Chapter IX: Part II: Instructions to Inspectors on Street Paving Work (1)

INTRODUCTORY NOTE

Any general code of instructions for inspectors on street paving work must necessarily be little more than tentative or suggestive, as applied to any one city.

That here presented is intended for use in connection with the specifications in Part I of this book. Different specifications might make necessary many changes in the instructions that follow. The local or special conditions in any city might also make them inapplicable without material modifications and additions.

The author believes that in every city where considerable street pavement work is prosecuted and a number of inspectors employed on such work, some such code of instructions to inspectors should be formulated and used. Even where the inspectors are of high character and fully competent, the adoption of a system of rules and regulations relating to their work will tend to unify procedure, prevent misunderstandings and promote good discipline.

The preparation of such a code of instructions requires no little time and thought, especially where there are no precedents to suggest what is needed, or to be used as rough patterns. It is with the hope that the code here presented may be found useful in this way, even though it may be not appropriate for adoption in any given city, that it is offered to municipal engineers.

GENERAL REMARKS ABOUT INSPECTION AND INSPECTORS

The necessity of having competent and honest inspectors upon any public work during its construction need not be here argued. It is generally understood and recognized in the case of work carried out by contract. Where the contractor is incompetent, careless or unreliable, inspection is absolutely necessary if good work is to be secured. Even where the contractor thoroughly understands his business and intends to faithfully comply with the specifications and to do all his work in a proper manner, the inspector cannot safely be dispensed with. The contractor cannot at all times be on the work; whatever may be his intention and instructions, foremen and laborers cannot be depended upon to exercise the proper care and judgment, even where they have no inclination, motive or interest to do otherwise, which is not always the case. It seems to be deeply and almost irradicably fixed in the mind of the average foreman on municipal work that he is expected to show his ability and skill by evading or circumventing the strict requirements of the specifications and the watchfulness of the municipal agents, whatever his employer may _say_ to the contrary. Even when fairly careful, honest and conscientious he may need friendly oversight. He is naturally and properly anxious to save all the money he can for his employer, whether from a desire to loyally serve that employer’s interest, or to enhance his reputation for doing work cheaply. He may not appreciate the importance of minor requirements of the specifications and may believe they can be ignored without real detriment to the utility of the completed work. Like other men he may sometimes be careless or forgetful, however good his intentions.

These human qualities are not confined to foremen on _contract_ work. They are liable if not likely to be found in the foremen on work done for the municipality by the direct, or day’s work system. They may be encouraged by the impression or belief that they will not be held by the municipal authorities to as strict an observance or accountability as they would be if the work were being done by a contractor—which is too often true. The absence of some of the motives of foremen employed by contractors is, therefore, not a sufficient reason for dispensing with inspectors on work done by the city direct.

It should be trite to say that inspectors should be chosen with some regard to their qualifications for the work they are expected to do. One cannot, of course, expect to secure experts for such positions at the rate of compensation usually paid; but it is reasonable to require that an appointee to such positions shall possess the following qualifications:

That he shall be honest, trustworthy and loyal.

That he shall be a man of at least average intelligence and common sense.

That he shall have some practical knowledge of or experience in the work he is employed to inspect.

That he shall be a man of good personal habits.

That he shall be habitually punctual, industrious, and alert, and shall possess a fair share of that quality commonly called “backbone.”

It will not, I am sure, be denied that a very large number of the inspectors found upon municipal public work fall short in one or more of these qualifications.

Inspectors who habitually expect or accept compensation or gratuities from the contractor violate the first requirement, and their number is astonishingly large. These are useless, or worse than useless, to the municipality. There are not a few contractors who will take advantage of the presence on the work of such inspectors to do things that they would not do if thrown wholly on their own honor and responsibility. Contractors can hardly be blamed for expecting some compensation for the money thus exacted or accepted by the inspector from them.

The requirement that the appointee shall have some practical knowledge of and experience in the work he is expected to do, while often disregarded, is of real importance. Good workmanship embraces many small details that are essential, and inferable from the specifications, but cannot be stated at length therein, and the inspector should have a good working knowledge of these.

Unfortunately, large numbers of inspectors are employed for personal or political reasons, or because more competent men are not available. They know little or nothing from practical knowledge and experience about the work they are assigned to inspect. Efficient service cannot be expected from such, even if they possess the other necessary qualifications. The obvious remedy, where a sufficient number of qualified inspectors cannot be obtained at call, would be to train up a permanent force by having the promising tyros serve a sufficient apprenticeship under older and more experienced inspectors; but this is seldom done.

Inspectors, whether appointed by the engineer in charge or not, should be absolutely under his control, including the power of dismissal without unnecessary formalities. Where they are under civil service regulations and can be dismissed only upon charges and after a hearing before some third person, the obstacles in the way of promptly getting rid of an incompetent or unfaithful inspector are often so great as to be discouraging if not deterrent. He may be clearly below a reasonable standard of honesty or efficiency but it may be very difficult to formulate distinct charges and support them with positive evidence. Thus, one may be morally certain that an inspector is accepting gratuities from a contractor, but unable to prove it by legal evidence. If in such cases the judgment and integrity of the responsible engineer cannot be trusted, he is not fit, himself, for the position he occupies.

