FR2635320A1 - QUICK-TENSILE CONCRETE COMPOSITIONS FOR COATING CONCRETE - Google Patents

Abstract

A cementitious composition comprising: cement, an adjuvant which is or contains a copolymer of a polycarboxylate and a rapid setting agent or accelerator.

Description

CC: QUICK-TICKET E-OCN POSITICNS FOR BETCN

COATING

  The invention comprises compositions and

  ceded manufacturing and acclicatlon of quick-setting concrete.

  Concrete is able to maintain its fluidity during a

  luncue period and then take quickly.

  The quick-setting compositions of this invention

  apply in particular to the construction by coating.

  Coating is a process in which concrete is applied to a surface (eg a tunnel or subterranean cavern). There are two main types of coating construction processes which are:

1. Projection of concrete.

  This can be achieved by means of an ob-

  held by dry blending (dry blending system) or

  obtained by wet mixing (the system by wet mixing).

a) Dry mixing system

  The dry mixing system is a system in the

  dry mixed concrete is conveyed by compressed air.

  through a distribution hose and is applied by pressure blasting from the nozzle, water and a

041 FR

  quick setting agent being added upstream of the. nozzle just before passing through the nozzle. With this system, it is

  difficult to regulate the amount of water added and consequently

  to control the water-cement ratio (hereinafter referred to as E / C ratio). In addition, there is a loss of dust, which is a disadvantage. Alternatively, the rapid setting agent may be introduced at the mixing point at

  instead of being in the vicinity of the nozzle.

  b Wet mixing system Wet mixing system is a system in which concrete is mixed in the presence of water and is conveyed by compressed air through a distribution hose to a nozzle and is then sprayed from the nozzle , a quick setting agent being introduced upstream of the nozzle just before passing through the nozzle. There are also examples of this system where the bee can be pumped, rather than conveyed by compressed air, to a point midway between the mixing point and the nozzle in the distribution hose, followed by

  of a transport: pneumatic between this median point and the nozzle.

  The system ensures good control of the E / C ratio and produces

little dust.

  2. Injection Method This is also known as a pressure bond. The concrete is mixed and is then pumped (not conveyed by compressed air) to a nozzle through a hose, the quick setting agent being introduced upstream of the nozzle just before passing through the nozzle. The concrete is then poured into a formwork on. an excavated surface. The concrete is very fluid (about 18 cm in terms of subsidence) after

  poured into the formwork until shortly before hardening

  in other words, for several minutes after addition of the fast setting agent. This long setting time may be a disadvantage, because to increase the efficiency we would like to be able to remove the formwork envelopes as quickly as possible for the following operation and before being able to

  make, the concrete should have hardened in 3 to 5 minutes until

  to dye a resistance 2 the compression of at least 1cm2.

  dye a compressive strength of at least l lcm

  According to the invention, there is provided a

  cement-based composition for eg coating construction, comprising:

  a) cement and, preferably, a granulate (hereinafter

after by component a)

  b) an adjuvant which is or contains a copolymer of a polycarbonate;

  xylate (the adjuvant is hereinafter referred to as component b) and

  (c) a quick setting agent or accelerator (hereinafter

after by component c).

  There is further provided in accordance with the invention a method of making and applying a cementitious composition comprising: a) mixing components a) and b), preferably in the presence of water;

  b) transferring the mixture to a nozzle for ejection

  mixture c) to introduce the component c) upstream of the nozzle before passing the mixture through the nozzle and,

  d) expelling the mixture through the nozzle for the purpose of

  plication of the mixture on the surface to be coated.

  Component a) is preferably concrete. This happiness

  may contain a high proportion of fine aggregate (eg sand) in the total amount of aggregate. In component a), the cement employed is preferably Portland cement and the granulate whose presence is desirable is a fine aggregate, preferably sand having an average particle size of less than 5 mm. The granulate, when present, may also include a coarse aggregate having a particle size of about 15 mm. The quantity of granulate is preferably between 50 and 400% by weight per

compared to cement.

