KR100870673B1 - Concrete admixture using malto-dextrin with reduction function of bleeding and rebound - Google Patents

Abstract

A concrete admixture is provided to show a low hygroscopic and a compaction preventing effect using a maltodextrine having a bleeding and a rebound reducing function, to improve a construction property, to secure equal quality of the concrete and to improve a water-tightness and durability. An admixture mixes a maltodextrine in order to increase a viscosity and reduce a bleeding or a rebound. An antiseptic of 0.2 ~ 0.5 parts by weight is mixed into the maltodextrine of 1 parts by weight in order to prevent a decay of the mixed maltodextrine. The maltodextrine of 2 ~ 10 parts by weight is mixed when being mixed into a liquid phase and the maltodextrine of 1 ~ 5 parts by weight is mixed when being mixed into a gas phase.

Description

Concrete Admixture using Malto-dextrin with reduction function of Bleeding and Rebound}

The present invention relates to a concrete admixture using maltodextrin, and more specifically, maltodextrin, which is a starch sugar material prepared by enzymatic reaction using starch as a raw material, is added to a concrete AE water reducing agent and a high performance AE water reducing agent (including PNS and PC system). The present invention relates to a concrete admixture using maltodextrin having a function of reducing bleeding and shotcrete rebound by mixing at a constant ratio.

In general, concrete mainly used in construction and civil works requires a product of uniform quality that satisfies the conditions for securing fluidity and less material separation and less effective shrinkage. However, concrete can be easily separated by the difference in specific gravity of each material in the construction process, such as compaction because it is composed of a number of materials having different properties such as specific gravity and particle size powder. In addition, even if the same material is used depending on the degree of moisture of the water, the phenomenon that the material is separated according to the humidity occurs frequently.

The bleeding, which is one of the material separation phenomena, refers to a phenomenon in which internal surplus water floats on the concrete upper surface by separation of water from cement paste and mixed material in formwork or concrete placed on the surface. Therefore, when the bleeding phenomenon occurs, there is a problem in that water tightness and durability are deteriorated due to the lack of concrete, poor workability, deterioration of upper quality due to voids caused by surplus water, and internal waterway caused by surplus water. In addition, due to the injuries of the lattices and other foreign matters caused by the bleeding water, the poor bonding of the concrete surface occurs, and the quality of the concrete structure is totally reduced by the bleeding, which causes the deterioration of the concrete due to the shrinkage of the concrete. Cause.

Therefore, in order to prevent deterioration of the quality of concrete and concrete structures due to the bleeding phenomenon, a bleeding reduction method is required. Conventionally registered viscosity adjusting and bleeding reducing agents (methyl cellulose type) have a problem of compatibility with the fluidizing agent used together, or the bleeding reducing agent itself entrains the air, etc. It is an expensive product in terms of phosphorus and has a disadvantageous lighting to use.

Therefore, the present invention is a means for solving the above problems,

In the concrete admixture to be mixed with concrete, the admixture is characterized in that the maltodextrin is mixed to increase the viscosity to reduce bleeding or rebound.

Concrete admixture using maltodextrin having a bleeding and rebound reduction function of the present invention,

By mixing maltodextrin, which has low hygroscopicity, anti-shaping and anti-caking effect, to concrete admixtures in a proportion to produce concrete admixtures that have bleeding and rebound reduction functions, the bleeding of concrete is reduced or adjusted to improve the workability of non-solid concrete. As well as ensuring the uniform quality of concrete and improving the watertightness and durability, it is possible to produce high quality concrete that is advantageous in terms of shrinkage crack control.

In addition, it is possible to provide an environment-friendly and useful product that reduces the amount of mixing of chemicals such as reducing the rebound amount of concrete by increasing the viscosity by increasing the mixing ratio of maltodextrin to the admixture added to shotcrete concrete, which is a spraying concrete. Was done.

Concrete admixture using maltodextrin of the present invention for achieving the above object,

Maltodextrin can be mixed to reduce the bleeding or rebound by increasing the viscosity of the concrete.

When used as a bleeding reducing agent, 1 to 10 parts by weight of maltodextrin may be mixed with respect to 100 parts by weight of the AE water reducing agent and the high performance AE water reducing agent, but the amount of maltodextrin may be adjusted according to the properties of the concrete.