The question of how much authority and power shall be given to the inspector is always a troublesome one. If he be too much limited or restricted, he cannot properly discharge his duties or command the necessary respect from the contractor and his employees; if he be given too much authority and is disposed to be arbitrary or unreasonable, the contractor may be unjustly treated. So far as the definite requirements of the specifications are concerned there can usually be no room for going astray, but in the numberless little details not specifically covered in the specifications, or where their language and intent is not clear, differences and disputes may result which require a degree of knowledge and judgment that the inspector may not possess, and where his decisions might be against the interests of the municipality or unjust to the contractor. In such cases the matter should always be referred to the engineer or his assistant.

Where inspectors are employed upon work done directly by the municipality the relation between them and the superintendent or foreman should be clearly defined and understood. Briefly stated, this relation should be the same as that between the inspector and the contractor on contract work.

INSTRUCTIONS FOR THE GUIDANCE OF INSPECTORS ON STREET PAVING AND
INCIDENTAL WORK

GENERAL

=1.= The chief duty of the inspector is to see that the work to which he is assigned shall be carried out in full and strict accordance with the plans and specifications therefor, and with such additional instructions as may from time to time be given by the engineer.

=2.= These instructions are intended to supplement but in no case to take the place of the specifications for the work, which must be fully and strictly complied with, unless they are changed or modified by the engineer.

=3.= Wherever the words “_the engineer_” are used in these instructions they refer to the chief engineer in charge of the work for the municipality, or his authorized deputies or agents.

Wherever the words “_the contractor_” are used they refer to the person, or firm, or corporation under contract to perform the work to which you are assigned, or his agents or employees engaged upon the work.

=4.= You will report to and be under the exclusive direction and control of the engineer.

=5.= Upon being assigned to any work you will obtain copies of the plans and specifications under which it is to be done, and will carefully read and acquaint yourself with all their provisions and requirements. If any part of these plans and specifications are not clearly understood by you, you will ask the engineer for explanations and instructions, and will be governed thereby. Failure to understand or to be familiar with the plans and specifications will in no case be accepted as an excuse for not complying with and enforcing them.

You will also obtain, study and familiarize yourself with all the blank forms, reports, etc., that are to be used by you on the work, so that they may be correctly utilized; you will also obtain a proper supply of such apparatus, tools, stationery, etc., as you will need upon the work.

=6.= In inspecting any work done under contract you are to assume that the contractor is bound to carry out in good faith the plans and specifications attached to his contract, and that he may be, and must be, held to a strict compliance with them unless you receive instructions to the contrary from the engineer. You will be held responsible for the enforcement of these plans and specifications so far as they relate to the doing of the work.

=7.= In case the contractor or his agents shall neglect or refuse to comply with the plans and specifications or to perform the work in a proper manner, or in accordance with the instructions of the engineer, you will direct him to suspend the particular work in fault and will report all the facts promptly to the engineer and await his instructions, which, when received, you will proceed to enforce.

=8.= You will be expected to be upon the work at all times when work is in progress, whether during ordinary working or office hours, or not. But in case the contractor shall work continuous day and night forces, or otherwise so conduct the work as to require the presence of an inspector for unusual or unreasonable hours of service, you will notify the engineer and ask instructions or assistance. If for any reason you are to be unable to be present whenever work is in progress you will promptly notify the engineer in time to enable him to supply a substitute.

=9.= All reports and records required of you by the engineer must be promptly made up and forwarded to him at the time and in the manner he may direct. You will promptly acknowledge in person or writing any instructions received from the engineer and in case such instructions are not clearly understood by you, you will ask for explanation or advice.

You will keep a notebook or diary in which all occurrences or matters of interest relating to the work will be recorded each day, which book will be delivered to the engineer on the completion of the work, or whenever your connection therewith may end. All diaries, notebooks and records kept on the work are the property of the city.

=10.= While your first duty is to see that the work is done in accordance with the plans and specifications, you will, so far as consistent with this duty, be considerate of the interests of the contractor and facilitate his work as much as practicable. Materials should be inspected promptly upon delivery and in such a manner as not to delay or discommode the contractor more than is necessary. Errors, defects or delinquencies in the work should be detected and called attention to promptly, so as to avoid tearing up and re-construction as far as practicable.

=11.= Orders and instructions should be given to the contractor or his foremen or representatives on the work and not to the laborers, unless in urgent cases.

=12.= You shall not at any time, before, during, or after the completion of the work, ask or accept from the contractor or any of his agents or employees, or from any other person whom you may have reason to believe is acting for the contractor, any money, gifts, gratuities or other considerations of value, whether as compensation for services rendered him or otherwise. The penalty for violation of this rule will be dismissal from the service followed by such legal prosecution as the engineer may direct. This rule does not apply to the ordinary small courtesies common between gentlemen associated in business.

