JPS604155B2 - Low-density concrete composition for energy absorption and impact attenuation and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to low density concrete compositions for energy absorption and impact attenuation and methods of making the compositions.

More particularly, the present invention provides a low density concrete composition that is formed and hardened and that reduces the deceleration of a vehicle as it approaches a fixed obstacle adjacent to a highway.
The present invention relates to a method of making the above composition useful as a highway crash barrier for electronic vehicles. Considerable research has been devoted to the development of highway safety devices that behave as energy absorbers and shock attenuators.

These devices or attenuators are used as protrusions around fixed roadside obstacles to absorb without harm the energy that would be transferred when a vehicle collides with an otherwise solid roadside obstacle. It is a structure that can be installed for protection. The material from which the energy damping device is made should be capable of dissipating substantially all of the shock energy transmitted by the impact, while limiting the force transmitted to the vehicle to a minimum amount and preventing its rebound into the traffic flow. be. The structure itself should also be able to absorb, by plastic deformation or other means, nearly all of the energy being transferred from the crashing vehicle. It was generally known that the amount of energy absorbed by a material is inversely proportional to the density of the material.

Therefore, low-density concrete can be used as a shock attenuator. It has been proposed because it is expected to absorb more impact energy than the standard high density concrete currently used as a structural material for highway barrier devices, overhangs and dividers. Such low density concrete should be capable of absorbing a substantial portion of the energy of a vehicle impact by undergoing local crushing or plastic deformation. In addition, low-density concrete has the advantage of being easily and inexpensively rebuilt after a collision. One method that has been proposed for reducing the density of concrete mixtures to create low density concrete useful as impact attenuators involves reducing the amount of cementitious binder per unit volume of concrete mixture.

This is achieved by the use of chemical foams or by the addition of significant amounts of lightweight aggregates such as perlite or expanded polymer beads. The amount of cementitious binder per unit volume of concrete mixture can be further reduced by entraining air into the concrete in addition to the use of expanded polymer beads or lightweight aggregates. Lightweight aggregate concrete with entrained air has a density of 32
It usually has a density of 0 to 800 k9/a. Some of the currently available foam and lightweight aggregate low density concretes have been subjected to impact testing. The test was completed in July 1974 by the Ohio Department of Transportation.
(ortation), Report No. OHIO-DOT-23-73J. D. “Development of low-density concrete impact attenuators” by Dr. Bekos, Jr.
Impact on Low Density ConCre
In this study, the energy-absorbing properties of low-density concrete containing lightweight skeletons such as vermiculite, perlite, foam, and expanded polystyrene were investigated for the use of low-density concrete in energy-damping applications. Impact tests of various low density concretes made of lightweight aggregates such as vermiculite, perlite, foam or expanded polystyrene with entrained air were tested to determine the
It has been shown that such low density concrete compositions do not fully satisfy all requirements required for highway impact attenuators.

Some of the low-density concretes have shown properties approaching some of the requirements required for impact attenuators or crush barriers, while some have not had the necessary energy absorption properties, while others have shown satisfactory properties. Does not have freeze-thaw properties. Also, very large masses of low density concrete are required for any significant shock attenuator.

Additionally, some tested low-density concretes exhibit pulverization or longitudinal cracking upon impact.
lcrackjng).

Such behavior results in unsatisfactory energy transfer between the crashing vehicle and the crash barrier or impact attenuator made of low density concrete. The unsatisfactory freeze-thaw properties of low-density concrete concrete stem from the large coefficient of thermal expansion exhibited by the concrete. A significant loss of strength is seen after numerous freeze-thaw cycles for these concretes. Depending on the lightweight aggregate used in low-density concrete, concrete specimens exhibit undesirable water absorption properties. These characteristics are manifested as severe spalling of the surface of low density concrete. In some cases, the fragmentation is so severe that it breaks up large amounts of the concrete surface. The inability to resist water absorption results in reduced durability of any impact attenuators made with these low density concretes. The low density polystyrene aggregate concrete used in the above impact tests was the low density concrete described in US Pat. No. 3,272,765.

