Epoxy resins and their application techniques and products have long been widely used in the field of civil engineering and construction, and over the last thirty years have accumulated and withstood data from long-term application durability tests, on the basis of which many new uses have been promoted and developed. The following focuses on the application of epoxy resins in building materials coatings, adhesives, epoxy cement mortars, concrete reinforcement, etc.
- Epoxy resin architectural coatings
Due to the application of epoxy resin coating, a series of reforms have been caused in the construction works.
- Sanitary ware coating
The cement sanitary ware manufactured on site with cement mortar, or prefabricated, such as bathroom bathtubs, vanity tops, bathroom floors, walls, etc. are coated with epoxy resin coating on their surfaces, as the epoxy resin coating can have good adhesion with the porous cement surface, so that it is isolated from air, water, sunlight, external corrosive dirt, salt, chemical detergents, etc., and the coating surface is bright and can be The surface of the coating is bright and can be made into different vibrant colors. The coating film has excellent resistance to water, general media corrosion, abrasion, heat and durability. It can replace tiles or enamel products and is easy to maintain.
With the development of rural buildings in China, the sanitary equipment in farm houses has also increased. The use of cement products instead of ceramic products with epoxy resin enamel paint is an important application in the current epoxy resin building coatings.
In principle, solvent-based or solvent-free epoxy resin coatings can be applied
- Kitchen coatings
Kitchen wainscoting, flooring, cooktops and sinks need to be impermeable, resistant to general acids and alkalis, and resistant to water, heat and oil. And it should be easy to clean. Epoxy resin coating is the most suitable for these performance requirements, can effectively protect the cement surface and bright and beautiful, bright and pleasant, can prevent the adhesion of water, mosquitoes, flies, cockroaches, insects and microorganisms and other erosion effect.
- Epoxy resin floor coating
In recent years, the development of polyvinyl alcohol polymer cement floor, if the surface is coated with epoxy resin self-levelling floor coating (commonly known in China: porcelain paint coating or color paint coating) for the cement floor covering layer, can make this cement floor has the effect of glass tile. In industrial buildings, such as pressed workshops, hospitals, pharmaceutical workshops, purification workshops, office buildings, etc., this type of coating is currently used, and its durability is at least ten years without maintenance.
Epoxy resin coating, coated on the wooden floor its wear resistance and durability greatly exceeds the ordinary floor paint, and polyurethane coating as good. Suitable for coating floors in public places. For example, wooden floors in gymnasiums, meeting rooms, hotels, etc.
- Corrosion resistant coatings
China’s epoxy resin coating for concrete storage tank wall of the protective coating research and application has nearly forty years of history. Concrete storage tanks have more advantages than steel tanks, in the construction of 500 ~ 5000 cubic meters of large concrete storage tanks, the project cost and technology are cheaper than steel and easy. China built a large number of reinforced concrete tanks in the mid and late 1960s, with a volume of 500 to 5000 cubic metres respectively for underground, semi-underground or cave-type structures. Its concrete tank wall using a modified amine curing agent formulated without fusing agent epoxy resin coating, as well as with phenol closed ketone imide moisture-curing type of bad oxygen resin coating, to adapt to the characteristics of the construction in a humid environment and confined space. These storage tanks, storing petroleum crude oil and its oil products, epoxy resin coating for aviation gasoline, aviation paraffin pollution of the index – gum content to achieve the storage of aviation gasoline indicators, after more than thirty years of use of good results. The volume of small concrete oil tanks with epoxy resin coating for oil resistance and impermeable layer in 50-100 cubic meters is widely distributed in the storage of agricultural oil in rural areas and oil storage pools in gas stations, which not only saves steel, but also is convenient to construct, and the practice for many years proves that epoxy resin coating is a good oil resistant coating.
Epoxy resin coating is not only resistant to petroleum, but also resistant to vegetable oil. Concrete pools and tanks painted with non-toxic curing agents can store cooking oil, and the manager’s chemical test and biological toxicity test prove that they are non-toxic.