=13.= It is a condition of your employment that your services shall be loyal to the interests of the municipality, efficient, and satisfactory to the engineer, and that whenever in his opinion your service falls short of this standard he may dismiss you at any time, without previous notice.

STREET PAVING WORK

=14. Sub-foundation.=—The usual procedure in preparing the sub-foundation for a pavement is:

The removal of the old pavement if one exists on the street.

The setting of new or the resetting of the old curbing. (If concrete combined curb and gutter is used it is not constructed until after the rough grading is done.)

The rough grading of the street.

The fine grading of the street.

In this work the main things for the inspector to look after are the following:

If an old pavement is to be taken up and any part of it is to be reserved for use by the city, see that the material is not injured in handling and is disposed of as the specifications or the instructions of the engineer require.

=15. Curbing.=—New curb stone should be inspected as soon as practicable after it is delivered on the street so that the contractor may have time to replace any that may be rejected. Rejected stones should be plainly marked on their tops with red paint, and the contractor required to remove them from the street. Stones that are defective in dressing should be given some distinctive mark and the attention of the contractor called to them so that the necessary redressing may be done well in advance of the setting, and reinspected.

If the old curb stone is to be redressed and reset, it should be inspected as soon as possible after it is taken out and all stones that are not suitable for re-use rejected and removed from the work. The redressing of the stones should be looked after carefully. The tendency in this work is toward the use of old stones that do not, or cannot be made to comply with the specifications, and toward laxity in the dressing.

=Setting Curbing.=—In the setting of curbing the points to be looked after are:

To see that the trenches are excavated to the full dimensions so as to provide space for the use of the full quantity required of concrete, gravel or broken stone in which the curb is to be embedded.

To see that the stones are set to true grade and alignment.

That the concrete, gravel or crushed stone used is of the proper quality, the proper quantity used, and that it is placed and compacted so as to fill the spaces designated under and around the stone. The tendency of the workmen is to treat these details as unimportant and to slight the work.

After the curbing is set any spaces between it and the edge of the sidewalk are to be cleaned out, filled and trimmed with Portland cement mortar.

=16. Rough Grading.=—If plows and scrapers are used in the rough grading, see that they are not allowed to penetrate or to disturb the natural soil below the true grade, and to prevent this it is better to require that the plowing and scraping shall not approach nearer than one or two inches to the true grade.

If embankment or filling is necessary, the filling material must be deposited in regular layers not more than six inches deep and each layer must be well compacted by rolling or ramming before the next layer is applied.

=17. Fine Grading.=—The fine grading (with pick or mattock and shovel), to bring the sub-grade to the true grade and contour required, should be done with reasonable accuracy and care. Allowance must be made for compression under the roller, so that when completed the surface shall not vary more than half an inch below nor more than a quarter of an inch above the true grade, in order that room for the full thickness of concrete foundation may be provided, and no more. Humps, depressions and irregularities of the surface are to be avoided. The fine grading will be completed by thoroughly rolling or tamping the surface to make the soil firm and dense. On some soft or wet, clayey soils, excessive rolling may produce a plastic or “liver-like” condition and the rolling should be discontinued where such a tendency appears.

=18. Work Incidental to Grading.=—Where it is a part of the contractor’s work to reconstruct or readjust catch basins, manholes, covers, and other structures, he should be required to keep this work done well in advance of the laying of the concrete foundation. If this work is delayed until after the main body of the concrete is in place, leaving openings to be filled later, hurriedly and perhaps carelessly, it may result in weak patches in the concrete around these structures, where, in fact, the concrete should be strongest.

CONCRETE FOUNDATIONS

=19.= The concrete foundation of a pavement is a most important part of the work, and must not be slighted in any way.

=20. Quality of Materials.=—The quality of the materials used for making the concrete are fully described in the specifications, and they must be substantially and uniformly adhered to.

The Portland cement delivered on the street will presumably have been previously inspected and accepted by the engineer, but any change in the kind, or brand, or apparent quality of the cement delivered after the beginning of the work should not be permitted without the approval of the engineer. Barrels or bags of cement not plainly marked with the brand, or name of the manufacturer must be rejected. You will frequently make balls of stiff mortar from the cement and sand used (1 part cement, 2 parts sand) and set them aside for observation. If in eight hours these balls do not set up hard the fact should be promptly reported to the engineer.

The sand and stone will naturally vary slightly from time to time, but should not differ materially from the requirements of the specifications or the standards adopted by the engineer. Stone or gravel that contains any considerable quantity, say more than 5%, of foreign matter, such as soil or refuse, should be rejected. Stone containing an excessive quantity of fine fragments or screenings bunched together in the pile, should be mixed with the mass of larger stone before it is used, so as to produce a mass of fairly even composition. Stone that is coated with mud, or that is not sound and hard should be thrown out.

Sand that is moderately coarse and does not contain more than 7½% of clay or soil, and is free from vegetable refuse, may be used.