An energy absorbing device made of low density concrete with vermiculite aggregate is shown in US Pat. No. 3,666,055. Furthermore, a light structural concrete with a special low density is shown in East German Patent No. 2345692. The conclusion to be drawn from the above studies on the use of low-density concrete as impact attenuators is that the stronger, denser materials of this class have poorer energy absorption than the more vertical, weaker types. It means that there is. Binding agent (
The production of weaker materials by conventional means, such as further reduction of Bortland cement), has several disadvantages. A certain amount of water is required to wet the aggregate and a decrease in cement content results in an increase in the water/cement ratio. This increase has several disadvantageous consequences. One disadvantage is the formation of a hothy binder phase in articles with thick and thin walls or sections that increases shrinkage and can even cause foam collapse or excessive cracking. Another disadvantage is the long production cycle, since excess water must evaporate, thus resulting in a columnar article with poor green strength. Yet another disadvantage is the creation of a more porous matrix in the concrete which increases water absorption, reduces freeze-thaw resistance and shortens service life. Another approach to reducing the density and strength of low-density concrete is the addition of additional amounts of lightweight aggregate, such as expanded polystyrene beads with a uniform shape. This study has limitations as increasing the amount of expanded polystyrene beads and the high volume of beads quickly approaches the total volume of the compound for low density concrete. This makes the compound for low density concrete dilatant and therefore virtually impossible to mix or charge into molds or moulds. The above-mentioned problems and disadvantages of current low density concrete compositions used for impact attenuation and energy absorption are solved by the use of the shaped and hardened low density concrete compositions of the present invention and methods of making the same. be done.

The formable and hardenable low density concrete compositions and formed and hardened low density concrete compositions and methods of making the same of the present invention provide many advantages not provided by prior art low density concrete compositions. These advantages include low density concrete compositions or methods of making them that avoid dilatancy in mixing and yet have energy absorption capabilities, deceleration capabilities, freeze-thaw properties, durability, and resistance to water absorption. Accordingly, the present invention provides compositions that can be formed and cured into low density concrete compositions for energy absorption and impact attenuation, low density concrete compositions, and methods of making the same. The composition, which can be formed and cured for energy absorption and/or impact attenuation, comprises about 40-8% by volume (based on the total composition) a first lightweight aggregate phase, a binder phase containing a surfactant and water. (as) of the matrix mixture, and 20 to 60% by volume (based on the total composition) of a second lightweight aggregate phase.

The first lightweight bone phase comprises closed cell, porous, expanded polymer particles having an average diameter in the range of 1 to 4 ribs and a density of 16 to 160 k9/m. 1 bag of cement (
The binder phase comprises hydraulic cement such that the blending ratio of 42.6 k9) to 28.3 polymer particles in the first lightweight aggregate phase is from 1:2 to 1:8.

A first lightweight aggregate phase and a binder phase including a surfactant are mixed such that the binder phase contains entrained air in an amount of 13.5 to 50% by volume based on the binder phase. The second aggregate phase is 4 to 6
．． Consisting of closed-cell, porous, expanded polymer particles with a density of 4K9' and an average diameter substantially greater than 4K, such that the smaller polymer particles of the first lightweight aggregate phase together with the pond component of the matrix mixture The second lightweight bone phase fills the voids between the larger polymer particles. The disparity between small and large particles, filling the interstices between larger particles with smaller particles, allows for a lower density of lightweight concrete compositions than those containing only the first lightweight aggregate phase, and also increases dilatancy. allows you to avoid problems. The density is also reduced while maintaining the same water-to-cement ratio as lightweight concrete with only the first lightweight aggregate phase. Therefore, the binder phase is not reduced in strength. The mixture of the first lightweight aggregate phase and the binder phase of cement, surfactant, and water is non-dilatasotho with good flow properties. When a second lightweight aggregate phase with larger shaped particles is added to the mixture, a new system is created in which the mixture becomes a matrix and fills the interstices formed by the larger shaped particles. This second system is not dilatant and produces concrete compositions with good flow properties and lower densities than those currently available in the industry. A method for producing a low density concrete composition for energy absorption or impact attenuation having a dry density of 160 to 800 k9' comprises a first lightweight aggregate phase of polymer particles having an average diameter of 1 to 4 ribs under air entrainment conditions; A binder phase of hydraulic cement, water and surfactant is mixed to form a uniform matrix mixture and a second lightweight aggregate of polymer particles having an average diameter substantially greater than 4 bars is added to this matrix mixture. It consists of mixing the phases to form a homogeneous mold-curable composition.

