US1987152A - Sea wall - Google Patents

Description

Jan. 8, 1935. L. MASON 1,987,152

SEA WALL Original Filed Dec. 19, 1952 Jig 72015'176 Jfrehgf/z Lbs. Peru) R,

v a '50 a0 Percenf FIX/e [/2 FIX/e0 Asp/2212 v LEGEND-- v CURVE FILLER A= 100% DIAT'OMACEOUS EARTH B=m 50% n 50 ROCK DUST C A 25% as, n n

as as a) INVENTOR. Landon Rfi/ason A TTQRNE Y. I

Patented Jan. 8, 1935 PATENT OFFICE SEA WALL Landon 8.. Mason, Los Angeles, Calif., assignor to Union Oil Company of California, Los Angeles,

Calif., a corporation of California. Original application December 19, 1932, Serial No.

647,850. Divided and 1933, Serial No. 678,662

5 Claims.

The present invention relates to a bituminous composition adapted for use in sea walls, breakwaters, ripraps, revetment, levees and the like and to methods of constructing or repairing sea walls. etc. employing said bituminous composition and is a division of my copending application, Serial Number 647,850, filed Dec. 19, 1932.

It is generally known to construct rubble sea walls, breakwaters, ripraps, levees and the like by placing stones one above the other in irregular courses. Reliance is placed upon the weight of the stones to hold them into a fairly compact wall. However, this type of construction is subject to the destructive action of large waves of water impacting against, the wall structure. It has not been uncommon for large waves or swells to lift massive stones weighing many tons and to throw them completely off the structure, thus resulting in a gradual and almost complete destruction of the wall. Furthermore, this type ofstructure has suflicient amounts of voids which' permit the waves to penetrate through and come into con-' tact with the earth protected by the wall, thus causing the receding waves to carry considerable amounts of the earth protected by the wall. Eventually, when suflicient amounts of the protected earth has been washed away, there will be a settlement and consequent tumbling of the rock structure and perhaps, an almost complete destruction of the sea wall. Sea walls and the like are also subject to the destructive action of impacts of floating logs and similar objects tossed by the sea against the wall.

Repeated attempts have been made to prevent the foregoing destructive action by filling the voids between the stones with Portland cement concrete. However, the use of Portland cement concrete has proven unsatisfactory since sea walls and breakwaters are necessarily subjected to constant motion due to their unstable foundations and their necessarily inflexible construction re-- sults in breaking of the bond of concrete retaining the large stones. Once this bond is broken, the sea wall is subject to destruction by the wave or water action.

One of the primary objects of my invention is to correct the aforementioned difficulties and di advantages attending prior sea wall, breakwater, etc. construction and to present structures which cannot be easily destroyed by wave or water action.

Another object or this inventionresides in an asphaltic mastic or concrete adapted for the voids of sea walls, etc. which'is tough, dense,

- adhesive, flexible and selff heaiing.

this application July 1,

It is another object of this invention to present an asphaltic mastic or concrete having its ingredients proportioned in such manner as to prethe drawing and in the uses to which my invention is put.

Referring to the drawing:

Fig. 1 represents a series of curves showing the efiect of mineral fillers upon the tensile strength of asphalt.

Fig.2 is a section of a sea wall or the like.

In its broadest aspects, my invention comprises a composition of matter containing a mixture of a bituminous substance, such as asphalt and a finely comminuted filler such as diatomaceous earth, the mixture having a tensile strength greater than that of the bituminous substance in the mixture., An important feature of my invention resides in the production of a filled asphalt having an extremely high tensile strength, a reasonable high ductility, a moderately low penetration and a high melting point. Another important feature of my invention resides in a filled asphalt having such a concentration of filler as to produce a mastic of maximum tensile strength and impact resistance and which is adapted for filling the voids in sea walls and the like. In some instances, my filled asphalt may have tensile strengths between 150 and 400 lbs. per square inch depending upon the concentration and character of filler or combination of fillers in the composition.

More specifically, my invention resides in a filled asphalt comprising a mixture of asphalt and between approximately 5% and 40% by weight of diatomaceous earth and having a tensile strength between arproximately 150 and 400 lbs. per square inch.

