What are the properties of concrete, such as high performance concrete and low strength concrete

Summary. The difference between high-performance concrete and ordinary concrete is:

What is high-performance concrete and what are the differences between it and ordinary concrete?

The difference between high-performance concrete and ordinary concrete is:

1.High-performance concrete is a new type of high-tech concrete, which is made of fly ash, expansion agent, silica fume and other materials.

2.The material used in ordinary concrete is a concrete superplasticizer, which can change the durability of high-performance concrete and make the concrete withstand the test for a longer time.

High-performance concrete is a new type of high-tech concrete, which is made of concrete using modern concrete technology on the basis of greatly improving the performance of ordinary concrete.

3. The service life of high-performance concrete is long, and for the special parts of some special protection projects, it is not the strength of the concrete that controls the structural design, but the durability. The ability to make concrete structures work safely and reliably for more than 50 100 years is the main purpose of high-performance concrete applications.

4. High-performance concrete has high volume stability, that is, concrete should have a low heat of hydration in the early stage of hardening, and a small shrinkage deformation in the later stage of hardening.

To sum up, high-performance concrete is concrete that can better meet the requirements of structural function and construction technology, which can maximize the service life of concrete structures and reduce the cost of projects.

There are three properties of concrete, which are as follows:

1. Impermeability

Impermeability refers to the ability of concrete to resist pressure water penetration.

2. Frost resistance

The frost resistance of concrete refers to the ability of concrete to maintain its strength and appearance integrity during multiple freeze-thaw cycles in the use environment.

3. Erosion resistance

The erosion of concrete by environmental medium is mainly the erosion of cement stone, usually soft water erosion, acid, alkali and salt erosion.

Requirements and functions of concrete:

1. Function. In concrete, sand and stone play the role of skeleton and are called aggregates; Cement forms a cement slurry with water, which wraps around the surface of the aggregate and fills its voids. Before hardening, the cement slurry plays a lubricating role, giving the mixture a certain workability and facilitating construction.

After the cement slurry hardens, the aggregate is cemented into a solid whole.

2. Requirements. The technical properties of concrete are largely determined by the properties of the raw material and its relative content. At the same time, it is also related to the construction process.

Therefore, it is necessary to understand the nature, function and quality requirements of its raw materials, and reasonably select raw materials, so as to ensure the quality of concrete.

High Performance Concrete (HPC) is a new concept of concrete proposed by some developed countries based on the durability design of concrete structures in the late 80s and early 90s of the 20th century, which takes durability as the primary design index, and this kind of concrete has the potential to provide more than 100 years of service life for infrastructure projects. Different from traditional concrete, high-performance concrete is considered to be the most comprehensive concrete in the world due to its high durability, high workability, high strength and high volume stability and many other excellent characteristics, so far it has been used in many important projects, especially in bridges, high-rise buildings, harbor buildings and other projects to show its unique advantages, in the safe use of the project, economic rationality, environmental conditions adaptability and other aspects of the obvious benefits, so it is accepted by scholars from all over the world. It is considered to be the future development direction of concrete technology.

1. Background of high-performance concrete.

Although traditional concrete has been around for nearly 200 years and has undergone several big leaps, today it faces an unprecedented challenge:

1) With the development of modern science and technology and production, the construction needs of various ultra-long, ultra-high and super-large concrete structures, as well as major concrete structures used in harsh environments, such as high-rise buildings, cross-sea bridges, submarine tunnels, offshore oil production platforms, nuclear reactors, toxic and hazardous waste disposal projects, etc., are increasing. These concrete projects are difficult to build, the use environment is harsh, and the maintenance is difficult, so the concrete is required not only to have good construction performance, but also to have good durability and long service life.

2) Since the 70s of the 20th century, many industrialized countries are facing the aging of some reinforced concrete structures, especially the bridges built in the early years, and need to invest heavily in maintenance or renewal. In 1987, a report by the National Bureau of Materials Consulting pointed out that among the 10,000 bridges in the United States at that time, about 10,000 were in varying degrees of damage, some of which were less than 20 years in use, and the number of damaged bridges increased by 10,000 every year.

In 1991, in a report to the U.S. Congress, "The State of National Highways and Bridges," it was stated that $91 billion would be needed to repair or replace existing defective bridges; If the repair process is delayed, the cost will increase to $131 billion. The total number of existing concrete projects in the United States is about $6 trillion, and the annual cost of repairs is as high as $30 billion.