- Concrete pipe coating
Every year, a large number of concrete pipes are installed as water, sewage and other fluid pipelines, only in 1995-1998, the country laid a variety of calibres of concrete pipes for water, agricultural drainage up to 323,800 km, in order to reduce fluid friction, reduce fluid and suspended matter on the wear and tear of the pipe body, to achieve energy saving, and leakage prevention purposes. Many pipelines to be coated with epoxy resin asphalt coating.
- Oil pipeline, gas pipeline heavy anti-corrosion epoxy resin powder coating
China’s major projects in the development of the west, the first major project is the “West-East gas transmission”, “West-East oil transmission” project, are used is a large diameter seamless steel pipe (length: 12 meters, diameter: 1.1 meters), long distance laying, while buried deep in the ground The long-distance laying of seamless steel pipes (length: 12 metres, diameter: 1 metre), which are buried deep underground, requires up to 30 years of corrosion protection. The inner wall of the steel pipe is coated with high polymer reduction (less) resistance (force) coating; the outer diameter of the steel pipe is coated with hot-melt epoxy resin corrosion prevention powder coating, according to the technical requirements of the coating thickness: 300μm ~ 400μm. “West-East gas transmission” main line is 4300 km long, calculated according to this thickness, the need for heavy anti-corrosion epoxy resin powder coating of about 6000 tons; the length of the branch pipeline (the diameter of the pipeline is smaller than that of the main pipeline) is longer than that of the main pipeline. At present, China has made a breakthrough in the formulation and manufacturing technology of heavy anti-corrosion epoxy resin powder coating, special epoxy resin and curing agent can be mass-produced, thus making the steel oil and gas pipeline special heavy anti-corrosion epoxy resin powder coating to achieve localization.
- Adhesives for construction
Epoxy resin is a kind of structural adhesive with excellent performance, about 5-15% of the total annual output of epoxy resin in the world is used as adhesive.
From 1946, Ciba developed the epoxy resin adhesive with the brand name of Araldite. Since the 1950s, the epoxy resin adhesive has effectively solved the bonding problems between new and old cement mortar layers and new and old concrete layers, as well as completely solved the influence factors such as moisture, humidity and alkaline substances at the interface of the bonding layer, thus it has been applied in large quantities and opened up a new and largest market for epoxy resin. Epoxy resin new largest market. In Japan, the technology and market for epoxy resin construction adhesives was rapidly developed from the 1960s onwards and is used in almost all areas of construction and cement products.
China has been using epoxy resin adhesives in construction projects since 1966. After more than 30 years of practical application and examination, it has proved the bonding effect and the reliability of the structural role of epoxy resin adhesives in construction projects. Nowadays, epoxy resin adhesives are widely used to bond and repair concrete elements, protecting the steel reinforcement from corrosion in the cracked parts of concrete damaged by stress cracking or vibration and playing a mechanical structural role. The use of epoxy resin adhesives to bond and strengthen various prestressed reinforced concrete products, such as cement concrete dams, gates, bridges, concrete pressure pipes, electric culverts, railway concrete sleepers and other prefabricated parts of the repair, due to cracks or broken parts in production or use, to improve the product qualification rate and ensure quality, become an indispensable and important material.
In construction projects, epoxy resin adhesives can replace rivets, nails, welding and other structural jointing processes. It can be used to bond various metal products, natural stone, marble, man-made plates and other metal and non-metal products, to achieve bonding with concrete, to withstand gravity and fast curing at the bonding point and to meet the requirements of seam-free press fitting.
Requirements for epoxy resin adhesives, in technical performance, in addition to mechanical properties and other basic conditions, should also have a good viscosity at room temperature, and in the vertical direction, the top of the construction of the glue does not flow (that is, with thixotropic effect); high, low temperature curing speed and curing degree in the environment to basically the same; wet air and wet base surface can be cured (water-based); low or non-toxic; non-flammable or Non-combustible (solvent-free or less solvent), easy to use in large quantities, easy to operate, easy to clean.
The domestic construction epoxy resin adhesive has a variety of products marketed, such as: epoxy resin type building structure adhesive, general type building structure with anchor adhesive, high strength building structure with anchor adhesive, cement crack grouting adhesive, etc. However, with the development of China’s construction projects, the existing commercialized epoxy resin construction adhesives cannot yet fully meet the new technical requirements. Therefore, the continuous development of epoxy resin adhesives with various technical requirements for construction projects is a requirement of the market, which can also bring benefits and reputation to enterprises.
