US1987151A - Bituminous composition for use in sea walls - Google Patents

Description

Jan. 8, 1935. L, R, MASON 1,987,151

BITUMINOUS COMPOSITION FOR USE IN SEA WALLS Filed Dec. 19, 1932 7??!75179 Sfrengfh ibs. Pe/"Sg /n.

percenf Y/[er [n Y/[ed Aspha/z LEGEND- CURVE. FILLER A +1007: DIATOMACEOUS EARTH E El'- 50% 5o QOCK DUST C 25% n n D= 10% SO 71 u E: 100 n n IN VEN TOR.

[anaon A. Mac

ATTORNEY.

Patented Jan. 8, 1935 I m 1 umrso smlrss PATENT v OFFICE BITUMINOUS COMPOSITION FOR USE IN I I SEA WALLS Landon R. Mason, Los Angeles, Calif., assignon to Union Oil Company of California, LosA-ngeles, Qalif af'corporation of California Application December 19,.1932, Serial Ne; 641,850 I n j 3'Claims.' (o1. 106 31)... I The present invention relates to a bituminous ()therancillary objects of my" invention will be composition adapted for use in sea walls, bre'aksuggested in the following description taken from waters, ripraps, revetments, levees and the like. the drawing and inthe uses to which my invenf,

It is generally known to construct rubble sea tion is put.

5 walls, breakwaters, ripraps, levees and the like Referring to-the drawing? 5 byplacing stones one above the otherin irregular Fig. 1 represents a series of curves showing thecourses. Relianceis placed upon the weight of effect of mineral fill'ers' upon the tensile strengththe stones to hold them into a fairly compact of asphalt. n I l 7 Wall; However, this type of construction is sub- Fig. 2 is a section of a sea Wall'or the like.

10" ject to thedestructi'veaction of large waves of "In its broadest aspects, my inventioncomprises 0" Water impacting against the wall structure. It a composition of matter containinga mixture-of a has not been uncommon forlarge waves or swells bituminous substance, such as asphalt and a finely to "lift massive stones weighing many tons and comminuted filler such as diatomaceous'earth-, the-' and to throw them completely off the structure, mixture having a tensile strength greater than destruction of the wall. Furthermorethis type An important feature of my invention resides in of structure has sufiicient amounts of voids which the production of a filled asphalt having an expermit the Waves" to penetrate throughand come tremely high tensile strength, a reasonably high into contact with the earthprot'ectedby the wall, ductility, a -moderately low penetration and-a -10 thus causing the receding-waves to carry conhigh'melting point. Another-important feature siderable'amounts of the earth protected by the of my invention resides in a filleol asphaltrhaving wall. Eventually, when sufi'icient amounts of the such a concentration of filleras' to produce a masprotected earth has been Washed away, there will tie of maximum tensile strength and impact rebe a settlement and consequent tumbling of the sistanceand which is adapted for-filIing-the-voids :5 rock structure and perhapsanalmost complete in sea walls and the-like. In some -instan'ces,= my destruction of the seawall. Sea walls and the like filled asphaltmay-h-ave tensile strengths betweenare also subject to thedestructive action of im ,50 and 400 lbs. per square inch depending upon-- pactsof floating logs and similar objects tossed the concentration and character of filler or comby the-seaagainst theiwall. binationpf fillers in'thec'omposition.

P10 Repeated attempts have been made to prevent More specifically, my invention residesin atheiforegoing destructive action by filling the voids filledasphalt comprising a mixture of asphalt and between the stones withPortland cement con between approximately 5%-and 40%lby weightiof crete. However, the use of Portland cement cons diatomaceous earth and havinga tensile strength crete has 1 proven unsatisfactory since sea walls between approximately 150 and 400 lbs:per square and breakwaters are necessarilysubjected to con-" inch. stant motion due to their unstable foundations My invention alsocomprises a sea wall or the and their necessarily inflexible construction-relike and: a method for constructing the'same, sults in breaking-of the bond of concrete retainthe" wall comprising i a pluralityof large" stones: ing' the large stones. Once this bond is broken," placed in irregular courses and provided with a it) the sea wall is subject to destruction by the wave sticky asphaltic mastic or concrete of high tensile" 40 or water-action. i h strength in the voids presented by the stones in One ofthe primary objects of my invention is order to prevent impacts from disturbing thepo to correct the aforementioned difi'icultles and dissition of the stones and also to prevent rapidly advantages attending prior-sea wall, breakwater, moving masses of water from penetratingthrougk etc. constructionand to present structures which the wall and washing the protected earth out: 45