=21. Storing Materials.=—Cement stored on the street must be stacked up on dry lumber floors at least four inches from the ground and effectually covered to protect it from rain or snow. Packages of cement which, when turned out for use contain hard lumps should be rejected.

Sand and stone must be stored on tight lumber floors to prevent their admixture, when being shoveled up, with street soil or other impurities. This requirement must be enforced.

=22. Proportioning Concrete.=—The proportions of cement, sand and stone or gravel named in the specifications must be strictly adhered to.

A barrel of Portland cement will be considered as four cubic feet and a standard bag of cement as one cubic foot.

It is usual for the contractor to measure the sand and stone by wheelbarrow loads. In that case you will measure and determine the capacity, in cubic feet, of the convenient or average wheelbarrow load, and determine the size and number of loads each of sand and stone required for one batch of concrete (if made by hand) and thereafter see that the quantities thus determined are used, and the wheelbarrow loading uniform. To measure the contents of a wheelbarrow load, use a square box holding one cubic foot. It cannot be accurately measured on the barrow.

As a check upon the proportioning of materials, you should occasionally keep a record of the quantities of cement, sand and stone used for, say, one or two hours, and mark and measure up the quantity of concrete made with them, and from this data compute the ratios of the materials used. (In ordinary street concrete, proportioned 1:3:6, the volume of rammed concrete made will just about equal the volume of the stone used.)

Where the concrete is mixed by a machine with automatic feeding devices, reliance must not be placed upon the machine for proper proportioning. Frequent tests of the materials used and the volume of concrete turned out should be made as described above, and any necessary corrections made in the feeding devices of the machine. This test should be made daily if practicable. The eye will usually detect any material change in the composition of the concrete, and whenever such changes are observed the composition ought to be at once checked up by measurement.

=23. Mixing Concrete.=—See that the specifications are followed. Use sufficient water to make what is commonly called a wet concrete but not so wet that free water will drain from the mixed batch before ramming. The test for proper mixing will be that all the fragments of stone are completely covered with mortar.

=24. Placing Concrete on Street.=—All concrete must be placed and rammed before it begins to stiffen or set. Concrete should be so handled that the mortar will segregate or separate from the stone as little as possible. When in place on the street it should make a mass of uniform consistency and appearance. The concrete should, as soon as placed on the street, be graded to a proper thickness and surface, and then well compacted by ramming. Insist on good ramming; this part of the work is not often properly done. The surface of the concrete should be brought to the true grade by proper grading and tamping. Where necessary to raise the surface, additional concrete, made of small stone, may be applied during the tamping. Neat mortar should not be used for this purpose. Sweeping mortar over the surface with street brooms should not be permitted—it is useful only to cover up defects and to produce an extra smooth surface (which is not usually desirable). To measure the thickness of the bed of concrete, lay a straight-edge upon the surface with the end of the straight-edge projecting a foot or two beyond the edge of the concrete, and measure the space from the lower edge of the straight-edge down to the sub-foundation.

Care must be taken to finish the surface of the completed concrete at the proper distance below and truly parallel to the grade and contour of the finished pavement. This is more important in the case of sheet asphalt pavements, since irregularities in the concrete will cause variation in the thickness of the finished asphalt surface, which will affect the durability of the pavement. The grade stakes for the concrete should therefore be carefully set and worked to, and humps or depressions between the stakes should be avoided.

=25.= In hot, dry, weather the concrete must be kept damp by watering it until it is at least five days old, and horse-travel over it must be prohibited until it has set up hard enough not to be injured thereby.

=26. Old Paving Stone Foundations.=—If a foundation is to be made of old paving stone blocks reset, the important points to be looked after are,

The preparation of the sub-foundation.

The sand bed.

The setting of the blocks.

The grouting of the blocks.

The sub-foundation should be prepared, where necessary, as stipulated in Sects. 16 and 17 of these instructions. This part of the work is likely to be carelessly done unless proper work is insisted upon.

The sand used as a cushion course must be of good quality and reasonably clean. The use of mixed sand and soil taken from the street excavation should not be permitted.

The blocks, after being cleaned from adhering dirt, should be set with reasonable care, well bedded in the sand cushion, and laid at such an elevation below the completed pavement surface, that after being well rammed, the surface will be at the proper elevation below the pavement datum.

The grouting of the joints is the most important part of the work. See that the mortar is made and used in accordance with the specifications, and that the joints are completely filled.

=27. Broken Stone Foundations.=—The specifications for broken stone foundations are sufficiently explicit, and compliance should be insisted upon. Thorough rolling is especially important.

SHEET ASPHALT PAVEMENTS

=28.= The manufacture of the mixture for sheet asphalt pavement, and the laying of it on the street, involve a number of separate elements or operations. The quality and durability of the pavement will depend largely upon the skill, intelligence and accuracy with which each and all parts of the work are carried out. The inspector, both at the mixing plant and on the street, must give constant and intelligent attention to the work.