The polymer particles of the second aggregate form interstices that are filled by the polymer particles in the first lightweight aggregate phase. The form-curable composition is formed into low density concrete and then cured. Shaping and curing are accomplished by equipment known and conventional to those skilled in the art. A low density concrete composition suitable for energy absorption and impact attenuation uses a first lightweight aggregate phase of closed cell, porous polymer particles having an average diameter of 1 to 4 skins: 13. based on the binder phase. a binder phase of hydraulic cement, water and surfactant with 5 to 6 percent entrained air; and a second of closed-cell, porous polymer particles having an average diameter substantially larger than the four sides. Consists of lightweight bone material.

An average diameter that is substantially greater than four ribs is a diameter that allows the formation of interstices between particles of the second lightweight aggregate phase that can be filled by particles of the first lightweight aggregate.

The ratio of the larger polymer particles of the first lightweight aggregate phase to the larger polymer particles of the second lightweight aggregate phase is between 0.26 and 2.
．． The range is 4. The low density concrete composition and method of making the same is an improvement over the low density concrete composition of US Pat. No. 3,272,765, which is incorporated herein by reference. The improved low density concrete mix of the present invention is more capable and effective for energy absorption or impact attenuation than other low density concretes currently available. The low density concrete composition includes a first lightweight aggregate phase, a matrix mixture of cement with entrained air and a binder phase of surfactant and water, and in addition to the matrix mixture a second lightweight aggregate phase.

The first lightweight aggregate phase can be in any amount up to 48% absolute volume of the total composition, but preferably the amount should be at least 3% absolute volume of the composition. This amount suppresses the density of the matrix mixture consisting of the first lightweight aggregate and the binder phase of cement surfactant and water (ho
lddown). The amount of the second lightweight aggregate phase can be any amount up to 6% by volume of the composition.
Preferably the amount should be at least 2% absolute volume in order for the effect of large particles to be beneficial. In a low density concrete composition, the total amount of components (all in absolute volume % of the total composition) is: 1. The first lightweight aggregate phase 16~
Group 4 capacity%: b Hydraulic cement containing entrained air 16~
4 muscle absolute volume %: c Surfactant 0.001-0. Mirror absolute volume %: and d Matrix mixture consisting of 3-14 absolute volume % water 40-8 absolute volume % b Second light aggregate phase 20-6 pig absolute volume %.

The preferred amounts of these ingredients (all absolute volume % of the total composition) are: 30-3 technique absolute volume %
;b Hydraulic cement with entrained air 39-4% absolute volume;c Surfactant and preferably air entrainment synergist 1
．． 8-2. d water 10-12% absolute volume; and d water 10-12% absolute volume; matrix mixture 75-7% absolute volume.

D Second lightweight aggregate phase 21-2% absolute volume. True or absolute capacity is the bulk capacity minus the volume of voids between particles. Any entrained air will be between 13.5 and 6% muscle volume based on the binder phase after mixing the composition.
exists in an amount of The high volume units of the components constituting the matrix mixture to be added to make the low density concrete of the invention are: 1. A first lightweight bone structure of foamed polymer particles with an average diameter of 1 to 4 sides. ...
...267-800 kg/composition 2 Hydraulic cement...336-1007 kg/composition 3 Surfactant and air entrainment synergist...10.6-339
0k9/composition, and 4 water...30-1
Bulk volume amounts in these ranges are used to make the matrix present in amounts ranging from 40% to 80% by absolute volume of the composition.

Also, when high volume amounts in these ranges are used, the second lightweight bone phase of the expanded polymer particles is present in an amount ranging from 20 to 6% absolute volume of the composition. The closed-cell, porous, expanded polymer particles used in the first and second bone phases are
Any shape of suitable diameter, i.e. sphere, oval, pellet, bead, or twisted peanut
nutswists).

These particles are made of polystyrene or other synthetic resins such as polyethylene, polypynychloride, polyacrylonitrile, polyacrylic esters, polymethacryloesters,
It may also consist of copolymers of styrene with comonomers such as butadiene or acrylonitrile, or phenol/formaldehyde condensation products. The polymer particles in the first lightweight aggregate phase, having an average diameter in the range from 1 to 4 sails, are preferably expanded such that their final density is in the range from 16 to 160 k9/, preferably from 16 to 48 k9/. It is made of polystyrene beads.

