6-233
B.Foundation. The area upon which the prefabricated, aggregat e-filled concrete block gravity wall structure is to rest, and within the limits shown on the submitted Plans, shall be graded for a width e qual to, or exceeding, the length of the blocks. Prior to wall and leveling pad construction, this foundation material sh all be compacted to at least 95 percent of maximum la boratory dry density (AASHTO T-18 0 Method C or D). Frozen and unsuitable soil shall be removed and replaced w ith gravel borrow compacted to 95 percent of AASHTO T-180, or as shown on the Pla ns. A concrete leveling pad shall be constructed a minimum of 6 inc hes beyond the front and back of the concrete wall units, or as indicated on the Pla ns. Dimensions may be modified per the wall supplier’s recommendations, with written approval of the Geotechnical Engineer. The leveling pad shall be cast to the d esign elevations as shown on the Plans, or as required by the wall supplier upon wr itten approval of the Geotechnical Engineer. The allowable elevation tolerances from the design elevations a re +0.01 ft and -0.02 ft. Leveling pads which do not meet this requirement shall be repaired or replaced as directed by the Resident at no additional cost to the Departmen t. Placement of wall units may begin after the strength of the concrete leveling pad reaches 1000 psi or is adequate to support the proposed loads. Contractor may begin p lacement of concrete block units after 12 hours at their own risk.
C.Method and Equipment. Prior to e rection of the wall, the Co ntractor shall furnish the Resident with detailed information concerning the proposed cons truction method and equipment to be used. The erection procedure shall be in accor dance with the manufacturer’s instructions. Any units that are damaged due to handling will be replaced at the Contractor’s expense.
D.Installation of Concrete Wall Units. A field representative from the wall system being used shall be available, as needed, during the erection o f the wall. The services of the representative shall be at no additional cost to the pro ject. The contractor shall place the first course of wall units direc tly on the leveling pad and check for level and alignment. Adjacent units should be in contact. The prefabricated concrete wall units shall be installed to a toler ance of plus or minus 3/4 inch in 10 ft in vertical and horizontal alignment. Fill all voids between and within the wall units with drainage stone as described in this specification. The drainage stone fill shall extend a min imum of 6 in behind the tails of the wall units unless a geotextile filter is placed ov er the inside joint at the back of adjacent wall units. If used, the drainage geotextile shall conform to the requirements of Section 722.02.
E.Backfill Placement. Backfill pl acement shall closely follow the erection of each row of prefabricated wall units. The maximum lift thickness shall be 8 inches loose. The 6-234 Contractor shall decrease the lift thickness if necessary to ob tain the specified density. The backfill shall be compacted in accordance with Section 203. 12 except that the minimum required compaction shall be at least 92 percent of max imum density as determined by AASHTO T-180 Method C or D. Backfill compaction shall be accomplished without disturbance or displacement of the concret e wall units. Sheepsfoot rollers will not be allowed. Whenever a compaction test fails, no additional backfill shall be placed over the area until the lif t is recompacted and a passing test achieved. The moisture content of the backfill material prior to and duri ng compaction shall be uniform throughout each layer. Backfill material shall have a placement moisture content less than or equal to the optimum moisture content. Ba ckfill material with placement moisture content in excess of the optimum moisture co ntent shall be removed and reworked until the moisture content is uniform and acceptable throughout the entire lift. The optimum moisture content shall be determined in accordance with AASHTO T-180, Method C or D. At the end of the day’s operations, the Contractor shall shape the last level of backfi ll so as to direct runoff of rainwater away from the wall face.
681.07 Method of Measurement Precast Aggregate-filled Concret e Block Gravity
Wall will be measured by the Square Foot of front surface not t o exceed the dimensions shown on the Contract Plans unless authorized by the Resident. Vertical and horizontal dimensions will be from the edges of the blocks. No field meas urements for computations will be made unless the Resident specifies, in writing, a chang e in the limits indicated on the Plans.