  The copolymer of component b) is preferably a) a water-soluble copolymer of an olefin and a dicarboxylic acid, f-unsaturated, b) a water-soluble copolymer of an ester of a monoaryl

  polyethylene glycol ether with maleic acid and,

  culturally, monomers capable of copolymerizing with said ester c) i a water-soluble copolymer of isobutylene-styrene and maleic acid,

  d) a water-soluble copolymer of isobutylene-acrylic ester

  and maleic acid, e) a water-soluble copolymer of isobutylene-styrene-acrylic ester and maleic acid and

  f) a water-soluble salt of a copolymer derived from a mono-

  polyalkylene glycol acrylate or a monomethacrylate of

  polyalkylene glycol and acrylic acid or methacrylate

  league, facetiously with a monomer capable of being copo-

lymérisé with this one.

  Examples of monomers likely to be

  po'lvmyrt are esters of aliphatic alcohols in C1 to

  C20 and methacrylic acid or acrylic acid; metha

  crylamide or acrylamide, maleic acid or

  marlcue or their mono-cu diz-rsav-esavc sla.lccls in Cà

  C 2 -C 4 alkylene glycols or polyalkylene glycols;

  C.sub.1 -C.sub.4, C.sub.4 -C.sub.4 alkenyl acetates (e.g.

2 4 '2 6

  vinyl acetate and propenyl acetate); vinyl aromatic compounds (eg styrene, p-methylstyrene, styrenesulphonate) or vinyl halides (e.g.

vinyl chloride).

  It is preferable that the copolymer derives from a

  C2-C4 polyalkylene glycol methacrylate or mono-

  C2 to C4 polyalkylene glycol acrylate and acrylic acid or methacrylic acid, optionally neutralized with an alkali. The copolymer is more preferably derived from a) a monomer of formula I CH 2 = C (R 1) -COLO (R 2 -O) n -R 3 (I); and b) a monomer of formula II

CH = C (R) -COOX (II)

2 1

  wherein each R is, independently, hydrogen or methyl; R2 is a C2 to C4 alkylene R3 is hydrogen or a C1 to C6 alkyl n is an integer from 1 to 100 inclusive and

  X is hydrogen, a monovalent metal or an equiva-

  slow of a divalent metal, an ammonium or an amine group.

  The copolymer of component b) preferably has a molecular weight of 23,000 to 27,000.

  The dosages of the component b) employed are preferably

  at least 0.01%, more preferably 0.01% to 0.5% based on the weight of the cement, and more preferably in the range of 0.03 to 0.2%. What is known as "super-fast accelerator effect" becomes more important as dosage increases, but when dosages are used

  exceeding the upper limit of 0.5%, the efficiency

  and a new additio devi: ent thus uneconomic.

  "The accelerator" (component c) is as defined

  pages 106-7, 548 of V.S. Concrete Admixtures Handbook

  Ramachandran 1984 Noyes Publications whose content is in-

corporately for reference.

  "Fast setting agent" (component c) is defined

  in JIS A 0203, "Concrete Terminology", as "a chemical mixture

  to accelerate the cement hydration reaction

  and to markedly shorten the setting time of the cement ".

Typical examples include:

  a) inorganic salts (solid or liquid) composed of aluminum

  alkaline miners and alkali carbonates or mixtures thereof, b) cement minerals and c) natural minerals (eg aluminates, glass

  soluble and calcium sulfoaluminate).

  As quick-drying agents based on inorganic salts

  Examples include fast setting agents comprising a

  aluminate and / or carbonate. Fast-setting agents to-

  natural mineral base include calcined alunite

  to which carbonates and / or aluminates have been added.

  Fast setting agents based on cementitious cement minerals

  take cementitious materials composed of calcium aluminates such as CaO.A1203, 12CaO.7A1203, CaO.2A1 203, 11CaO.7A1203 CaF2 and 3CaO. 3A1203 CaF2 amorphous forms of these minerals and may also include additional gypsum and / or quick-setting agents based on

inorganic seis.

  The calcined alunite is obtained by calcining the alunite at a very high temperature below its melting point. Alunite (or alum stone) is a mineral based on aluminum sulfate and potassium hydrate

  which served as a source of potassium carbonate and alumina.

