High performance concrete (abbreviation HPC) is a new type of high-tech concrete. It is a concrete made using modern concrete technology on the basis of greatly improving the performance of ordinary concrete. The following Xiao Bian will introduce you to the performance of high-performance concrete. Let's look at it together.
High performance concrete performance
First, high-performance concrete has excellent self-compacting properties.
In the process of using high-performance concrete, its water consumption is small, but the material after mixing and stirring has the characteristics of good fluidity and high segregation resistance, so the filling performance of high-performance concrete is very good, and the self-compactness is not good enough. Suspected.
The second point is that high performance concrete has good volume stability and extremely low hydration heat.
The volume stability of concrete is mainly reflected in the elastic modulus, shrinkage value and creep, and the amount of temperature deformation after the concrete is used. In the process of using high performance concrete, the use of cement paste has been greatly reduced, and the shrinkage value is less than 0.04% according to the specified mix ratio. Because of the decrease in the amount of water used, its heat of hydration performance also decreases.
The third point is that high-performance concrete has higher strength.
Experiments have shown that the compressive strength of the 28-day high-performance concrete test block has exceeded 200 MPa, and the tensile strength is 100 to 120 MPa. Its strength is much higher than ordinary concrete.
Fourth, high-performance concrete has good durability.
The durability of concrete is mainly reflected in its ability to resist chemical corrosion. Because of the high self-compactness of high-performance concrete, its ability to prevent chemical penetration is also extremely high, so its durability is unmatched by ordinary concrete.
Fifth, high-performance concrete has good fire resistance.
Perhaps many of my friends will think that the use of high-performance concrete water is relatively small and its high self-compacting, its fire resistance will be lower. In actual fact, because the high-performance concrete raw material is added with specific organic fibers, its fire resistance has been improved.
High-performance concrete mix requirements
The mix ratio of high-performance concrete should be determined according to the requirements of the raw material quality, design strength grade, durability, and work process performance of the construction process, through calculations, trial search and hard adjustment. The following provisions shall be complied with when designing the mix ratio:
1. The total amount of cementitious materials for concrete with different strength levels should be controlled. Below C40 should not be more than 400kg/m3; C40 ~ C50 should not be more than 450 kg/m3; C60 and above non-pump concrete should not be more than 500kg/m3, pump Send concrete should not be more than 530 kg/m30 Reinforced concrete structure, the maximum water-binder ratio and the minimum use of cementitious materials in single concrete should meet the design requirements under different environmental conditions.
2. Adequate amounts of mineral admixtures such as fly ash, ground slag powder or magnetic ash should be added to the concrete to improve its durability and improve its construction performance and crack resistance. The amount of concrete should be based on concrete. Performance requirements are determined experimentally and should not exceed 20% of the total amount of cementitious material. When the proportion of fly ash in concrete is greater than 30%, the ratio of concrete to concrete should not exceed 0.45; in prestressed concrete and concrete that is subject to freeze-thaw cycles, the amount of fly ash should not exceed 20%, and pulverized coal should not be used. The carbon content of ash should not exceed 2%. The amount of fly ash should not be greater than 20% for the concrete of concrete exposed to air, and the amount of Portland cement used in cement concrete should not be 240kg.
3. For concrete structures with high requirements for durability, comparative tests on the crack resistance of concrete and cementitious materials should be conducted during test fittings, and concrete raw materials and mix ratios with good crack resistance should be selected.
4. Admixture of additives should be appropriate in concrete, but reliable and stable multi-functional compound admixtures should be selected.
5, concrete under freezing and thawing conditions should use air-entrained concrete. Concrete with a degree of freeze-thaw environment of Grade D and above must be blended with air-entraining agents and meet the requirements for the maximum water-binder ratio and the minimum amount of cementitious material in the corresponding strength class; for concrete in other environmental impact levels, it can also be The addition of air-entraining agents (air content of not less than 4%) improves its durability. The Durability Index (DF) of frost-resistance of concrete shall comply with the current industry standard "Technical Code for Corrosion Prevention of Concrete Structures for Highway Engineering" (JTG/T B07-01). The appropriate air content and air bubble spacing coefficient of air-entrained concrete should comply with regulations.
6. The control of the total alkali content in concrete shall comply with the regulations. The total content of chloride ions in concrete shall not exceed 0.10% of the total mass of cementitious material for reinforced concrete and 0.06% for prestressed concrete.
7, the slump of concrete should be determined according to the requirements of the construction process, when the conditions permit, low slump concrete construction should be used.
The above is a brief introduction for Xiaobian. If you want to know more related information, please continue to pay attention to Qijia Consulting. More exciting consultation, please stay tuned.
Concrete staircase
Torque Hinges,Constant Torque Hinge,Adjustable Torque Hinge,Torque Door Hinges
Ningbo Hengchieh Locking Technology Co., Ltd. , https://www.hengchieh.com