=29. Inspecting at Paving Plant.=—Inspectors at the plant where the asphalt paving mixture is made will be provided with the following apparatus:

1 nest of standard sieves, Nos. 10, 30, 50, 80, 100 and 200

2 thermometers for sand

1 tank thermometer

2 standard flow-plates and one dozen cartridges for same

1 balance for weighing sand

6 dishes, glass or porcelain, 4 inches in diameter.

=30.= The more important things for the Plant Inspector to watch during the manufacture of asphalt paving mixture are:

_a._ Quality and grading of the sand.

_b._ Temperature of heated sand.

_c._ Uniform quality of the refined asphalt and flux.

_d._ Temperature of melted bitumens.

_e._ Uniform consistency of asphaltic cement.

_f._ Correct ratios of sand and asphaltic cement.

_g._ Thorough mixing of materials.

=31. Sand.=—The general quality and grain-size of the sand, required by the specifications, must be closely watched and adhered to.

It is hardly ever possible to secure a natural sand that will conform strictly to the theoretical composition, but _substantial_ compliance should be required unless the Chief Engineer directs otherwise. After any sand has been approved for a given contract or street, all the sand thereafter used for that street should conform closely to the standard so approved; for any material change in the quality of the sand will change the quality of the pavement produced, unless the proportions of the other materials are changed accordingly. Any material change in the sand should therefore be promptly reported to the Chief Engineer.

=32.= Sand for the sieve tests should be taken from the hot-sand box and allowed to become cold. From the sample thus taken, weigh out 50 grams. Arrange the nest of sieves with the No. 200 at the bottom followed by Nos. 100, No. 80, No. 50, No. 30 and No. 10 at the top.

Place the weighed sample upon the No. 10 sieve and thoroughly shake the nest until all the sand that will, has passed through the various sieves; then weigh the various portions, beginning with that which has passed the No. 200 (deducting in each case the weight of the dish). The portion _remaining_ on the No. 200, is the quantity _passing_ the No. 100, etc. The sum of all these portions should be 50 grams, though it will usually be slightly less because of unavoidable waste. In use, keep the sieves clean and as free as possible from adhering grains by using a bristle brush.

=33. Temperature of the Sand.=—The temperature of the heated sand should be frequently noted by plunging the thermometer into the mass. It should not fall below 315° F. nor exceed 375° F. It is very important to avoid over-hot sand, because, in the mixer, the very thin films of bitumen covering the hot-sand grains are readily and quickly scorched by the excessive heat in the sand.

=34. Refined Asphalt and Fluxing Oil.=—Unless otherwise notified by the Chief Engineer you will assume that the stock of refined asphalt on hand at the beginning of the work has been inspected and is satisfactory. You will, however, note the appearance of the material and the character and marking of the barrels or packages, and will not permit the use of any new shipments of materials of different appearance or brand without authority from the Chief Engineer. The above instructions apply also to the oil used for fluxing.

=35. Ratio of Asphalt and Flux.=—You will frequently note and record the weight of asphalt and of flux used in charging the melting tanks.

=36. Temperature in Melting Tanks.=—The melting kettles are usually equipped with fixed thermometers, but their reading should be frequently checked with your detached tank thermometer. You will see that the temperatures in the kettles are kept within the limits named in the specifications. See that the melted asphaltic cement is kept constantly agitated as required by the specifications.

=37. Uniformity of Asphaltic Cement.=—It is very important that the asphaltic cement shall be of uniform composition and consistency, or hardness.

When the composition and consistency of the asphaltic cement to be used for the surface-course of any street has been determined upon and approved by the engineer, you will take out and preserve a sufficiently large quantity to be used thereafter as a standard, and each subsequent tank of cement, before it is used, should be tested by comparing it with this standard in the following manner, using the flow-plate apparatus:

Melt and fill two cartridges with the standard cement, and two with the cement to be tested, marking them for identification. When cold, carefully remove with a wetted dull knife any surplus cement from the ends of the cartridges so as to leave them exactly full and the metal ends clean. Immerse them in cold water until they are all of the same temperature. Then place and fasten these filled cartridges on the grooved plate with their lower ends exactly to the zero line on the plate, the standard samples alternating with the new. Then place the plate, at an inclination of about 45°, in front of a source of uniformly distributed heat, as, for instance, near a steam boiler or large steam pipe, or (when the weather is favorable) in the sunshine, facing the sun. Leave the plate in this position until the bitumen in the cartridges shall have melted and flowed down the grooves an average of from four to five inches. Then measure the lengths of flow of each from the zero line on the plate. If the average flow of the new samples differs more than 5 per cent. from that of the standards, the new cement should be regarded as unsatisfactory and should be corrected by adding more asphalt or flux, as may be required.

(If a _penetration apparatus_ is supplied or is available, the penetration method may be used instead of this flow-method for determining the consistency of the cements. Proper instructions for its use will accompany the apparatus.)