Small expanded polystyrene beads are commercially available from several manufacturers, e.g.
It is an expandable polystyrene sold by LITE. 4
The polymer particles in the second lightweight aggregate phase having an average diameter substantially larger than 1.5 mm, preferably from 8 to 18 mm, are preferably polymers of polystyrene or a copolymer of styrene and acrylonitrile.

These particles are foamed so that their bulk density is between 4 and 6.4 kg/m. Large expanded polystyrene and styrene and acrylonitrile copolymers are preferably manufactured by Arco Polymers, Inc.
oPolvme Dai Inc. ) from product name Dailight KF
P524 and Dyrite KFP525 are each commercially available bead forms. The binder phase of the low density concrete compositions of the present invention is the portion of the concrete composition that supports the first and second lightweight aggregate phases.

The binder phase includes hydraulic cement, water, a surfactant, and preferably an air-entraining synergist filling the interstices formed by the particles of the first lightweight aggregate by the particles of the second lightweight aggregate. The first and second lightweight aggregate phases are comprised in proportions that function to provide support to homogeneously distributed polymer particles in the lightweight aggregate phases. These proportions are the same as those required to support lightweight bone structures in US Pat. No. 3,272,765. The cement may be any common inorganic hydraulic cement, such as conventional Boltland cement, high alumina cement, or gypsum products readily available from many commercial sources. The cement can be either conventional cement or high initial strength cement. Water is added to cement to give it fluidity.

Surfactants may also be added to impart castability to the binder phase and to ensure that the first and second lightweight aggregate phases are homogeneously distributed throughout the binder phase. Examples of surfactants found useful under the teachings of the present invention include all types of anionic, cationic, and nonionic surfactants;
For example, alkylaryl sulfonates, sodium salts of formaldehyde, and commercially available naphthalene sulfonic acids, quaternary ammonium salts such as laurylpyridinium chloride and the trade name Alcamus (AIK).
AMS) and ethylene oxide products commercially available under the trade names TRNTON x 45, TRITON x 100 and DMS. A preferred surfactant used in the low density concrete composition of the present invention is available under the trade name Tamol.
) One SN and Rohm Asod 'Haaskanpa'1 (Roh
MandHaas Company).

Surfactants also tend to keep the first and second lightweight aggregate phases homogeneously distributed throughout the binder phase while reducing the water normally required to impart fluidity to the hydraulic phase. do. Under the teachings of the present invention, at least 3.0% of the binder phase may also be used.
It is necessary to entrain air in an amount of % string volume.

Certain surfactants, alone or in combination with supplemental air entraining agents or synergists, are useful in achieving this outcome. If not enough air is entrained to meet the minimum requirements of the product of this invention, the addition of a small amount of air entrainment synergist will satisfy the minimum air entrainment requirements. The air entrainment synergist thus selected should be able to reduce the viscosity of the new concrete mix.

Liquid aliphatic, naphthenic or aromatic hydrocarbons as air entrainment synergists can achieve the required results. The air entrainment synergist selected should be relatively non-volatile so that it remains suspended in the binder during the curing period of the concrete. The synergist should also be slow enough to coat the surface of the polymer particles so as not to cause agglomeration of the particles in the mixed phase, disintegration of the particles themselves, or uneven coverage on the surface of the particles in the aggregate phase. . A particularly useful synergist is commercially available under the trade name VmSOL NVX, which is a polymeric hydrocarbon thermoplastic resin.

A preferred air entraining agent for use in the low density concrete compositions of the present invention is Nebony L-
Nebill Chemical Company (Nebill)
Commercially available from eChemicat Company. Other synergists include mixed aliphatic naphthenic hydrocarbon mixtures, or tar creosote aromatic mixtures. It is desirable that the air entrainment synergist chosen be capable of maintaining uniform and stable air entrainment throughout the binder phase. Uniform air entrainment is necessary to produce low density concrete compositions. The distribution of air bubbles throughout the binder is stabilized by the surfactant. The surfactant and air entraining agent selected should ensure air entrainment in an amount of at least 13.5% by volume of the binder phase. If the volume of entrained air exceeds 6% by volume of the binder phase, there is no longer enough binder phase to ensure uniform distribution of air bubbles. At this point, the air bubbles become large irregular cells causing the mixture to foam. As a result of foaming, the concrete binder phase itself becomes irregular and weakened, and the compressive strength of the concrete composition is significantly reduced. The amount of air-entraining synergist used is usually 2.0% of the amount of cement in the binder phase. or around 20% of the amount of surfactant. If the amount of surfactant is in the range of 1 to 3,990 liters per hour in composition 1, then the amount of air entrainment synergist is 2 to 2 liters per il in composition 1.
It is in the range of ~799 evenings. In accordance with the present invention, a novel method for producing impact damping and energy absorbing low density concrete is manufactured under the trade names KFP524 Alco Polymers and KFP
Preferably an expandable copolymer polystyrene commercially available from 525 Alco Polymers is added to a matrix mixture comprising a lightweight aggregate phase and a binder phase with cement, a surfactant, preferably an air-entraining agent, and water. With post-addition.

