US2479434A - Method of constructing center parting and contraction joints and sealing expansion joints in pavements - Google Patents

Description

Aug. 16, 1949. w. J. VAN LONDON 2,479,434

METHOD OF CONSTRUC'I'ING CENTER PARTING AND JOINTS IN PAVEMENTS Filed Dec 11, 1943 INVENTOR. W.JT VAN LONDON. Y v

. slabs Patented Aug. 16, 1949 UNITED STATES PATENT FFICIS'.-

METHODOF'CONSTRUCTIN G CENTER PART- ING AND CONTRACTION J OINTS" AND SEALING EXPANSION JOINTS IN PAVE- MEN TS William J. Van London, Houston, lex. Application December 11, 1943, Serial No. 513,956 6 Claims. (01. 9442) slabs will settle and an irregular crack will form longitudinally along the slab. In order to insure that such crack will occur in a straight line along the center of the slab a plane of cleavage can be formed by providing a center parting joint longitudinally of the slab.

Contraction or dummy joints are formed at spaced intervals along the slabs so as to form a transverse plane of cleavage as the slab expands and contracts so as, to insure astraight crack across the slab. The present invention contemplates that the location of these cracks for both the center parting joint and the contraction joint can be determined by positioning a suitable strip of material in the green concrete as, the pavement is formed or by routing out somc of the. concreteafterit has aken a set and a. suitable strip of material positioned in the groove or recess thus formed. This in substance reduces the thicknessof the slab at this point and when stresses are applied .to.the concrete slab due to expansion and contraction longitudinally or to raising or lowering of the edges thecrack will naturally occur along the strip thus formed. It is therefore one of the objects of the inven tion to provide a strip of precompressed material which can be inserted in either green or existing concrete which will swell due to the absorption of moisture to fill the therefor.

In providing expansion iointsatspaced intervals for concrete difiiculty has been encountered in sealing-sucha joint and maintain a seal joint to pevent. the entrance of foreign matter and water and the present invention contemplates. a sealing strip for any type of expansion joint wherein a strip of precompressed material is inserted in either green concrete or in existin expansion joints so that it will swell by the absorption of moisture and provide a seal for the joint.

Another object of the invention is to provide 55 pavements; slabs-and the like a sea-ling strip for expansion joints, contraction joints and center parting joints which will fill the joint at all times due to its inherent ability to expand upon the absorption of moisture.

Another object of the invention is to provide a wood or fiber board stripwhich has been precompressed to the desired percentage-of its original thickness and to then insert it in a groove the invention is to provide a sealing strip for existing pavement joints of various types wherein a precompressed member is inserted in the joint at the-surface so as to expand to fill and seal the surface of the joint by absorption of moisture. 5 V

Another object of the invention is to provide a sealing strip having various configurations adaptable to expansion joint and parting joint configurations so that the-strip may expand upon the absorption of moisture and lockitself in p0- sition in the concrete.

Another object of the invention is the method of "providing an expansion positioned in the formsfpriorxtothe depositing of panying drawings-wherein:

the concrete andthe'concretethenlaid to a depth ofapproximating one inch "over" the top of the strip so that the strip doesnot interfere with l the finishing operations and then after the con crete has taken its. initial set the material over the strip may be routed out to form a groove of a suitable configuration into which a retainer or locking strip of precompressed material ma be thereafter inserted so that it will expand and .form a seal against the entry of foreign matter.

Other and further objects ofthe-invention will be readily apparent when the following description isconsidered in connection with the accom- Fig' 1 is a topplan viewlookin'g down on a concrete slab construction which has been pro- .vided withthe expansion joint of the invention.

Fig. 2 is a transverse' vertical section across the joint showingthe. expansion strip and. thelocking strip disposed inlposition j Fig. 3 shows the same, section as that of Fig. 2 with the retainer strip finished oil to the level of the pavement. 7

Figs. 4, 5,. 6 and, 7 are all vertical sectional views showing a center parting or contraction joint strip which is adapted to effect a plane of cleavage asv the concrete sets, but which strips joint wherein a, precompressed waterproofedzstrip of material is will expand to fill the joint adjacent the surface of the pavement.

The present invention relates to some extent to the general disclosure of my copending application Serial Number 506,995 for an expansion joint filler filed October 20,1943, and since abandoned, wherein various details of procedure are outlined and which are hereby incorporated herein.

