3.3.1 Clearing and grubbing.
This item shall consist of the cutting of vegetation, brush and trees, the grubbing out of roots, stumps, logs, rubbish and similar objectionable material within the rights-of-way of the street or road and the removal of all such materials and debris from the site
The entire area between the right-of-way of the street shall be so cleared and grubbed unless otherwise directed by the municipal authorities
3.3.2 Rough grading.
All topsoil shall be stripped from areas of street excavation or fill to a minimum depth of six (6) inches, or to the full depth of excavation when so directed by the municipal authorities, and stored in stockpiles for future use on the job site or as directed by the Engineer Unsuitable subgrade materials shall be removed from the site
3.3.3 Excavation.
Upon completion of clearing, grubbing and stripping of the topsoil within the street right-of-way limits, excavation of the subgrade shall be completed to the lines, grades and limits of slopes indicated on the typical cross section of the standard detailed drawings of these specifications," or as otherwise directed by the Engineer All stable and suitable materials from the excavation shall be used as far as practicable for embankment fill Drainage facilities shall be excavated conjunctive with this work, and the bottom of the excavated subgrade shaped uniformly and compacted to the limits established by the typical cross section of the aforementioned standard detailed drawings When solid rock, shale or similar material is encountered, the excavation shall be carried twelve (12) inches below the subgrade elevation within the proposed pavement area The undercut area shall then be backfilled to the required subgrade elevation with select material approved by the Engineer and compacted by approved methods
3.3.4 Embankment.
Embankments shall be formed of approved materials in horizontal layers to the width, lines and grade shown on the approved drawings and as directed by the Engineer
It is to be definitely understood that whenever possible, and subject to the approval of the Engineer, materials excavated within the limits and scope of the project shall be used in the formation of embankments and for backfilling in accordance with these specifications However, all materials from all classes of excavation which are unsuitable for the formation of embankments, shoulders, approaches, widening of roadway or embankment slopes shall, as directed by the Engineer, be classified as waste material and shall be disposed by the contractor outside the limits of the roadway Waste material shall not be disposed of within any drainage or flood channel without the approval of the governing officials Where solid rock, shale or similar material is encountered, the excavation shall be carried to a depth of twelve (12) inches below the established subgrade elevation of the proposed pavement width area of the roadway, and such material so excavated shall be used as embankment material only when and as directed by the Engineer
Earth, granular materials or other friable materials shall be placed in successive layers of loose material not more than eight (8) inches in depth for the width specified and shall be spread uniformly by use of a self-propelled, pneumatic-tired grader or other approved road equipment customarily used for this purpose and rolled until thoroughly compacted by the use of an approved three-wheel ten-ton power roller Approved sheep-foot rollers shall be used when soil conditions warrant their use and/or when specified by the Engineer Frozen materials shall not be placed in embankments At points inaccessible to the roller, the embankment shall be constructed in horizontal layer of loose material not exceeding four (4) inches in depth and thoroughly compacted by use of mechanical tampers
The top one-half (1/2) foot of all embankments shall be formed of granular material or soil within which no material of a size larger than three (3) inches shall be placed.
The finished slopes in cut sections or embankments shall not be steeper than one and one-half to one (11/2 1) and shall be two to one (2 1) when the character of the material encountered warrants the flatter slope
3.3.5 Special subgrade.
This item shall consist of a layer or layers of predominantly granular material constructed on the prepared graded subgrade, to provide a foundation and drain for pavement and base course, in accordance with the design and dimensions shown in the standard detailed drawings of these specifications
Material for special subgrade shall consist of durable natural granular material or granular aggregates mixed or blended with sand, stone dust, granulated slag or other filler materials to provide a uniform mixture meeting the requirements herein specified
These materials shall be obtained or be produced from approved sources and shall contain no vegetable or organic matter or lumps or an excessive amount of clay or other objectionable or foreign substances
Pit-run or run-of-bank materials may be used, provided that the material meets the requirements herein specified
Local deposits of loosely cemented conglomerate sand, gravel or stone which meet the requirements specified except for maximum size grading limits may be used without processing, provided that all oversize lumps or masses in such material are completely broken down in place prior to compaction by suitable equipment approved by the Engineer.
