217.01 Description.
SPECIAL PROTECTION FOR ROCK SLOPES
217.01 Description.
This Section shall cover the work of providing special treatments to rock slopes for protection against excessive weathering, popouts, and other detrimental conditions which may endanger the highway roadbed. In general the following metho ds, used as directed by the Engineer, shall be applied to exposed rock surfaces or rock surfaces exposed by the construction. • Rock Bolting - This work shall cover the anchoring of large blocks of rock which may be bounded by joints or cracks that might pro ve unstable by bolting them to more solid sections of rock. • Seam Sealing - This work shall cover the partial removal of relatively thin seams of very soft unsatisfactory material and the resealing of the seams with a durable cap of concrete. • Asphalt Surfac ing - This work shall cover the surfacing of relatively flat horizontal sections of rock berms with an asphalt surface to prevent excessive wear or weathering of soft, unstable rock. • Pneumatic Concrete Blanket - This work shall cover the construction of a protective blanket layer of concrete over an area of broken or loose boulders and/or unstable rock to prevent fallouts from erosion and weathering. Special attention is directed to the fact that the items of work provided under this section are estimated a nd cannot be accurately determined until the work is exposed; therefore, only the amounts actually used will be measured for payment and no claims will be considered for extra compensation due to overruns or underruns of the items covered by this Section.
217.02 Materials.
a.General . All materials furnished for use under this Section shall conform to the applicable sections of
Division 800 — , Materials, unless noted herein or provided on the plans.
b.Rock Bolting . Material fabricated for use in the rock bolting operations shall conform to the following:
1.Bolts .
a.Slotted. All slotted bolts shall be steel conforming to the requirements of ASTM A 588, Grade A.
b.Headed. All headed bolts shall be steel conforming to the requirements of ASTM A 588, Grade A.
2.Wedges . All wedges shall be steel conforming to the requirements of ASTM A 588, Grade A.
3.Expansion Shells . All expansion shells shall conform to the requirements of ASTM A 47, Specification for Malleable Iron Castings, Grade 32510. Tapered plugs used with expansion shells shall be forged from steel conforming to the requirements of ASTM A 663 and A 675, Grade 60 to 65.
4.Roof Plates. All roof plates shall be steel conforming to the requirements of ASTM A 242, Type 2, or ASTM A 588, Grade A.
217.03 Construction Details.
a.Rock Bolting .
1.General . Rock bolts shall be installed at the direction of the Engineer at any point where the stability of the rock cut is questionable. When bolting is deemed desirable, it shall be done as quickly as possible. Rocks should be kept tight and not pulled back into place once it has been loosened by successive blasting or cons truction operations. The holes for the rock bolts shall be drilled as closely as possible to the diameter recommended by the manufacturer of the wedge or shell.
217.03 Construction Details.
2.Torque . The diameter and length of the rock bolt to be used shall be determined by the Engin eer. All installations shall be in accordance with the recommended procedure or method as given by the manufacturer of the rock bolts. When directed by the Engineer, proper tests will be made to determine what torque the rock can withstand. If the tests sh ow that the highest torque practical is of a certain value for a particular grade of rock, then torque shall be applied to the rock bolt provided the torque does not exceed the maximum recommended by the manufacturer of the rock bolts. It is recognized tha t any over -application of torque will only destroy the anchorage in the rock and in due time destroy the initial tightness of the bolt. It is desired that a minimum torque of 125 foot pounds {170 N•m} be applied in all cases where the rock will withstand s uch pressure.
3.Installation Details. Extreme care shall be taken to keep the drill hole aligned perpendicular to the plate bearing surface. The diameter of the drill hole shall be as recommended by the manufacturer for the type of expansion unit to be used for anchorage into the rock. Expansion units shall not be used in holes larger than that for which they are designed. When slotted type rock bolts are used, the bolt with wedge shall be inserted in the hole until the wedge hits the bottom of the hole. The bolt shall then be driven into the hole with an air -percussion hammer forcing the wedge into the slotted end of the bolt, thus anchoring the bolt in the hole. The plate and nut shall then be installed on the collar end of the bolt and the nut tightened to the torque recommended by the manufacturer.
b.Seam Sealing .
