Hydraulic concrete cracks have become a major concern. The reason for cracks is that the material itself is heated by hydration heat. For example, if fly ash is added to concrete, although it can reduce the temperature rise of water and electric heating, the early strength is relatively low, which limits the quantity of fly ash. At the 15th International Conference on Dams, Norwegian mesolith mixed with micro silica powder in FORRREASS dam and produced good results, which attracted the attention of the participants. After the meeting, Nanjing Academy of Water Sciences undertook the research task of improving the crack resistance of concrete by modifying micro silica powder in the "Seventh Five Year Plan" project.
In 1987, it was proved in the spiral case test of the hydraulic turbine of Fanhou Hydropower Station in Fujian Province that by adding a proper amount of micro silica powder compared with no addition, the cement was saved by 38%, the hydration heat was reduced by 30%, the on-site strength assurance rate was more than 98%, the unit material cost was not increased, and the material cost was saved by 140000 yuan compared with the original design of steel fiber concrete.
It takes 28 days for roads to be opened to traffic with ordinary concrete, and it takes 3 days for early strength concrete to be opened to traffic. Damage to the concrete road surface is inevitable. Repair with conventional methods. It often causes traffic interruption, thus causing serious economic losses. In order to solve this problem, according to foreign advanced experience, Nanjing Academy of Agricultural Sciences designed micro silica powder concrete with early strength and wear resistance in 1986. The actual application shows that the effect is very ideal.
In 1988, the central trunk road in the plant area of Yizheng Chemical Fiber United Company was replaced with prefabricated blocks, which was required to be open to traffic in 12 hours. Nanjing Academy of Water Sciences was invited to design a 12 hour formula to reach 200 # super early strength micro cinnamon poplar concrete, and 100 m3 concrete was poured on the central trunk road of the plant in early September. The results of field sampling test show that the concrete can reach the compressive strength of 25MPA in 12 hours, the abrasion resistance is doubled, and the compressive strength of 37MPA in 24 hours. The concrete can be opened to traffic in half a day. Only the automobile bypass fee during the construction period saved nearly 50000 yuan, and the increased material cost was only 4000 yuan, indicating that its technical and economic effects were very significant.
The runway of the airport requires the use of concrete of more than 80MPA and good wear resistance, that is, the sample can also show its skills.