cannot be easily destroyed by wave or water action. with the receding water. I

Another object of this invention resides m an, I have discovered that when, the voids in' sea asp a t m or concrete ad pt d f r filling ,Walls, breakwaters and'thelike'are filledwlth a:

the voids of sea walls, etc. which is tough, dense, specially designed bituminous mastic 'OTCOIICIGtE thus resultingin a gradual and almost complete that'of the bituminous substance in the'mixture.

adhesive, flexible and self-healing. hereinafter described,- the life of 'these structures 50 I It is another object of this invention to present is lengthened considerably dueto; the great an asphaltic mastic or concrete having its ingree strength and permanent flexibility oi the bitudients proportioned in such manner as to present minous mastic or concrete and due, also to the a masticor concrete of extremely high tensile self-healing properties of saidbituminousmastic strength andresistance to impact. or concrete,"

The composition which I desire to particularly employ for filling the voids of the aforesaid structures is composed of asphalt, a carefully selected and graded finely comminuted filler or combination of such fillers, graded sand and carefully graded sharp, crushed stone. The combination of asphalt and filler shall be hereinafter referred to as filled asphalt or asphaltic mastic and the combination of filled asphalt with sand and the crushed rock comprising aggregate shall hereinafter be termed asphaltic concrete.

I have discovered that filled asphalt, rather than pure asphalt, is most suitable for filling the voids of sea walls and the like because filled asphalts possess greater toughness. reasonable high ductility, high melting point and moderately low penetration and have very little tendency to become unstable even when mixed'with mineral aggregate in extremely high concentration as I have found necessary in asphaltic concretes for filling the'voids of sea walls and the like. D grade asphalt is preferable over other grades of asphalt for this purpose due to its extreme purity, high ductility, great adhesive powers and absolute freedom from decomposition products so common in asphalts carelessly refined. This type of asphalt is also free of paraff n and contains less than 1% of sulfur. Paraffin in asphalt renders the same less adhesive so that it will not stick to rock, whereas sulfur makes the asphalt brittle. However, the small amount of sulfur which is ordinarily present in D grade asphalt renders the same more adhesive but asphalts containing larger quantities of sulfur should be avoided. A D grade asphalt is a steam refined asphalt having a 40 to penetration at 77 F a melting or softening point of 110-130" F. and a ductility of greater than at '7'7 .F. I prefer to employ an asphalt having a penetration of approximately 40 to 60, although asphalts of higher and lower penetrations may be used with success and are within the scope of my invention.

It will be observed that all mention herein of penetration, softening or melting point and ductility are according to the methods outlined by the American vSociety of Testing Materials as follows: I

Penetration D- 5-25 Melting point (ball and ring) D- 36-26 Ductility- I 11113-264? Any type of'filler may be employed for admixture with asphalt. The best results are secured when using diatomaceous earth due to the absorptive properties of this type of filler which absorbs the oil in the asphalt and prevents it from evaporating, such as occurs when unfilled asphalt is exposed to the atmosphere. The evaporation of the oil from the asphalt shortens the life of the asphalt. Diatomaceous earth is also to be preferred due to the factthat it fills the minute voids in the asphalt which can be filled only by fine materials such as diatomaceous earth. This phenomenon aids in the production of a bituminous composition of great tensile strength and resistance to impact.

The diatomaceous earth which I prefer to use is one of suflicient lightness as to remain in suspension during the process of hot mixing with asphalt; Diat'omaceo'us earths lighter than 12 lbs. per cubic foot are suitable. However, other types of fine fillers, such as fillers of the rock dust type whichincludes limestone dust, marble dust and slate dust, may be used either alone or in Other types of fillers may admixture with diatomaceous earth. It is preferable to mix a certain amount of diatomaceous earth with the rock dust due to the oil absorptive characteristics and due also to the fact that diatomaceous earth fills the voids in the asphalt. Rock dust does not have these properties, except in aminor degree.

be employed for admixture with asphalt, such as clay, infusorial earths, talc, coke, chalk, terra alba, lampblack, fullers earth, ashes, kaolin, coal, peat, bone meal, ores, shale, marl, quartz meal, serpentine and asbestos. The only requirement in the use of these materials is that they be ground or pulverized prior to their admixture with asphalt. These materials may also be employed with diatomaceous earth and/ or rock dust. When using coarse fillers such as rock dust, it is preferable that they be ground to such extent as to pass 200 mesh screens and finer. Fillers such as diatomaceous earth may be readily pulverized topass screens of 1000 mesh and finer.