1.General . The seam designated by the Engineer for sealing shall be examined carefully during the grading operations for evidence of seepage which will require construction of weep holes in the sealing cap as well as for the best method for placing the sealing cap.
2.Cleaning of the Seam. The material in the seam to be treated shall be routed out or otherwise removed to a depth at least equal to the thickness of the seam or layer to be trea ted or to a depth which will give firm support to the sealing material.
3.Sealing the Seam , The clean seam shall be sealed or packed with one of the following types of concrete mixes. The method of packing or placing the sealant shall be left to the Contractor provided the method used produces the desired results and presents an acceptable appearance. Weep holes, when deemed necessary, shall be placed as directed.
a.Low Slump - Class A c oncrete as provided by Section 501 of the Standard Specifications.
b.Pneumatic Concrete of an approved mix of cement, additives, aggregates, and water applied pneumatically. (Mix designed by the Contractor to produce a 28 day cylinder strength of 5000 psi {35 Mpa})
c.Retempered - Class A c oncrete.
c.Asphalt Surfacing .
1.General . An Asphalt Surface shall be placed on areas designated by the Engineer to prevent excessive erosion from surface runoff over relatively soft and erodible materials.
2.Preparation of Surface. The surface to receive the asphalt surfacing shall be fairly uniform, without excessive high and low spots, suitable for coverage with asphalt. The surface shall be clean and free from loose rock fragments before applying the surfacing material.
3.Surfacing Material. The surfacing material shall be Asphalt Cement Grade 40 or an approved equal. The bituminous material shall be applied at the rate of 1.25 gallons per square yard {5 L/m²}. The method of application shall be that of the Contractor's provided it is approved by the Engineer and it produces the desired results and presents a pleasing appearance.
217.04 Method of Measurement.
d.Pneumatic Concrete Blanket .
1.General . The exposed surface designated by the Engineer to receive this type treatment shall be carefully examined to determine the installation procedure which will be ne cessary to conform to the reinforcing details shown on the plans.
2.Cleaning the Area to be Treated. The area to be treated shall be cleaned of all loose scaly rock or soil fragments by the use of pressurized water and air jets or other approved means as directed by the Engineer.
3.Placement of the Protective Blanket.
a.Reinforcement shall be placed in accordance with the details shown on the plans or as directed. Anchorage of the reinforcement to the slope shall be accomplished by the use of the anchor bolts of the size and shape shown by plan details.
b.The pneumatic concrete blanket shall consist of an approved mix of cement, additives, aggregates, and water pneumatically applied to the surface to be treated. (The mix shall be designed by the Contract or so as to produce a 28 day cylinder strength of 5000 psi {35 Mpa}). Placement of the pneumatic concrete shall be in accordance with the supplying producer’s recommendations, provided the method used produces the desired results and presents an acceptable appearance. (Note - It is not the intent of this specification to require a uniform surface, but to provide a fairly uniform layer of concrete of not less than the depth shown on the plans, which in general parallels the surface being treated.)
217.04 Method of Measurement.
a.Rock Bolting . The measurement for rock bolts will be the linear feet {meter} of the specific size designated by the Engineer, complete in place and accepted.
b.Seam Sealant . The seam sealing material will be measured in cubic yards {cubic meters}, complete in place. The volume of material actually placed will be computed from measurements of the actual length, width, and depth of the excavated seam opening. No allowance will be made for the replacing of material removed beyond the depth directed.
c.Asphalt Surfacing . The Asphalt Surfacing material will be measured in gallons {liters}.
d.Pneumatic Concrete Blanket . The measurement of the Pneumatic Concrete Blanket will be measured in square yards {square meters}, computed from th e areas actually ordered treated. No allowances will be made for material placed outside of the designated areas nor for crevices, etc., required to be filled in order to obtain a continuous blanket over the area.
217.05 Basis of Payment.
a.Unit Price Co verage .
1.Rock Bolting . The accepted length of rock bolts placed as directed will be paid for at the contract price per linear foot {meter}, complete in place, which price shall be full compensation for furnishing and installing all materials, including bolts, wedges, expansion shells, and accessories and for all equipment, tools, labor, and incidentals necessary to complete the work.
