JP2008088040A - Cement composition for fixing bolt and continuous construction method for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cement composition for fixing bolt which has small sagging property while securing flowability enough to smoothly carrying out construction and capable constructing even under a place where water is existed without being diluted with water and separated. <P>SOLUTION: In the cement composition for fixing the bolt, which contains cement, fine aggregate and a separation preventing agent, the ratio by mass of cement/fine aggregate is 1/1.5-2/1 and the ratio of the separating preventing agent which is a water soluble cellulose ether to 100 pts.mass in total of cement and the fine aggregate is 0.01-0.2 pts.mass. In the continuous construction method of the cement composition for fixing the bolt, a continuous kneading mixer pump is used and in such a case, the ratio of water/cement composition is controlled to 0.17-0.30. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is used in the civil engineering and construction fields, particularly in tunnel construction such as roads, railways, and waterways, for fixing bolts in the lock bolt method and bolts used in the auxiliary method and anchoring in anchor methods such as slopes. The present invention relates to a fixing cement composition and a continuous construction method thereof.

Conventionally, in order to ensure long-term safety of structures in tunnels and slope works, rock bolt methods and anchor methods have been carried out for the purpose of stabilizing the ground around the structure.
These methods are performed for the purpose of constraining soil and preventing collapse by drilling the ground to a predetermined depth with a drilling machine, then inserting steel bolts and integrating with the ground. Yes. Also, as a method of fixing steel bolts, the method of fixing bolts by filling materials and fixing the bolts is called fixing type. Generally, mortars that are adjusted by adding water to the dry mortar mixed with cement and sand are generally used. in use.

When the rock bolt construction method is applied upward with respect to the cross section of the tunnel, the fixing material that is normally used may sag due to its own weight and gradually flow out of the hole, and the bolt fixing may be partially incomplete. In addition, in order to prevent the loss, it is necessary for the operator to close the mouth of the hole during or after the insertion of the bolt, and there is a problem that it is difficult to work safely at a high place.
On the other hand, when the ground on which these bolts are constructed is below the groundwater level or has high water permeability, there are cases where spring water flows out through the drilled holes or water accumulates in the holes after drilling. If the fixing material is filled in such a situation, the mortar is washed away by the spring water and the bolt cannot be fixed, or the bolt is exposed to cause rusting. Even when the amount of spring water was enough to be applied, the mortar filled was diluted with water until it hardened, resulting in a decrease in strength and a sufficient effect could not be obtained. As a countermeasure, the water / material ratio of the mortar is lowered and the flowability (flow value) is lowered to increase the separation resistance against water. Further, when the lock bolt is inserted after that, the insertion resistance increases, and the workability is lowered.

Bolt to solve the above problems and to obtain a mortar that can maintain good fluidity when filling into the hole and show a sudden increase in viscosity when allowed to stand after filling, preventing flow and material separation A fixing cement composition is known (see Patent Document 1).
The configuration of the invention of Patent Document 1 is “a cement composition in which an expansive material, an alkali metal aluminate and an alkali metal carbonate are blended into cement, or a cement composition in which a fine aggregate is blended with this. The mortar obtained from the cement composition is injected into the drilled hole and fixed by inserting a bolt, or the bolt is inserted into the drilled hole, and then the cement composition is mixed with water. It is characterized in that the bolt is fixed by filling through the gap between the kneaded hole and the bolt and the bolt "(paragraph [0005]). By using this cement composition for fixing a bolt," road, The rock bolt method in tunnels such as railways and waterways, injection methods during excavation, and anchor methods for slopes, etc. maintain good fluidity when pumped with a pump, and suddenly stand still after pumping is stopped. This increases the degree and prevents the escape from the hole and material separation, so that the bolt can be firmly fixed. ”(Paragraph [0007]). There was further demand.
JP 2005-112648 A

In addition, in order to impart a certain degree of viscosity to the bolt fixing material (bolt fixing cement composition) to reduce sagging and dropping, a cellulose, acrylic acid polymer system, welan gum, or the like may be used as a thickener. It is known (see Patent Document 2, paragraph [0006], claims 1 to 4). Patent Document 2 states that “when a suitable amount of welan gum is blended in a cement paste or cement mortar as a fixing material, it is possible to prevent dripping from a hole without significantly reducing fluidity” (paragraph [0012]. ) "The fixing material added with welan gum can make the breathing zero under pressure even if the water-cement ratio is 30% or more. Therefore, the adhesive strength of the fixing material is improved" (paragraph [ The fixing material (paragraph [0029]) in which 2.5 g of welan gum is blended with “premix cement (portland cement and sand premixed 1: 1 at 20 kg + water 5 kg)” Although it is shown, the fixing material added with thickeners other than welan gum prevents dripping and material separation while ensuring fluidity. There is no description of the cement / fine aggregate ratio, the addition rate of thickener (separation inhibitor), and the like.
JP-A-7-208097

