Reinforced Concrete Alkali Resistant Glass Fiber Alkali Resistant Glass Fiber Chopped Yarn

 

Alkali resistant glass fiber is a kind of rib material used to strengthen concrete. Its advantages are alkali resistance, corrosion resistance, impact resistance, tensile strength, bending resistance, frost resistance and crack resistance. It has strong designability and can replace asbestos and steel. Concrete is a brittle material. Adding alkali resistant glass fiber can effectively improve its mechanical properties. Alkali resistant glass fiber has become a new material widely used to strengthen road concrete due to its advantages. In order to ensure the reinforcement effect of alkali resistant glass fiber and the safety and reliability of the structure, it is necessary to keep the glass fiber in the concrete with long-term strength and toughness. However, the cement-based materials used in the project will corrode the alkali resistant glass fiber, damage the performance stability of the material and reduce the strength of the material.
characteristic
It is characterized by good alkali resistance, can effectively resist the erosion of high alkali substances in cement, strong grip, high elastic modulus, impact resistance, tensile strength and bending strength, strong incombustibility, frost resistance, temperature and humidity change resistance, excellent crack resistance and impermeability, strong designability and easy molding. It is a new green environmental protection reinforcement material widely used in high-performance reinforced (cement) concrete.
It is widely used and has good performance in applications requiring "high temperature resistance, alkali corrosion resistance and acid corrosion resistance".
Analysis of raw materials and curing conditions
Cement: grade 32.5 ordinary portland cement meeting the requirements of GB 175-99 produced by a cement plant.
Alkali resistant glass fiber: the alkali resistant glass fiber produced by a glass fiber company is used in the test. The standard of the fiber is: the length is 12mm, the tensile strength is 2480mpa, the zirconium content is about 16.7%, and the alkali resistant glass fiber is about 2.7g in 1cm.
Powdered carbon ash and aggregate: the adopted powdered carbon ash is class II material of Xinjiang power plant, which meets the provisions and quality requirements of GB 1596-91; For fine aggregate, it is mainly river sand, and the fineness modulus MX of these river sand is 2.7. As for coarse aggregate, it is mainly composed of artificial crushed stone with a diameter of no more than 20mm.
In the standard curing process, the concrete specimen shall be placed in water for curing immediately after the formwork is removed, and the water temperature shall be controlled at about 20 ºC. For thermal curing, it is usually carried out within 3 days after the standard curing. It is mainly heated slowly with different gradients of temperature. When the temperature reaches 80 ºC, it starts to maintain constant temperature until the test age is reached.
Analysis of corrosion inhibition effect of active admixture
Based on the test observation, if a certain amount of alkali resistant glass fiber is directly put into the mortar, the fiber will suffer from severe corrosion and eventually lose its compressive performance, which will have a negative impact on the overall performance of cement to a large extent. In practice, by adding the active admixture to the cement mortar for test operation, the following conclusions can be drawn from the test results, that is, during the application of the active admixture, it can adversely affect the alkali resistant fiber inhibition, and even cause it to suffer serious corrosion.
After the addition of fly ash, the net increased bending resistance of alkali resistant glass fiber mortar will decline in a short time, and then it will always be in a relatively stable state of good bending resistance, which indicates that the alkali solution of cement mortar at this stage rarely produces corrosion to alkali resistant glass fiber; When the amount of fly ash is more than 30%, the bending resistance of alkali resistant glass fiber is basically stable. However, silica fume has high activity and can be hydrated in a short time. Therefore, although the strength of mortar mixed with silica fume has been decreasing, the corrosion of alkali solution to alkali resistant glass fiber can be suppressed to a certain extent. The specific performance is that the flexural strength of mortar mixed with silica fume has been at a relatively stable level from 3D after the compressive strength decreases to 11d. However, because the cost of adding silica fume to mortar is relatively high, fly ash will be added in large-area road construction to reduce the construction cost.
Method of preparing alkali resistant glass fiber concrete for road
The addition of fly ash can effectively inhibit the corrosion of alkali resistant glass fiber in the hydration process of cement, but the test pieces with small capacity are used. In actual road construction, a lot of concrete is required, so it is difficult to grasp the amount of fly ash to be mixed. Here, the method of preparing alkali resistant glass fiber road concrete is the closest packing method.
Design idea of the most compact packing method
Based on the research of traditional mix proportion design theory, it can be seen that the early strength of concrete will be reduced when a large amount of fly ash is added. To solve this problem, the closest packing method can be adopted. The so-called closest packing method is actually to take the aggregate as the most basic main framework in the design process, and reduce the amount of aggregate by continuously increasing the cement slurry. It should be noted that the reasonable proportion of aggregate and sand cannot be changed during this process. When the cement slurry quantity is fixed and the water cement ratio is changed, the quality of cement slurry will also change. The advantage of the most compact stacking method is that a large amount of aggregate is used as the support framework, and the proportion of sand and stone in the aggregate is strictly controlled, so as to effectively improve the reliability of concrete application. After adding proper fly ash, it can not only effectively exert the chemical effect of the concrete itself and continuously strengthen the compactness of the microstructure, but also effectively increase the physical compactness of the concrete itself, so as to suppress the corrosion of alkali resistant glass fiber
Performance analysis of alkali resistant glass fiber concrete for road
According to the design method of the most compact packing method, two kinds of alkali resistant glass fiber concrete are prepared. During the application of the most compact packing method, the splitting pressure ratio of the alkali resistant glass fiber concrete prepared is between 0.14 and 0.182, and the rising range of the splitting pressure ratio in the late hydration period is larger than that in the early period. For the general concrete splitting ratio, it is in the range of 0.045 ~ 0.071, which indicates that the alkali resistant glass fiber concrete prepared by this method has better flexural performance, and can effectively meet the flexural requirements of the current road, especially the subgrade.
(1) Mechanical properties
In general, concrete aggregates are mainly used in the most compact stacking method and as the basic framework. When more than 33% fly ash is added, its strength will rise to about 28.9mpa in the next three days, which effectively meets the early strength demand of concrete. After the addition of fly ash, the secondary hydration will occur. At this time, the absorbed water will be poured out to effectively protect the subsequent hydration of cement and the later strength of concrete structure.
(2) Shrinkage property
The alkali resistant glass fiber in the concrete is evenly distributed, which can effectively cut off the pores and greatly reduce the number of pores, so as to reduce the pressure of pores and reduce the shrinkage value of the concrete itself; In the process of curing, fly ash can effectively reduce the shrinkage value of concrete. The shrinkage performance of concrete is relatively good, which can prevent the cracking of the road, improve the impermeability of the road, and improve the frost resistance of the road. This is very consistent with the climate characteristics of Xinjiang, and can be further applied and popularized.
summary
Based on the above analysis, it can be seen that adding an appropriate amount of alkali resistant glass fiber to the concrete during the construction of the road project can improve the flexural strength of the concrete itself, improve the impermeability and wear resistance of the concrete structure Road, so as to prevent serious cracking disease of the road. It is widely used in the process of modern highway construction.