In Fig. 1 a pavement 2 has been illustrated as including the slabs 3 and 4 whose ends are "arranged in spaced relation to iormiithe expansion joint 5.

Fig. 2 shows a sectional View of the joint wherein the expansion strip I has been positioned on edge in the forms and the concrete material making up the slabs 3 and 4 -:.deposited.therearound. It will 'be noted that the upper edge B of this expansion strip 1 is positioned a short distance below the surface 9 of the pavement slabs and that when the concrete is deposited it will be floatedover the upper edge 8 so that the finishing operation may be a continuous one so that the stoppingfliiting and carrying of the finishing equipment over the expansion joint is avoided. This-results in a substantial saving a in the cost of operationof the finishing'm-achine and is the common practice in highway, street, and airport construction.

After the concrete has 'taken'its'initial set, any

suitable tool may be used to rout out 'a portion a of the material above the upper --edge1l"o f*the strip so as to form a groove or recess 1-0. "This recess may take any desired configuration, but in Figs. 2 and ;3 it is shown as an inverted keystone whereinthe base H thereof is considerably wider than the entrance l2 at the surface '9 oi? the concrete.

. After theconcrete has taken its 'final -set,-and

the groove is a rigid construction, a looking or sealing strip l can-be inserted therein in a precompressedconditionsothat it-has a lesser width than the neck 12 of the groove II]. This strip is of a material which has the'ability to absorb moisture and due to itspre-compression will be of lesser thickness than the neck of the-groove and which will expand due to the absorption of moisture after it is insertcdfinthegroove. Itwill then swell to the shape'shown in Fig. 2 so as to completely fill the groove ill) and form a seal which will be' compressedand expand with the expansion and contrac n of "the concrete slabs respectively. p After the strip l5 has had sufiicient opportunity to swell to the sizeof the groove, the upper edge thereof :maybefinishedo'fi as at 11in Fig. 3 so that it will be flush wlththe surface 9 of the pavement. V l

The foregoing procedure results in an expansion joint which completely fills the area between the slab ends 18 and 19 but which .is capable of compressing when the slabs expand. TheeX- panding operation of the slabs, however, merely tends to compress the material of the strips 1 and I5 and possibly squeeze some of the moisture therefrom. When the slabs contract the inherent expansibility of the strips 1 and [5 causes them to expand and ,follow the slab ends [.8 and is .so as to maintain .a tight and sealed joint at all times.

7 The material of the strips 1 and may be any suitable material "which can be pre-dri'ecl if necessary, pre-compressed the desired percentage of its normal thicknessand which is capable of swelling upon the absorption of moisture. 'In actual practice, however; I have found that wood or fiber board is a suitable material and that preferably pine, creosote treated or untreated, Calibe shaped to the desired configuration to receive an expansible sealing strip.

For purposes .of description of an expansion joint .iormed by the combination of the strips 1 and i5 as seen in Figs. 1 to 3 the strip 1 may be a board of a suitable wood which has been compressed to say of its normal thickness and room dried if desired. Such board may then'be waterproofed with a layer '20 of waterproofing material on the sides thereof as seen in'Fig. 2. The bottom edge '2'! and the top edge-8 may or may not be waterproofed as desired. If the strip is to be applied immediately it can be deposited on edge in the forms and the concrete positioned about it. If the upper edge 8 is waterproofed it will prevent the entrance of moisture to a substantial extent while the :concrete is takin its initial set. After the recess I0 is routed out this waterproofing material may beremoved from the upper edge 8 just prior to inserting the sealing strip I5.

The thickness of thestrip 1 will be such that when-it is setit will be approximately of its original thickness so as to allow for both expansion and contraction of the slabs and a working range for the strip of approximately 30% for either expansion or contraction. This thickness may be computed or determined due to various circumstances such as the atmospheric conditions in the location where the joint is being formed, the temperature atthe time the "pavement is being laid, the nature of the sub-soil and various other factors may come into consideration, but generally it is intended that the "strip will be of such a thicknessthat when the slabs are contracted the -maximum contemplated amount that the strip will have swelled due'to the absorption of moisture so as to completely fill and maintain a'tight joint. In other words,

the strip must'be of such thickness that itwill swell sufliciently when it absorbs moisture so as to fill the joint even under the maximum dryness or low temperature to be encountered'in 'thejparticularlocality of the joint,

If the strips are to be compressed and then transported to the location it may be desirable to enclose them in suitable moisture proof containers or it may be desirable to place the waterproofing material on all sides and .ends of the strip after it has been dried and compressed so as to maintain it at the desired dimensions .prior to use.