The effect of copolymerization with acrylonitrile is that the molecular structure of the polystyrene particles is much more irregular than that of polystyrene homopolymers. Particles thus treated will absorb more pentane blowing agent. When passed twice through a conventional steam expander, polystyrene copolymers exhibit exceptionally low density and large grain size (4-6.4k).
9/cane and 8 to 18 costal diameter). When added as a post-addition to a Dycon IJ-X mixture, the binder phase and the lightweight aggregate phase of expanded polymer particles in low-density concrete compositions commercially available as Dycon Concrete IJ- The beads have the extraordinary effect of reducing the ultimate compressive strength of the concrete composition without causing excessive shrinkage, slow hardening or increased water permeability. Copolymer polystyrene peas are generally made from 1 to 2 parts of the total composition.
It is added as a post-addition to the matrix mixture in an amount ranging from 0 to 6% absolute volume, preferably from 20 to 60% per part of the total low density concrete composition. The diameter of the selected copolymer polystyrene beads is preferably between 8 and 18
Willow diameter range. The introduction of large diameter expanded copolymer polystyrene peas had the unexpected surprise of reducing surface area phenomena that would hinder the compressive strength of concrete if the amount of small particles in the concrete composition were simply increased. It has certain advantages. Since polystyrene has closed cell properties and is substantially water permeable, the selection of the copolymer polystyrene does not render the concrete composition water permeable. After the subsequent addition of the second lightweight aggregate of copolymer polystyrene beads, the mixture is mixed until homogeneous and then shaped and cured.

Shaping and curing can be performed by any method known to those skilled in the art. The mold may be of any design known in the art that maximizes the energy absorption and impact attenuation of the crash barrier. Generally the composition is poured into molds with stirring and then AT for lightweight structural concrete.
Cures under the standard conditions of M Method C-33 Yodokisen. FIG. 1 shows a surface view of the low density concrete of the invention with two lightweight aggregate phases.

The binder phase is indicated by line 10. The first lightweight aggregate phase is represented by 12. First lightweight aggregate phase 12 and binder 10
fills the gap between the third lightweight aggregate phase 14. This low-density concrete structure has compressibility and durability, making it particularly suitable for use as an impact-damping and energy-absorbing crash barrier. Low density concrete compositions have a kiln density of 160 to 800 k9' and are well suited for energy absorption and impact attenuation.

The composition comprises first a lightweight aggregate, preferably expanded polystyrene beads having an average diameter of 1 to 4 willows, and a matrix of a binder phase consisting of hydraulic cement, a surfactant and an air-entraining synergist, and air. Mixture: and second lightweight aggregate,
Preferably, the expanded copolymer styrene beads have a preferred average diameter of 8 to 18 willow. The ratio of smaller diameter beads/larger diameter beads is 0.
26 to 2.4, preferably 1.2 to 1.8/first of low density concrete compositions. The present invention will be explained by the following examples, but the scope thereof is not limited in any way.

Example 1 In a mixer, there is a 30.
0k9/O densely foamed DYLITE (DYL)
ITE) F-6 polystyrene beads 1.6 times, 3.1
9 k of drinking water and 60 k of Drj-ResN, surfactant were added.

40 to 5 yen per minute. p. m. Mixing continued at speed S.

