1.the slurry mix design
High-performance grout compared with ordinary cement paste, the main difference in the ratio of raw materials of low water-cement ratio and multi-component, its purpose is to increase the density of cement slurry, cement slurry to improve the performance, so as to achieve high strength and durability purposes.
Grout specimen using 70.7 × 70.7 × 70.7mm steel model, at room temperature for 24h Chaimo conducted laboratory maintenance. The results showed that: Hu small water-cement ratio, the higher the intensity, with 525 # ordinary Portland cement seven days to reach maximum intensity 78MPa, much higher than the required strength. Change the selection 425 # ordinary Portland cement, seven days to reach maximum intensity 55MPa or more, therefore, the choice of 425 # ordinary Portland cement to meet the requirements.
2.vacuum grouting construction process
(1) Prestressed concrete pore forming tube
Prestressed concrete members in a straight beam bending and U-beams and other fabric reinforcement way, metal bellows tube into the hole in terms of tendons can not meet the
requirements of fabric reinforcement and a U-shaped beam bending small radius, so the use of new a porous material - plastic bellows. Compared with metal bellows, in terms of strength and resistance to corrosion, better protection.
(2) Construction steps
First, the preparatory work
① Check the amount of material, the type is available, whether quality assurance;
② Check the equipment is complete and intact;
③ Check the water supply, power supply is complete, easy to use;
④ Press formula weighing slurry material, reducing agent first dissolved in some water and set aside;
⑤ shown by the various components connection installed.
Second, try to vacuum: the filling valve, exhaust valve are all closed, the vacuum valve find open; start vacuum pump, vacuum gauge readings observed that the degree of vacuum tube, when the vacuum tube is maintained at (pressure as low as possible as well), to stop the pump for about one minute, the pressure can be maintained if the channel can be considered to achieve and maintain the vacuum.
(3) Mixing the slurry
① grout requirements before stirring, add water idle for several minutes, the water was a net, so that the inner wall of the mixer fully wet. The mixed mortar to do to make basic Royal.
② loading: first weighed water, cement, expansive cement, fly ash into a blender, stirred for 2 minutes; the water-soluble reducing agent into the blender, the material was stirred for 3 minutes; grout out after the material should be pumped immediately, otherwise they will be constantly stirred; water must be strictly controlled, otherwise all the water secretion pay more, could easily lead to the top of the pipe there is a gap; not timely use of reduced mobility grout, prohibited the use of increased water ways to increase the mobility of the mortar.
(4) grouting
① was added to the mortar grout pump, the high-pressure rubber tube outlet grout slurry pump play until the slurry concentration and the concentration of the same grout pump, the grout pump turned off, this high-pressure rubber hose terminated to the bore the filling tube, fasten.
② turn off the filling valve, the vacuum pump, when the degree of vacuum reached is maintained at -0.06 ~ -0.09MPa degree value, the pump starts filling, filling valve opened, commencing the injection, when the slurry through the air cleaner, turn off the vacuum pump and pumping valve, open the exhaust valve.
③ The exhaust pipe of a slurry, when the slurry consistency and the consistency of the poured into the same, turn off the exhaust valve, continued filling ~ 2 minutes so that a certain pressure inside the tubes, and finally turn off the filling valve.
(5) cleaning to remove two union vacuuming, remove the vacuum pump; Remove the air cleaner and grout hose, cleaning grout pumps, mixers, valves, air filter and sticky mortar tools.