FR2653794A1 - CONCRETE ADDITIVE FOR FLUSHING COMPACTED BY CYLINDRING. - Google Patents

Abstract

The additive composition for use in roll compacted pavement concretes comprises, as an active ingredient, a hydrolyzable derivative of tannin. This hydrolyzable derivative is chosen from the group consisting of: gallotannin (I), corilagin (II), chebulagic acid (III) and chebulinic acid (IV). Application to the making of concrete pavements which do not exhibit cracks after hardening.

Description

The subject of the present invention is concrete additives for

  pavements compacted by rolling. In particular, it relates to additives improving the properties of pavements in cement and in concrete compacted by rolling. A pavement compacted by rolling has recently been developed, which can use zero shrinkage concrete whose properties are significantly different from that of conventional concrete. In particular, it is necessary to considerably reduce the water content of the concrete and there is then a decrease in the settlement of the concrete in the period between the initial mixing of the raw material and the application of the concrete by

  following the evaporation of water due to the heat of the hydra-

  tation and heat from the sun, which reduces the strength of the concrete obtained and causes cracks in the hardened concrete. In particular, these defects are

  often encountered in concrete laid in summer.

  It should also be noted that the thickness of the layer of a roadway compacted by rolling cannot exceed

  cm, for reasons of difficulty in settling the concrete.

  When it is necessary to make a heavy roadway whose

  thickness exceeds 30 cm for reasons of heavy traffic, we must apply the installation process in two stages. It should be noted, in this case, a certain weakness of the adhesion between the layers. In the conventional process of making a pavement compacted by rolling, it is difficult to control the water content or the settlement of the concrete used in the

construction of this roadway.

  One of the aims of the present invention is to provide an additive composition to be used in concrete for pavements compacted by rolling, which makes it possible to control the heat of hydration and thus prevent the reduction in compaction of the concrete during the period between the initial mixture and the laying operation, especially for

  pavements compacted by rolling carried out in summer.

  Other objects, advantages and characteristics of the present invention will become more apparent when considering the

  detailed description which follows, made for non

  limiting and opposite the attached drawing, where the single figure represents chemical structures of typical examples of hydrolyzable derivatives of tannin used as active additives for concrete intended for making pavements

  compacted by rolling, according to the present invention.

  The inventors have studied the cracks in detail

  appeared during the laying of compact concrete pavements in summer

  ted by rolling and they then concluded that the hydra-

  The cement used is accelerated by the influence of the high ambient temperature which heats the concrete mixture, this reheating then leading to the cracks thus mentioned in hardened concrete. In fact, the temperature of the concrete was measured during the laying or the formation of the concrete roadway compacted by rolling and it was found

  that the rise in temperature over temperature

  The ambient temperature is around 20 ° C maximum and, a few days later, slots of 2 mm wide have been observed in hardened concrete (thus called "thermal cracks in concrete").

  The present invention is therefore based on these observations.

  tions. Conventional agents for retarding the hydration of the cement and reducing the water content of the cement have been used for concrete pavements compacted by rolling but, when the laying or forming of this pavement is carried out at an equal ambient temperature at around 30 C and when an excess quantity of the above-mentioned additives is added to obtain a greater delay in the hydration of the cement, the temperature of the concrete rises as much as for "concrete compacted by rolling" normal and rapid hydration occurs due to the inability to control the exothermic reaction [see

  pages 86 to 89, Cement Cijutu-Nenpou (Annual report), vol. 41].

  Next, the inventors studied different kinds of additives making it possible to avoid thermal cracks in hardened concrete and they observed that, when hydrolyzable tannin derivatives were added to the concrete mixture to be used for making pavements. in concrete compacted by rolling, they could be made with

good results.

  A hydrolyzable derivative of tannin used as a compound

  active in concrete during the formation of shoes

  sées compacted by rolling, according to the present invention is a derivative obtained by an ester bond of phenolic carboxylate and saccharide, the structures of some

  typical derivatives being shown in the single figure.

  A hydrolyzable derivative of tannin, used as an active additive for concrete in the formation or laying of concrete pavements compacted by rolling, according to the present invention, can include the following derivatives, the chemical structures of which are shown in the single figure: - gallotannin (I) - corilagin (II) - chébulagique acid (III) chébulinic acid (IV) It is also possible to use mgallotannic acid or

  digallic acid known as tannic acid.

