DE1646883C - Artificial aggregates for concrete, in particular for concrete for biological radiation protection - Google Patents

Description

The invention concerns kün ilicha aggregates for the production of structures, in particular made of concrete for biological radiation protection made of cement-bound solids in the form of pourable Grits.

Special requirements must be placed on concrete or on structures made of concrete when used in radiation protection technology Requirements are made. For example, it is used to slow down fast neutrons too take into account that the shielding effect depends essentially on the hydrogen content of the concrete, i.e. the content of chemically bound water in the concrete. Through the essay "Concrete in Radiation Protection Technology" by Thomas Jäger in Nuclear Energy 1958 are a series of special cements and aggregates for concretes became known. As special cements, cements of the oxychloride type are and oxysulfate cements have been investigated, which have a higher water content. These special cements but have proven to be unsatisfactory in terms of their durability. Steel punching waste and steel scrap are suggested as special aggregates for ordinary gravel concrete. Due to the low water content, however, this concrete is attenuated in terms of neutron radiation unfavorable.

Through the German patent specification 338 552 it has already become known to use broken concrete as an aggregate to use concrete. The broken concrete consists of concrete of the same quality as the one which it is now added as an aggregate, so that the properties of the finished concrete cannot be changed by this additive. As a further aggregate for radiation protection concrete come next to normal sand and gravel z. B. barite, magnesite, hematite, brown iron ore, ilmenite, ferrosilicon, Ferrophosphorus, heavy slag (chrome and lead slag) and substances containing boron, e.g. B. Borcabide and boride, in question.

The invention is based on the object of artificial aggregate for the production of construction bodies, in particular made of concrete, to create that have a high shedding effect against radioactive rays and are therefore suitable for biological radiation protection. The term “structure” includes not only those made of concrete, but also structures or components on another known basis, for example a plastic basis.

This object is achieved according to the invention in that the aggregates consist only of set cement of high strength.

Furthermore, the artificial aggregates can be used in addition to cement and chemically bound Water and other fine-grained, ground inorganic substances with a specific gravity of 4

O UÜWI glüOw VMtl> _a l «.n.

The artificial additives according to the invention for the production of structures have opposite the well-known shielding concrete has significant advantages. Through the use of cementitious Solids can be used as artificial additives with their content of chemically bound water the hydrogen content of the concrete compared to the usual concrete composition, if necessary by more than double, to achieve an optimal braking effect against fast neutrons to achieve.

In addition, corresponding investigations showed that concrete bodies containing these aggregates, a significantly increased flexural tensile and compressive strength compared to concrete bodies of usual composition.

Likewise, in addition to the main ingredients, the artificial additives can also contain a chemical one Compound and / or minerals of such elements

contain, which oesitzen a particularly effective capture cross-section for thermal neutrons. on In this way it is possible for the first time in an excellent manner to use the chemical compounds mentioned, e.g. B. Boron compounds, in the finest, very even distribution of the individual grains of artificial aggregates and thus to be expediently introduced in the entire irradiated cross section of the building, so as to to achieve a particularly intensive absorption effect against thermal neutrons. Through the different Material compositions of the artificial aggregates can be the building structure or the concrete can be optimally adapted to the type and intensity of the radiation to be shielded. Furthermore, through the use of artificial aggregates in the manufacture of concrete structures an important technical advance for radiation protection can be achieved in that ar Place of poorly workable, bulky, broken, heavy aggregates cement-bound Solid bodies as artificial aggregates with rounded grain shape and good processability occur.

Cement-bonded solids are generally those of great strength which are made from commercially available cement alone with the addition of water, and also those which in addition to cement as a binding agent also contain other fine-grained or finely ground substances, in particular such ' of high specific gravity. Oi 'cement-bound solid according to the invention are as washable, granular goods, preferably as rounded granules according to known procedures in graded grain sizes placed.

Concretes that are produced according to the known rules of concrete technology with the additives according to the invention advantageously have, under comparable conditions, a considerably higher flexural and compressive strength and concrete strength than ordinary concrete.

According to a preferred embodiment, the /.ementgebundenen body with a content of chemically bound water can only be from set cement in the form of pourable grains .

