.Cofferdams and Cribs . Construct cofferdams and protect fresh concrete against damage from a sudden stream rise or from erosion. Do not place timber or bracing inside cofferdams or cribs that cannot be removed without damage to the concrete. Use cofferdam or crib material of sufficient length to a llow a 2 -foot lowering of footings. Prevent concrete materials from being carried away when pumping from the foundation enclosure interior. Do not pump when placing concrete or for at least 24 hours thereafter, unless it is done from a suitable sump or well point separated from the concrete work. Remove cofferdams, cribs , sheeting, and bracing down to the elevation of the original ground l ine or to the new stream bed elevation for a channel change or to the top of footings in dry holes. Remove so there is no damage to the new structure.
C.Foundation Seal. Construct a concrete foundation seal when specified. Pump out the foundation enclosure and place the masonry in the dry. Ensure the seal has set sufficiently to withstand the hydrostatic pressure before pumping to dewat er a sealed cofferdam . When weighted cribs are used and the weight is used to partially overcome the hydrostatic pressure acting against the bottom of the foundation seal, provide special anchorage (e.g., dowels, keys) to transfer the entire weight of the crib into the foundation seal.
D.Drainage of Substructure . Thoroughly and effectively drain the material behind abutments, retaining walls, and wing walls by using granular backfill .
E.Bearing and Anchora ge. Set bearing plates in exact position to have a full and even bearing on the masonry. Ensure that anchor bolts are in the correct location and elevation. Adjust the position of expansion bearings to correspond with the temperature at the time of installation.
F.Placing Concrete . Place the concrete in slab spans, T -beams, or deck girders in 1 continuous operation. for Highway Construction Page 300 of 71 5 If continuous placem ent of concrete girders or decks of a multi -span continuous structure is required or approved, the Department may require a set retarding admixture. If a set retarding admixture is required, submit a placing schedule for approval showing the proposed amount of admixture to be used. Provide chemical set retarding admixtures that meet AASHTO M 194 Type B or Type D. The Department will not allow a reduction in the concrete 28- day strength.
G.Construction Joints . Make construction joints only where located in the plans or shown on the placement schedule. Place construction joints as directed, if not detailed, or in the case of an emergency. Use shear keys where necessary to transmit shear. Extend reinforcement beyond the construction joint, at least the splice length of the reinforcing bar. Re-tighten the forms before placing new concrete on or against concrete that has hardened. Roughen the concrete to a depth of at least ¼ inc h where shear keys are not provided. Roughen the surface of the hardened concrete so there are no loosened particles of aggregates or damaged concrete at the surface. Thoroughly clean construction joints of foreign matter and laitance and saturate with water before fresh concrete is placed against the joint. Continuously place concrete from joint to joint. Carefully finish, true to line and elevation, the joint face edges exposed to view.
501.04 Method of Measurement.
Not s pecified.
501.05 Basis of Payment .
Not specified. for Highway Construction Page 301 of 71 5 SECTION 502 – CONCRETE
502.01 Description.
Provide portland cement concrete . Separate bids may be taken on Schedule no. 1 concrete placed in the substructure and Schedule no. 2 concreted placed in the superstruc ture.
A.Classification . Provide the classes of concrete specified in Table 502.01-1 . Table 502.01- 1 – Basic Mix Design Parameters Concrete Class in (100 psi) (28 day) (a) Minimu m Cementitious Content lb/yd3 (b) (c) Maximum Cementitious Content lb/yd3 Maximum Water Cement Ratio Air Content Percent 65 and greater, Self - consolidated concrete (d)(e)(f)(g) 660 NA 0.42 0-6.0 45 to less than 65 (d)(e)(f)(g) 560 710 0.44 0-6.0 35 to less than 45 (d)(e)(f)(g) 470 615 0.44 0-6.0 30 470 570 0.50 6.5±1.5 Seal Concrete 660 N/A 0.60 0 - 6.0 Mass Concrete(d)(e)(g)(h) 560 N/A 0.44 0-6.0
a.Numerical part of class designation is the specified compressive strength when using the applicable tests as specified in 502.02.
b.Cementitious is cement and secondary cementitious materials (SCM).
c.It may not always be possible to produce concrete using the minimum SCM content that will ensure mortar bar expansion does not exceed the standard limit when tested in accordance with CRD C 662 or ASTM C 1293. If additional SCM is needed to meet mortar bar expansion requirements, the Contractor may add it to the mix without a corresponding increase in cement provided the strength requirements are met. Obtain approval to add lithium or other mitigating measures to meet the mortar bar expansion requirement. A separate payment will not be made by the Department for additional cementitious material required to meet the specified compressive strength. The alkali content of the concrete must be kept below 3.0 lb/yd3 Na2Oe.
d.Concrete designated as Class A will have an air content of 6.5 plus or minus 1.5 percent.
e.Concrete designated as Class C will have a maximum water cement ratio of 0.40, water reducer required, and air content of 6.5 plus or minus 1.5 percent.
f.Concrete designated as Class F will contain SCM. Minimum SCM content varies by product; for fly ash and slag cement (slag) minimum content is 20% by weight of total cementiti ous material. Fly ash will not exceed 25% of total cementitious material. Slag will not exceed 35% of the total cementitious material. For silica fume, minimum content is 7.5% by weight of total cementitious material. Silica fume will n ot exceed 10% of the total cementitious material. Ternary and quaternary blends will contain at least 20% SCM. Total SCM content will not exceed 50%.
g.Provide SCM meeting the requirements of 714.
h.Use only Type I, II, IL, IP or IS cements. An y combination of slag or Class F fly ash. Class C may be used with a maximum substitution of 20%. Maximum total substitution of SCM must not exceed 50%, including the amount of blended cement. Water reducing or retarding adm ixtures may be used to aid in air entrainment . Non -chlorine accelerators are allowed.
Source: Idaho Standard Specifications for Highway Construction, 2023 Edition. Pages 335–336 of 768.