  The alunite is KAi3 (SO4) 2 (H) 6 having a hardness of 3.5 to 4 at

the Mohs scale.

  The amount or dosage of the component c) used may be expressed in percentages by weight relative to the weight of the cement in the cementitious composition. These are a) approximately 2-8% (solid or liquid product)

  in the case of fast setting agents based on inorganic salts

  (b) approximately 5 to 10% in the case of cementitious mineral quick setting agents and (c) approximately 4 to 10% in the case of

  quick setting based on natural minerals.

  Since fast setting agents are expensive,

  compared to cement, sand and gravel (the main

  materials used in concrete which is the cement composition

  preferred) and that the dosage of the quick-setting agent

  necessary to obtain a super-fast accelerating effect op-

  timal is generally stronger than for chemical mixtures

  This is an important factor for the evaluation of

  the cost of a coating concrete. It is therefore

  desirable to obtain the super-fast accelerator effect required

  - with a dosage as low as possible.

  Furthermore, with the wet mixing concrete spraying method, the super-fast accelerator effect is lower than with the dry blast process. One of the reasons for this is that the cement particles are in contact with the water long before they come into contact with the quick-setting agent and so a thin layer of cement particles is formed on the surface. initial hydration product film that prevents contact between cement particles

  and the quick setting agent. In the case of a system of pro-

  jection of concrete by wet mixing, the consistency of the concrete

  must be made fluid enough so that it can be easily

  transferred through the distribution hose to the nozzle and it is therefore inevitable that the E / C ratio is high. Since, however, the W / C ratio is higher in the case of the wet-blast process than in the dry-blast process (the dry mix concrete blasting method requires

  E / C ratio of about 0.45: 1, whereas for the process of

  In the wet state it is 0.55: 1 or more

  high) and that the super-fast accelerating effect decreases

  As the I / C ratio increases, the fast setting effect is very negatively influenced in the wet blending process. This applies to the consistency of the concrete used in an injection molding process

  or pressure bonding to ensure good flow

  when the concrete is poured into formwork.

  The use of component b) in a concrete to be mixed before the addition of a rapid setting agent has made it possible to increase the super-fast accelerating effect of the agent

  quick setting in concrete without reducing the fluidity of

  intended for use as a coating concrete, in which case the concrete is kneaded before the subsequent addition of the setting agent and is then applied to the excavated surface

  tunnel or underground cavern.

  Using the method according to the invention in a wet mixing concrete spraying operation, there is a marked improvement in the super accelerating property.

  rapid shotcrete while maintaining the fluidity of the concrete.

  your. It is therefore possible to reduce the dosage of

  the quick set agent to obtain a high accelerating effect

  same fast per comparison compared to that required in a conventional wet mixing projection process. In addition, since the super-fast accelerating property is improved, there is a decrease in the material rebound (proportion of material falling off when spraying on a surface) in the concrete spraying process, which is an advantage. very positive economic. In addition, the production of concrete coatings by a process

  injection or pressure connection, it is possible to increase

  Maintain productivity by shortening the time required for the setting before adding the quick-setting agent while maintaining the fluidity of the concrete. This is of great importance.

  The invention will now be illustrated by the

following jobs.

Examples 1 and 2

  The concrete of the examples is prepared in the proportions

  indicated in the table to form a coating concrete.

  is lying. (1) Concrete Ingredients: (a) Cement: A mixture of ordinary Portland cements in equal amounts

  Onoda, Mitsubishi and Sumitomo.

  b) Coarse aggregate: Crushed stone Ohme graywacke (density 2.64, absorption

  0.67%, m.p. = 6.35, maximum size 15 mm).

  c) Fine aggregate: a mixture of equal amounts of Sand-Oi River System

and Chiba sand pit sand.

  d) Adjuvant: a) Polycarboxylic acid Calcium salt of the copolymer of a monomethacrylate

  of C2 to C4 polyalkylene glycol and methacrylate

  lique (designated "A": manufactured by Nisso Master

Builders Co., Ltd.).

  bi Lignosulfonate Name of the specialty: Pozzolith n 8 (designated "B": manufactured by Nisso Master Builders Co., Ltd.) c) Oxycarboxylate

  Sodium gluconate (referred to as "C" ')

  d) Condensation product of naphthalene sulfone-formaldehyde

  Name of specialty: Mighty 150 (referred to as "D",

broken by Kao Soap Co., Ltd.).

  e) Sulphonated melamine condensation product for, aidedhyde.

