KR20010053808A - The method for manufacturing of composition of tunnel mortar - Google Patents

Abstract

PURPOSE: A reinforcing mortar composition for preventing a water leakage and rock fall in tunnel construction is provided, which improves compression strength and bending strength and has excellent adhesion and generates little amount of rebound, and a method for constructing the same is also provided, which prevents generation of dust particles and increases tunnel boring speed and working stability. CONSTITUTION: The reinforcing mortar composition comprises: (i) 30-35% of cement; (ii) 28-33% of sand(S1) having a particle size of not more than 0.6 millimeter; (iii) 25-28% of sand(S2) having a particle size of more than 0.6 millimeter and not less than 2.4 millimeter; (iv) 5-10% of fly ash; (v) 0.1-5% of high strength mixing agent; (vi) 0.1-0.65% of super plasticizer; (vii) 0.004-0.007% of methyl cellulose; and (viii) aluminate accelerator. The method comprises steps of: (i) stirring the reinforcing mortar composition in a mixer; and (ii) pumping the stirred composition of the step (i) with a rotor starter where the composition is sprayed on the inside of the tunnel by the accelerator and compressed air being connected to a pumping nozzle.

Description

Reinforcement mortar composition and construction method to prevent leakage and rockfall during tunnel construction {The method for manufacturing of composition of tunnel mortar}

The present invention relates to a reinforcement mortar composition and construction method to prevent leakage, rockfall during tunnel construction.

Recently, as construction of highways, high-speed railways, subways, etc., has increased rapidly, tunnel construction has increased. Tunnel construction is mainly done by NATM (New Austrian Tunnel Method) method for this tunnel construction, but recently after the first drilling by TBM (Tunnel Boring Machine) equipment which prioritizes tunnel excavation speed and work stability, 2 By the way, tunnel construction by NATM construction method is performed in parallel. Shotcrete work is indispensable to reinforce the excavation surface after tunnel excavation.

The disadvantage of shotcrete work is that the work environment is poor due to the high rebound amount and the dust generated during construction. This is a problem that arises even more when construction by the TBM method. In other words, the construction conditions to be met during the construction by TBM method should be possible to work in a narrow space (round diameter of 4.5m), spraying and attaching at the same time as excavation, extremely low rebound amount and extremely low dust generation The conditions such as must be satisfied. The material developed to meet these conditions is the tunneling mortar.

In order to solve the above problems, the present invention is a product that compensates for the shortcomings of Shotcrete work consisting of concrete reinforcing tunnel mortar. The tunnel reinforcement mortar uses sand of less than 2.4mm as a wet method, and has high compressive strength and flexural strength, excellent adhesion, low rebound amount, and low dust generation amount. This makes it possible to miniaturize the equipment required for shotcrete, which can be installed in excavating machinery such as TBM, making it useful in tight spaces. This tunnel reinforcement mortar provides reinforcement mortar composition and construction method to prevent water leakage and falling rocks during tunnel construction, which is necessary at the construction site where the dust should not be generated when reinforcing small caliber gangs or closed gangs. It is.

In order to achieve the above object, the present invention provides a reinforcement mortar composition to prevent leakage, rockfall during tunnel construction composed of cement, fly ash, durability improver, fluidizing agent, adhesion promoter, air entrainer, sand and quickener. It relates to a construction method using the same.

Cement was manufactured by our company, and the particle size of cement was 3,219㎠ / g based on Blaine, and its specific gravity was 3.15.

The fly ash has a specific surface area of 3,844㎠ / g, the high strength mixture has blast furnace slag as its main component and the specific gravity of 2.9 average particle size is 5 ~ 6㎛, and the admixture used a high plasticizer (SP). . M.C (methyl cellulose) was used as the adhesion promoter, and aluminate-based liquid quickener based on inorganic aluminate and carbonate was used as the fastener.