In other words, the concrete admixture using maltodextrin is a starch-based powder or liquid product of maltodextrin, a starch sugar produced by the enzymatic reaction to a high-performance AE water-reducing agent including an AE water reducing agent or PNS-based and PC-based Add, then mix for a period of time to produce a bleeding reducer.

Preservatives are added to the admixture to prevent rot of maltodextrin. The mixing ratio of the added preservative is preferably used to mix maltodextrin: preservative in a weight ratio of 1: (0.2 to 0.5) by weight, so that the mixture is stirred for 30 minutes to 1 hour to uniformly mix maltodextrin and preservative. It is desirable to.

At this time, when the preservative is mixed in an amount of 0.2 parts by weight or less, there is a problem that the maltodextrin is decayed due to low anti-corruption effect, when mixing more than 0.5, the improvement of the anti-corruption effect is insufficient but the strength of the concrete falls Therefore, it is preferable to use the mixture within the above range, and the stirring is preferably stirred at a time when the baltodextrin and the preservative are mixed uniformly.

Next, when the maltodextrin is added in the liquid phase, it is preferable to use 2 to 10 parts by weight, and to mix the maltodextrin into powder, it is preferable to use 1 to 5 parts by weight.

The liquid maltodextrin is gradually reduced bleeding amount up to 10 parts by weight with respect to 100 parts by weight of the AE reducing agent, which is a concrete admixture, but it is preferable to mix and manufacture within the above range because the improvement of the bleeding reduction efficiency is insufficient at 10 parts by weight or more. .

In addition, in the case of powder maltodextrin, the mixing amount of 1 to 5 parts by weight with respect to 100 parts by weight of the AE reducing agent greatly reduces the amount of bleeding, but if it is more than that, the efficiency of bleeding reduction is insufficient. desirable. As such, the mixing amount of the liquid phase and the powder phase must be prepared in the same mixing ratio because the solid content of the maltodextrin contained in the liquid phase and the powder is different from each other. In addition, the viscosity of the liquid and the powder is also because they have different properties.

In addition, the AE reducing agent and high performance AE reducing agent may be used lignin (LS), naphthalene (PNS), melamine-based (PMS) or polycaroxylate (PC). In general, LS, PNS, and PMS systems adsorb on cement particles to generate inherent negative charges to disperse the cement particles, and the PC system has a mechanism to generate three-dimensional repulsive force by adsorbing on cement particles. When maltodextrin is added to the admixture, maltodextrin particles function as moisture, thereby increasing the viscosity of the admixture itself, and increasing the viscosity of the concrete when added to the concrete.

On the other hand, the maltodextrin may be used as a rebound reducing agent by mixing 5 to 30 parts by weight with respect to 100 parts by weight of the fastener for shotcrete. The shotcrete is to prevent rebounding by increasing the viscosity by cutting the indentation work, and when the mixed use is less than 5 parts by weight, the rebound reduction effect is low due to the lack of viscosity increase, and when mixed at 30 parts by weight or more Is increased, but the strength is lowered and the rebound reduction efficiency is inadequate and can be mixed within the above range and used as a rebound reducing agent.

As such, the viscosity control and bleeding reducing agent using maltodextrin can be mixed and compatible with LS, PNS, PC, and PMS systems by dividing the raw materials of chemical admixtures. In addition, there is no need to use an antifoaming agent to control the amount of air, the inherent properties of maltodextrin has the characteristics that can reduce and control the viscosity and bleeding of cement concrete. Therefore, unlike the prior art, there is no problem in compatibility with various types of AE water reducing agents and high performance AE water reducing agents, and it is possible to secure considerable economics.

In addition, maltodextrin, which can be used as a bleeding reducing agent according to viscosity control, can control the amount of rebound by adjusting the viscosity of cement concrete spraying (typically shotcrete expression) used in the NATM method, one of tunnel methods during civil engineering work. have. It uses the dry and wet fasteners used in the spraying method to achieve the fluidity and workability of the sprayed concrete by adjusting the amount of fluidizing agent and the unit to secure the fluidity of the concrete, but surplus for securing the fluidity The water can increase the rebound that the sprayed concrete will stick to the tunnel walls and fall off. It has the effect of reducing 50% of the rebound amount by adjusting the mixing amount of the maltodextrin viscosity control mechanism. In other words, maltodextrin also acts as a rebound reducing agent to reduce the amount of rebound by controlling the viscosity of the concrete to be sprayed by adjusting the viscosity of the concrete with low hygroscopicity and floating properties.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

Example 1

A concrete admixture was prepared by varying the amount of liquid maltodextrin mixed in the AE water reducing agent according to the present invention. This was tested according to the Korean standard bleeding test method KSF 2421 and the amount of bleeding was shown in FIG. 1.