Shale shall not be used in special subgrade
Gradation shall be as specified in the current PennDOT specifications for special subgrade
The materials shall be placed, without segregation of course and fine particles, on the prepared subgrade having the required stability and which has been graded to drain properly and to a tolerance of one-half (1/2) inch
Two (2) or more materials may be plant blended, mixed prior to delivery at the site of work or site mixed when approved by the Engineer The required proportions of each material, together with sufficient water to ensure nonsegregation and satisfactory compaction, shall be thoroughly mixed, spread and compacted without undue loss of moisture
The uniformly spread material shall be compacted by means of steel-wheel rollers or with tamping or rubber-tired rollers as may be permitted Rolling shall progress gradually from the sides of the center with each succeeding pass uniformly overlapping the previous pass The rolling shall continue until the material in the layer is satisfactorily compacted While rolling progresses, the entire surface of each layer shall be shaped and dressed with a motor grader, in order to maintain-a uniformly smooth surface conforming to the required hues and grades
3.3.6 Course crushed aggregate base course.
This item shall consist of filler bedding and a base course composed of crushed stone or crushed slag constructed on a finished special subgrade in accordance with these specifications and in conformity with the lines, grades and typical cross sections as shown on the standard detailed drawings of these specifications. Approved fine material for an initial layer for the course aggregate base course shall be applied to the special subgrade, spread uniformly over the subgrade as a bed and filler prior to placing the course material, at the rate of one (1) cubic yard of fines for each thirty-six (36) square yards of base course This material shall not be placed on wet or frozen special grade
All materials shall be obtained from sources which are listed within the current certified and approved list of suppliers for the PennDOT
Crushed stone or crushed slag shall consist of hard, durable particles or fragments of stone or slag, free from an excess of flat, elongated, soft or disintegrated pieces, earth or other objectionable matter, and shall be of the following Pennsylvania Department of Transportations gradation
The course material shall be spread uniformly on the special subgrade by means of spreader boxes or approved mechanical equipment or from moving vehicles equipped to distribute the material in a uniform layer to the full width of the base Each layer shall be not more than six (6) inches in thickness after compaction A base course more than six (6) inches in compressed thickness shall be constructed in two (2) or more layers, unless vibratory equipment is used, in which case the maximum depths of layer may be ten (10) inches after compaction
Immediately following the spreading of the course aggregate, all materials placed shall be compacted to the full width by rolling with a smooth-wheel power roller weighing not less than ten (10) tons The rolling shall progress gradually from the sides to the center, except on superelevated curves where the rolling shall begin on the low side and progress to the high side The rolling shall be parallel with the center line of the street uniformly lapping each preceding track by one-half (1/a) the width of such track and shall continue until all the surface has been rolled and has been thoroughly keyed and the interstices of the aggregate reduced to a minimum and until the material ceases to creep or wave ahead of the roller wheels
Any irregularities or depressions which are developed under such rolling shall be corrected by loosening the material at these locations and adding or removing material until the surface is smooth and uniform under the roller
After the course aggregate has been thoroughly keyed and set by the rolling operation described above, choker stone or slag in an amount that will completely fill the interstices shall be applied gradually over the surface and rolling shall be continuous while the choker stone or slag is being spread, so that the jarring effect of the rolling will cause the small fines of the stone or slag to settle into the voids of the course aggregate
The choker stone or slag shall not be dumped in piles on the course aggregate but shall be spread in thin layers, either by spreading motion with hand shovels, by -mechanical- spreading or directly from trucks In no case shall the choker stone or slag be applied so fast or thickly as to cake or bridge on the surface in such manner as to prevent the filling of all voids or prevent the direct bearing of the roller on the course aggregate
Hand brooms shall be used to sweep the choker stone or slag into unfilled voids and to distribute the stone where needed The spreading, sweeping and rolling shall continue until no more choker stone or slag can be forced into the voids
Shaping and rolling shall be performed alternately as required-to maintain a uniform compacted base until a-surface or treatment has been applied to the base The contractor shall not haul heavy loads over this base course or permit rutting or displacement of material by traffic or equipment
Along curbs, headers and walls and at all places not accessible to the roller, the base course material shall be tamped thoroughly with mechanical tampers or with approved hand tampers.