=38. Ratio of Sand and Cement.=—When the proper ratio of sand and asphaltic cement has been determined for any street you will see that this ratio is carefully adhered to. The correctness of the weighing scales used should be frequently tested.

=39. Mixing.=—When the sand and asphaltic cement are properly mixed the appearance of the mass will be perfectly uniform throughout, with every grain of sand entirely and evenly coated with cement. The mixing should, however, be continued somewhat beyond the attainment of this condition, so as to insure thoroughness. After the proper result has been arrived at, either the _time_ in the mixer, or the _number of revolutions_ of the mixer shaft should be noted and the standard thus determined substantially adhered to thereafter. With the standard mixers commonly used, the hot sand and the filler (dust) should first be put into the mixer and mixed for about fifteen seconds; then the asphaltic cement added and the mixing continued as long as necessary (in the usual mixer not less than sixty seconds).

=40. Records.=—You will keep complete records of the results of your observations and tests in a book which will be provided for the purpose, and will make such reports to the Engineer as he may direct.

=41. Inspection on the Street.=—The leading things to be kept in mind by the street inspector, in the laying of asphalt pavement on the street, are the following:

_a._ Temperature of mixtures when applied to the street.

_b._ Proper preparation of the street surface before material is laid.

_c._ Laying and rolling of the binder-course.

_d._ Laying of the surface-course.

_e._ Rolling the surface-course.

=42. Inspector’s Equipment.=—The inspector will be supplied with the following apparatus:

1 armored thermometer reading from 200° F. to 500° F.

1 graduated spatula.

1 twelve-foot straight-edge.

1 fifty-foot tape line.

=43. Temperature of Mixture.=—If proper care has been taken at the mixing plant the mixture will not arrive on the street at too high a temperature, and your principal care will be to see that it is not laid at too low a temperature. The minimum temperature named in the specifications should be adhered to. While the main or interior mass of a wagon load may be well above that temperature, the top and outer part of the load may be, particularly in cold weather, too cold to be safely used. Some of this colder portion may usually be sufficiently reheated by mixing it with the hotter material, if properly handled in unloading; but any material that is so cold as to be lumpy when unloaded, or, more particularly, when being raked out, should be discarded. This applies to both surface and binder mixtures.

It must not, however, be overlooked that the different kinds of asphalts have different appropriate working temperatures, and for some asphalts the minimum temperature named in the specifications may be too low. The best practical guide is the manner in which the mixture behaves in raking. It must always be so hot that it will, under the rake, break up into a uniform, crumbling or powdery mass. If it does not do this it is (unless the mixture is excessively rich in bitumen or improperly compounded) too cold.

=44. Preparation of Street Surface.=—Before the binder-course is laid, all loose material, rubbish, street dirt and other matter foreign to the concrete surface must be removed and the concrete surface swept, if necessary, to properly clean it, with street brooms. Neither binder nor surface mixture shall be laid upon wet surfaces. Before the spreading of the surface mixture on the binder the latter must be cleaned of all foreign matter and, if necessary, swept. If the binder is covered with mud from wagons or other travel, the surface must be scrubbed clean. Any part of the binder-course that may have become broken or loosened before the surface-course is applied must be taken up and new material laid in its place with the same care as the original.

=45. Laying Binder-course.=—The binder mixture must be carefully spread and raked to such thickness that after being rolled it will present an even, true surface not varying more than one-fourth inch from the intended finished surface of the binder. The tendency is to lay the binder-course carelessly and to roll it insufficiently. Nearly the same care in raking and rolling as for the surface-course, should be insisted upon. If the binder is not thoroughly compressed before it becomes cold it is likely, in future hot weather, to soften and yield under heavy travel and thus to start depressions in the pavement which will increase with time.

=46. Laying the Surface-course.=—The requirements of the specifications should be rigidly enforced in the laying of the surface-course. Joints against a cold edge of previously laid surface must be cut back until solid, fully compressed material of full thickness is reached, and the raw edge completely but thinly painted with liquid paving cement or pitch. No masses or fragments of cold mixture, whether of binder or surface, must be allowed to remain on the surface of the binder in advance of the placing of the surface-course, to be covered up by the latter. Such cold masses will not be compressed by the roller, but will later, under a hot sun and heavy travel, yield and start depressions in the pavement. The raking out requires to be properly and skilfully done. The tines of the rakes must penetrate to the binder, so that the raked material will be a uniform mass from top to bottom.

=47. Rolling.=—You will insist upon the rollers being placed upon the freshly raked surface just as soon as the material will bear them without being squeezed out or displaced laterally. The tendency is to keep the rollers off too long, thus permitting the chilling of the surface and preventing its proper compression. Do not take the contractor’s word as to how soon the rolling may be begun, but have trials made until you are able yourself to judge. The rolling by the heavy roller should be very thorough: keep the roller at work constantly until the surface is too cold to be impressed. In operating the roller lengthwise of the street begin at the gutters and work toward the center of the street. Cross rolling and diagonal rolling must be insisted upon wherever the width of the street will permit it.