According to another embodiment, the / ementgebundenen solids other than cement and chemically bound water also contain other .körnige k 1ι, preferably milled, heavy inorganic ι s

nischc Stotte with a specific Uewtcht of ei ά a 4 and above.

According to a further embodiment, dv / ementbonden solids contain _e em according to the present - Hrfindung such chemical compounds and / ci.Wr minerals, such as. B. boron, have a large virKsamen capture cross-section for thermal innovations.

/ ur manufacture can use the artificial surcharge be treated with saturated steam or with pressurized steam, sometimes at 8 to 15 atmospheres.

Examples of the invention are presented and explained below.

The diagrams in FIG. 1 the measured attenuation factors for the shielding of a normal concrete N and a special concrete S ₅ depending on the thickness of the concrete slab, and / was for gamma radiation E = 0.662 MeV. The curves N and S _{5 of} the diagram apply to radiation including the scattered radiation and the curve of N ' and S ₅ for radiation without scattered radiation.

The diagrams of FIG. 2 show the attenuation factors for fast neutrons, depending on the thickness of the concrete slab for normal concrete N and special concrete S ₅ and S ₀ .

For comparison, various vibrated concretes with the following composition were produced and tested:

Concrete B, special concrete

Aggregates: quartz powder 0 / 0.2 mm and grain sizes from fig. Cement of sizes 0.2 / 3.3 / 7 and 7/15 mm

Portland cement

Water, w / c = 0.55

Air pores, 1 percent by volume ο ·· «· ~» ™ · »μ π / η ">

Used grain

0.2 / 3

3/7

7/15

To To Ciewiciit Raumlei len in ¹ ) 380 0.121 209 0.209 0.010 175 0.066 504 0.224 358 0.159 475 0.211

2091

1,000

The hardened concrete contained around 165 to 170 kg / m ^{3 of} formerly used water.

The compressive strength was measured on three test cubes with an edge length of 20 cm and the flexural strength Determined on three bars measuring 70 χ 10 χ 15 cm, the mean value being:

40 special concrete B ..
Normal concrete A.

Compressive strength (kp / cmr ¹ )

7 I 2S days

90

490

355 '

603 463

645 489

Flexural strength (kp cm ² ;

28 days

95 61

Concrete A, normal concrete made of gravel sand, largest grain 15 mm

1 m ^{3 of} compacted fresh concrete, consisting of

45

To
Weight
(kg) To
Room sharing
(m ³ ) Portland cement
Water, w / c = 0.55
Air pores, for example
1 percent by volume
Sand 0 to 3 mn
Sand 3 to 7 mm
Gravel 7 to 15 rriTi 380
209
770
418
562 0.121
0.209
0.010
0.290
0.158
0.212 2339 1,000

Numerous measurements on concrete slabs measuring 40 40 χ 5 cm resulted in the extraordinarily good shielding effect against neutron and gamma radiation. Such slabs were made from normal concrete N with gravel as aggregate and from special concretes S with the existing artificial aggregate.

The following table contains the half-life layer thicknesses determined in tests in centimeters, The corresponding values for paraffin and lead are also given for comparison:

55

60

The hardened concrete contained about 65 to 70 kg / m ^{3 of} formerly used water.

N ....
S ₁ .... Neutron
shielding Gamma·
shielding
at 1.7 MeV 8.0 '
8.0 > Comparison S ₂ ....
S, .... cm cm 6.7
6.0 Normal concrete S ₄ .... 15.2
11.8 ■ 6.0 Special concretes 10.4
9.0 8.4 7.7
ι - At

Concrete / V, normal concrete made of gravel sand 1 m ^{3 of} compacted fresh concrete, consisting of

To
Weight
(kg) To
Room parts
(m ³ ) Portland cement
Water, w / c = 0.55
Air voids, 1.5 percent by volume
Sand, 0/3 mm
Sand, 3/7 mm
Sand, 7/15 mm 380
209
782
382
572 0.121
0.209
0.015
0.295
0.144
0.216 2325 1,000

Concrete S3, special concrete

Aggregates: gebr. Iron ore 0.2 / 3 mm and grains of set cement

The hardened concrete contained about 65 to 70 kg / m ^{3 of} formerly used water.