Furthermore, it is also known to use a cellulosic polymer compound as a separation inhibitor in a cement composition used as a PC grout material, a self-leveling material, or the like (see, for example, Patent Documents 3 to 5).
JP 2002-285152 A JP 2003-313069 A JP-A-2005-231967

  Patent Document 3 states that “especially when a cellulose-based polymer compound is used as a thickener, the occurrence of breathing is prevented. The occurrence of this breathing can be suppressed by adjusting the amount of the thickener. The addition amount is 0.20 to 0.32 parts by weight with respect to 100 parts by weight of cement.If the addition amount of the thickener is less than 0.20 parts by weight, there is no effect of preventing bleeding, and the thickener Although the fluidity is deteriorated when the addition amount exceeds 0.32 parts by weight ”(paragraph [0009]), the invention described in Patent Document 3 describes“ a premix type low-viscosity PC grout material. The problem of improvement in fluidity and sagging property and prevention of material separation is not suggested for the bolt fixing cement composition containing fine aggregate.

  Patent Document 4 states that “a base material obtained by adding 100 parts by weight of a cement / aggregate ratio (weight ratio) 75/25 to 20/80 and 10 to 40 parts by weight of water has a 2% aqueous solution viscosity of 100 to 100%. By adding 0.01 to 1 part by weight of cellulose ether of 30,000 mPa · s and 0.005 to 1 part by weight of microbial fermentation thickening polysaccharide, there is no material separation and a mortar composition having improved fluidity is obtained. “The maximum particle size of the aggregate affects the minimum coating thickness of the composition and the surface smoothness after curing. Fine aggregate for ready-mixed concrete or plastering sand can be used. Natural sand such as river sand, mountain sand, land sand, sea sand, dredged sand, crushed sand or mixed sand of crushed sand and natural sand, the particle size is 5mm In the following, the FM is about 1.5 to 3.0. Good, preferably 2.5 mm or less is desirable ”(paragraph [0010]),“ the cement fine aggregate ratio S / C used in the composition of the present invention is in the range of 0.5-4. If it is less than 5, plastic shrinkage cracks and floating occur in the formed cured body, whereas if it exceeds 4, the fluidity of the S composition is lowered, and the level accuracy of the finished surface of the formed cured body is lowered. (Paragraph [0011]), “Thickeners prevent material separation during curing of the composition, suppress breathing water, maintain level accuracy and smoothness, and improve whiteness on the surface of the cured product. Specific examples of thickeners include methylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, hydroxyethylmethylcellulose, and glyoxal-added hydroxypropylene. Examples thereof include cellulose ethers such as methylcellulose and carboxymethylcellulose, water-soluble polymers such as polyacrylamide, polyethylene oxide, polyvinyl alcohol, polyacrylic acid, sodium polyacrylate, etc. The thickener is 0.01 to 1 part by weight. (Paragraph [0013]), the invention described in Patent Document 4 is premised on use as a “high-fluid mortar composition for floor construction”. , When applied to a bolt fixing cement composition containing fine aggregate, while maintaining fluidity, the cement / fine aggregate ratio to prevent dripping and material separation, the addition rate of separation inhibitor, It does not suggest the particle size of the fine aggregate.

  Patent Document 5 states that “The anti-separation agent used in the present invention is used to improve the filling properties and separation resistance of PC grout, and the viscosity of a 2 mass% aqueous solution at 20 ° C. is 5, In the case of less than 5,000 (cp), the fluidity of the PC grout is improved, but the filling property tends to decrease, and bleeding is observed. In addition, when it exceeds 50,000 (cp), the fluidity of the PC grout tends to decrease, and as a component of the separation inhibitor that can be used, a cellulose polymer compound (for example, , Carboxymethylcellulose, methylcellulose, hydroxypropylmethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose) and ... "(Paragraph [0019])", but the problem of improvement in fluidity, sagging property, and prevention of material separation is suggested for the bolt fixing cement composition containing fine aggregate. It has not been.