After the completion of the application and rolling or dry choker stone or slag, the surface of single-layer construction or the surface of each layer of two (2) or more layer construction shall be sprinkled with water and rolled All excess fines formed in piles or cakes upon the surface shall be loosened and scattered by sweeping The sprinkling and rolling shall be continued and additional fines applied where necessary, until all the voids are filled and until a slight wave of excess water and fines forms a grout in front of the roller wheel on the surface Hand brooms shall be used to sweep the grout into unfilled voids and to distribute the grout evenly After the wave of grout has been produced over the entire section of the base course, this portion shall be left to dry The surface shall be sprinkled and rerolled on succeeding days as much as may be necessary to bond it thoroughly and produce a satisfactory surface The quantity of fines and water used shall be determined by the Engineer and shall be sufficient to produce a smooth, hard monolithic surface Diagonal and cross-rolling of the grout shall be done as required by the Engineer
The sprinkler for this work shall be of a size and design approved by the Engineer and shall be mounted on a motordriven chassis equipped with pneumatic tires Other methods of sprinkling may be used only if approved
Alternate method Utilizing vibratory equipment as outlined and approved by Pennsylvania Department of Transportation specifications, Form 408, current edition, may be used after approval has been obtained from the Engineer
No base course material shall be deposited or shaped when the subgrade is frozen or thawing or during unfavorable weather conditions
3.3.7 Portland cement base course.
This item shall consist of a portland cement concrete base constructed on a finished special subgrade in accordance with these specifications and in conformity with the lines, grades and typical cross sections as shown on the standard detailed drawings of these specifications 29
All materials shall be procured from suppliers who are listed within the current certified and approved list of suppliers for the Pennsylvania Department of Transportation Bulletin No 42) All concrete shall be batched at the central plant and truck mixed in transit or at the site, as directed by the Engineer All concrete shall be a certified concrete by the supplier as to weight, proportioning of aggregates and water-cement ratio
The concrete base course shall be class B normal strength concrete The concrete shall have a minimum allowable compressive strength at twenty-eight (28) days of three thousand (3,000) pounds per square inch and shall contain a minimum of five and one-fourth (5 1/4) bags of portland cement per cubic yard of concrete, and the maximum allowable water content shall be five and one-half (5 1/2) gallons per bag of cement, including the free water in the aggregates In proportioning the concrete mix, the said aggregate ratio shall be approximately thirty-two percent (32%) by volume for gravel concrete and thirty-four percent (34%) to thirty-six percent (36%) by volume for slag concrete The ratio of sand to course aggregate may-be varied slightly to obtain a -good-workable-mix and to maintain the yield for the specified cement factor Slump shall be two (2) to four (4) inches These proportions shall, whenever necessary, be adjusted as specified or required by the Engineer to provide concrete of satisfactory workability and maximum density at all times Adjustments shall be made without exceeding the maximum specified volume of water, maximum specified volume of sand or the slump designated At no time shall less than the specified volume of cement per cubic yard be used
If the foregoing requirements cannot be met because of the materials available for fine or course aggregates fail to meet volume percentages in the mix as herein specified, the contractor may be required to make a trial mix design which shall be submitted to the Engineer for his approval
Forms for concrete paving shall be of metal and shall have a minimum length of ten (10) feet, except that on sharp curves wood forms may be used as directed by the Engineer All forms shall be free from bends and warps and shall be so set that they rest firm throughout their entire length of the special subgrade and shall be joined neatly and securely together Forms shall not vary by more than one-eighth (1/8) inch from line and grade, braced in such manner that they will remain true to line and grade under the pressure of the concrete as it is applied and the impact of the finishing machine screed All forms shall be sufficiently watertight to prevent loss of fines through segregation and undue honeycombing along the edges All forms shall be thoroughly cleaned and oiled before constructed in the work