  It is known that these derivatives can decompose easily in the presence of an acid or alkaline agent. These derivatives can give rise to the formation of gallic acid or ellagic acid and of saccharide by hydrolysis. These hydrolysates can significantly control the

  hydration speed of the cement and we can therefore control

  Also the heat of hydration of the cement.

  These additives selected in accordance with the present invention can be used in admixture with one another or with another mixing agent, or with another additive, to reduce the heat of hydration, for example a known agent for reducing the absorption of water, such as a lignin derivative, a formalin / naphthalenesulfonate condensate and known retarders or retarders, such as lignin derivatives, carboxylic acid derivatives, silicon fluoride. It is also possible to use a known wetting agent such as, for example, a nonionic surfactant such as polyoxyethylene-alkylallylether, a surfactant

  anionic such as alkyl sulfate, dialosulfosuccinate

  kyle and nonionic defoamers such as

  as propylene glycol / ethylene glycol block copolymers.

  The types of cements which can be used for the formation, application or laying of concrete pavements compacted by rolling, according to the present invention, can include ordinary cement, Portland cement type I, Portland cement with rapid setting (type III), Portland cement with moderate sulphate resistance (type II), Portland cement with low heating or hydration (type III) and Portland cement with low heat of hydration (type IV) (USA), [note that the terminology of these cement species depend on the state and industrial level of each country and, therefore, the cement to be used can include any type of cements which can be used for making pavements]; normal Portland cement (10), extremely fast setting Portland cement (30), blast furnace slag Portland cement (10S), moderate Portland cement (20), sulphate resistant Portland cement (can also be used) 50), moderate Portland cement (20) and low heat of hydration cement (40) (Canada); ordinary Portland cement (A), quick setting Portland cement (B), Portland blast furnace slag cement (SA), Portland quick setting blast furnace cement (SB), sulphate resistant Portland cement ( D), low heat Portland cement (C), low heat Portland cement with fly ash (FC) and low heat Portland cement with blast furnace slag (SC) (Australia); Portland artificial cement (CPA), Portland composite cement (CPJ), blast furnace cement (CHF), clinker slag cement (CLK) and supersulphated cement (CSS)

  (France); cements called in German: "Portland-

  zement (PZ), Eisenportlandzement (EPZ), Trasszement (TrZ),

  Hochofenzement (HOZ), Portlandzement mit Hohem Sulfatwider-

  stand [HS (PZ)], Hochofenzement mit hohem Sulfatwiderstand [HS (BLF)] und Mit Niedriger Hydrations-warme (NW) (FRG) ", cements called in Spanish:" Portland (P), Portland de alta resistencia inicial (P- ARI), Portland con adiciones activas (PA), cementos compuestos (C), siderurgico I -III (SI - III), puzzolanico I - II (PUZ I - PUZ II), Portland blanco (PB), cementos compuestos blancos (BC), Portland

  resistente al yeso (P-Y), Portland de bajo calor de hidra-

  tacion (P-BC) and aluminoso (A) "(Spain); which are in fact all Portland cements whose constituents have various origins and are obtained from, for example

  blast furnace, pozzolana, aluminum clinker clinker

  neux, these materials having resistance properties which can differ and whose heats of hydration can

  be diverse; and alumina cement containing as a compo-

  major health of aluminate, super hardening cement

  containing C1lA7 * CaF2, and the special cement using

  calcium sulfoaluminate (C4A3S).

  The additive composition used in accordance with the

  present invention can be used in concrete to use

  riser for making pavements compacted by cylinder

  drageage in an amount of about 0.05% by weight to 3% by weight relative to the weight of the cement. The amount of additive according to the invention can vary depending on the types of cements. The preferable quantity of additive according to the invention to common Portland cement to be used for concrete pavements compacted by rolling is between 0.1 and 1.08 in

  weight relative to the weight of the cement.

  The additive composition used in accordance with the present invention can be mixed or added during its preparation of the cement in powder form. Alternatively, due to its solubility in water, it can be

  dissolve in water to be used for making concrete.

  The additive composition used in accordance with the present invention can be effective in retarding hydration or the reaction of cement during the formation of concrete pavements compacted by rolling, so that thermal cracks in the concrete are avoided. hardened concrete, since this additive can slow down the exothermic reaction

of hydration.

  The present invention is further illustrated by the following examples intended to illustrate an additive which can be used for cement intended for making pavements by rolling but should not be interpreted as limiting

the invention.