=48. Proper Thickness and Surface.=—While the completed surface is still warm enough to permit it, measure the thickness of the surface-course by forcing the graduated spatula through it to the binder and noting the depth of penetration. Also test the trueness of the finished surface with the straight-edge, and if found defective in either thickness of pavement or trueness of surface, insist on more careful grading and raking on the further work. Try the completed gutters with water to see that they are so truly laid that puddles of water will not stand in them.

=49.= Asphalt surface must not be laid when rain or snow is falling, or so long as the street surfaces are wet. Surface mixture raked out and caught in a shower before it is well enough rolled to exclude water must be taken up and discarded.

Unless unavoidable, neither binder nor surface should be laid when the street surface or the air is below 40° F. As a rule, the lower the temperature the of air the greater is the care necessary to properly lay asphalt pavement.

=50.= Measure each day the area of pavement laid and record that, and the quantity (number of batches) of surface mixture used, and note any lack of uniformity in the area laid per batch.

ASPHALT BLOCK PAVEMENT

=51.= You may assume, unless otherwise instructed, that the Engineer has inspected and approved the general character of the blocks already delivered for the work, unless their inferiority be obvious, but you will be expected to observe them carefully as laid and to reject blocks that vary in dimensions from those permitted by the specifications, and those that are broken, disfigured or injured. But during the progress of the work you will note the character of subsequent deliveries and report to the Engineer any apparent change in the quality of the blocks.

The more important points to look after in the laying of the asphalt blocks are: the quality and grading of the mortar bed in which the blocks are set, and the care and accuracy of the block setting. The mortar must be of cement and sand in the ratios specified, and sufficient water used to make a medium stiff mortar; the use of merely moistened powder must not be permitted; and any mortar that has begun to set up before the blocks are laid and rammed must be discarded.

=52.= In setting the blocks the principal requisites are: that they be well bedded in the mortar; that they be set so that after ramming their tops will be accurately in the pavement datum; that they be set and pressed as closely together as possible, levers or mauls being used to force them into close contact, both at ends and sides.

GRANITE BLOCK PAVING

=53.= Assuming that the foundation has been properly constructed, the more important things for the inspector to look after are:

_a._ The quality and shape of the blocks.

_b._ The sand cushion.

_c._ The setting of the blocks.

_d._ The ramming of the blocks.

_e._ The filling of the joints.

=54. The Blocks.=—Assuming that the general _quality_ of the granite has been approved, you will need only to observe and reject blocks made from soft or weathered or otherwise defective stone. Any material divergence of the blocks from the correct form or from the sizes specified as permissible will be readily caught by the eye as they are brought to the street, and they can then be thrown out. The proper dressing of the blocks is important and should be watched carefully. While you are not expected to examine each individual block, close observation of the blocks as they are handled and laid will enable you to detect and reject those that are materially defective in shape or dressing; or excessively wide joints will call attention to these defects as the blocks are set.

=55. Sand Cushion.=—The sand used for the cushion bed should be moderately coarse and must be fairly clean and pure. The tendency with contractors is to use any dirty sand or sandy loam available on the street. Such material, especially if it becomes filled with water, will yield under the blocks and will not support them properly. The sand bed should not vary materially in thickness. It should be laid and graded not more than fifty nor less than twenty feet in advance of the setting of the blocks.

=56. Setting of the Blocks.=—The blocks should be delivered in front of the block setters on the blocks already set. The blocks must be set in straight courses from curb to curb, the courses running at right angles to the street (except at street intersections). All the blocks in any one course must be of the same width. Each block should be so set that the whole of its bed will be seated upon sand. The usual practice of block setters is to make a bed by drawing the sand into a small ridge upon which the outer edge of the block is rested, its weight canting it against the course already laid. This usually leaves a cavity under the back edge of the block which neither the subsequent joint filling or ramming closes up, so that the block may rest permanently on only a part of its bed. The practice is so fixed with block setters that it will require firmness and persistency to prevent it, but you should insist that it be so modified as to give a solid bearing for each block over its whole base.

The blocks must be set solidly against each other so as to make the joints of the least possible width. Unless close attention is given to this the joints are likely to greatly exceed the width permitted by the specifications. Care should be taken that the blocks are set truly vertical so that their upper face shall be parallel to the plane of the street. In setting the blocks their straightest and truest face should be placed upward so as to make the surface of the pavement as smooth and even as possible. Block setters are often careless about this.

Ordinarily no grade stakes are set for the surface of the pavement and templates are seldom used, the block setters using only their eyes to make the surface conform to the intended contour of the street. This usually results in the completed street being more or less wavy and irregular, and in a lack of regular and uniform cross-section in different parts of the street, often very perceptible to the eye. Care should be taken to avoid this as much as possible. Straight-edges and templates, cut to the proper curve for the surface, should be provided and used.