The epoxy adhesives used in construction projects can be basically divided into several categories.
- Concrete “whole project” bonding
Large cement concrete projects, such as: bridges, tunnels, dams, reservoirs, high-rise buildings, docks, deep-sea projects, offshore oil fields and other projects, the design requires the connection between the cement concrete components, so that the structural engineering becomes a whole, in order to ensure the mechanical stability. In engineering, these constituent members are prefabricated and even cast-in-place ones cannot be poured into a massive whole in one go. The problem of improving and solving the integrity of the connecting parts between concrete is therefore an important issue in concrete engineering.
The bonding strength of newly mixed cement mortar and concrete to the hardened cement mortar and concrete surface is very low, the bonding layer is not durable, and the bonding layer will soon be detached. The study showed that the bonding between the hardened cement mortar and concrete surface was carried out with epoxy resin adhesive, and then the bonding strength and tensile strength were tested, and under stress, the cement mortar and concrete layer was pulled off while the adhesive layer was not. This shows that the strength of the epoxy resin adhesive layer exceeds the tensile strength of the cement and concrete material and that the adhesive has a structural effect.
This excellent bonding performance of epoxy resin adhesives was soon widely used in construction projects, solving the bonding problem between cement and concrete, making the engineering process of the whole structure possible and promoting the development of construction and large-scale overall projects. In recent years, some of the world’s most famous buildings, such as the roof of the Sydney Opera House, the platform of the North Sea oil field in the UK, the Hong Kong Club exhibition hall and the Narita Airport in Tokyo, Japan, have all used epoxy resin adhesives to bond the components to achieve a monolithic structure.
The epoxy resins used are mainly modified bisphenol An epoxy resins, and most of the curing agents are modified aromatic amines or end-amino polyether’s, together with reactive tougheners and fillers, all of which can be manufactured domestically.
- Repair of buildings
Cracks often appear in parts of buildings and concrete structures that are in use. Or due to poorly treated joints, etc., leaks occur. This is manifested in elevated road surfaces, columns, roofs, wall and floor slabs, basements, etc. It affects production and life. In the past, asphalt was used for repair, which had to be carried out on dry surfaces and there was no structural effect at the repair, so that the mechanical distribution of the patched parts was different from that of other parts, resulting in stress cracking over time, which eventually reduced the strength of the structure.
The use of epoxy resin adhesives that can be used on wet surfaces and cured in water, for example: modified bisphenol A epoxy resin, water-based modified aromatic curing agent and water-absorbent filler formulated adhesives. They can be used to repair leaks as they occur. Excellent results have been achieved in practice.
This type of epoxy resin adhesive is widely used in construction projects and is often used in water conservancy projects for underwater repair of dams, as well as in the repair of piers, bridges and cement ships. After repairing, the original integrity is maintained and the original performance of the structure is preserved.
- Repair of cement products
There are nearly 500 professional factories in China producing cement poles, cement pressure pipes, various cement pipes, prefabricated assembly building wall panels, supporting components rail sleepers, bridge components and other enterprises. During production or transport, they are often damaged by non-destructive damage, producing cracks or bumps, which do not affect the structural performance of the products, but affect the use (e.g. appearance, water penetration, etc.) effect. In such cases, the use of epoxy adhesives is most effective.
We have used special epoxy resin construction adhesive cement products repair paste to repair the cement poles of a project of the Ministry of Railways, after 5 years of natural aging, the repair place can maintain the original state, improve the utilization rate and service life of the poles, save costs and receive good economic benefits. We repaired the wall of a cement pressure pipe produced by a factory, which was leaking. The cement pipe failed to pass the water pressure test, after pumping away the water, immediately use the epoxy resin adhesive in the water seepage parts to repair the construction, wipe dry the obvious water stains, coated with adhesive repair, after the wet surface curing, and then test the water pressure, test qualified. It has changed the previous situation where the base surface had to wait until it was dry before repairing, and improved the work efficiency.