Process degree

Briefly describing the process diagram, in the reinforcement mortar construction method for preventing leakage and rockfall during tunnel construction, the composition of the present invention is put into a mixer and stirred and then pumped by a rota starter, and a fastener and compressed air connected to the pumping nozzle Reinforced mortar construction method to prevent leakage and rockfall during tunnel construction, characterized in that by spraying the composition into the tunnel to prevent dust and improve tunnel excavation speed and work stability

High-performance plasticizers (super-plasticizer) used in the present invention include KK Chemistry Powercon-100 (trade name).

Hereinafter, the present invention will be described in detail through examples.

Example 1

35% of cement, sand S1 (less than 0.6mm in size): 32%, sand S2 (size of 0.6-2.4mm): 26%, fly ash 7%, high performance water reducing agent 0.53%, MC (methyl cellulose): 0.007% After preparing the mixed composition, and then kneading unit amount of 15% with respect to 100% by weight of the mortar composition and 4-6% by weight of cement or silicate liquid grade with respect to 100% by weight of cement How to shotcreting by adding 13% payment.

Experiment 1 (mixture and physical property)

division C Sand F / A S.P M.C S ₁ S ₂ combination 35 32 26 7 0.53 0.007

C: cement, S1, S2: sand, F / A: fly ash, sp: high performance water reducing agent,

MC: methyl cellulose

(Sand size: S1 = 0.6mm or less, S2 = 0.6-2.4mm)

* W / R (water / mortar) = 14.5-17.0% added

* Aluminate type liquid quickener = cement x 4 ~ 6% added

division Flow (cm) Compressive strength (㎏ ¹ / ㎠) Flexural Strength (㎏ ¹ / ㎠) 1d 3d 7d 28d 1d 3d 7d 28d Experiment result 21 135 274 410 512 31 63 76 90

Experiment 2 (Physical Characteristics by Flow)

W / R (%) Flow (cm) F / M (㎏ / ㎥) Air (%) 14.0 17.2 2054 8.4 14.5 21.2 1980 9.9 14.7 21.5 1971 10.1 15.0 22.1 1906 13.2 16.0 22.7 1797 17.0 17.0 23.5 1765 17.7 17.5 25.7 1837 14.2 18.0 26.2 1854 12.9

Titration W / R (water / mortar) = 14.5-17.0%

14.5% or less: Difficult to work due to low fluidity

17.0% or more: Bleeding and material separation of dough

Experiment 3 (MC (methyl cellulose) addition amount characteristics)

division C Sand F / A S.P M.C S ₁ S ₂ combination -One 35 28 28 9 0.65 0.004 -2 〃 〃 〃 〃 〃 0.007 -3 〃 〃 〃 〃 〃 0.010

division W / R (%) Flow (cm) F / M (㎏ / ㎥) Air (%) Compressive strength (㎏ ¹ / ㎠) 흼 Strength (㎏ ¹ / ㎠) 3h 1d 7d 28d 3h 1d 7d 28d result -One 14.5 21.3 2030 8.2 10 181 246 362 8 39 54 55 -2 15.2 19.0 1924 13.1 10 171 244 351 4 36 55 59 -3 16.4 15.1 1702 20.3 6 133 194 279 3 30 44 48

The appropriate amount of M.C that can improve adhesion within the appropriate strength is 0.004 ~ 0.007%. However, when the amount of M.C added is large, the strength was found to decrease.

Experiment 4 (Rebound Rate)

division Flow (cm) Air pressure (atm) hose Rebound Rate (%) Adhesion Dust generation degree Length (m) Particle diameter (mm) Wall 21 5-9 26 35 5 Can be installed in case of 5cm thickness Slightly Temple of Heaven 〃 〃 〃 〃 7 Wall 23 〃 〃 〃 4 Good when pouring more than 5cm 〃 Temple of Heaven 〃 〃 〃 〃 6 Wall 25 〃 〃 〃 4 When cast more than 5cm in thickness, some deflection is seen, but construction is possible 〃 Temple of Heaven 〃 〃 〃 〃 8

The rebound rate of the wall part was best at 4% when the flowability was 23-25 cm, and the best at the top end was 6% when the flowability was 23 cm. Therefore, the rebound rate of the wall part is 4 ~ 5% and the ceiling part rebound rate is 6 ~ 8%, which is much less than the 30-40% rebound rate of the existing shotcrete.