2.Seam Sealant . The accepted volume of seam sealant, measured as noted above, will be paid for at the contract unit price bid for the seam sealant which shall be payment in full for the item complete in place and shall include all excavation, disposal of excavation, materials, furnishing of the sealant, placing of the sealant, and for all equipment, tools, labor, a nd incidentals necessary to complete the work.
3.Asphalt Surfacing . The accepted volume of asphalt surfacing placed as directed will be paid for at the contract unit price bid per gallon {liter} which shall be payment in full for the bituminous material c omplete in place and includes furnishing the bituminous material, preparing the surface, transporting and heating
219.02 Materials.
of the material as required, placing the material in the areas designated, and for all equipment, tools, labor, and incidentals necessary to c omplete the work.
4.Pneumatic Concrete Blanket . The accepted area treated under this item will be paid for at the contract unit price bid per square yard {square meter} which shall be payment in full for the pneumatic concrete blanket complete in place an d includes preparation of the surface to be treated, furnishing all materials, installation of wire reinforcement, its accessories and anchor bolts, placement of the pneumatic concrete, and for all equipment, tools, labor, and incidentals necessary to comp lete the work.
b.Payment will be made under Item No .: 217-A Rock Bolting, 1" {25 mm} Slotted - per linear foot {meter} 217-B Rock Bolting, 5/8" {16 mm} Headed - per linear foot {meter} 217-C Rock Bolting, 3/4" {19 mm} Headed - per linear foot {meter} 217-D Rock Bolting, 7/8" {22 mm} Headed - per linear foot {meter} 217-E Seam Sealant - per cubic yard {cubic meter} 217-F Asphalt Surfacing - per gallon {liter} 217-G Pneumatic Concrete Blanket, ___ inches {mm} thick - per square yard {square meter} SECTION 219 LANDSLIDE CORRECTIONS
219.01 Description.
This Section shall cover the work of correcting a landslide in an existing roadway slope within the designated areas shown on the plans or directed by the Engineer, all in accordance with the details shown on the plans or noted in this provision.
219.02 Materials.
Materials furnished for use shall conform to the appropriate requirements of the Standard Specifications for the type work performed or noted herein.
a.Geote xtile Filter . A geotextile to be used as a special underdrain shall meet the requirements of plan details, AASHTO M 288 for Subsurface Drainage Geotextile, Class 2, and Section 810 of these specifications. The geotextile shall be selected from List II -3, of the Department's manual titled "Materials, Sources, and Devices With Special Acceptance Requirements". Information concerning this list is given in Subarticle 106.01(f) and ALDOT -355.
b.Horizontal Drainage Pipe . The drainage pipe shall be PVC, Schedule 80, Type I or II, or Schedule 120 conforming to the requirements given in ASTM D 1785. The I.D. of the pipe shall be 1.5 inches {38 mm} unless noted otherwise on the plans. The pipe shall be furnished in lengths suitable for use with the drilling equipment approved for use. The ends of the pipe shall be machined to provide a smooth wall slip coupling when joined using appropriate solvent welding material thus precluding the use of conventional slip couplings. Fittings necessary for the outfall connections outside the drilling limits shall be PVC, Schedule 80, Type I or II, or Schedule 120 fittings having a burst strength equal to or greater than the pipe noted herein. All pipe and fitting connections shall utilize solvent weld joints. Slotted pipe shall be furnished unless noted otherwise on the plans. Slotted pipe shall have two rows of slots circumferentially cut 120 degrees apart. The average configuration shall be 46 slots per row, per foot {300 m m} with a maximum 0.010 inch {0.25 mm} slot opening when used in a silty or clay soil or 42 slots per row, per foot {300 mm} with a maximum 0.050 inch {1.3 mm} slot opening when used in a granular material. The configuration and the slot opening size shall be as shown on the plans.
c.Rock Buttress Material . Unless otherwise noted on the plans, rock buttress material shall be sandstone, limestone, dolomite, or granite free of dirt and debris. Rock buttress material shall have the physical properties for so undness, wear resistance and limited deleterious material content given in Section 814 for riprap.
Source: Alabama Standard Specifications for Highway Construction, 2022 Edition. Pages 135–137 of 934.