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wet shotcrete spray process

Views:10     Author:Site Editor     Publish Time: 2018-10-16      Origin:Site

1. Raw material selection and control

The coarse aggregate should be washed with water after 0.5mm sieve before mixing; in order to reduce the shrinkage crack, the fine aggregate should be medium and coarse sand, the fineness modulus is more than 2.5, and the sieve is 0.5mm before mixing.

2, the determination and selection of the mix ratio

For the water seepage or dripping section (such as K137+910-920), the T1 type is incorporated, and the ratio is c:s:G:w:TJ=1:2:2:0.45:0.04. Admixture speeding agent 4‰ For the rock surface with large local water seepage or dripping water, change the mixing ratio. Only use coarse aggregate without coarse aggregate, add 6% quick-setting agent, spray 2cm thick first and then spray according to normal mix ratio. Dry or wet the wall (such as K137+920-930) with a ratio of C:S:G:W:EA-c:lT-G=1:2:2:0.45:0.12:0.8%, admixing speed Coagulant 4%.

3. Control of the mixing process

Strict control of water-cement ratio, admixture and water must be accurate. The feeding sequence and mixing time are: coarse, fine aggregate, cement, admixture (stirring 90S), one water (stirring 12Os), one discharge.

4, rock surface treatment and water seepage treatment

Rock surface treatment. Carefully check the size of the excavation surface, remove the loose rock, and excavate excessively excessive local treatment; clean the surface with high pressure wind or water, clean the dust and debris on the excavation surface; Sign. Water seepage treatment. Do a good job of drainage drainage: install soft spring blind tube, a total of two types of blind tubes are arranged, one is a circular blind tube every 5m, and the end of the blind tube at both sides of the side wall is drained. The hole, the second is to set a local blind pipe at the concentrated water outlet point or the surface watering point to connect with the adjacent ring blind pipe.

5, the spraying step

① Before the injection, adjust the water-cement ratio according to the degree of moisture on the rock face.

② The jet should be segmented, divided, and divided. The first wall is arched and the bottom is sprayed upwards. The nozzle needs to make a uniform clockwise spiral rotation on the rock surface, and a half turn in half. The diameter of the spiral is about 20~30cm, or it is moved forward by S-shaped.

③ The length of the section should not exceed 6cm when spraying, and the division should be first down and then on, and the size of the block is 2m*2m.

④ The distance between the nozzle and the rock face is lm, the nozzle is perpendicular to the surface to be sprayed, and slightly inclined to the part just after the injection (inclination angle is about 80°). The rock face depression should be sprayed first and sprayed more, and the convex part should be sprayed and less. spray.

shotcrete machine

6, wind pressure and water pressure control

Since the length of the conveying pipe is 40m, the adjusting wind pressure is 0.45-0.7Mpa, the water pressure is 210N/cm2, and the water pressure of the water supply system should not be more than 40N/cm2. To ensure the water pressure of the water supply is stable, the pressure water tank is used.

7, the determination of the thickness of the spray

The thickness of one shot is 6cm for the vault and 8cm for the side wall, for the seepage or dripping section. Spray a layer of 2cm thick aggregate concrete first, then spray the concrete to the design thickness.

8. Interval control of stratified injection

At 15℃~ 25℃, using 8604 liquid quick-setting admixture, it is advisable to re-spray after 30 min.

9, maintenance

After the sprayed concrete is finally condensed for 1 hour, it is sprinkled and maintained to keep the spray surface moist, and the curing time is not less than 7d.

 


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