My invention also comprises a sea wall or the like and a method for constructing the same, the wall comprising a plurality of large stones placed in irregular courses and provided with a sticky asphaltic mastic or concrete of high tensile strength in the voids presented by the stones in order to prevent impacts from disturbing the position of the stones and also to prevent rapidly moving masses'of water from penetrating through the wali and washing theprotected earth out with the receding water.

l"; have discoveredthat when the voids in sea walls, hreekwaters and the like are filled with a specially desie bituminous mastic or concrete sand and 32 by volume of filled asphalt. In

preparing the briquets for tensile strength tests, all of the ingredients for each separatemixture were weighed together into the same iron dish and were heated to about 400? F. The ingredients were hand stirred until a homogenous mixture was obtained. The hot mixture was then rammed by hand into the molds ordinarily used for making tensile strength briquets of Portland cement concrete and then were allowed to cool in the molds. After removing the briquets .from the mold they were allowed to stand overnight at room temperature and were then placed in a water bath at 77 F. for one hour or more before testing. The briquets were then pull'ed apart in a tensile strength'testing apparatus. Table I illustrates the results of the test, that is, the tensile strengths of briquets composed of filled asphalt and Ottawa sand. It will be observed that the volume percentage of sand was maintained constant throughout the series of tests thus giving a direct comparison of the various filled asphalts. Only the amount of filler in the filled asphalt and the proportions of various types. of fillers were varied.

TABLE I The efiect of mineral fillers upon the tenszle strength of asphalt Tensile I strength of as- Composition of filled as- Composition of filler phalticconphalt-percent by weight percent by weight crete at 77.

' F. in lbs. per square inch Filler Asphalt Dial. earth Rock dust 10 90 50 50 125 20 80 50 50 193 30 70 50 50 240 40- 60 50 50 2 3 45 50 so 9 50 5O 50 322 55 45 6O 50 209 60 40 50 50 5 The observed data of Table I has been charted as shown in Fig. 1 or the drawing where curve A represents a filled asphalt containing a filler comprising 100% diatomaceous earth; curve B represents one containing 50% diatomaceous earth and 50% rock dust; curve C, one containing 25% diatomaceous earth and 75% rock dust; curve D, one

containing 10% diato'maceous earth and rock dust and curve E represents one containing rock dust. It will be observed that in each combination of filler or combination of fillers and asphalt, the tensile strength increased with the addition of filler until a maximum tensile strength was reached, after which the addition of more filler to the asphalt produced a sharp decrease in the tensile strength of the filled asphalt. Furthermore, in each instance, a filled asphalt was produced having an extremely high tensile strength. The highest maximum tensile strength was obtained when using the optimum concentration of filler comprising 100% diatomaceous earth which approximated 400 lbs. per square inch as represented by curve A. With the substitution of In terms of cost, rock dust is the cheaper filler for producing filled asphalt of high tensile strength, but it requires a lower concentration of asphalt in the mastic to produce a mastic of high tensile strength than does diatomaceous earth and a visual comparison of diatomaceous filled and rock dust filled mastics indicates clearly that the former type of filled mastics are greatly superior with regard to self-healing after fracture. This characteristic is important when the asphaltic mastic or concrete is employed for filling the voids in. sea walls, breakwaters and the like when the stones are dislodged bylarge waves or swells and the bond of asphaltic concrete holding the stone together is broken. Furthermore, I have determined that inorder to obtain an asphalt for use in sea walls having long life, it is necessary to incorporate as much asphalt as possible and at the same time to obtain the high tensile strengths necessary to resist impacts. Consequently, diatomaceous earth will permit the use of larger amounts of asphalt for a given tensile strength such as 300 lbs. per square inch.

From Table I and the curves in Fig. 1, it is evident that anyone of the five fillercombinations shown is capable of forming a filled asphalt having a tensile strength of approximately 300 lbs. per square inch or greater. The combinations listed in Table II have tensile strengths of approximately 300 lbs. per square inch when mixed with standard Ottawa sand in exactly the correct I proportions to fill the voids in the sand, 1. e. 67 /270 'mately 250 lbs. per square inch for filling voids in sea walls and the like, such structures will resist impacts from waves and the like much better than when the voids are filled with the best mixtures A filled asphalt having a tensile ings of one-quarter inch in diameter and under,

was 229 lbs. per square inch.