I have discovered that there is an optimum proportion of any given filler to obtain a filled asphalt of maximum tensile strength with respect to the filler employed and when two or more different fillers are used simultaneously, there is again an optimum proportion which may be added to asphalt to obtain a maximum tensile strength. My experiments have revealed that for any given composition of filler, there is a maximum percentage of filler which can be added to asphalt with beneficial effect upon the tensile strength of the asphalt, but that an excess above the maximum merely produces a non-cohesive, mealy mixture entirely unsuitable for the production of a sticky mastic. Thus, by mixing various percentages of fillerto the asphalt, I have found that the tensile strength of the asphalt increased gradually with the admixture of filler in the asphalt until a condition is reached where the filled asphalt has a maximum tensile strength. Upon addition of more filler to the asphalt, the tensile strength sharply decreased and merely produced a filled asphalt having substantially little or no tensile strength. I have found that by adjusting the proportion of filler in the asphalt, a filled asphalt may be produced having an extremely high tensile strength and impact resistance than filled asphalts heretofore produced.

In order to determine the optimum concentration and kind of filler to be used to obtain a filled asphaltof high or maximum tensile strength and resistance to impact, I have conducted experiments with filled asphalt composed of the aforementioned D grade asphalt and fillers, such as diatomaceous earth and rock dust. A series of mixtures of the foregoing ingredients was prepared and the various mixtures which are designated herein as filled asphalt were used with Ottawa sand of 20 to 30 mesh to prepare al arge number of cubical briquets for determining tensile strengths. Standard Ottawa sand was used as the mineral aggregate due to the uniformity of successive batches as determined by the U. 8. Bureau of Standards and the American Society of Testing Materials; This sand is invariably employed as aggregate in determining tensile strengths of Portland cement concrete as anyone skilled in the art will readily understand.

I have also discovered that the maximum tensile strength and resistance to impact is obtained when the voids of the mineral aggregate are completely filled with the filled asphalt. Since the s. insane 1 .the bniquets.'f.0rl:tcnsi1e; strengthirtests;iallc ofiahe ..-ing-redients nfOil' :rBaGh ...-separate i mmture zmere --WQi hed:-t@gstherinto thei'sameiron' dishand were :heated rim-about QQME'E. The" .ingredientsvwere hand stirred until a. hQmQgBHflllsdlliXfilEte waszobl-The hot; ithen rammeda-by "rhand into tha molds: ordinarilynusedufon making :tens'ile strengthibriqite'ts; ofePortlands cement :conicretesand ithem werezallowed tor-cool imthezmold's. infter' removing.the.briquetsxfromzthesmbld.ithey .awe ai allowed to. stand: overnight at ".rtoomutem- .aperatur andawer "iithens placed maiawaitemhath forzione sl rounz. mmoreilbeforevitesting. The:floriquetsiwterewthencpulled apart-fin 311381151518 .streng-th testing:apparatusw .Eable; Id Illustrates the mesultsot the testpthatziwthez tensile strengths of briquets composed otfizlled asphaltrandifittawa .sandi llIt viz-ill be "observdmhatkthe .volume rper- .centagelect wand was. a= maintained. sconstant throughoutthe series ofi tests givingiard'mect .comparison ofthe vanious 'fil ledgasphalts; Only the-amwntmfinuer inahe filiea as naluanda the proportions of various types of -fillers werevari'ed. "III g 'ITQB EI The efiect of miner. uthewt zw le .t' mnmthtass i- The observed data of .Table I has been charted:

as shown in Fig. 1 of the drawingnvvhere curve A represents a filled asphalt containing a filler com prising 100% diatomaceous'earth curve-B representssone containing .5,0,-.%,.diatomaceous:earthzand 9 c fq ks lfii $44 3 1Q cna ontsininsizmruia tamaceohsrearthzand 75% rockidust; =curve"D; one wcontaining.10%.idiatomaceousearth and: 90% rock izdusteand ourveE; representsione containing: 100% uroclccdustx It.=will he:.-observed that in eacln-com- =Was-reached;::after which the" addition ofl'more fil1er: toithe asphalt producedta sharp decrease in :thewtensilestrengthyof' the. filled. asphalt. ""Furthermore-,1Lin: :each: instance; a filled: asphaltwas aproduced' having .an extremely high tensile strength. The highest maximum. tensile strength was obtained when using theoptiinum concentration of fillercomprisinglIOO diatomaceous'earth which approximated 400 ;lbs; per square inch as v.represented by-curve A. Withthe substitutioncof mock dust for thediatomaceous. earth; the maximumtensilestrength that could-be reachedwas :lower :thanwhen Fusing straight diatomaceous .earth. In the discussion of-my'invention; that percentage or: concentration of: filler in asphalt which-s will' result in the; production of. a: filled asphalt of maximum-tensile strength for the-given [filler or. combination of fillers-shall be termed the opbimum percentage or concentrationof filler.

termsofcost, rock-l dust is thecheaper filler -forproducing filled asphalt of high; tensile strength, but it requires a::lower concentration of asphaltin the mastic to produce a" mastic of: high ,tensileistrength than does :diatomac'eous 'earthand a isual compariscrr of :diatomaceous filled and rock dust filled mastics indicates. clearly that the for-men type of filledma'sti'cs-are greatlysuperior with negardto self-healing; after: fracture; characteristic is- .-imp,ortant i when the asphaltic masticorconcrete isemployed for'filling the; voids in, seawalls, breakwaters and the like (when the stonesare-dislodged bylargewaves-or swells and the bond. of. asphaltic concrete. holding the .stone together is broken. Furthermore li have determined .that in order to obtain. anvasphalt foruse in-.sea walls having long. life, it-is necessary to incorporate as much .asphaltas;-"possible and at the same time .tcobtain the high tensile/strengths tomaceous; earth will permit .theuse of.-1arger amounts of. asphalt. for a. given tensile strength such as 300' lbs. per. square. inch.