- Bonding of decorative and decoration materials
Modern buildings not only require a reasonable structure, but also the interior and exterior decoration works of the building are equally important. For certain high-grade buildings (e.g. hotels, high-class shopping malls, gymnasiums, swimming pools, halls, exhibition halls, etc.), the decoration costs are basically almost equal to, or may even exceed, the cost of the main building works.
Technically, it mainly solves the problem of bonding various decorative materials with concrete, for example: marble, artificial marble, artificial stone, tiles, mosaic, etc. and mortar or concrete walls (internal and external walls), ground paste or for exterior maintenance. Bonding with aluminum alloys, metal decorative materials to concrete surfaces. Bonding of timber and veneered wood panels to concrete surfaces. Decoration of suspended ceilings, decorative lighting with gravity, installation of central air conditioning ducts, etc. The construction process does not allow for nailing and fixing. The use of epoxy resin adhesives for jointing and positioning greatly simplifies the process of fitting these projects, and the structure is firm and stable. Currently, epoxy resin anchor adhesive is used in a large number of construction projects to fix metal ceiling and metal structural parts and other load-bearing components, saving 80% of wood and 30-50% of working hours, simplifying the installation process and providing reliable performance. After investigation, several construction projects using epoxy resin anchoring adhesive have been continuously tested in the field for more than five years, with no minor shifts, reliable and safe.
Three years ago, Shanghai started a major landscape construction project, the “flat to slope” project for residential buildings, in which the epoxy resin anchor adhesive was used to fix the metal frame to the concrete. The results of the test showed that after the steel and concrete were bonded with epoxy resin anchor adhesive, the adhesive layer could withstand a tensile force of over 10 tones without damage. This landscape project is now in full swing in Shanghai.
- Repair of architectural ceramics
In the epoxy resin adhesive selection, the epoxy resin adhesive that can be cured in wet surface and water is most suitable for the installation and maintenance of architectural ceramic facilities, such as: sanitary ware, tiles, floor tiles, wall tiles, bathtubs, bathrooms, washbasins and other installation and maintenance.
For example, the artificial marble washbasin, due to improper use and caused by the corners of the washbasin broken and cracks, the past with mortar repair often effect is not good and scrapped. Now with epoxy resin building bonding agent color mixing bonding, repair basically can be similar to the original marble, construction operation is simple, the value of 600yuan of artificial marble vanity basin (crack broken length 65mm, width 0.5~0.9mm) only cost 0.8yuan repair fee.
- Epoxy Resin Composite Products
Epoxy resin as the base resin and glass fiber or cloth into epoxy resin FRP products, but also unsaturated polyester resin, vinyl resin, etc. as the base resin of FRP products. But in special circumstances, such as the requirement for heat resistance, organic solvents and inorganic acids, alkalis, oils and other media corrosion and high strength requirements of structural products, but also must use epoxy resin as the matrix resin.
These products are: integral storage tanks, tanks, which are used to store and transport petroleum products. Storage tanks for corrosive media (e.g., acids, alkalis, organic solvents) combined with cement storage tanks, which can be subjected to hot and cold changes. Boats with structural strength that can withstand the effects of seawater and atmosphere.
- Polymer cement mortars and concrete and admixtures
Of all the man-made building materials, cement is the most important and widely used building material in terms of production. Concrete and cement products based on cement have been the material basis of modern civilization for over 170 years. However, there are some shortcomings in cement and concrete that hinder the development of modern construction technology and cannot adapt to the needs of modern building projects, such as slow hardening, especially in cold climates; low tensile and flexural strength; dry shrinkage, denseness and poor seepage resistance; poor corrosion resistance to various media.
In recent years, the rapid development of polymer-based concrete and cement, polymer additives for concrete applications, effectively improve and enhance the performance of cement and concrete, becoming an indispensable component of modern concrete. Polymer additives to construction engineering and technology has brought new breakthroughs, epoxy resin is one of the polymer additive materials.
- Epoxy Cement Mortars and Concrete
The development of materials science at home and abroad today has led to the development of epoxy cement mortars and concrete into a specialized discipline with considerable research results. The epoxy resin replaces all or part of the cement as the cementing material, so that the aggregate (sand, stone, etc.) is bonded and cured, the process and product is called epoxy resin cement mortar or epoxy resin concrete.