Furthermore, it will be observed by inspection of the curves in Fig. 1 that it is possible to produce two filled asphalts of the same tensile strength with the same type of filler or combination of fillers when producing filled asphalts containing an amount of filler other than the optimum concentration. This may be accomplished by choosing an amount of filler which will produce a filled asphalt of the desired tensile strength either on the rising slope of the curve or on the falling slope beyond the. optimum concentration of filler. For example, if it were desired to produce a filled asphalt having a tensile strength of approximately 300 lbs. per square inch using straight diatomaceous earth (curve A) this may be accomplished by employing either from 27 to 28% of diatomaceous earth or from 42 to 43% of the filler with the asphalt. However, it is preferable to choose the lower concentration of filler for producing a filled asphalt of the desired tensile strength for filling the voids in sea walls because it is desirable to use as much asphalt as possible in order to give the structure as long a life as possible and to give the structure the self-healing characteristics heretofore mentioned. Moreover, it is possible to control the production of a filled asphalt of the desired tensile strength much easier when using the smaller concentration of filler than when employing the larger concentration because the slope of the rising curve is not as sharp as the falling portion of the curve after reaching the optimum concentration. In other words. small variations in the amount of filler in the asphalt will not effect the tensile strength materially when using the lower concentration, whereas a small variation in filler when using the higher concentration may vary the tensile strength considerably from the one desired.

Briquets of the proportions of asphalt and filler resulting in tensile strengths of approximately 300 lbs. per square inch were tested for melting or softening points, penetrations, ductilities and -specific gravities. The results are tabulated in It is evident from Table II that by selection of the proper fillers and filler concentration, it is permissible to produce a filled asphalt having unusually high ductilities as compared with air blown and steam refined asphalts of the same melting point. A filled D grade asphalt com posed of 57% by weight of asphalt, 21.5% diatomaceous earth and 21.5% rock dust has a softening point of 219 F., a penetration of 4 at 32 F., 18 at 77 F. and 75 at 115 F., and a duetility of 6.5 at 77 F. Unfilled D grade asphalt merely has a melting point of 119 F. and penetrations of8 and 52 at 32 F. and 77 F., respectively, (the asphalt being too soft at 115 F. for measurement of penetration) and a ductility of over at 77 F. The tensile strength of the unfilled asphalt is merely 111 lbs. per square inch as compared with approximately 300 lbs. per square inch for the various filled asphalts shown in Table II. The penetrations of filled D grade asphalt compare favorably with air blown asphalts of the same melting point as filled asphalt, i. e. 219 F. The penetrations of air blown asphalt are 10, 18 and 30 at 32 F., 77F. and 115 F., respectively, while the ductility is only 2 at 77 F. which is lower than that of filled asphalts. A steam refined asphalt having a melting point of 219 F. has a penetration of 2 at 32 and 77 F., respectively, while its penetration at 115 F. is zero and its ductility is zero at 77 F. An asphalt of this character is entirely unsuitable for use for filling the voids in sea walls, etc. due to the fact that it has no ductility.

It is thus evident, filled steam refined asphalts have most of the physical advantages of air blown asphalts which are more expensive to produce than D" grade steam refined asphalts containing, a filler. In other words, the addition of diatomaceous earth to steam refined asphalt imparts air-blown characteristics to the steam refined asphalt, i. c. it increases the melting point and produces a reduction in penetration and ductility in a manner similar to the chemical action of the air blowing process. However, it will be observed that for any given melting point, a filled asphalt will have a higher ductility at 77 F. than an air-blown asphalt.

In order to compare the relative brittleness of the foregoing filled asphalts, having tensile strengths of approximately ,300 lbs. per square inch, 2 inch cubical briquets made by hot mixing Ottawa sand and filled asphalts in the proportions of 67.2% by volume of sand to 32.5% by volume of filled asphalt and cooling in exactly the same manner as that employed in making tensile strength tests were tested at 77 F. by dropping a 2 inch steel ball weighing 1.175 lbs. upon the cube.

Table II. allowing the ball first to drop 6 inches and then TABLE II I Comparison of physical characteristics and impact resistance of various filled asphalts having tensile strengths of approximately 800 lbs. per sq. m.