Concrete shall be placed on a moist subgrade rapidly in successive batches by means of chutes, spouts or other discharging devices which will prevent segregation Chutes, if used, shall be such that the concrete slides in them and does not flow The chutes shall be of metal or metal-lined The discharge end of the chute shall be provided with a baffle plate Chutes with a flatter slope than one (1) on three (3), or steeper than one (1) on two (2), will not be permitted There shall be no free vertical drop greater than five (5) feet which maximum shall be reduced if separation occurs
Immediately upon placing, the concrete shall be spread and distributed to the required depth and for the entire width of the pavement by shoveling or other approved methods Pneumatic vibrators shall not be used for the spreading of the concrete base course nor shall rakes be used in the handling of the concrete Concrete adjacent to joints shall be deposited on the subgrade as near to the joints as possible without touching them It shall be shoveled against both sides of the joint simultaneously maintaining equal pressure on both sides
Concrete placed adjacent to the forms or on exposed faces shall be spaded by hand (using wooden, not metal, spades) with a puddling motion in order to obtain smooth, dense, even surfaces The concrete shall be compacted and worked in an approved manner into all corners and angles of the form to avoid honeycombing After spreading and distributing of the concrete, it shall be leveled and immediately struck off by means of an approved transverse mechanical finishing machine or an approved hand method The template shall be shaped to the desired cross section and have sufficient strength to retain its shape under all working conditions The template shall be moved forward with a combined longitudinal and crosswise motion If necessary, the template shall be used a second time or until a true surface is obtained After the concrete has been screeded, it shall be finished as follows
(a) The concrete shall be floated with a wooden transverse float and the float shall be moved forward with a combined longitudinal and crosswise motion The float shall be used until all free water has been removed and the surface presents a smooth appearance The surface shall be roughened by dragging a street broom, or its equivalent, across the surface perpendicular to the center line The outer edge of the concrete shall be tool rounded Before the final finishing, the concrete shall be tested with a ten-foot straight edge, laid parallel to the edge of the pavement so as to bridge any depression Any irregularities exceeding-one-fourth (1/4) inch shall-be corrected
Concrete which has become compacted or segregated during transportation to or on the site of work shall be satisfactorily remixed just prior to being placed in the forms
Partially hardened concrete shall not be deposited in the forms The retampering of concrete which has partially hardened will not be permitted
The interval between loads shall be such that fresh concrete always shall be placed before previously placed concrete with which it comes in contact has taken its initial set
The maximum elapse of the time between the proportioning of the materials and the placing of the concrete in its final position shall in no case exceed two (2) hours
No concrete shall be placed in the forms when the atmospheric temperature is above one hundred degrees Fahrenheit (100 F) or below thirty-eight degrees Fahrenheit (38 F), without special permission from the Engineer
Transverse contraction joints, when required to control cracking of the pavement, shall be so located and spaced as directed by the Engineer Longitudinal joints shall be placed at the centerline of the pavement All longitudinal construction joints shall be keyed Expansion joints shall be provided at the intersection with other pavements
Transverse contraction joints and longitudinal joints which join another section of the base course or which join curbs or curb gutters shall be painted with a coating of bituminous material prior to placing the abutting concrete course
All longitudinal joints formed by concrete curbs adjacent to concrete base courses, also all transverse joints butting concrete curbs, shall be sealed with one-fourth-inch premolded expansion joint material They shall be resealed if necessary prior to final acceptance
Expansion joints shall be provided with a smooth steel dowel bar and expansion cap of the length, diameter and spacing designated by the Engineer
On all concrete base course work, whenever a longitudinal construction joint is indicated oil the drawings or specified on or permitted by the Engineer, it shall mean that a doweled longitudinal joint shall be used