=57. Ramming the Blocks.=—This part of the work is likely to be slighted unless carefully watched. The important thing is to have each block equally and sufficiently rammed to bring it to a firm bearing on the sand, as well as to bring its top to the proper grade. The rammers will be disposed to touch lightly blocks or areas which if thoroughly rammed would be driven below the true surface of the pavement, and subsequent travel may force these down, making depressions in the surface. It is a very common practice for the men working the rammers to shirk on this work by allowing the rammers to fall with little more force than that due to their own weight. This should be detected and remedied.

=58. Filling the Joints.=—The specifications are quite full and clear regarding this part of the work and little further need be said.

Care is necessary, whether the joints be filled with gravel and bituminous cement or with grout, to secure the complete filling of all the joints. If the weather is cold at the time the work is done, the gravel filling may become so chilled before the bituminous cement is poured that it will not flow to the bottom of the joints. For this reason it is important that the cement be worked at the highest temperature that it will bear without injury.

If grout filling is used care is necessary to make the mortar of the right consistency. If too thick it will not flow freely to the bottom of the joint; if too thin its strength will be materially reduced. Experiments should be made to determine the proper consistency, and when this is found, the quantity of water used in making the mortar should be determined and thereafter measured out for each batch.

The mortar must be kept constantly stirred until used, otherwise the sand is likely to settle to the bottom. Whatever filling is used, a second and sometimes a third pouring will be necessary to completely fill the joints.

BRICK PAVEMENT

=59.= The matters requiring most attention in the construction of brick pavement (assuming that the foundation is in place) are the character and quality of the brick, the sand cushion, the setting of the brick, and the filling of the joints between the brick.

=60. Inspecting the Brick.=—The examination, testing and acceptance, in a general way, of the brick to be used for the work will be made in the engineer’s office, and your duty will be confined in this matter to seeing that the brick delivered and used are in accordance with the standard established and the general requirements of the specifications. You can best inspect the brick as they are being laid or after they have been laid, and before the surface has been rammed or rolled. Presumably the brick-setters will discard most of the unsuitable brick during the progress of their work, particularly if they are given to understand distinctly the defects that will cause rejection.

As the setting is completed, go carefully over the surface of the pavement and mark plainly all the bricks that are to be removed for defects and see that all such are taken out and replaced with good brick. The principal defects that should be observed are: soft or underburned bricks; those that are warped or deformed so that they will not fit closely to their neighbors, or have warped or ill-shaped tops; those that are broken or chipped or show injurious cracks, and those that are perceptibly wider or narrower than their neighbors in the same course.

Soft or underburned brick may be detected with most certainty by having the contractor wet the surface of the pavement by sprinkling. The soft brick will absorb more water and remain damp longer than the hard brick and can thus be readily detected. This test can be applied, however, only to pavements the joints of which are to be filled with grout, as bituminous filling should not be applied to brick with wet surfaces, and to wait until they become dry after the wetting would delay the work unwarrantably.

=61. Sand Cushion.=—See that the sand used is free from foreign matter and pebbles, as required by the specifications, and that the sand bed is of uniform thickness, correctly gaged, and rolled to the true plane of the pavement, additional sand being added or surplus removed where necessary to secure this result. See that the cushion is not thereafter disturbed or, if disturbed, that it be restored to its original condition.

=62. Setting the Brick.=—The bricks are to be set as closely together as possible both at sides and ends, so that the joints will not be wider than permitted by the specifications. Where the bricks have lugs or letters on one side, the lug-sides shall in no case be laid together. The courses must be reasonably straight entirely across the street. See that the bricks in adjoining courses break joint not less than three inches. Brick-setters are likely to be careless about this. Do not permit bats to be used except where necessary at the ends of courses or to fit the pavement against street railroad rails or around manholes or other structures in the street, and insist that this filling in shall follow immediately after the brick-setting, and that close fits shall be made.

=63. Rolling the Pavement Surface.=—This should be carefully and uniformly done so as to insure the even surface and contour of the pavement. Do not allow the roller to make sharp turns on the freshly laid brick surface as it will disturb and cant the loose brick. The roller should run back onto the fully completed pavement to make any necessary turns or considerable changes of direction. Quick starts or stops of the roller on the fresh-laid brick should be avoided for the same reason.

=64. Filling the Joints.=—Whether grout or bituminous filling be used the important thing is to get all the joints completely filled. Where bituminous cement is used, if the work is done in very cool weather the brick is likely to chill the cement before it reaches the bottom of the joints unless the cement be applied as hot as possible without injuring it, and the pouring be rapidly and carefully done.

If grout filling be used, see that the mortar is made of the proper ratio of sand and cement and that it is of the proper consistency to just flow into the joints, and that after mixing it is kept stirred until used. Repour all joints where necessary to completely fill them.

=65. Gutters and Expansion Joints.=—See that the gutters are laid with longitudinal courses of brick and their joints filled with bituminous cement as provided in the specifications.

WOOD-BLOCK PAVEMENT

=66. Foundation.=—The instructions relating to the preparation of the sub-foundation and the concrete foundation already given apply to wood-block pavement.