Next, add 5.70 kg (3.35 kg) to the above mixture.
Type Bortland cement was added. Mix about 3 inkstone sand,
He continued again. The matrix mixture is then treated with 10~
1.1 DiLite KFP524 expanded copolymer polystyrene beads having a mean diameter of 16 mm and a density of 4.0 kg were added. Mixing was continued for an additional minute to obtain a uniform suspension of large beads. The wet cement mix was poured from the mixer into shaped billets and cured according to standard conditions and procedures. This formulation is 360k9' wet (
wet) density, but could be taken out and handled after curing for one day. The strength of the formed block cast product after one night was 3.5k9/m. After approximately 5 additional months of external curing, the compressive strength increased to 5.5k9'. Table 1
presents comparative data of the novel low density concrete composition of the present invention and several low density concretes with lightweight ribs in impact attenuation and energy absorption. The suitability of concrete for use as an impact attenuator is related to its energy absorption capacity and its attenuation index. Average Absorbed Energy is a measure of the energy absorbed by a 10-2 cylinder test cylinder that is impacted by a mass attached to a pendulum arm and spring. The relationship between impact energy and absorbed energy is given by: (However, the impact energy is constant and is 3413k9 one arc.) Ei = Es 1 Eb + Er + Ea (However, Ei = Input kinetic energy Es = Energy absorbed by the spring Eb = Energy absorbed by bending the pendulum arm Er = Repulsion Energy Ea = Energy absorbed by the test specimen Desired impact damping materials have very high E even with a minimum *Er in order to minimize the energy available to transfer back to the crashing vehicle.
It should have a.

Another useful variable is the damping index, which describes the material's deceleration ability and absorbed energy measured at its peak value (Ta's), which is calculated by plotting the density against its peak deceleration (Ta's). The relationship between Table 1 The data in Table 1 for concrete specimens of perlite, foam, vermiculite, and Dycon concrete are provided by J. D. Report by BECOS, JS expert “Development of low-density concrete impact attenuator” OD
Quoted from Tables 5 and 6 on page 105 of OT Report No. 23-73, July 1974.

Data for a new low density concrete with two lightweight bone structures were obtained according to the test procedures used in ODOT Report No. 23-73, according to J. D. Obtained by Bekos, J Tsuji Gunshi. Table-1 shows that low density concrete with two lightweight aggregate phases has the first best Er with the third best Ea and foam specimens. It also has a good attenuation index. ODOT Report No. 23-73 shows some drawbacks (fla ship) to low density concrete with better Ea value than low density concrete of this invention, so low density concrete of this invention can be used as highway crash barrier. and for use in shock attenuators. Example 2 Two lightweight aggregate phase low density concretes of the present invention (hereinafter referred to as D
4) is Youngstown State University (Yo Sarabukuro Sto)
Tested with a scale model crash barrier by Dr. Ginbekos at wnState University.

The results of these tests were published in the “Scale Model Study of Low Density Concrete Impact Attenuators, Final Report (Scale Mode
l Study of Low DensityCon
Cre, Impactat, nuabrs, FjMI
Report)''J. ○． January 1977 U.S. Department of Transportation, Federal Highway Administration, Bureau of Public Highways
This has been reported to the Ono-Io Transport Bureau, which is in cooperation with the au of public Roa ship. In these tests, two experiments were conducted on low density concrete of the invention made in a manner similar to that shown in Example 1. This concrete was mixed at a water/cement ratio of 0.46. It's 320-352k9' that wet density and 280-3
It had a cure density of 12k9/m and a compressive strength in the range of 5.5-5.6 kg'. The crush barrier for these experiments had a honeycomb design with a wall thickness of 5.6 mm. The first experiment was 0. It was carried out with a scale model car made to resemble a mochi car, which collided with a crash barrier. The second experiment was conducted using a scale model vehicle that resembled a railcar. 0.9 car test average evening force
was higher than the allowable 12#'s, which means that the barrier is 0. $ It showed that it was somewhat too stiff to stop the car safely.

However, the results of tests conducted on two cars were
ycon) The results are identical to those obtained with crush barriers made from concrete. The conclusion from these tests was that D4 concrete cannot be fully recommended due to the limited test data available.

Two impact tests performed on the D4 concrete model showed that this concrete had potential and warranted further consideration. One reason why the impact test results for D4 concrete were lower than expected was that the scale model crash barrier wall thickness 5.6 skin did not take into account the unscaled shape of the polymer particles in D4 concrete. It is. 5.6
The wall thickness of the canal is actually smaller than the average diameter of the large expanded copolymer polystyrene beads (9.5 to 15 mm).