681.08 Basis of Payment The accepted quantity of Precast Aggr egate-Filled
Concrete Block Gravity Wall will be paid for at the contract un it price per Square Foot complete in place. Payment shall be full compensation for furn ishing geotechnical design as required, all labor, equipment and materials including all prec ast concrete units, hardware, joint fillers, geosynthetic, drainage pipe, and technical field representative. Excavation, foundation material and backfill material will all be incidenta l to the Precast Aggregate- Filled Concrete Block Gravity Wall. Cost of cast-in-place concrete for leveling pad will not be pa id for separately, but will be considered incidental to the Precast Aggregate-Filled C oncrete Block Gravity Wall. There will be no allowance for excavating and backfilling for the Precast Aggregate- Filled Concrete Block Gravity Wall beyond the limits shown on t he approved submitted Plans, except for excavation required to remove unsuitable subs oil in preparation for the foundation. Payment for excavating unsuitable subsoil shall be full compensation for all costs of pumping, drainage, sheeting, bracing and incidentals f or proper execution of the work, and will be paid as common excavation in accordance with Section 203. Payment will be made under: 6-235 P a y I t e m P a y U n i t Precast Aggregate-Filled Concrete Block Gravity Wall Square F oot 7‐1 Chapter 7 DIVISION 700 - MATERIALS GENERAL STATEMENT MATERIALS CERTIFICATION LETTER For all materials used in the work for which there is no speci fied acceptance testing by the project Inspectors or the Labor atory, the Contractor shall subm it a Materials Certification Letter similar to the following, prior to acceptance as specified in S ection 107.9.4. Company Letterhead M r . / M r s . , R e s i d e n t D a t e A d d r e s s P r o j e c t N o. T o w n This is to certify that all materials incorporated into the pr oject for which there is no specified acceptance testing by project inspectors or the labor atory, comply with the pertinent specified material requirements of the contract. Processing, p roject testing, and inspection control of raw materials shall be in conformity with the applic able drawings and/or standards for all articles furnished. All records and documents pertinent to this letter and not sub mitted herewith will be maintained and will be available by the undersigned for a perio d of not less than three years from the date of completion of the project. The Materials Certification letter must be signed by a person having legal authority to bind the Contractor. Materials listed in the above Certificate may be subject to ra ndom sampling and testing by the Department at any time. When random verification samples a re obtained from the project, they shall be provided by the Contractor at no cost to the Depa rtment. Certified materials, which fail to meet specification requirements, may not be accep ted and may require replacement with materials that do meet the specifications. The Contractor may be required t o submit to the Resident, for i nclusion in the project records, certification and other data from the Manufacturer per taining to materials used on the project. The Certificate shall include the actual test results of the ma terial in storage from which the shipments are being made. Certificates shall be supplied for e ach lot, batch, or blend of each type and grade of material. A new certificate shall be issued at least every 30 days or upon receiving or manufacture of a new material. 7-2 The Contractor shall give the supplier sufficient advance noti ce of orders to permit testing. Material not represented by tests will not be accepted for use on the work. Deliveries of asphalt materials shall be accompanied by a load ing invoice, delivery ticket, or slip, as required under Section l08.1.3 f. The Loading Invoice shall include the applicable certificate number and shall include a printed or stamped state ment such as the following: “THIS IS TO CERTIFY THAT THE ASPHALT MATERIAL REPRESENTED BY THIS LOADING INVOICE CONFORMS TO THE SPECIFICATIONS OF THE PURCHASER FOR THE MATERIAL TYPE AND GRADE STATED THEREON.” In the event an intermediate hauler of the asphalt material is involved, a copy of their own delivery slip shall be furnished, as well as a copy of the supp lier's loading invoice. The hauler's delivery slip and the supplier's loading invoice shall be cross -referenced by use of their respective serial numbers. All