Specifications for street roadway pavements / with instructions to inspectors on street paving work

by Samuel Whinery

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.