What are the technical measures to eliminate cracks in Grout?
The Grout material of the beam node of the beam is carried on the principle of high and low first, which is to pour the Grout material of high strength grade first, and then pour the Grout material of low strength grade. At the junction of the Grout materials, the wire mesh is set up so that the operator can easily control the casting range of Grout.
2, high strength grade of conventional of Grout material mix adjustment, namely under the condition of satisfy the intensity and the pumpability, try to reduce dosage of cement, sand ratio, increase the gravel content, reduce slump, reduce water consumption, and the dosage of powdered coal ash and admixture also make corresponding adjustment, to try to reduce Grout material hydration heat temperature, reduce because of the different strength grade Grout material shrinkage or Grout material cracks caused by temperature difference between inside and outside.
3. The Grout material of the beam is used in the secondary pouring method, which means that the Grout can be cast again before the final coagulation of the Grout material, especially the liang wish node, in order to increase the density of the Grout material and reduce the shrinkage.
4. Increase the horizontal structural reinforcement on the side of the beam prone to fracture, and improve the crack resistance of the beam.
5, strict control of Grout material mixture slump, in the field of every car Grout material, slump test, found abnormal, immediately return, and make records, prevent caused by Grout material slump through large shrinkage crack.
Because the coal ash has chemical activity, particle morphology and micro aggregate effect, thus adding fly ash can reduce the water requirement of Grout material, improve the liquidity of Grout material mixture, water retention and pumpability and plaster, such as performance, reduce bleeding, segregation and slump loss, extension of the Grout material, setting time, reduce the hydration heat of Grout materials, improve resistance to chemical attack of the Grout, impermeability, inhibit JianJiLiao reaction, etc.
1. Work; When the coal ash is equal to the same amount of cement, it can reduce the unit water consumption of the Grout material and improve the pump ability, hydrogenation and extension of the pump. The degree of water consumption of the unit depends on the quality of fly ash, the replacement rate of cement, the mix ratio of Grout material and the granularity of fine aggregate.
2. Strength; The Grout material with fly ash and the cement is replaced, the early strength is somewhat reduced, and the strength of the long period is increased. The quality and replacement rate of fly ash, the quality of cement, water ash ratio of Grout material, curing condition and age are all influences on the strength growth of the long period.
3. Anti-permeability; Of fly ash Grout material and after adding fly ash Grout material, compared to the early resistance and permeability is low, and the permeability resistance of long age has a lot to improve, so should pay special attention to in the construction to strengthen the early curing of mixing fly ash Grout material, in order to prevent the Grout material early cracking.
4. Durability; With equal strength and air content compared to the same base Grout material, mixing fly ash Grout material freezing-thawing resisting ability basic quite, but the carbon content of fly ash (ignition loss) is high, freezing-thawing resisting of Grout material has a great influence and carbonation resistance.
5. Hydration heat; In the process of hardening, the speed of hydration heat will be reduced, and the total amount of hydration heat will be reduced.