  Name of the specialty: NL-4000 (designated by "E":

  manufactured by Nisso Master Builders Co., Ltd.).

  f) Rapid setting agent based on inorganic salt powder

  Name of the specialty: QP-500 (referred to as "F"):

  bribed by Nisso Master Builders Co., Ltd.) (g) Cement Mineral Quick Setting Agent,

  name of the specialty: QP-55 (referred to as "G"):

  manufactured by Nisso Master Builders Co., Ltd.) The strengths of all adjuvants are the usual dosages recommended by the manufacturers and are expressed in

  percentage by weight relative to the cement.

  Table 1 Proportions of mixing N-test concrete Example of adjuvant, Fast setting agent Quantity (kg / m3) Type Determination Type Determination Cimont Water Granulate Fine coarse aggregate 1 Example 1 A 0.12 F 3 360 176 1058 705

2 I - - F 3 360 200 1047 698

3 II B 0750 F 3 360 176 1058 705

4 III C 0) 20 F 3 360 176 1058 705

IV D 0) 45 F 3 360 176. 1058 705

6 V E 0.50 F 3 360 1; 6 1058 705

  7 Example 2 A 0 12 G 6 360 1/6 1058 705

8 VI - - G 6 360 200) 1047 698

9 VII B 0150 G 6 360 1/6 1058 705

VIII C 0 20 G 6 360 176 1058 705

11 IX D 0.45.G 6 360 176 1058 705

  12 X E 0.50 G 6 360 176 1058 705 o LM Ul o to C, 1: In Table 1 above, Examples 1 and 2

  illustrate the invention and Examples I to X are comparative.

  After mixing the cement, water, fine granulate, coarse aggregate and, if appropriate, adjuvant A to E, the resulting mortar, obtained by separating the mortar and coarse aggregate using a 5 mm sieve. The quick setting agent is added and mixed by hand for 20 seconds. The initial setting time (the time required to achieve a penetration resistance of 35 kg / cm 2 according to the "concrete setting time test" method) is measured for each mortar. The setting time is considered here as the time (minutes and seconds) from the addition of the agent of

quick decision.

  Test results The test results in the case of the use of the fast setting agent F are those shown in Table 2 and the test results in the case of the use of the agent

  rapid setting G are those shown in Table 3.

Table 2

  Curing time measurement results (fast setting agent F) N of test N of example Initial setting time (min-sec) 1 1 13 min 40 sec 2 I more than 20 min 3 II more than 20 min 4 III more than 20 min IV more than 20 min 6 V 17 min 20 sec! 2 ableau Curing time measurement results (fast setting agent G) N, test N of exeMple Initial setting time (min-sec) 7 2 less than 1 min 8 VI 3 min 30 sec 9 VII 4 min 20 sec VIII more than 20 min il IX 4 min 12 X 3 min 10 sec

  Where the fast setting agent used is F, the

  Tier ccnfected in the absence of any of the adjuvants AE cu with any of these other comparative admixtures B to E do not set the initial intake in the escace of 17 minutes, but using the adjuvant-based polycarboxylate (A),

  the initial shot is reached in 13 minutes and 40 seconds.

  Where the rapid setting agent used is G and the adjuvant is the polycarboxylate (A), the initial setting is reached within 1 minute, whereas none of the other comparative tests show an initial below 3 minutes. This illustrates that setting time is greatly shortened by using A rather than B to E with

the same quick-setting agent.

  The degree to which the fluidity of the concrete is maintained (before addition of the agent) is also shown.

fast setting).