inmmrramer andlthe curves.in.'l'ig. 1, it.is evident" that' any one offthel five filler combinations jshownlis capable ofIforming .-a filledasphalt having a tensile strength of approximately 300- lbs. per square inch .01 greater. The combinations listed in Table II have.ten'sile strengths of approximatelyBOO lbs. per square.- inch When..mixed with standard Ottawa. sandin exactly the correctpropoi'tionstolfillithe voids inthe sand, i; e. 67 %by volume of Ottawa sand. to.-32 by volume of filled asphalt. A filled asphalt having a' t ens'ilfe strength ofapproximately' llodbs. pen .z-squarainchi is' 'more than satisfactory to fillthe' voids in sea walls, breakwaters, etc., under atmospheric temperatures ordinarily present where "this type of construction is employed. In fact, 1 .by usingfilledjasphalts either alone or iwithadmixture with aggregate having tensile strengths of approximately 250 lbs. per square inch for: fiiliriigivoids in; sea walls'a'nd'the like; 51101125131110- ;tures {will resist impacts from -waves and the 1ike=much better than when thevoids are filled with the best mixtures ofPortland cement concrete'and will-"additionally" possess the property of;self-hea ling;.:which;"'ofi'course; isrnotiapp'arent in --Pontland;:oement: concrete: a'llensilesstrength tests performed upon one inch cubical briquets permissible to produce-a filled asphalth aving composed of one part of Portland cement to three unusually high ductilities as compared with air parts of Ottawa sand revealed tensile strengths blown and steam 'refined' asphalts of the-same of only 210 lbs. per square inch; The tensile Imelting point. A filled D gradeasphalt comstrength of a briquet composed of one part'of posed. of 57% by weight of asphalt, 21.5% dia-' 5 Portland cement, two parts of commercial sand tomaceous earth and=2l.5% rock dust has a sofand four parts of small rock, i. e. passing a screen tening point of 219 F., a penetration of '4 at having circular openings of one-quarter inch in 32 F., 18. at 77 Frand 75 at 115 F., and a ducdiameter and under, was 229 lbs. per square inch. tility .of 6.5 at 77 Unfilled D grade asphalt Furthermore, it will be observed by inspection merely has amelting point of 119 F. and pene of the curves in Fig. 1 that it is possible to protrations of 8 and 52'at 32 F. and 77 F., respecduce' two filled asphalts of the same tensile tively, (the asphalt being too soft at 115 F. for strength with the same type of filler or combinameasurement of penetration) anda ductility of tion of fillers when producing filled asphalts conover 100 at 77 F. The tensile strength of the taining an amount of filler other thanthe optiunfilled asphalt is me e y 111 per Square inch mum concentration. This may be accomplished as c mpar d h approximately 300 p by choosing an amount of filler which will prosquare inch for the various filled asphalts shown duce a filled asphalt of the desired tensile strength in 'Tab II The Penetrations 0f filled grade either on the rising slope of the curve or on the p a c mpa favorably With air own sfalling slope beyond the optimum concentration p a 0 the a melting Point as filled p of filler. For example, if it were desired to pr0- 9* Penetration-S of r b own 91 duce a filled asphalt having a tensile strength D lt a 0, 3 d 0 at d of approximately 300 lbs. per square inch using p v y, While'the ductility iS y a straight diatomaceous earth (curve A), this may vWhleh lower then that Of filled esphalts- A be accomplished by employing either from 27 to st a r fi d asp alt v n a m n p nt f 28% or" diatomaceous earth or from 42 to 43% 9 as a penetration of 2 at 32 a d 77 F-. of the filler with the asphalt. However, it is prefr spectively, Whilev its penetration at F.- is erable to choose the lower concentration of filler Zero and its ductility is ZerO a R All asphalt for producing filled asphalt, of th d ire t of this character is entirely unsuitable for use sile strength for filling the voids in sea walls for filling the Voids ih 'W e due t0 t because it is desirable to use as muchasphalt as e -that it has no ductility. possible in order to give the structure as lon It is thus evident, filled steam refined asphalts a life. as possible and t give t Structure t have most of the physical advantages of air blown self-healing characteristics heretofore mentioned. asphalts which more expensive t Produce Moreover, it is possible to control the production than D grade Steam refined asphalts eentain- 35 v of a filled asphalt of the desired tensile strength a filler- In other Words the addition of much easier when using the smaller concentra tomaceous earth to steam refined asphalt t of filler t when employing t larger nparts air-blown characteristics to the steam recentration because the slope of the rising curve is fined asphalt, it increases the melting point not as sharp as the falling portion of the curve aftand produces a reduction in p et on a d duc- 4'0 er reaching theoptimum concentration. In other tility in a manner similar to the chemical action words, small variations in the amount of filler of the air blowing process weve it will be in the asphalt will not affect the tensile strength Observed t for y given melting poi t. a filled materially when using the lower n nt at n asphalt will have a higher ductility at 77 F, than whereas a small variation in filler when using the an alr'blown asphalt- 1 '45 higher concentration y vary t tensile In order to compare the relative brittleness of strength considerably from the one desired. the foregoing filled D v g t ns e Briquets of the proportions of asphalt, and filler strengths of approximately per square resulting in tensile strengths of approximately c 2 inch eU-bieal q s made by ot miX- I 300 lbs. per square inch were tested for melting ing wa Sa d filled a p in the D O- or softening points, penetrations, ductilities and P s of 2% y Vo ume of Sand to 32.5% specific gravities. The results are tabulated] in y Vqlume 0f filled p a t d eeelihg in act y T bl I1, the same manner as that employed in making TABLE II tensile strength tests were tested at 77 F. by

dropping a 2 inch steel ball weighing 1.175 lbs. Comparison of physical characteristics and imupon the cube, allowing the ball first to drop 6 pact resistance 0 various filled asphalts havinches and then progressively increasing the ing tensile strengths of approximately 300 lbs. height of fall one inch per blow until destruction per sq.'z'n. of the cube resulted. The proportions of asphalt compostlon by weight of fined Physical characteristics of filled asphalt asphalt Impact at tcub? det s we 10h a Softening Penetratlon at Ductility 77 F. it Asphalt Diat. earth Rock dust point (B. t 77 F lbs.

and 32 F. 77 F. 115% F.

Percent Percent Percent F.