EXAMPLES

  A normal Portland cement with a specific weight of 290 kg / m3 is used to prepare the concrete for a concrete pavement compacted by rolling, the ratio of water to cement being 36.4% by weight, and the ratio s / a (sand / aggregate ratio: volumetric ratio of sand to gross aggregate) being 41.5%, and 108 kg / m3 of water, 875 kg / m3 of sand and 1223 kg / m3 are mixed '' coarse aggregate (gravel) so as to obtain a value of K (ratio of the volume of cement paste used in 1 m3 of concrete obtained compared to the volume of pores in the aggregate in 1 m3 of concrete obtained) equal to 1, 10, a value of Km (ratio of the volume of cement paste used in 1 m3 of concrete obtained to the pore volume of the raw aggregate used in 1 m3 of concrete) equal to 1.75. Then, the additive (s) indicated in table 1 for each example are added and each concrete mixture is stirred. The concrete obtained is applied at a temperature of 20 C so as to produce the concrete compacted by cylidnrage. On each of the concrete samples thus applied, the settlement speed (VC valve) is determined by

  a consistency test procedure after vibration (VC test).

  The packing rate (valve VC) and the resistance of each of the samples as a function are shown in table 2.

time.

  The VC valve indicates the settlement index of the concrete and it is preferable that as little variation as possible occurs.

TABLE 1

  Types of additives used in concrete for pavements compacted by rolling Additives Example 1: 0.25% tannic acid Example 2: 0.25% tannic acid + 0.2% retarder based on lignin derivative AE Example 3: 0.25% tannic acid + 0.2% retarder based on oxycarboxylate derivative Example 4: 0.25% tannic acid + 0.01% retarder based on polyoxyethylene-alkylallylether Reference Example 1: no additive Reference Example 2: 0.25% retarder based on lignin derivative AE

TABLE 2

  Valve VC and concrete resistance as a function of time Valve VC (%) Resistance after (kg / cm2) Initial 60 min 1 day 7 days 28 days Ex. 1 97, 0% 94.5% 126 kgf / cm2 300 kgf / cm2 380 kgf / cm2 Ex. 2 97.5% 95.0% 120 kgf / cm2 310 kgf / cm2 395 kgf / cm2 Ex. 3 97.0% 96.0% 128 kgf / cm2 320 kgf / cm2 404 kgf / cm2 Ex. 4 99.0% 97.0% 120 kgf / cm2 350 kgf / cm2 420 kgf / cm2 Ref. L 96.0% 87.0% 130 kgf / cm2 270 kgf / cm2 330 kgf / cm2 Ref. 2 97 , 0% 90.0% 130 kgf / cm2 280 kgf / cm2 350 kgf / cm2 It is apparent from the results given in Table 1

  and Table 2, that the additives used in compact concrete

  Tee by rolling shows less variation at the VC valve of the concrete over time and the hardened concrete obtained has a relatively high resistance after 7 days and

  more, in comparison with the concrete used in a standard way-

sic in the roadways.

  The addition of the specific additive according to the present

  invention of the concrete composition used for the formation

  tion of pavements compacted by rolling improves the performance of the concrete used, which has less variation in settlement and improved resistance due to

  that this specific additive can control the heat of hydra-

  during hardening of the concrete so as to minimize cracking and thermal cracking in the hardened concrete of the pavements. As a result, pavements made of hardened concrete can be improved. In particular, the specific additive

  in accordance with the present invention exerts a significant action

  cative on concrete pavements applied by compaction

by rolling in summer.

  Of course, the present invention is not limited to the embodiments described and shown, but it is susceptible of numerous variants accessible to humans.

  art without departing from the spirit of the invention.

Claims (4)

  1.- Additive composition for concretes intended to be used for the construction of pavements compacted by rolling, characterized in that it comprises, as active ingredient, a hydrolyzable derivative of tannin. 2.- Additive composition for use in concrete   for roadways compacted by rolling according to the claim   tion 1, characterized in that it contains from 1 to 99% by weight of the tannin derivative as active ingredient and from 1 to   99% by weight of a surfactant.   3.- Additive composition for use in concrete   for roadways compacted by rolling according to the claim   tion 1 or 2, characterized in that said hydrolyzable derivative   tannin is chosen from the group consisting of: gallo-   tannin, corilagin, chébulagique acid and chébulinic acid.   4.- Method of manufacturing a concrete pavement compacted by rolling which consists in preparing a cement concrete mixture containing a hydrolyzable derivative of tannin, cement, sand, coarse aggregates and other additives if necessary, to apply the mixture thus obtained on an area which should constitute the roadway and compact it by rolling with a steamroller. concrete mixture thus laid.