Composition by weight of filled I asphalt Physical characteristics of filled asphalt Im t t :1 do t Softening Penetration at- Ductility 13: Asphalt Diat. earth Rock dust point B. at

. a R) 32 PF. 71 1'. 115 F. F

Percent Percent Percent 72 28 o 178 4 23 111 10.5 3.32 51 21.5 21.5 219 4 1s 1a 0.5 3.13 50 12.5 37.5 180 3 21 91 9.2 3.32 02 3.8 34.2 128 3 32 220 00 2.35 25 0 70 180 3 17 58 2.9. 3.22

progressively increasing the height of fall one inch per blow until destruction of the cube resulted. The proportions of asphalt to filler and the results of the tests are also shown in Table II. The impact at cube destruction was calculated by multiplying the height of fall in feet at cube destruction by the weight of the steel ball in pounds, i. e. 1.175. v

To show the relative impact resistance of filled asphalt to Portland cement concrete, tests for impact resistance were performed on 2 inch cubical briquets of Portland cement concrete in the proportions by weight of one part cement, two parts sharp, clean sand and four parts sharp, clean. broken stone. The briquets had been cured seven days under water. The tests revealed an impact resistance of nearly 2.85 ft. lbs. which is considerably lower than the impact resistance for most of the filled asphaltic concretes.

While practically all of the'foregoing data with regard to both tensile strength. and impact resistance had been obtained by using Ottawa sand aggregate due to the fact that this type of sand is more uniform than other types and consequently more accurate comparisons may be made, I have obtained similar results using commercial aggregates with filled asphalts and have found the same to be superior to Portland cement concrete. For example, I have tested slabs of asphaltic concrete 2'? inches wide, 36 inches long and 2 inches thick with reinforcing wire through the slab. These were constructed by placing a one inch course of small crushed stone in a form and filling the voids with filled asphalt composed of 72% by weight of D grade asphalt and 28% by weight of diatomaceous earth at 450 F. Wire fencing for reinforcement was placed over this course and. then a second one inch course of crushed stone was laid over the reinforcing and first course. Hot filled asphalt was again applied to the crushed stone. Immediately after the second application of asphalt, screenings were broomed over the slab and the entire slab was consolidated by hard tamping.

Portland cement concrete slabs of exactly the. same size as those made with asphaltic concrete and with the same type of reinforcing mesh wire were prepared. The concrete had a composition by weight of one part Portland cement to four parts of clean, sharp, graded sand. This composition is stronger than concrete'containing by weight one part Portland cement, two parts sand and four parts crushed stone. These slabs were cured for seven days under water prior to testing.

After seven days of aging, a slab of Portland cement concrete was tested by impacting a falling hammer weighing ten pounds dropped from a height of three feet on the slab which was placed on a dry sand bearing three to four inches thick and in such position. that the falling hammer struck exactly the center of the slab. On the second blow, the Portland cement concrete slab cracked through its entire length and was held together merely by the reinforcing. It was completely destroyed a few blows thereafter. The reinforced asphaltic concrete slab was tested in exactly the same manner. One hundred blows from a height of three feet produced no fracture whatever and merely beat down a slight depression under the hammer due chiefly to the smashing of the screenings which formed the upper course of the slab.

To illustrate the flexibility of the asphaltic concrete slab, it was placed across a pile of sand so that the slab was supported only at its center.

This test showed that although the slab bent to follow the contour of the sand pile, it did not crack. To illustrate the self-healing character-" istics, the slab was purposely cracked by a Sharp blow and was then placed on a. fiat surface and in a short course of time, the crack disappeared.