In addition, dust generation was very low compared to shotcrete, and when the thickness of 3 ~ 5cm was poured, the adhesion surface was relatively good.

Experiment 6 (High Strength Mixture Effect)

The high-strength mixture is a powdery inorganic admixture with blast furnace slag as the main component (80-100% of blast furnace slag, 0-20% anhydrous gypsum) and powder of Blaine 8000cm2 / g.

division C Sand F / A High Strength Mixture S.P M.C S ₁ S ₂ combination -One 31 28 28 9 4 0.65 0.004 -2 35 28 28 9 0 0.65 0.004

division W / R (%) Flow (cm) F / M (㎏ / ㎥) Air (%) Compressive strength (㎏ ¹ / ㎠) Flexural Strength (㎏ ¹ / ㎠) 3h 1d 7d 28d 1d 2d 7d 28d result -One 13.5 26.6 2150 4.7 57 231 360 471 14 48 66 70 -2 14.5 21.3 2030 8.2 10 181 246 362 8 39 54 55

When using high strength composites, compressive strength is 8-20%, and flexural strength is 22-31%. It also has an effect on compressive strength but has a greater effect on flexural strength.

In particular, the strength immediately after pouring (within 3 hours) shows a significant strength improvement when a high strength mixture is used.

This is because when the high-strength mixture of about 8000 (cm 2 / g) is mixed and kneaded, it fills the voids formed between the particles of cement and improves the flowability, reduces the unit quantity and air quantity, and increases the unit volume weight. In addition, slag among the main components of the high-strength mixture proceeds very slowly with water, but exhibits hydration activity in a single-calorie atmosphere. Especially when co-existed with compounds such as strong alkali hydroxide (ROH), weak acid non-silicate (R ₂ CO ₃ , R ₂ S, RF), silicate (R ₂ O, (n) SiO ₂ ) Alkali Activated Slag) causes Alkali Silica Reaction, resulting in initial strength, durability, chemical durability, high strength, rapid hardening, long-term strength, reduction of required quantity, impermeability, low heat of hydration, chemical resistance, freeze-thawing resistance, rebar It is reported that advantageous physical properties have the same advantages in various aspects such as protective action (R: Na, K, Li). In addition, the anhydrous gypsum contained in the high-strength mixture is hydrated with the cement to form Ettringite, so that the initial strength increase and the closest filling by slag have a great influence on the long-term strength increase.

The present invention as described above can be used in a narrow place, the dust generation is significantly reduced, the rebound rate generation of about 5%, the pouring is smooth, there is an effect capable of expressing high strength.

Among the characteristics required in the reinforcing composition in the tunnel construction, the flexural strength property is more important factor than the compressive strength, and in the present invention, the flexural strength was improved by about 30% with the mortar composition.

Claims (3)

Mortar composition for reinforcement to prevent leakage and falling during tunnel construction, cement 30-35%, S1 (size 0.6mm or less): 28-33%, S2 (size 0.6-2.4mm): 25-28%, fly ash 5-10%, high-strength mixture 0.1-5%, high-performance reducing agent 0.1-0.65%, MC: 0.004-0.007% and aluminate-based liquid quickener for reinforcement to prevent leakage and rockfall during tunnel construction Mortar composition. The method according to claim 1, wherein 14.5-17.0% of the unit quantity is kneaded with respect to 100% by weight of the mortar composition and 4-6% with respect to the weight of cement, or 4-6% of the silicate liquid with respect to 100% by weight of cement. Reinforcement mortar composition to prevent leakage, rockfall during tunnel construction, characterized in that shotcreting by adding 10-15% of the payment. In the construction method of reinforcing mortar to prevent leakage and rockfall during tunnel construction, the composition of claim 1 is added to a mixer and stirred, and then pumped into a rota starter. Reinforcement mortar construction method to prevent leakage and rockfall during tunnel construction, characterized by spraying to prevent dust and to improve tunnel excavation speed and work stability.