It is evident from Table II that by selection to filler and the results of the tests are also shown of the proper fillers and filler concentration, it is inTableII. The impact at cube destruction was tggzxml 5 Tfi9 ,vblume Y .o ,gommer ial .ag n i a e .qem r ei I t? mi s uxe 9 150. 1% .b JV. 99k and 39-15% P5 ye u eatsand' -fl ';l ;;w l the .observed tha m fil rawhelfii m st qseqi pqe rt esfi e et rel dissimilalfitqorarymvin hi umi qu y qn it' m my 9 mastics 01' concretes are much richer asphalt than any m Xture that cangbe practically successful fox-paving; The particulax objects in vfewiin selectingjth-e composition for my'mastic orconfcreteareto use-asmueh asphalt as can beabsorbedby the stone,-sa.n d-and 1i11er so astdbtgin t .t e maximum; toughness and cementingpower and 1 gig-g: $3 32 at t1 1 e same time to protect the asphalt within themasticagainst the action ofsunyair and-moisture'arfd' to thus obtainanindefinitely'long-"life .for'ithe tasphaltic' concrete: Paving mixtures are too leazi'inasphalt to meet the foregoing-require,- merxts andare-too rigidyrequiring' constant -c'ompactiomby trafiic to maintetm them ingood condition. "'Exce'ssive"'asphaltfover the requirements Q5 "for" good-"pavement iwesSen'tiaI t6 my sylstem "of "seaiWQJllPbreakWater, "etc. p'l otectitii in Order to lled ggghalt to exactly fill the voids 5 phaltic Concrete could stand considerable more asphalt is due to the fact that I employ considerable more filler than can be used in asphaltic concrete for use in pavements or other purposes; The excess filler and asphalt makes for a concrete which is a tougher, more stable, cementing agent than any asphalt suitable for paving purposes.

The method for constructing sea walls, ripraps or breakwaters such as the one represented by 10 in Fig.2 consists in dumping the plastic asphaltic concrete or mastic 11 at a temperature of 250 to 450 F. upon each course of stone 12 above low tide level and subsequently laying the next course of stone upon the mastic while the latter is still in a plastic state. The stones 12 employed should be large, weighing from 15 to 30 tons. Each stone laid upon the concrete then sinks into the latter and thus forms a perfect bed. In a short time, the large stones and asphaltic concrete will form a monolithic structure. It is not desirable to fill in the large voids on the water side 14 of the sea wall with mastic or concrete excepting to such extent as is required to form a firm bed for each stone, since it has been found that sea walls and breakwaters should preferably have very rough and irregular faces in order to most effectively absorb, deflect and break-up the impact of waves or swells. However, it is desirable to fill as completely as possible with asphaltic concrete all of thevoids within the wall in order to prevent rapidly moving masses of water from striking the rocks from below and thus lifting them out of place and from preventing receding water from carrying the protected earth 15 out with the'wave. Preferably, where extremely large voids are presented by the large stones, the voids are filled with smaller stones 16 of approximately 50 to 100 lbs. These are placed in the voids either prior to filling of the voids with asphaltic concrete or afterwards. This increases the stability of the asphalt against fiow due to the fact that the asphaltic concrete fills the voids in the stones.

For sea walls and breakwaters which have already been completed without the use of 9 asphaltic mastic or concrete, the concrete may be placed in the voids by any convenient method, such as, for example, buckets, conveyors, pipes, chutes and the like. Where necessary to insure complete filling of the voids spading, rodding or ramming by means of hand or machine driven implements may be used. By applying the asphaltic mastic or concrete sufiiciently hot or considerably above its melting point, the use of implements is not necessary since the hot mastic or concrete will readily fiow into the voids and crevices of the lower courses of stone until it contacts thesea water, whereupon it will harden to prevent further fiow. However, it is believed that if the hot cementing agent reaches the low tide level, the sea wall is sufficiently protected to combat large waves or swells, since it has been found that substantially all ofthe destructive action of the waves or swells occurs above water level. Large stones forming the foundation below the water level are rarely, if ever, disturbed by the waves.