Concrete Sl, special concrete

Aggregates: quartz powder 0 / 0.2 mm and grain sizes from fig. cement

To To Gcwichl Room parts (kg) (m ³ ) Portland cement *) 400 0.127 Water. W / c = 0.45 180 0.180 Air pores, 1.5 volume percent . 0015 Used iron ore, 0/3 mm 1526 0.339 sp. Weight 4.50 Round grain, 3/7 mm 313 0.136 Round grain, 7/15 mm 468 0.203 2887 1,000

To
Weight
(kg) To
Room sharing
(m ³ ) Portland cement
Water, w / c = 0.55
Air pores, 1 percent by volume
Quartz flour, 0 / 0.2
Browned grain, 0.2 / 3
Round grit, 3/7
Round grit, 7/15 380
209
175
510
400
530 0.121
0.209
0.010
0.066
0.211
0.165
0.218 2204 1,000

*) 2% CaB ₆ counts.

The hardened concrete contained about 130 to 140 kg / m ^{3 of} formerly used water.

The hardened concrete contained around 165 to 170 kg / m ^{3 of} formerly used water.

Concrete S 2, special concrete

Aggregates: gebr. Iron ore0 / 3 mm and grains from fig. cement

1 m ^{3 of} compacted fresh concrete, consisting of concrete S4, special concrete

Aggregates: Gebr. Eisenerz 0.2 / 3 mm and grain sizes of 2 parts by weight cement + 1 weight partially ground iron ore, 3/7 and 7/15 mm

1 m ^{3 of} compacted fresh concrete, consisting of

To To Weight Room sharing (kg) (m ³ ) Portland cement *) 350 0.111 Water, w / c = 0.50 175 0.175 Air pores, 1.5 volume percent - 0.015 Used iron ore, 0/3 mm 1318 0.293 sp. Weight 4.50 Round grit, 3/7 403 0.175 Round grit, 7/15 531 0.231 2777 1,000

Portland cement *) ... Water, w / c = 0.50. Air pores, 1.5 volume percent

Geor. Iron ore, 0.2 / 3 mm

Cement + ore grain

3/7

7/15

To

Room sharing (πι ¹ !

0.127 0.200

0.015 0.329 sp. Weight 4.5

0.132 0.197

1,000

• *) 1% tetraboric _{carbide (B 4} C) ground.

The hardened concrete contained about 135 to 140 kg / m ^J formerly born water.

*) 2% CaB ₆ ground.

The hardened concrete contained about 11 5 to 1 20 kg / formerly used water.

Concrete S5 and S 6. Special concrete

Aggregates: 0 / 1.5 and 1.5 / 3 mm used Iron ore and grains of 2 parts by weight of cement + 1 part by weight ground iron ore, 3/7 and 7/15 mm

Portland cement *)
Water, w / c = 0.50 ..
Air voids, 1.5 percent by volume

Eisenerz
0 / 1.5 mm

1.5 / 3 mm

400 200

792

475

0.127 0.200

0.015

0.165 sp. Weight 4.8

0.099 sp. Weight 4.8

*) In concrete S 5: 1% CaB ,, in cement as a binding agent.

To
Room sharing

Cement + ore grain

7/15 **)

, 000

* ·) In concrete i '6: 1% CaB ₆ in the cement as a binding agent, and also in the cement content of grain sizes 3/7 and 7/15.

The hardened concrete contained about 115 to 120 kg / nr formerly born water.

Due to the excellent shielding shafts are components, especially made of concrete which keep the present artificial aggregate ent, well suited to reactors, linear accelerators niger, betatrons, cobalt and cesium sources ii of radiation therapy, X-rays, etc. shield.

1 sheet of drawings

709636 /

Claims (3)

i 646 883 claims: 1. Artificial aggregates for the manufacture of structures, in particular made of concrete for the door biological radiation protection from cement-bound solids in the form of pourable Grains, characterized in that these only consist of tied High strength cement exist. 2. Artificial aggregates according to claim 1, characterized in that these except cement and chemically bound water still others fine grain. ground inorganic substances with a specific uewicni from t uuci giootj contain. 3. Artificial aggregates according to claim 1 or 2, characterized in that these in addition to the main constituents also include a chemical compound and / or minerals of such elements contain, which have a particularly effective capture cross-section for thermal neutrons.