test procedures shall conform to the requirements of AASHT O unless otherwise noted. Gradation tests shall be completed in accordance with AASHTO T 27 except that the sample may be separated on the ½ inch screen. Testing as specified in AASHTO T 11 shall be performed on any materials for which there is a specification l imit on the amount of material passing a No. 200 sieve. The Department may require the Contractor to submit, for inclu sion into the project records, certification that new Work Zone Category 1 and Category 2 Devi ces meet National Cooperative Highway Research Program (NCHRP) Report 350 guideli nes. Work Zone Category 1 Devices include plastic drums, cones, and tubular ma rkers. Work Zone Category 2 Devices include portable sign stands (with signs), Type I, Type II, and Type III barricades, vertical panels, intrusion alarms, and other work zone devices under 100 pounds. All Work Zone Category 1 and Category 2 Devices shall meet NCHRP Report 350 and MUTCD guidelines. Vendors/Contractors will be allowed to self-certify Work Zone Category 1 Devices with a letter of self-certification. A letter of self-certification s hall contain at a minimum
a.A title e.g., “Certificate of Crashworthiness”, b. Name and Address of the Vendor making certification, c. Unique identification of the certificate (such as a serial n umber) and of each page and the total number of pages,
d.Description and unambiguous identification of the item teste d,
e.Identification of the basis for the self-certification proce ss used and to what test level of NCHRP 350,
f.Signature and title of person(s) accepting responsibility fo r the content of the certificate and date of issue, and
g.A statement that the certificate shall not be reproduced exc ept in full. 7-3 Crash test information is available on the FHWA Office of Highw ay Safety’s Homepage: http://safety.fhwa.gov/programs/roadside_hardware.htm. SECTION 701 - STRUCTURAL CONCRETE RELATED MATERIAL
701.01 Portland Cement and Portland Pozzolan Cement Portland cement shall
conform to the requirements of AASHTO M 85, Type II. A Type I, Type II or Type III cement meeting AASHTO M 85 may b e used when making precast units. A Type IP (MS) Portland-pozzolan cement (blended hydraulic cem ent with moderate sulfate resistance) meeting the requirements of AASHTO M 240 , may be used instead of Type II or where Type I Portland cement, meeting the requiremen ts of AASHTO M 85, is allowed. The definitions of the two hydraulic cements mentione d above are as follows: (See ASTM C 219) Portland cement - a hydraulic cement produced by pulverizing Po rtland cement clinker, and usually containing calcium sulfate. Portland-pozzolan cement - a hydraulic cement consisting of an intimate and uniform blend of Portland cement or portland blast furnace slag cement and fine pozzolan produced by intergrinding Portland cement clinker and pozzolan, by blend ing Portland cement or portland blast furnace slag cement and finely divided pozzolan, or a combination of intergrinding and blending, in which the amount of the pozzolan constituent is within specified limits. Only one brand of cement shall be used on any one contract unle ss otherwise permitted, in writing, by the Resident. The cement shall be protected from dampness during storage. Partially set cement or cement that contains caked lumps shall not be used. The Contractor shall arrange for the cement supplier to provide a Manufacturer’s Certification (Mill Test Report) for all cement materials furni shed for use on the project. Reports shall include all mandatory and optional requirements s pecified in AASHTO M 85 or AASHTO M 240 including any processing additions. Reports sha ll represent the cement incorporated into the project and reports shall be supplied, at a minimum, on a monthly basis. Reports shall be submitted to the Department’s Materials Testing Engineer.
701.02 Water Water used in mixing or curing concrete shall be reasonably clean and
free of oil, salt, acid, alkali, sugar, vegetation, or substanc es injurious to the finished product. If required by the Resident, it shall be tested in ac cordance with the requirements of AASHTO T 26. Water known to be of potable quality may be us ed without testing. Where the source of water is relatively shallow, the intake sha ll be so enclosed as to exclude silt, mud, grass, or other foreign materials.
Source: Maine Standard Specifications for Road and Bridge Construction, 2020 Edition. Pages 703–708 of 817.