The strip l5 will be formed similar to the above description for the strip 1 and as detailed in my copendlng application .Serial No. 506,995. l .It seems obvious that this strip 15 may take various configurations, but the inverted keystone shape which has been shown seems to beadaptable for the purpose because the swelling of the strip will cause it to lock itself in position and to also maintain the joint filler in the intended position. The sides of this strip I5 may be waterproofed as seen in'Figs. 2 and 3 if desired. This strip may take a rectangular form so that the greatest compression of the'material due to swelling will be at the neck l2 of the groove so that the material will prevent the entrance of foreign matter into the joint under all circumstances and also present a compressed surface I I to the trafiic. While the strip l may be waterproofed on its sides to the elevation of the surface, such waterproofing preferably extendsto the top and may be'omittedfrom the bottom and top of the strip as shown in Fig. 2. The manner of forming these pieces l5 may vary, and they may be either cut to the shape and pressed, pressed first and then cut, or they may be moulded of fiber. g

In using the sealingstrip I 5 here disclosed in new expansion joints constructed of semi-plastic or other material of the usual types the groove or suitably shaped recess can be formed as desired and the pro-compressed strip, either waterproofed or not as desired, inserted and. allowed to swell by the absorption of moisture to form a seal.

In laying most pavements a center parting strip or joint is provided so that as the concrete slab settles at the edges in dry weather and rises due to expansion of the sub soil in wet weather that the center of the slab will act as a hinge to permit this working of the edges of the slab. If no definite plane of cleavage adjacent the center is pro- Vided an irregular crack develops which is unsightly and undesirable. In'order to provide a plane of weakness at the center it is contemplated that the positioning of a, strip 30 of material such as seen in Figs. 4 to 7 may be employed. In such a situation the fact that a groove 3| extends partly into the slab 3 causesa plane of weakness at this position so that a crack will develop from the base 3| of th groove on down to the base 32 of the slab.

Figs. 4 to 7 inclusive show diii erent configurations of the strips 30 which can be positioned by routing out a groove in the concrete before it has taken its initial set and the insertion therein of the strip 30 which may be made in accordance with the previous description for the preparation of the strips l5, and such strips may or may not be waterproofed, as desired.

Fig. 4 shows a triangular strip, Fig. 5 shows a wedge shaped strip 35 whose base 35 is wider than the neck 31 of the opening in which it is positioned. Fig. 6 shows the groove 39 as having been formed with a double taper or double wedge shape to receive the double tapered strip 40.

Fig. 7 shows a rectangular strip 4| which is deposited in a similarly shaped groove or recess 42. All of these strips are of pre-compressed material and of sufiicient depth to extend into the concrete to give a self sealing joint. It is important that this partin strip joint be sealed at the surface to prevent any flow of water therethrough into the sub-surface at the center of the pavement causing any such infiltration of water to cause expansion of the sub-soil and additional cracking of the concrete.

Contraction or dummy joints are formed transversely of the pavement intermediate the spaced expansion joints so as to control location of transverse cracks. Such a joint should be initially formed by a. material which will remain in firm contact with the upper portion of the concrete as the crack opens and should compress without extrusion when the concrete expands while still having the capability of reexpanding if necessary. The filler for such a contraction joint must exclude sand, soil, pebbles, and water; it must remain flush with the pavement surface; be practically permanent, and preferably blend in color with the pavement. The constructions shown in Figs. 4 to 7 and described as center parting strips may be used inproviding contraction or dummy joints transversely of the pavement.

As an illustration of positioning a center partin strip or a contraction or dummy joint strip a piece of suitable wood such a Redwood, cypress, cedar or the like will be cut to the desired length, and formed to say two and one-half inche wide with a. thickness of one-quarter inch at one edge and one-half inch at the other edge. This strip is then compressed to half or two-thirds of its original thickness and waterproofed. The strip is then inserted in the surface of the concrete to a depth of about two inches in the green finished concrete. The concrete is then refinished along the edges of the strip and the corner of the concrete should not be rounded. Afterthe concrete hardens if the strip extends above the surface of the concrete it will be trimmed flush with the concrete surface and a suitable liquid which may include a non-evaporating or non-freezing liquid applied so as to cause swelling. This swelling action creates a compressive force against the concrete which not only fills thespace to exclude foreign matter, but also sets up a pressure tending to prevent the undue flexing of the concrete and tends also to support the concrete at the joint. Where the strip is to be inserted in replacement of a prior strip or where the concrete has set and a groove routed out to receive it the strip need not of necessity be waterproofed.