  The materials used in the tests and the

  concrete mixing portions are the same as those indicated

  Table 1 of Example 1 and Comparative Examples I, IV and V. In addition, the adjuvants employed in these tests are the polycarboxylate (A), the naphthalene sulfonated-formaldehyde condensation product (D) and the

  sulphonated melamine-formaldehyde condensation product (E).

  After mixing the cement, water, granulate and adjuvant with a rocking mixer,

  all the concrete and measure sagging. We give the baby

  tone in the mixer while continuing the rotation of the

  langer at low speed (2 rpm) for the required time.

  The subsidence is measured after 30 minutes and 60 minutes.

  Results of the tests The results of the tests are given in Table 4

Table 4

  Results of Concrete N Loss Loss Test N of Example Example Adjuvant Sag (cm) (Table i) Tvpe Assay Immediate After After min 60 min

13 1 A 0.12 13.5 10.0 8.5

* 14 I - - 14.0 9.0 7.5

iV D 0.45 13.5 8.0 6.0

16 V E 0.50 14.0 6.5 5.0

  Table 4 shows that subsidence of concrete

  using the polycarboxylate A adjuvant is not

  compared to others, even after a long period of time. In the comparative example using the adjuvant E, it can be noted that the setting time is relatively fast but that the variation of sagging as a function of time is

  significant (reaching less than 5 cm after 60 minutes).

RE EVZICANS

  A cementitious composition comprising a) cement (hereinafter referred to as component a); b) an adjuvant which is or contains a copolymer of a polycarboxylate (the adjuvant being hereinafter referred to as component b) and

  (c) a quick setting agent or accelerator

signed below by component c).

  2. A composition according to claim 1 in

  I which component a) is concrete.

  3. A composition according to claim 1 or 2 in which component b) is a) a water-soluble concylmer of an olefin and an,-unsaturated dicarboxylic acid, a water-soluble copolymer of an ester of a monoaryl

  polyethylene glycol ether with maleic acid and,

  cultally, monomers capable of copolymerizing with said ester; c) a water-soluble copolymer of isobutylene-styrene and 2C of maleic acid,

  d) a water-soluble copolymer of isobutylene-acrylic ester

  and maleic acid, e) a water-soluble copolymer of isobutylene-styrene-acrylic ester and maleic acid and

  f) a water-soluble salt of a copolymer derived from a mono-

  polyalkylene glycol acrylate or a monomethacrylate of

  polyalkylene glycol and acrylic acid or methacrylate

  optionally with a monomer capable of being copoly-

lymérisé with this one.

  4. A composition according to any one of the

  in which component b) is constituted by the copolymer derived from a monomethacrylate of

  C2-C4 polyalkylene glycol or a polyalkyl monoacrylate

  alkylene glycol and acrylic acid or methacrylic acid

  crylic, optionally neutralized with alkali.

  5. A composition according to any of the

  Claims 1 to 3, in which component b) consists of a copolymer derived from a) a monomer of formula I ## STR1 ## of formula II

CH2 = C (R1) -COOX (II)

  wherein each R 1 is, independently, hydrogen or methyl; R2 is C2-C4 alkylene; R3 is hydrogen or C1-C6 alkyl; n is an integer from 1 to 100 inclusive and

  X is hydrogen, a monovalent metal or a scavenger

  are worth of a divalent metal, an ammonium or an amine group.

  6. A composition according to any of the

  preceding vendlcations in which the copolymer of the com-

  positing b) has a molecular weight of 23,000 to 27,000.

* 7. A composition according to any one of the

  previous sales in which the amount of

  (b) employed is at least 0,01%, by weight

cement.

  8. A composition according to claim 7 wherein the amount of component b) employed is 0.01 to 0.5%.

  9. A composition according to any of the

  in which component c) is selected from a) mineral salts (solid or liquid) comprising

  alkali aluminates and alkali carbonates or their metals

  (b) cementitious minerals and

(c) natural minerals.

  10. A composition according to any of the

  previous sales in which the amount of

  (c) the employee is 2 to 10% of the weight of

dry.

  11. A process for the manufacture and application

  of a cementitious composition according to any one of the

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