Sea walls or breakwaters constructed in the above manner and with my asphaltic mastic or concrete are capable of withstanding the destructive action of large waves or swells even in stormy weather. In extreme storms it may be possible to lift the large stones from their embedment to some small extent, thus breaking the bond of asphaltic concrete. However, the protection afforded by the asphaltic mastic or con crete will never permit the waves to lift the large stones completely ofi the wall. Furthermore,

the fracture-will occur inthe asphaltic mastic or concrete itself. Considerable amounts of the asphaltic material will adhere-to the large stones and when they fallback to their former positions, the effective healing characteristics of the asphaltic material will soon bind the fracture to again form a monolithicstructure.

Any of the filled asphalts disclosed in Table 11 which have tensile strengths 'of approximately 300 lbs. per square inch may be employed with commercial aggregate for filling the voids in sea walls, breakwaters, etc. A specific example would be a filled asphalt composed of equal partsby weight of D grade steam refined asphalt and filler where the filler is composed of one part by weight of diatomaceous earth to three parts by weight of rock dust. The only care that must be exercised is to so proportion the amounts of filled asphalt to aggregate that the former exactly fills the voids in the aggregate, neither in deficiency nor in excess. The voids in dense aggregates may comprise from 15 to 25% by volume so that approximately 75 to by vol ume of filled asphalt should be employed to exactly fill the voids in the aggregate. I have shown that when using an aggregate comprising graded sand and small crushed rock of onehalf inch or less that the voids are about 20.5% and consequently this percentage of filled asphalt should be used in the proportion vof 50.5% by volume of rock to 49.5% by volume of sand. However, I do not wish to be limited to the size of aggregate employed nor to the use of any aggregate sinceI have obtained equally good results with merely the use of sand as aggregate.

In some instances, it is desirable to use an asphaltic concrete of greater than 300 lbs. ,per square inch tensile strength. For this purpose, any'of the combinations of asphalt to filler disclosed in Table I having tensile strengths of greater than 300 lbs. per square inchmay be employed and if necessary the optimum concentration of filler may be used to produce a filled asphalt of maximum tensile strength. If it is desired to use filled asphalts of lower tensile strength than approximately 300 lbs. per square inch, any of the combinations'of filler to asphalt disclosed in Table I having approximately the desired tensile strength may be employed. However, it will be observed that the ductilities rise proportionately to the decrease in tensile strength, varying with theiquantity of filler used. In other words, I do not wish to be limited to filled asphalts having approximately 300 lbs. per square inch tensile strengths since both higher and lower tensile strength filled asphalts may be used for'filling the voids in sea walls and the like. However, I prefer to employ an asphaltic con: crete or mastic having anamount of filler approaching the optimum concentration.

While the above inventionhas been described using "D grade asphalt as the preferredasphalt, it is evident that other grades of asphalt having both higher and lower penetrations, softening or melting points and ductilities than D grade as- 'phalt may be employed in combination with fillers and with a certain degree ofsuccess. Furthermore, it must be understood that this invention is not limited to the use of the preferred steam refined asphalt'since other types of asphalt, such as air blown asphalt, may be employed, nor is the invention limited toan asphalt as the plastic ingredient since other bituminous products having more or less cementing characteristics may be employed such as cracked and uncracked petroe leum residues, cracked and uncracked coal tar residues, pitch, tar and the like. 7

7 The above disclosure is to be taken merely as illustrative of a preferred embodiment of my invention and is not to be considered limiting, since many variations thereof may be made within the scope of the following claims:

I claim: i

1. An asphalt composition comprising asphalt and a finely divided filler, the filler comprising more than percent of the composition by weight and the asphalt in said composition having a penetration at 77 F; between and 90, a melting point between 110 and 130 F. and a ductility greater than 100 at'77 F. i

2. An asphalt composition comprising asphalt and a finely divided filler, the filler comprising more than 35 percent of the composition by weight and the filler including diatomaceous earth, and the asphalt in said composition .hav-

filling the voids presented by massive stones used in constructing breakwaters, sea walls and the like, said concrete containing approximately to percent by volume of aggregate and 25 to 15 percent by volume of an asphalt composition containing a finely divided mineral filler, the asphalt in said composition having a penetration at 77 F. between 40 and 90, a melting point between and F. and a ductility greater than 100 at 77 properties, high tensile strength, high impact resistance, low penetration marked flexibility and strong adhesive qualities for the stones, whereby breakwaters and sea walls constructed therewith show marked resistance to destructive wave action.

' LANDON R. MASON.

R, the asphaltconcrete having self healing

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