In order to employ filled asphalts with commercial aggregates, it is preferable to adjust the percentage of filled asphalt to exactly fill the voids in the commercial aggregate and to select a commercial aggregate comprising a mixture of sand and rock having a maximum density and a minimum of voids. The percentage of voids in aggregate using a mixture of graded sand and small rock capable of passing a screen having circular openings of one-half inch diameter and under and its density may be determined by filling a container level full of the aggregate and compacting the same until no more of the aggregate could be placed in the container. By first weighing the dry mixture and then weighing the mixture with water added thereto in amounts sufficient to fill the can, the true specific gravity and the percentage voids by volume can-easily be calculated as understood by those skilled in the art. I have found that the percentage of voids in the aggregate was considerably high when the aggregate contained no graded sand. With addition of the sand in the aggregate, the percentage voids gradually decreased until a mixture of 50.5% by volume rockand 49% by volume sand was reached which had about 20.5% voids, after which an increase in the proportion of sand gradually increased the percentage of voids in the mixture of sand and crushed rock. I have thus found that the maximum density of asphaltic concrete using commercial aggregate could be obtained by mixing 20.5% by volume of filled asphalt and 79.5% by volume of commercial aggregate comprising a mixture of 50.5% by volume rock and 49.5% by volume of sand. v It will be observed'that my filled asphaltic mastics or concretes are entirely dissimilar to ordinary paving bituminous concretes since my mastics or concretes are much richer in asphalt than any mixture that. can be practically successful for paving. The particular objects in view in selecting the composition for my mastic or concrete are to use as much asphalt as can be absorbed by the stone, sand and filler so as to obtain maximum toughness and cementing power and at the same time to protect the asphalt within the mastic against the action of sun, air and moisture and to thus obtain an indefinitely long life for the asphaltic concrete. Paving mixtures are too lean in asphalt to meet the foregoing requirements and are too rigid,.requiring constant compaction by traflic to maintain them in good condition. Excessive asphalt, over the require.- ments for good pavement is essential to my system of sea wall, breakwater, etc. protection in order to obtain maximum adhesiveness and flexibility, whereas excess asphalt in paving mixture forms poor pavements which will push and bleed. However, it is one of the essential features of my invention of my mastic for sea wall protection that exactly the correct quantity of filled asphalt to fill the voids in the aggregate shall be used in order to obtain the greatest tensile strength and impact resistance. Neither a deficiency nor an excess of filled asphalt to ex-- actly fill the voids in the aggregate will result in an asphaltic concrete of maximum strength, although a slight excess will give good results.

Moreover, I am able to incorporate considerable more asphalt into my asphaltic concrete than can be added in asphaltic concretes suitable for paving or other purposes. The reason that my asphaltic 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 methodsfor 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-mono1ithic 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 the voids 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 flow 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 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 sufficiently 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 the sea 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 sufilciently protected to combat large waves or swells, since it has been found that substantially all of the 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 ture will occur in the asphaltic mastic or concrete itself. Considerable amounts of the asphaltic material will adhere to the large stones and when they fall back to their former positions, the effective healing characteristics of the asphaltic material will. soon bind the fracture to again form a monolithic structure. Y

Any of the filled asphalts disclosed in Table II 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 afilled asphalt composed of equal parts by 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 85% by volume 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 one-half inch or less that the voids are about 20.5% and consequently this percentage of filled asphalt should be used in the proportion of 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 since I have obtained equally good results withv 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 inch may 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 approxi-' mately 300 lbs. per square inch, any of the com- .having an amount of filler approaching the optimum concentration.

While the above invention has been described using "D grade asphalt as the preferred asphalt, it is evident that other grades of asphalt having both higher and lower penetrations, softening or melting points and ductilities than D" grade asphalt may be employed in combination with fillers and with a certain degree of success. 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 to an asphalt as the plastic ingredient since other bituminous products having more or less cementing characteristics may be employed such as cracked and uncracked petroleum residues, cracked and uncracked coal tar residues, pitch, tar and the like.

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. V

I claim: v

1. A sea wall, breakwater and the like structure comprising a course of massive stones laid upon a foundation so as to present voids and filled asphaltic concrete filling said voids.

and the like strucmassive stones laid 2. A sea wall, breakwater ture comprising a course of upon a foundation, a second course of massive stones laid on said first mentioned course, and filled asphaltic concrete filling the voids between the stones of said further course to provide a selfhealing matrix, to cement the stones together, and to prevent water seepage through said voids.

3. The structure as in claim 2 wherein the asphaltic concrete is composed of asphalt, diatoms.- ceous earth and aggrega I a. The structure as in claim 2 wherein only the voids above no ta water level are filled with the asphaltic concre 5. The structure as in claim 2 wherein the large voids between the. massive stones contain smaller stones and the thus formed smaller voids are filled with the asphaltic concrete.

' .1 N 3. MASON.

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