  Therefore, the problem to be solved by the present invention is a trade-off with respect to the bolt fixing cement composition that cannot be solved by the above-described prior art, and that the workability is poor when the viscosity is raised and the physical properties are lowered when the viscosity is lowered. It is a problem. Furthermore, in detail, the problem of the present invention is that there is little sagging property while ensuring fluidity so that the construction can be performed smoothly, and even if there is water in the construction site, the construction is performed without being diluted and separated in water. An object of the present invention is to provide a possible bolt fixing cement composition and a method for continuously applying the cement composition.

The present invention employs the following means in order to solve the above problems.
(1) A bolt fixing cement composition comprising a cement, a fine aggregate and an antiseparation agent, wherein the mass ratio of cement / fine aggregate is 1 / 1.5-2 / 1, and is a water-soluble cellulose ether A bolt fixing cement composition, wherein the addition rate of the separation preventing agent is 0.01 to 0.2 parts by mass with respect to 100 parts by mass in total of cement and fine aggregate.
(2) The bolt fixing cement composition according to (1), wherein an addition ratio of the separation preventing agent is 0.03 to 0.1 parts by mass with respect to 100 parts by mass in total of cement and fine aggregate. object.
(3) The bolt fixing cement composition according to (1) or (2), wherein the separation preventing agent is hydroxyalkylalkylcellulose.
(4) The cement composition for bolt fixing according to (3) above, wherein the anti-separation agent has a 2% aqueous solution having a viscosity of 1,000 to 30,000 mPa · s.
(5) Using a continuous mixing mixer pump that continuously supplies water and cement composition, and kneads and feeds the mixture, and kneads the water / cement composition ratio in the range of 0.17 to 0.30. The continuous construction method for a bolt fixing cement composition according to any one of (1) to (4), wherein the bolt fixing cement composition is mixed.
In the present invention, “parts” and “%” are based on mass unless otherwise specified.

  By using the cement composition and construction method of the present invention, it has the same fluidity as a conventional fixing material, less drooping, and reliably fixes bolts without being diluted even in ground where spring water is generated. Possible fixing materials and construction methods are now possible.

  Cement used in the present invention is usually commercially available, such as normal, early strength, moderate heat and super early strength, such as Portland cement, various mixed cements such as fly ash and blast furnace slag mixed with these Portland cements, Any cement can be used, but in particular, early-strength cement is preferable in terms of strength development.

The type of fine aggregate used in the present invention is not particularly limited, and any of river sand, mountain sand, lime sand, silica sand, and the like can be used.
The maximum size of the fine aggregate is preferably 3.0 mm, more preferably 2.0 mm or less. If it is larger than 3.0 mm, the flow value of the mortar after kneading becomes low, so that the pressure at the time of pumping becomes high and the pump stops, and further, the pumping is blocked in the hose and the workability may be deteriorated.

  In the composition of the present invention, the content ratio of cement and fine aggregate is preferably 1 / 1.5 to 2.0, more preferably 1 / 1.5 to 1.5 in terms of mass ratio. If the ratio is less than 1 / 1.5, the proportion of fine aggregate increases, so after mixing, the cement and fine aggregate are easily separated. Since the ratio is small, strength development is reduced. On the other hand, when the ratio is larger than 2.0, the strength development is sufficient, but the fluidity becomes high, so that it is easily separated from water.

  The anti-separation agent used in the present invention is a material that prevents separation of cement particles and fine aggregates constituting the cement composition in water by imparting viscosity to the mortar. As the separation inhibitor, water-soluble cellulose ether is preferable, and hydroxyalkyl cellulose or hydroxyalkylalkyl cellulose in which a hydroxyalkyl group is added to a part of the glucose ring is preferable, and hydroxyalkylalkyl cellulose is more preferable. Of hydroxyalkylalkylcelluloses, hydroxyethylmethylcellulose is preferable because it has high solubility and can impart a predetermined viscosity even at high temperatures.

  In the hydroxyalkylalkyl cellulose, the viscosity of the aqueous solution dissolved in water to be 2% is preferably 1,000 to 30,000 mPa · s at a water temperature of 20 ° C., preferably 3,000 to 15,000 mPa · s. Is more preferable, and 5,000 to 10,000 mPa · s is particularly preferable. When the viscosity is less than 1,000 mPa · s, the effect of preventing separation is low, and when it is greater than 30,000 mPa · s, the viscosity is high and mixing of the mixer becomes difficult, and the reaction of the cement is inhibited and the strength is reduced. Invite.