Example 2

A concrete admixture was prepared by varying the mixing amount of the powder maltodextrin to the AE reducing agent according to the present invention, and after adding it to concrete, curing was shown in FIG. 2 to measure the bleeding amount.

1 and 2, when the liquid maltodextrin is mixed into the concrete admixture, it can be seen that the amount of bleeding decreases proportionally as the mixing rate increases. That is, it can be seen that the bleeding decreases greatly in the mixing of 1 to 2 parts by weight of the liquid phase, and the bleeding decreases significantly until the mixing of 1 part by weight of the powder.

Example 3

When the concrete admixture mixed with the bleeding reducing agent according to the present invention is used, the change in the bleeding for each W / C is measured according to the mixing rate of the bleeding reducing agent and is shown in FIGS. 3A to 3C.

As shown in Figure 3a to 3c when the bleeding reducing agent according to the present invention is mixed with a different mixing rate when mixed with the concrete admixture (AE water reducing agent, high performance AE water reducing agent) compared to the amount of bleeding for each W / C When the bleeding reducing agent according to the present invention is mixed, it can be seen that the decrease is greatly reduced, and the bleeding reduction proceeds in a similar width irrespective of the amount of mixing in a predetermined amount or more.

Example 4

The effect of reducing the rebound amount generated during the spraying of the tunnel construction is mixed maltodextrin with different parts by weight with respect to the fastener, which is a admixture for shotcrete, to adjust the viscosity of the concrete and to measure the rebound amount during construction according to FIG. Shown.

As shown, the rebound amount is reduced according to the ratio of mixing maltodextrin to the shotcrete fastener, and a large rebound reduction is achieved at a mixing ratio of 10 to 15 parts by weight.

In addition, the above-mentioned example is only an example to demonstrate this invention. Therefore, it is obvious that the ordinary skilled in the art to which the present invention pertains uses the partial change with reference to the detailed description.

1 is a graph measuring the change in the amount of bleeding according to the change in the mixing rate by using the liquid maltodextrin according to the present invention as a bleeding reducing agent.

Figure 2 is a graph measuring the change in the amount of bleeding according to the change in the mixing rate using the powder maltodextrin according to the present invention as a bleeding reducing agent.

Figure 3a to 3c is a graph measuring the change in bleeding for each W / C according to the change in the mixing rate of the bleeding reducing agent when using a concrete admixture mixed with the bleeding reducing agent according to the present invention.

Figure 4 is a graph showing the measurement of the rebound amount by varying the amount of maltodextrin incorporation in the rapid-acting agent for shotcrete.

Claims (6)

delete In concrete admixtures mixed with concrete, The admixture is mixed with maltodextrin to increase the viscosity to reduce bleeding or rebound, the maltodextrin is mixed 1 to 10 parts by weight based on 100 parts by weight of the AE reducing agent for use as a bleeding reducing agent, the mixed maltodextrin of A concrete admixture using maltodextrin, characterized in that the preservatives are mixed in an amount of 0.2 to 0.5 parts by weight with respect to 1 part by weight of maltodextrin to prevent corruption. The method of claim 2, The maltodextrin is a concrete admixture using maltodextrin, characterized in that 2 to 10 parts by weight is used when mixing in a liquid phase. The method of claim 2, The maltodextrin is a concrete admixture using maltodextrin, characterized in that 1 to 5 parts by weight is used when mixing in powder form. In concrete admixtures mixed with concrete, The admixture is mixed with maltodextrin to increase the viscosity to reduce bleeding or rebound, the maltodextrin is mixed 5 to 30 parts by weight with respect to 100 parts by weight of the filler for shotcrete, to prevent corruption of the mixed maltodextrin A concrete admixture using maltodextrin, characterized in that used as a preservative to mix 0.2 to 0.5 parts by weight with respect to 1 part by weight of maltodextrin. delete

Images