Curing concrete Immediately after the finishing operations have been completed, the entire surface of the newly laid concrete shall be covered and cured by one (1) of the following methods cotton or jute mats, curing paper, burlap or liquid membrane curing compound The nonbitummous liquid for curing concrete shall conform to the requirements of the American Association of State Highway Officials' Specification
Designation M-148 (latest issue) It shall be applied with an approved pressure applicator. The coating shall be uniform to secure full coverage, and a minimum of one (1) gallon to every twenty (20) square yards of pavement shall be applied as soon as the water sheen has disappeared from the surface of the concrete Pavement edges shall be coated with the compound or banked with earth as soon as the forms are removed
All concrete shall be protected against damage from the elements and defacement of any nature during construction and curing operations Water shall not be permitted to rise on concrete within twenty-four (24) hours after it is placed, nor shall running water be allowed to flow over completed unprotected concrete within ninety-six (96) hours after it has been placed
When other methods of curing are used (other than curing compound application) the concrete shall be maintained in a continuous moist condition by sprinklers or otherwise completely saturating the mats, paper or burlap covering for a minimum period of ninety-six (96) hours after the concrete pour has been finished
Additional applications of curing compound may be required as directed by the Engineer for a period of seventy-two (72) hours after the initial twenty-four-hour curing period
Removing corms iv o forms shah be removed until permission has been granted by the Engineer Generally forms shall not be removed before the expiration of a minimum of twenty-four (24) hours after the concrete has been placed within the forms In cold or inclement weather, special precaution shall be taken in allowing the concrete to thoroughly set When conditions are such as to require it, the time limit shall be increased by the amount ordered by the Engineer
All areas of honeycomb exposed when the forms have been removed shall immediately be patched, as directed by the Engineer, with a cement mortar
Backfilling shall be of suitable material and shall be placed and tamped until firm and solid Backfilling shall follow immediately after the concrete forms have been removed
No concrete shall be poured on a frozen or thawing subgrade or during unfavorable weather conditions
3.3.8 Asphaltic concrete wearing surface (plant mixed).
This item shall consist of a tack coat and a wearing course composed of aggregate and bituminous material mixed in a central plant, constructed on the prepared base course in accordance with these specifications and in conformity with the lines, grades and typical cross sections as shown on the standard detail drawings of these specifications a
All materials shall be procured from suppliers who are listed within the current certified and approved list of suppliers for the Pennsylvania Department of Transportation
A.tack coat consisting of a thin application of bituminous material shall be sprayed over the surface of the base course at a rate and at such tune as directed by the Engineer or as herein specified The temperature shall be as directed by the Engineer [within a tolerance of ten degrees Fahrenheit (10 F) plus or minus] within the limits of one hundred twenty-five to one hundred seventy-five degrees Fahrenheit (125 F to 175 F )
Liquid asphalt for the tack coat shall be grade RC-2
The surface of all binder courses shall be sprayed with a tack coat when, in the opinion of the Engineer, the condition of the surface is unsatisfactory for the direct placement of the wearing course
(a) Bituminous surface course
Pennsylvania Department of Transportation, Designation ID-2
The asphalt cement to be used in the asphaltic concrete shall be uniform in character and free from water and shall not foam when heated to three hundred fifty degrees Fahrenheit (350 F ) and shall meet the following requirements for penetration
Penetration at seventy-seven degrees Fahrenheit (77 F), one hundred (100) grams, five (5) seconds, one hundred (100) to one hundred twenty (120)
No mineral matter other than that naturally contained in asphalt shall be present
The fine aggregate used may be fine gravel, sand, slag sand, disintegrated granite or other similar granular materials The portion of the material which passes a No 4 sieve shall be known as "filler"
The course aggregate shall be stone or slag unless otherwise specified by the Engineer The portion of the material retained on a No 4 sieve shall be known as "course aggregate "
The materials shall be graded and proportioned at the central plant to conform to the Pennsylvania Department of Transportation specifications for the designated bituminous surface course herein specified.