  The addition rate of the separation inhibitor of the present invention is preferably 0.01 to 0.2, more preferably 0.03 to 0.1, and more preferably 0.05 to 0 with respect to 100 parts of the total weight of cement and fine aggregate. .1 is particularly preferred. If it is less than 0.01, the effect of preventing separation from water is low, and if it is more than 0.2, the viscosity becomes too high and kneading becomes difficult, and further, the reaction of the cement is inhibited and the strength is lowered.

  The mixing method of the cement composition according to the present invention is not limited to a batch mixer such as a commonly used bread mixer and a forced twin screw mixer, but the mixing efficiency is inferior, but the mixer and the pump are integrated. The continuous mixer pump can be used, and the construction with the continuous mixer pump is preferable from the viewpoint of construction efficiency.

  Moreover, as conditions for kneading the present cement composition with a continuous mixer pump, it is preferable that the kneading water and the cement composition are adjusted to the mixer at a weight ratio of 0.17 to 0.3, 0.17 to 0. .27 is more preferred. If it is smaller than 0.17, kneading is difficult, and if it is larger than 0.3, the fluidity is too high, so that it is easily separated from water and the water resistance is lowered.

  The cement composition of the present invention can be used in combination with an antifoaming agent if necessary. The component of the antifoaming agent is not particularly defined, and any commercially available antifoaming agent can be used.

The cement composition of the present invention includes an inorganic powder having a brain value of 6,000 cm ² / g or more and a polycarboxylic acid such as silica fume, fly ash, slag, etc. It is possible to use a water-reducing agent such as lignin-based, lignin-based, or naphthalenesulfonic acid-based, and a hardening accelerator such as an alkali metal salt or calcium aluminate for early strength development.

  Hereinafter, although an example and a comparative example are given and the contents are explained in detail, the present invention is not limited to these.

0.05 parts of an anti-separation agent was mixed with 100 parts of a mixture of cement and fine aggregate shown in Table 1 to obtain a cement composition. Subsequently, it adjusted so that kneading water might be 20 parts with respect to 100 parts of each cement composition, kneaded for 2 minutes with the mixer, and produced the mortar, and measured various physical properties.
<Materials used>
Cement: Early strong Portland cement (manufactured by Electrochemical Industry)
Fine aggregate: Lime sand Maximum dimension 1.2mm or less (manufactured by Electrochemical Industry)
Separation inhibitor: Hydroxyethyl methylcellulose, 2% aqueous solution viscosity 5,000 mPa · S (commercially available)
<Kneading method>
Mortar mixer: Conforms to “JISR5201” <Measurement method>
a. Compressive strength: according to “JISR5201” b. Mortar flow: according to “JISR5201” c. Water resistance evaluation: 10 L of tap water (pH 7.6) is put into a water tank with a volume of 12 L. A portion of the mortar kneaded with a mixer is filled into a cylindrical container having a diameter of 8 cm and a height of 8 cm, which is put into a water tank, and then only the container is gently lifted. Next, place the stirrer shaft 10 cm from the side of the mortar and stir at 500 rpm for 10 minutes, collect water at regular intervals, measure the pH and turbidity (suspended substance amount), and determine the separation state of the mortar. evaluated.
d. pH: Conforms to “JISZ8802”. A pH meter D-51 manufactured by HORIBA was used.
e. Suspended substance amount: Conforms to “JISK0102” <Target value>
For compressive strength values and flow values, refer to the former Japan Highway Public Corporation “Tunnel Management Guidelines, Rock Bolt Fixing Material Quality Standards (Normal Mortar)”. The target value was set with reference to “Underwater separable admixture quality standard for concrete”.

  From Table 1, the mortar of the present invention example having a cement / fine aggregate ratio of 1 / 1.5-1 / 2 has little separation of cement and fine aggregate, has sufficient strength development, and has an appropriate flow. (Experiment No. 1-2 to No. 1-5). In order to reduce the separation of cement and fine aggregate and to suppress fluidity, the cement / fine aggregate ratio is preferably 1 / 1.5 to 1.5 / 1 (Experiment No. 1- 2 to No.1-4). On the other hand, the mortar of the comparative example having a small cement / fine aggregate ratio of 1/2 is too low in fluidity and easily separated from water (Experiment No. 1-1).

  The mass ratio of cement and fine aggregate was set to 1, and an anti-separation agent was mixed with the composition shown in Table 2 to obtain a cement composition. Subsequently, it adjusted so that mixing water might be 20 parts with respect to 100 parts of each cement composition, knead | mixed with the mixer, produced the mortar, and measured various physical properties.

