1, the concept of high performance concrete (HPC) was first put forward by the United States in the early 1990s, which is a successful example of the combination of new superplasticizer and concrete materials science.
2. 1824, British I.Aspdin obtained the patent of portland cement, and cement concrete was widely used.
3. 1962 Hattori, a Japanese company, first used formaldehyde condensate of naphthalene sulfonic acid (n≈ 10) as a dispersant for concrete, and 1964 Japan Huawangshi Alkali Company sold it as a product.
4. 1963, the Federal Republic of Germany developed melamine sulfonate formaldehyde condensate, and at the same time, polycyclic aromatic hydrocarbon sulfonate formaldehyde condensate appeared.
5. 1966, Japan applied high-strength concrete for the first time and began to produce prestressed concrete piles.
6.1971~1973, Germany developed superplasticizer into fluid concrete for the first time, and the vertical pumping height of concrete reached 3 10m.
7. At present, the development direction is the research of high performance concrete and the use of compound superplasticizer (CSP), so as to realize the full calculation method design and CSP formula design of high performance concrete.
Second, the development direction of concrete admixture
1. water reducer: modification of naphthalene series and melamine series water reducer, polyacrylate water reducer, polyacrylic acid grafted polymer water reducer, sulfamate water reducer, sulfonated ketone-aldehyde polycondensate, lignosulfonate water reducer produced by industrial waste.
2. Compound admixture: low alkali and low dosage liquid compound admixture, compound superplasticizer and its formula design, low alkali and low dosage liquid compound antifreeze, micro-expansion multifunctional waterproof agent, liquid expansion agent, liquid accelerator and super retarder.
3. Other additives: shrinkage reducing agent, alkali aggregate reaction inhibitor, surface hardening agent and high-efficiency release agent.
Third, the functional classification of concrete admixture
1, definition: Classification, naming and definition of concrete admixtures (GB8075-87) are substances added to improve the performance of concrete during concrete mixing, and the mixing amount shall not exceed 5% of the cement quality (except in special circumstances).
2, concrete admixture according to the main function is divided into four categories:
A, additives to improve the rheological properties of concrete mixture. Comprises a water reducing agent, an air entraining agent and a pumping agent.
B, adjust the setting time of concrete and the hardening performance of admixture. Comprise a retarder, an early strength agent and an accelerator.
C, improve the durability of concrete admixture. Include air entraining agent, waterproof agent and antirust agent.
D, additives to improve other properties of concrete. Include air entraining agent, expansion agent, antifreeze, colorant, waterproof agent and pumping agent.
IV. Admixtures are classified by varieties (1)
1, early strength agent:
Soluble inorganic salts: chloride, carbonate, nitrate, thiosulfate, silicate, aluminate, basic hydroxide, etc.
B. Soluble organic matter: triethanolamine, calcium formate, calcium acetate, calcium propionate and calcium butyrate, urea, oxalic acid and the condensate of amine and formaldehyde.
2. Accelerators: iron salt, fluoride, aluminum chloride, sodium aluminate and potassium carbonate.
3. Air entraining agent: wood resin salt, synthetic detergent, lignosulfonate, protein salt, fatty acid and resin acid and their salts.
4. Water reducer and coagulant: lignosulfonate and its modified or derivative, hydroxycarboxylic acid and its salt or its modified and derivative, inorganic salt (zinc salt, borate, phosphate and chloride), ammonium salt and its derivative, carbohydrate and polysaccharide acid or sugar acid, water-soluble polymer (cellulose ether, melamine derivative, naphthalene derivative, polysiloxane and sulfonated hydrocarbon).
5. Superplasticizer: naphthalene sulfonate formaldehyde condensate, polycyclic aromatic hydrocarbon sulfonate formaldehyde condensate, melamine sulfonate formaldehyde condensate, p-aminobenzenesulfonic acid formaldehyde condensate, sulfonated ketone aldehyde condensate, polyacrylate and its graft polymer, etc.
6. Air entraining agent: hydrogen peroxide, aluminum powder, and some activated carbon that absorbs air.
7. Grouting additives: retarder, gel, gel starch and methyl cellulose, bentonite, thickener, early strength agent and air entraining agent.
8. Expansion agent: iron powder or granular iron powder and oxidation accelerator, lime system and sulphoaluminate system.
9. Adhesives: synthetic latex and natural rubber latex.
10. Pumping agent: synthetic or natural water-soluble polymer to increase viscosity, organic flocculant, inorganic materials with high specific surface area (bentonite, silica, asbestos powder, asbestos short fiber, etc. ), and cement additives (fly ash, hydraulic lime, stone powder, etc. ).
1 1, flocculant: polymer electrolyte.
12. Colorants: gray to black (iron oxide black, mineral black, carbon black, ultramarine blue, phthalocyanine blue), light red to deep red (iron oxide red), brown (iron oxide brown, manganese-rich brown soil, burnt cinnamon soil), green (chromium oxide green, phthalocyanine), white (titanium dioxide), etc.
13. Bactericides and pesticides: polyhalides, dieldrin emulsions and copper compounds.
14. moistureproof agent: soap, butyl stearic acid and some petroleum products.
15. Impermeable agents: water reducer and calcium chloride.
16. Alkali aggregate reaction inhibitor: lithium salt, barium salt, part of air entraining agent, water reducing agent, retarder and volcanic ash.
17. Rust inhibitors: sodium nitrite, sodium benzoate, calcium lignosulfonate, phosphate, sodium fluorosilicate and sodium fluoroaluminate.
Five, the role of concrete superplasticizer
1. Without changing the proportion of various raw materials, adding concrete superplasticizer will not change the strength of concrete, and at the same time, it can greatly improve the rheology and plasticity of concrete, so that concrete construction can be carried out by gravity flow, pumping and vibration-free, thus improving the construction speed and reducing the construction energy consumption.
2. Without changing the proportion of raw materials (except water) and the slump of concrete, reducing water consumption can greatly improve the strength of concrete, and the early strength and late strength are improved by more than 60% and 20% respectively compared with the concrete without water reducer. By reducing water consumption, high-strength concrete with C 100 grade can be poured.
3. Without changing the proportion of raw materials (except cement) and the strength of concrete, the dosage of cement can be reduced. Adding 0.2%~0.5% concrete water reducer based on cement mass can save cement 15~30% above.
4. Adding concrete superplasticizer can improve the service life of concrete by more than one time, even the normal service life of buildings is more than one time.
Answer with satisfaction.