These scale model tests are not to scale, and the D4
Concrete was definitely used. Therefore, because the scale model tests did not use the scale mix of D4 concrete, the scale model tests for D4 are inconclusive and do not demonstrate the benefits of D4 concrete in impact attenuators and energy absorbers. Above, we have described a new concrete that can be used as a low-density concrete impact attenuator.

low density and crushability of the product
ty) provides a composition that is capable of dissipating substantially all of the energy of an impact vehicle by plastic deformation of the composition itself, leaving behind rebound energy that serves to deflect the impact vehicle.
A particularly desirable feature of the present invention is that the low density concrete composition can be scaled as a crash barrier in highway locations using one of two methods. The mold can be placed in the field and the low density concrete composition can be formed in situ at the field. Precast modular concrete may also be formed, cured, and then transported to the site of use for installation. On-site molding (
For cast-in-place concrete impact attenuators, the material crushed by the impact can be removed and that portion of the impact attenuator rebuilt with a new low density concrete composition. The novel low density concrete compositions of this invention are far-cured compositions that overcome the problems of cure time and poor green strength seen when other low density concrete compositions are used as impact attenuators. ASTM G-355
3.3 measured by drycup
A low water vapor permeability of PE-inches and a low water absorption of 0.16 as measured by ASTM C-1272 at two specific immersions of the low density concrete composition of the present invention for use in highway impact attenuation devices. Demonstrate increased aptitude for. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view of the surface of a low density concrete of the invention containing two lightweight aggregate phases.

Figure 1

Claims (1)