  From Table 2, the mortar of the present invention example in which 0.01 to 0.2 part of the separation inhibitor is mixed with 100 parts of the mixture of cement and fine aggregate has little separation between the cement and the fine aggregate, and develops strength. Is sufficient and has an appropriate fluidity (Experiment No. 2-2 to No. 2-5, No. 1-3). In order to reduce the separation of cement and fine aggregate and improve the fluidity, 0.03-0.1 part of an anti-separation agent may be mixed with 100 parts of the mixture of cement and fine aggregate. Preferred (Experiment No. 2-3, No. 1-3, No. 2-4). On the other hand, the mortar of the comparative example to which no separation inhibitor is added has sufficient strength development and high fluidity, but is easily separated from water (Experiment No. 2-1).

  The amount of the separation inhibitor added was 0.05 parts with respect to 100 parts of the cement composition, and the same conditions as in Example 2 were used except that the separation inhibitor having physical properties shown in Table 3 was used.

  As shown in Table 3, by setting the viscosity of a 2% aqueous solution of the separation inhibitor (hydroxyethylmethylcellulose) in the range of 1,000 to 30,000 mPa · s, there is little separation between cement and fine aggregate, and strength Since mortar with sufficient expression and appropriate fluidity can be obtained (Experiment No.3-1 to No.3-5, No.1-3), the viscosity of 2% aqueous solution of separation inhibitor is It is preferable to set it as the range. In order to reduce the separation of cement and fine aggregate, increase the strength development, and improve the fluidity, the viscosity of the 2% aqueous solution of the separation inhibitor is 3,000 to 10,000 mPa · s. It is more preferable (Experiment No. 3-2, No. 1-3, No. 3-3).

  The test was performed under the same conditions as in Example 1 except that the weight ratio of cement and fine aggregate was 1 and the maximum size of the fine aggregate was Table 4.

  From Table 4, the mortar of the present invention example with the maximum size of the fine aggregate of 3.0 mm or less has sufficient strength development, suitable fluidity, and good workability (pump pumpability). (Experiment No.4-2, No.1-3, No.4-3). On the other hand, the mortar whose maximum size of the fine aggregate is 5.0 mm has sufficient strength, but the fluidity is low, and when pumping with a pump, the hose is blocked. (Experiment No. 4-1).

The cement composition was adjusted under the same conditions as in Example 1 except that the weight ratio of cement and fine aggregate was 1. Using the composition, the amount of water was adjusted so that the water / cement composition ratio shown in Table 5 was obtained, kneaded with a continuous mixer to prepare a mortar, and various physical properties were measured.
<Kneading method>
Mixer: My pump M400 (Putmeister)

  From Table 5, the mortar of the present invention example kneaded at a water / cement composition ratio in the range of 0.17 to 0.30 has little segregation of cement and fine aggregate, has sufficient strength development, and is appropriate. It can be seen that it has a good fluidity (Experiment No. 5-2 to No. 5-5, No. 1-3) In order to further reduce the separation of cement and fine aggregate, to further increase strength development and to suppress fluidity, the water / cement composition ratio is preferably 0.17 to 0.27 (Experiment No. .5-2 to No.5-4, No.1-3). In contrast, the mortar of the comparative example having a water / cement composition ratio of 0.16 was too low in fluidity and could not be kneaded due to blockage (Experiment No. 5-1).

Claims (5)

  A cement composition for bolt fixing comprising a cement, a fine aggregate and an antiseparation agent, wherein the mass ratio of cement / fine aggregate is 1 / 1.5-2 / 1 and is a water-soluble cellulose ether. A cement composition for fixing bolts, wherein the addition ratio of the inhibitor is 0.01 to 0.2 parts by mass with respect to 100 parts by mass in total of cement and fine aggregate.   2. The cement composition for bolt fixing according to claim 1, wherein an addition rate of the separation preventing agent is 0.03 to 0.1 parts by mass with respect to 100 parts by mass in total of cement and fine aggregate.   The bolt fixing cement composition according to claim 1 or 2, wherein the anti-separation agent is a hydroxyalkyl alkyl cellulose.   4. The bolt fixing cement composition according to claim 3, wherein the anti-separation agent has a viscosity of 2% aqueous solution in a range of 1,000 to 30,000 mPa · s.   Use a continuous mixing mixer pump that continuously supplies water and cement composition, and mixes and feeds the mixture, and the water / cement composition ratio at that time is 0.17 to 0.30. The continuous construction method of the cement composition for bolt fixation as described in any one of Claims 1-4 characterized by these.