In Canada, the total amount of infrastructure work to repair deteriorating damage is estimated at $500 billion. In the United Kingdom, the survey counted 271 engineering deterioration and failure examples, including carbonization corrosion accounted for 17, environmental chloride corrosion accounted for 33, internal chloride corrosion accounted for 5, concrete frost corrosion 10, concrete abrasion 10, concrete alkali-aggregate reaction damage 9, sulfate chemical corrosion 4, and other infrequent corrosion damage 7.

High-performance concrete is a new type of high-tech concrete, which is made of concrete using modern concrete technology on the basis of greatly improving the performance of ordinary concrete, and is based on durability as the main design index, and the following key properties are guaranteed according to different use requirements: durability, construction, applicability, strength, volume stability and economy.

It is divided into ordinary concrete, high-strength concrete (greater than C50), impermeable concrete, pumped concrete, antifreeze concrete, freeze-resistant concrete, large-volume concrete, vibration-free concrete (self-leveling concrete), dry hard concrete, and high-performance concrete.

Answer]: a, envy lead b, c, d

Textbook, pp. p67-p69

Properties of high-performance concrete: 1High durability; 2.Strength; 3.High working performance; Selling Bureau 4High volumetric stability.

What is the specific content of the characteristics of <> high-performance concrete, the following Zhongda Consulting will answer for you.

High-performance government refers to the use of ordinary raw materials, conventional construction technology, through the addition of admixtures and admixtures to prepare with high workability, high strength, high durability of the comprehensive performance of the government. Specifically:

1) The mixture is high plastic or fluid, pumpable, non-segregating, and is easy to pour and compact;

2) The volume is stable during and after condensation and hardening, the heat of hydration is low, no micro-cracks are produced, and the creep is small;

3) It has high impermeability. Among them, high workability is the primary condition that high-performance government must have, that is, high fluidity, high separation resistance, high gap passability, high filling, high compactness, and high stability; And at the same time, it has the technical and economic rationality of low cost. At present, high-performance government has been widely used in the engineering practice of developed countries, and China is still in the initial stage of experimental research and popularization.

High-performance concrete has rich technical content, although the industry has different definitions and interpretations of high-performance concrete, but both agree that the basic characteristics of high-performance concrete are designed according to durability, to ensure that the mixture is easy to pour and dense molding, no or as little as possible cracks caused by temperature and shrinkage, hardening has sufficient strength, the internal pore structure is reasonable, with low permeability and high resistance to chemical erosion. Starting from China's current and preferred and on-site test mixing, the time loss of concrete slump is tested to meet the standard design and construction level, and the concrete with a strength grade of C50 or more is defined as a requirement to meet the high constructability requirements of engineering applications, so as to formally determine the selected high-strength concrete. Moreover, with the needs of engineering construction, the frequency of high-performance concrete is getting higher and higher, and the importance of strict quality control is also increasing.

<><1. What are the characteristics of high-performance concrete

1. It has high impermeability and certain strength, among which medium and low strength is more common, and high strength will be less than that of closure.

2. It has good workability, so that the high-performance concrete is not easy to segregation, delamination and other phenomena in the forming process, so that the model can be easily filled.

3. The service life is relatively long, and it can generally be used for about 50 to 100 years.

4. The volume stability is relatively high, so that the heat of hydration of the concrete in the early stage of hardening becomes lower, and the shrinkage deformation of the concrete in the later stage of hardening will become smaller.

Second, how to properly maintain high-performance concrete

1. The curing of high-performance concrete generally needs to be divided into two stages for curing, namely initial curing and wet curing, in which the initial curing stage starts immediately after the high-performance concrete is poured, and the wet curing stage can only start after the final setting of high-performance concrete. Different maintenance stages will take different maintenance methods, so you must understand them clearly in advance.

2. If the high-performance concrete is cured in a hot environment, the surface of the concrete should be watered to reduce its internal temperature, and the surface should be covered with a layer of material with good thermal insulation. Note: When watering, it should be done when the ambient temperature is relatively low.

3. If the high-performance concrete is naturally cured in a low temperature environment, the surface of the concrete should be covered with a layer of opaque plastic film, or a layer of curing liquid should be sprayed directly, and the surface should not be watered. In addition, when the construction of high-performance concrete is completed, it should be covered with hay, plastic film, etc., so as to effectively prevent the concrete from freezing.

The above is a detailed introduction to the characteristics of high-performance concrete and how to properly maintain high-performance concrete, I hope it will help.