Under some conditions water ma not be available due to arid conditions or in other situations the freezing of the water might be objectionable so that it may be desirable to use a non-evaporating and anti-freezing fiuid such as commonly used for automobile radiators. It has been found that such a non-evaporating, non-freezing fluid will expand precompressed Wood in much the same manner as will water.

If sufi'lcient water may not be available in some cases due either to high evaporation or arid climate it may be desirable to use a non-evaporating fluid to expand the compressed members. such a. fiuid does not evaporate it will be present in the filler to effect expansion at all times regardless of climatic conditions. Should the nonevaporating fluid become insufiicient for expansion of the members due to being squeezed out by repeated compressions of the members it ma be replaced by pouring additional fiuid into the opening left between the filler member and the end of the slab when the pavement contracts.

In locations where extremely low temperatures occur and water is used for expanding the compressed member, the water may freeze and the resultant expansion may result in damage to either the compressed member or the pavement and it may be advisable in some such cases to use an antifreezing fiuid as an expanding medium for the compressed member.

Broadly the invention contemplates a self sealing parting contraction or expansion strip capable of maintaining a seal durin expansion and contraction of the concrete by the absorption What is claimed is:

l. A method of creating a concrete pavement or slab construction including positioning a predried, pro-compressed waterproof strip of water swellabie material at the location of the joint, such strip .zhaying its upper edge below the level o'fcthesmface of the :sl'abs, depositing the connrete about and over said strip, allowing the concreteto itsv initial set, forming a groove in the surface of the concrete to the top edge of the strip, said groove having a wider base than top, inserting a pro-dried, pre-com'pre'ssed strip of water swell-able material in :said groove, allowing such strip to swell so as to fill the groove when the concrete expands and contracts.

2. A method of {creating a concrete pavement or slab construction including positioning a predried, tare-compressed waterproof strip of water sweilable material at the location of the joint, such strip having its upper edge below the level pf the surface of the slabs, depositing the concrete about and over said strip, allowing the concrete to take its initial set, removing a groove in the surface of the concrete to the top edge of the strip, said groove having a wider base than top, forming the waterproofing from the upper edge of said strip, applying moisture to the exposed said strip, inserting a pre-dried, pro-compressed strip of water swellable material in said groove, allowing such strip to swell so as to fill the groove when the concrete expands and contracts.

A self sealing concrete pavement joint including a body of pre-dried, pr'e-compressed, waterproofed material capable of swelling upon the absorption ofmoisture after having the green concrete deposited thereabout, a groove formed in the concrete to uncover the upper edge of such body before the concrete takes its final set, a retainer strip of like material inserted in said groove whereby the inherent expansibility of the body and strip upon the absorption of moisture causes the strips to bear against the slab ends and exclude foreign matter.

4. A self sealing concrete pavement joint including a body of pre-dried, pre-oompressed, waterproofed material capable of swelling upon the absorption of moisture before having the green concrete deposited thereabout, a groove formed in the eon'creteto uncover the upper edge of such body before the-concrete takes its final set, a retainer -.strip =of like material inserted in said groove "whereby the inherent expansibility of the body and strip upon the absorption of moisture causes the strips to bear against the slab ends and exclude foreign matter, the base of said groove and retainer strip being wider than said first strip so as to wedge said retainer strip against removal.

5. A method of sealing a. joint in concrete pavements which comprises inserting a strip of swellable material therein, and thereafter applying a non-evaporating, non-freezing fluid to the strip to be absorbedand efiect swelling of the strip to seal the joint.

6. A methodof providing a line of cleavage for contraction, dummy or center par-ting joints in pavement comprising shaping a strip of wood so that the bottomis wider than the top, compressing and drying the strip, forcing the wide bottom into a pavement oi -green concrete, refinishing the concrete to settle it about the strip, so that the strip will absorb moisture after the concrete has setto swell and anchor itself in the concrete.

WILLIAM J. VAN LONDON.

REFERENCES m ED The following references are of record in the file of this patent? UNITE D TATES YAIEN'ISM 106,852- Australia ntennae-bash; Mar. '7, 1939

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