The epoxy resin cement mortar is made of epoxy resin with surfactant to make water-soluble resin emulsion, then mixed with cement, sand, etc., and hardened together with cement hydration, where the epoxy resin can be cured by adding water-based amine curing agent. Water-soluble epoxy resin can be modified with bisphenol A epoxy resin and made into water emulsion with high efficiency surfactant; water-soluble epoxy resin can also be used, such as: glycerin epoxy resin, ethylene glycol epoxy resin, melamine epoxy resin, pentaerythritol epoxy resin, aniline epoxy resin and other epoxy resins with molecular structure, these are low viscosity water-soluble epoxy resins, which are extremely easy to mix with water and cement. These are low viscosity water-soluble epoxy resins, which are easy to mix with water and cement and are widely used in epoxy cement mortars.
- Cement and concrete strengthening additives
The hydrophilic water-soluble epoxy resin has a special effect on the hydration reaction process of cement. Studies have shown that the water-soluble epoxy resin can improve the dispersion of cement particles and make the cement particles finer, thus improving the effect of the hydration reaction. As a result, the properties of epoxy resin cement mortar and concrete are improved after hardening.
It is already known from physical and chemical tests and concrete studies that the water-soluble epoxy resin, whether it is ionic or non-ionic, has this effect. The functional groups contained in the molecule of the epoxy resin emulsion are the ones that make a difference to the hydration reaction of the cement. It is generally the molecule containing the amine structure that significantly increases the speed of the hydration reaction of the cement – accelerating the hardening; while the one containing the hydroxyl structure has the opposite effect of delaying the hardening (retarding the setting effect). By applying this change in chemical structure, we can make a reinforcing additive that regulates the rate of hardening of the cement – a conditioning agent. Due to the emergence and application of water-soluble epoxy resin cement mortar and strengthening additives, traditional concrete and cement products can not only improve the process, but more importantly, improve the performance, according to the mechanical requirements of engineering design to match the material, not only in the structural strength and in the appearance of decorative effect also completely changed the past course, heavy, monotonous appearance.
- Epoxy Resin Grouting Materials
Major construction projects, such as underground buildings, reservoirs, dams, docks, elevated roads, bridges, high-rise buildings, storage tanks and other large concrete projects, must be repaired when cracks are created by stress, external forces or earthquake damage, which can lead to leaks and accidents. Epoxy resin grouting technology is used to mechanically or pump epoxy resin material under pressure into the deep layer of the crack, and on the outer surface of the crack with carbon fiber cloth and epoxy resin composite to form a reinforcement layer, the resin cured to play a dual purpose of plugging and reinforcement, repairing the original facilities. Epoxy resin grouting materials and technology are not only important in maintenance, but also in foundation work and other areas. Epoxy resin has been widely used as a grouting material and the remarkable effect of this technology is that its bonding and cohesion force far exceeds that of cement concrete and the mechanical properties and strength of the repair are much higher than that of the original concrete, which is reliable and stable.
- Other Applications
Impregnated concrete, with low viscosity room temperature curing or UV curing epoxy resin solution, impregnated concrete products and cement products, curing at room temperature or under UV irradiation, so as to form a layer of resin bonding layer at a certain depth on the surface of concrete, changing and mentioning its concrete products and cement products to resist leakage, corrosion resistance of various media.
China’s construction industry will play the role of economic pillar in the development of the national economy, large-scale capital construction and civil construction, it is inevitable that a large number of various construction materials, the demand for polymer materials will increase significantly, a variety of cement products, the production and number of concrete projects will also increase significantly, all of these, a large number of applications of synthetic polymer materials, to develop chemical building materials. In 2002, the demand for epoxy resin in China has reached more than 290,000 tons, but the amount of epoxy resin used in construction projects and building materials only accounts for about 6% to 8% of the annual demand for epoxy resin, about 1.7 to 23,000 tons, and the gap with the world level is still large. According to the prediction of the relevant departments, by 2006, the amount of epoxy resin used in construction projects in China will increase to 10-12% of the annual demand.
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