What is fair-faced concrete?

It is easy for us to understand fair-faced concrete as a structural material, which is also used in most buildings in China. But in fact, concrete is also a decorative material with rich connotation and expressive force, and it also has good decorative expressive force. Without secondary decoration, it is decorated directly with its plain surface, achieving a modern and simple decoration technique, which can even be said to be a powerful expression of architectural art-fair-faced concrete with excellent decoration effect. ?

Fair-faced concrete is widely used in Japan and the United States, but it is different from ordinary concrete we imagined. The surface is very smooth and angular, and there is no external wall decoration. Just coat one or two layers of transparent protective agent on the surface, and it will be very natural and solemn. The clean water wall is the purest, without any unnecessary impurities, and there is a feeling of returning to nature.

Fair-faced concrete is a kind of concrete that directly uses the natural texture of concrete as decorative effect. Can be divided into ordinary fair-faced concrete, decorative fair-faced concrete and decorative fair-faced concrete. Fair-faced concrete is the most advanced form of concrete material. This process can be said to be the sublimation of concrete pouring, and the surface texture of concrete should be predicted at the beginning of concrete pouring. Fair-faced concrete is also a popular decoration technology at present. Fair-faced concrete takes the decoration of plain wall as the most authentic artistic expression, showing the most beautiful feeling and the taste of "plain face facing the sky".

Fair-faced concrete first emerged in Europe in the 1930s and prevailed in Japan in the 1970s. By the end of 19, more and more architects have adopted this technology, and world-class architects such as I.M. Pei and Tadao Ando have adopted fair-faced concrete in their designs. For example, the National Centre for the Performing Arts in Japan, the Pulitzer Foundation for Consciousness, the Prehistoric Museum in Paris, the Rein Museum of World Culture, the Ted Museum of Modern Art in London, the Museum of Modern Art and Architecture in Stockholm, and the Milan Opera House in Italy all use fair-faced concrete. ?

However, in China, fair-faced concrete is still a new construction technology, and few units really master this kind of architectural design and construction. Fair-faced concrete is different from ordinary concrete construction because it requires high construction technology. The cement used shall come from the same batch of the same manufacturer as far as possible; The proportion of cement used in each kind of concrete should also be very strict and consistent; Every time you hit the cement, you should block it. Compared with the previous color, you can continue to hit it only after the instrument has passed the test. The concrete must be vibrated evenly. The construction temperature is very strict, which is suitable for construction from April to June. It is also very important for the on-site management of construction personnel, and every working procedure should be meticulous; In particular, the formwork for concrete construction is very strict and needs to be designed and customized according to the building. Most of the templates used are disposable and the cost is high. It is best to use imported formwork (such as corners, beam-column joints, etc.). ) in important parts, at the same time, add sealing strips to prevent slurry leakage. The tie rod for fixing the formwork also needs plastic buckles, so as to facilitate formwork removal and reduce the damage to the concrete surface.

Key points of fair-faced concrete construction technology

(1) Key points of construction technology

The technical points of fair-faced concrete construction are as follows:

1. Concrete mixture ratio design and raw material quality control The cement mixture ratio used for each concrete should be strictly consistent; Fresh concrete must have excellent workability and cohesiveness, and stratification and segregation are absolutely not allowed.

2. Formwork for fair-faced concrete construction is very strict, and it needs to be designed and customized according to the building, and most of the formworks used are disposable, so the cost is high. It is best to use imported formwork for important parts such as corners and beam-column joints; Formwork must have enough uniformity, and it is not allowed to deform under the lateral pressure of concrete, so as to ensure the uniform geometric dimensions and cross section of the structure and prevent slurry leakage. There are also high requirements for template materials, such as smooth surface, high strength, corrosion resistance and certain water absorption. For the joints of the formwork and the bolts for fixing the formwork, the joints shall be tight and sealed to prevent slurry leakage; Metal caps or plastic buckles are also needed for the tie rods that fix the formwork, so as to facilitate the form removal and reduce the damage to the concrete surface.

3. If fair-faced concrete is not properly maintained, micro-cracks will easily appear on the surface due to water loss, which will affect the appearance quality and durability. Therefore, the exposed concrete surface should be covered with adhesive film or sprayed with curing film in time for moisture maintenance.

(2) The requirements of fair-faced concrete

1. Technical requirements for raw materials of fair-faced concrete

(1) cement: with high activity, stable quality, low alkali content, good adaptability and uniform color, silicate or ordinary portland cement is selected;

(2) Aggregate: well graded, consistent in color, specification and origin. Coarse aggregate is broken pebbles, with needle-like particle content less than 8%, mud content less than 0.8% and no sundries; Fine aggregate is medium-coarse sand with fineness modulus not less than 2.3, silt content less than 2% and silt content less than 0.6%;

(3) Mineral admixture: mainly L-grade fly ash and $75-grade granulated blast furnace slag, but the origin and specifications should be fixed, and high-calcium fly ash is prohibited;

(4) Admixture: water reducing rate is greater than 15%, and air content is 2l%. Do not change the color of the benchmark concrete.

2. Technical requirements for transportation, pouring and finished product maintenance of fair-faced concrete mixture

(1) The vehicle scheduling is accurate and reasonable, so as not to stop; Slump was measured by car, and the slump was18020 nun;

(2) The initial setting time of concrete should be controlled at 8- 10 hour, so as to ensure that there is no cold joint during concrete pouring;

(3) The mixture has good workability and working performance during transportation, pouring and molding. According to the changes of water content, temperature, transportation time and slump loss of sand and gravel, the concrete mixture ratio is fine-tuned.

(4) The formwork shall be removed as late as possible (the time of formwork removal depends on the temperature change), and a special person shall be responsible for the early curing of concrete (the curing time shall not be less than 14d), so as to keep the concrete surface moist all the time, and the surface covering shall not directly cover straw mats or straw bags, and shall not cause permanent color pollution to the concrete surface.

When decorating, there will be various styles of design, which will make people see things in a blur and make up their minds. After reading the introduction of fair-faced concrete, have you been attracted by its unique natural beauty? Original ecology, simplicity but not simplicity, minimalist style, industrial style and even Nordic style can be easily controlled. I want to decorate with fair-faced concrete, but I'm worried that I can't make it shine. Give it to us. After several years of development, Lanbao provides creative elements, realizes the connection between materials and buildings, and promotes the development of fair-faced concrete with the ecological concept of green, energy-saving and environmental protection.

The significance of developing fair-faced concrete;

Fair-faced concrete is a veritable green concrete: the concrete structure does not need decoration, and chemical products such as coatings and finishes are omitted; Conducive to environmental protection: the fair-faced concrete structure is formed at one time, and it does not need to chisel, repair and plaster, which reduces a lot of construction waste and is conducive to environmental protection;