(i) Applying Lack coat immediately before placing the asphalt concrete wearing course, the shall wearing surface or base course surface shall be thoroughly cleaned of loose or deleterious material by sweeping with a power broom or a hand broom The surface shall be thoroughly dry before applying the tack coat When the existing surface has been satisfactorily cleaned and in proper dry condition, a tack coat shall then be applied to the surface at the rate of one-tenth (1/10) gallon per square yard of surface by a power distributor of approved type, having a pressure of not less than forty (40) pounds
per square inch The -asphaltic concrete mixture shall be spread and finished immediately after the tack coat has been applied. A tack coat will not be used on a concrete base course where the base course has been roughened by brooming
(2) Spreading and finishing the wearing surface The bituminous mixture shall be delivered to the job site at a temperature of not less than two hundred fifty degrees Fahrenheit (250 F ) nor more than three hundred twenty-five degrees Fahrenheit (325 F ) with a plus or minus tolerance of ten degrees (10) to meet weather conditions and workability at the time of placement
The mixture shall be spread by means of a mechanical self-powered paver, unless otherwise permitted by the Engineer, capable of spreading the mixture true to the line and grade and to the crown as shown on the standard detailed drawings of these specifications
If mechanical equipment is not used, by permission of the Engineer, the mixture shall be deposited on the base outside the area on which it is to be spread, or placed on dumping boards, and distributed into place by means of hot shovels and spread with hot rakes in a loose layer of uniform density and correct depth Loads shall not be dumped and distributed faster than they can be properly handled by the shovelers and rakers The raking shall be carefully and skillfully done in such a manner that after the first passage of the roller over the raked mixture a minimum amount of back patching will be required
Placing of the mixture shall be as continuous as possible and the roller shall pass over the unprotected edge of the fresh laid mixture only when the laying of the course is to be discontinued for such length of time as to permit the mixture to become chilled
Immediately after compaction of the binder or wearing course, the outer edges where exposed shall be rounded or beveled with a hot smoothing iron or tamper to avoid a sharp, ragged open or unfinished appearance Adequate precaution shall be taken to prevent a breakdown of the edges Should breakdowns occur, they shall be immediately repaired
Longitudinal and transverse joints shall be well bonded, and sealed if necessary to obtain this result, the joints shall be cut back to the full depth of the previously laid course, painted with asphalt and heated Before placing the mixture against them, all contact surfaces of curbs, gutters, manholes, etc , shall be painted with a thin uniform coating of asphalt cement dissolved in naphtha In the case of concrete base course, all surface cracks or temperature cracks normal to the pavement shall be sealed prior to placing the wearing surface
When the wearing course is placed adjacent to curbs to form a bituminous gutter, it shall be sealed with hot asphalt cement, Class BM-1, for a distance of twelve (12) inches from the curb The seal shall be evenly applied to the surface by means of hot irons or squeegees so that the surface voids are completely filled and no excess bituminous material r remains on the surface
(3) Rolling-wearing-course The wearing surface course shall be thoroughly compacted, after spreading, by a tandem power-driven roller, weighing not less than ten (10) tons, as soon after being spread as it will bear the roller without undue displacement Rolling shall start longitudinally at the sides and proceed toward the center of the pavement overlapping on successive trips by at least one-half (1/2) the width of the rear wheel The pavement shall then be rolled diagonally in two (2) directions with a tandem roller, weighing not less than ten (10) tons, and the second diagonal rolling shall-cross the-lines-of the first
Testing of the finished wearing surface shall be made by the contractor at such tune, location and method as directed by the Engineer or as herein specified The finished surface shall be tested by the use of an approved straightedge The straightedge shall be held in successive positions parallel to the road center line in contact with the surface, and the whole area checked from one side to the other as necessary Any irregularities which vary more than one-fourth (1/4) inch when the base course is of flexible type, or more than one-eighth (1/s) inch when of rigid type, shall be corrected Irregularities which may develop before the completion of rolling shall be remedied by loosening the surface mixture and removing or adding material as may be required All minor surface projections, joints and minor honeycombed surfaces shall be ironed smooth to grade
When test of thickness show that the pavement is uniformly more than one-fourth (1/4) inch deficient from the specified correct thickness, the material shall be removed and replaced to the specified thickness or otherwise corrected to the satisfaction of the Engineer The checking of depth, cutting of test holes, refilling and compacting shall be done by the contractor as directed by the Engineer
No vehicular traffic shall be permitted on the newly completed surface course until it has cooled sufficiently, but in no case less than six (6) hours after surface has been finished
No asphalt material shall be laid when the atmospheric temperature is fifty degrees Fahrenheit (50 F) and falling or during unfavorable weather conditions