[Claims] 1 Ia 16-160 kg/m^3 bulk density and 1-4
A first lightweight aggregate phase of expanded polymer particles with an average diameter of mm...16-48% absolute volume based on 1 m^3 of the total low-density concrete composition, b(i) - 13.5-48% based on binder Hydraulic cement containing entrained air in an amount ranging from 60% by volume...16 to 48% by absolute volume based on 1 m^3 of total low density concrete composition, (ii) surfactants...
0 based on 1 m^3 of total low density concrete composition
．． 001 to 0.4 absolute volume %, and (iii) water...3 to 14 based on 1 m^3 of the total low density concrete composition.
Absolute volume %, a binder consisting of (b(i) + b(ii) + b
(iii))...Matrix mixture consisting of 19 to 62.4% absolute volume based on 1m^3 of the total low density concrete composition...40% to 80% absolute volume based on 1m^3 of the total low density concrete composition % absolute volume, and II bulk density 4 to 6.4 kg/m^3 and an average diameter substantially greater than 4 mm, the first lightweight bone being greater than the average diameter of the expanded polymer particles in the first lightweight aggregate phase. Foams having an average diameter in which the absolute volume ratio of material/secondary lightweight aggregate ranges from 0.26 to 2.4, such that the smaller average diameter particles together with the binder phase fill the interstices between the larger average diameter particles. A low density concrete composition for impact damping or energy absorption comprising a second lightweight aggregate phase of polymer particles...20-60% by absolute volume based on 1 m^3 of the total low density concrete composition. 2. The expanded polymer particles of both the first and second lightweight aggregates are polystyrene, polyethylene, polyvinyl chloride, polyacrylonitrile, polyacrylates, polymethacrylates, copolymers of styrene with comonomers such as butadiene or acrylonitrile, or The composition of claim 1 selected from the group consisting of phenol formaldehyde condensation products. 3. The composition of claim 1, wherein the expanded polymer particles of the first lightweight aggregate phase are polystyrene. 4. The composition of claim 1, wherein the expanded polymer particles of the second lightweight aggregate phase are a polystyrene copolymer of styrene and acrylonitrile. 5 The average diameter of the expanded polymer particles of the second lightweight aggregate phase is 8
A composition according to claim 1 in which the diameter is in the range of -18 mm. 6 (a) A first lightweight aggregate phase of expanded polymer particles with an average diameter in the range 1-4 mm and a bulk density of 16-160 kg/m^3 under air-entraining conditions and hydraulic cement, water and surfactants. binder phase in a matrix mixture in an amount ranging from 40 to 80% by volume based on the low density concrete composition and 13.5% based on the binder phase.
(b) 4 mm
having a larger average diameter such that the particles of the first lightweight aggregate, together with the binder phase, fill the interstices between the larger average diameter particles of the second lightweight aggregate phase, and from 4 to 6.4
25% by volume of a second lightweight aggregate phase of expanded polymer particles with a bulk density of kg/m^3 based on the matrix mixture.
-150% by volume is added to the uniform matrix mixture to form a curable composition, (c
160-800 kg, comprising: (d) molding and molding the curable composition and then (d) curing the molded curable composition to produce a low density concrete useful for energy absorption and impact attenuation. A method for producing low density concrete for impact damping or energy absorption having a dry density of /m^3. 7 The expanded polymer particles of the first and second lightweight aggregate phases are polystyrene, polyethylene, polyvinyl chloride, polyacrylonitrile, polyacrylic esters, polymethacrylic esters, copolymers of styrene with comonomers of butadiene or acrylonitrile, or phenol formaldehyde. 7. The manufacturing method according to claim 6, which is selected from the group consisting of condensation products. 8. The method of claim 6, wherein the expanded polymer particles of the first lightweight aggregate phase are polystyrene. 9. The method of claim 6, wherein the expanded polymer particles of the second lightweight aggregate phase are a polysterene copolymer of styrene and acrylonitrile. 10. The method of claim 6, wherein the average diameter of the expanded polymer particles of the second lightweight aggregate phase is in the range of 8 to 18 mm. 11 (a) A first lightweight aggregate phase of expanded polymer particles with an average diameter ranging from 1 to 4 mm and a bulk density of 16 to 160 kg/m^3 under air entrainment conditions and hydraulic cement, water, surfactants. and a binder phase of an air-entraining synergist in a matrix mixture in an amount ranging from 40 to 80% by volume, based on the low density concrete composition, and in an amount from 13.5 to 60% by volume, based on the binder phase. (b) an average diameter in the range of 8 to 18 mm and 4 to 6 mm;
．． 20 of foam beads of polystyrene copolymer of styrene and acrylonitrile with bulk density of 4 kg/m^3
-60% by volume (based on the low density concrete composition) is added to the uniform matrix mixture to form a moldable, hardenable composition; (c) moldable, hardenable composition; forming the article into a shape suitable for a highway crash barrier, and then (d) curing the shaped curable composition to produce a low density concrete composition for a highway crash barrier, 8
A method for producing low density concrete for highway crash barriers by impact attenuation or energy absorption having a dry density of 00 kg/m^3. 12 (a) Under air-entraining conditions, the following components: 267-800 l of polystyrene beads per m^3 of low-density concrete; 336-100 l per m^3 of low-density concrete;
7 kg of hydraulic cement; 10.6-3390 g of surfactant per 1 m^3 of low-density concrete; 2-800 g of air-entraining synergist per 1 m^3 of low-density concrete; and 30-140 l per 1 m^3 of low-density concrete. Water of,
40-80% by volume of the low density composition by mixing
12. A method according to claim 11, wherein the matrix mixture is produced in an amount in the range of . 13 consisting of a lightweight aggregate phase of closed-cell, porous foamed polymer particles and a binder phase of hydraulic cement, surfactant and water, where one bag of cement (42.6 kg) vs. 28.3
13.5 to 60% when the mixing ratio of 1 polymer particles is in the range of 1:2 to 1:8 and the binder phase is 100% by volume.
240-8, comprising entrained air in an amount of % by volume.
In low-density concrete for impact attenuators and energy absorbers having a kiln-dried density of 00 kg/m^3, the lightweight aggregate phase (a) has an average diameter of 1 to 4 mm;
(b) foamed polymer particles being a first lightweight aggregate phase having a bulk density of 0 kg/m^3 and (b) having an average diameter in the range of 8 to 18 mm and a bulk density of 4 to 6.4 kg/m^3; and a second lightweight aggregate phase of expanded polymer particles having an absolute volume ratio of expanded polymer particles of the first lightweight aggregate to expanded polymer particles of the second lightweight aggregate of 0.26 to 2.4. Improved low density concrete for impact attenuators and energy absorbers. 14 By volume % of concrete (a) 16-48 volume % polystyrene beads with an average diameter in the range 1-4 mm and a bulk density of 16-160 kg/m^3 (b) Hydraulic cement 16-48 volume % (c ) Surfactant 0.001-0.4% by volume (d) 8-
Average diameter ranging from 18 mm and 4.0 to 6.4 kg/
Polystyrene copolymer of styrene and acrylonitrile with a density of m^3 20-60% by volume (e) air 1
3.5 to 60% by volume (however, cement, surfactant,
(based on the binder phase of the air entrainment synergist), consisting of 1
Low density concrete useful for impact damping and energy absorption with a dry density of 60-800 kg/m^3.