What Is a Water Reducer?
Water reducing agent is a concrete admixture that can reduce the amount of water used for mixing under the condition that the slump of the concrete is basically unchanged. Most of them are anionic surfactants, such as lignin sulfonate and naphthalene sulfonate formaldehyde polymers. After adding the concrete mixture, it has a dispersing effect on the cement particles, which can improve its workability, reduce the unit water consumption and improve the fluidity of the concrete mixture; or reduce the unit cement consumption and save cement. [1]
Appearance form is divided into water and powder. The solid content of water agent is generally 20%, 40% (also known as mother liquor), 60
Suitable for pumping or normal state with strength class C15 ~ C60 and above
Polycarboxylic acid high performance water reducing agent
1.Dosage is
Polycarboxylic acid high performance water reducing agent
1. Water reducing agent is a liquid, we need to use barrels to store it when storing it;
2. Water reducing agent is a chemical, so we should store it in a cool and dry place. Avoid direct sunlight, otherwise it will cause volatilization, or cause deterioration of the water reducing agent. In winter, we must pay attention to Anti-freeze, keep in a warm place;
3. Generally speaking, the seal time of the water reducing agent is one year. If we find that the shelf life is exceeded when we open it, we can continue to use it.
HSB Aliphatic Superplasticizer
Storage and packaging
1. HSB can be stored at -20-40 degrees Celsius but cannot be exposed to sunlight. The shelf life is one year.
2. Packaging: 250KG iron drum or bulk supply, can also be packed according to user's requirements.
1. The water reducing agent should be of stable quality. The water reducing agent should have good compatibility with cement and admixture. When multiple additives with different functions are used in combination, there should be good adaptability between the additives and between the additives and the cement.
2. The technical requirements of high-efficiency water-reducing admixtures shall comply with the requirements in Table 1. The technical requirements of polycarboxylic acid-based water-reducing admixtures shall comply with the requirements in Table 2. The homogeneity of the water-reducing admixtures shall conform to the current national standard "Concrete Admixtures" ( GB8076) .
Table 1 Technical requirements of high efficiency water reducing agent
Serial number | Test items | skills requirement | Testing method |
Standard type | Retarded |
1 | Water reduction rate | 20% | Inspection according to GB8076 |
2 | Gas content | <3.0% | Inspection according to GB8076 |
3 | Atmospheric bleeding ratio | <20% | Inspection according to GB8076 |
4 | Pressure bleeding ratio (for the preparation of pumped concrete) | <90% | Inspection according to JC473 |
| | 1d | > 140% | / | Inspection according to GB8076 |
5 | Compressive strength ratio | 3d | > 130% | / | Inspection according to GB8076 |
7d | > 125% | > 125% | Inspection according to GB8076 |
| | 28d | > 120% | > 120% | Inspection according to GB8076 |
6 | 60mm slump retention value (for the preparation of pumped concrete) | / | > 150mm | Inspection according to JC473 |
7 | Set time difference | Initial setting | -90 min ~ "+ 120min | > + 90min | Inspection according to GB8076 |
Final coagulation | / |
8 | Sodium sulfate content (based on the solid content) | <10.0% | Inspection according to GB / T8077 |
9 | Cl- content (based on the solid content) | <0.6% | Inspection according to GB / T8077 |
10 | Alkali content (based on the solid content) | <10% | Inspection according to GB / T8077 |
11 | Shrinkage ratio | <125% | Inspection according to GB8076 |
Note: 1. For the items inspected according to GB 8076, the concrete slump control value is 80mm ± 10mm.
2. The cement used for spot test should be engineering cement.
Table 2 Technical requirements of polycarboxylic acid water reducing agent
Serial number | Test items | skills requirement | Testing method |
Early strength | Standard type | Retarded |
1 | Water reduction rate | > 25% | Inspection according to GB8076 |
2 | Gas content | <3.0% | Inspection according to GB8076 |
3 | Atmospheric bleeding ratio | <20% | Inspection according to GB8076 |
4 | Pressure bleeding ratio (for the preparation of pumped concrete) | <90% | Inspection according to JC473 |
| | 1d | > 180% | > 170% | / | Inspection according to GB8076 |
5 | Compressive strength ratio | 3d | > 170% | > 160% | / | Inspection according to GB8076 |
7d | > 145% | > 150% | > 140% | Inspection according to GB8076 |
| | 28d | > 130% | > 140% | > 130% | Inspection according to GB8076 |
6 | 60mm slump retention value (for the preparation of pumped concrete) | / | > 130mm | > 150mm | Inspection according to JC473 |
7 | Set time difference | Initial setting | -90 min ~ | -90 min ~ | > + 90min | Inspection according to GB8076 |
Final coagulation | + 90min | + 120min | / |
8 | Formaldehyde content (calculated as the solid content) | <0.05% | Inspection according to JG / T223 |
9 | Sodium sulfate content (based on the solid content) | <5.0% | Inspection according to GB / T8077 |
10 | Cl- content (based on the solid content) | <0.6% | Inspection according to GB / T8077 |
11 | Alkali content (based on the solid content) | <10% | Inspection according to GB / T8077 |
12 | Shrinkage ratio | <110% | Inspection according to GB8076 |
Note: 1. The items tested according to GB 8076 are the same as the technical requirements of Table 1 for superplasticizers.
2. The cement used for spot test should be engineering cement.
3. The air-entraining agent should be a product with stable quality and small bubbles, uniform distribution, and obviously improving the frost resistance of concrete. Air-entraining agent should have good compatibility with water reducing agent and cement. The technical requirements of the air-entraining agent shall meet the requirements in Table 3.
Table 3 Technical requirements of air entraining agent
Serial number | Test items | skills requirement | Testing method |
1 | Water reduction rate | > 6% | Inspection according to GB8076 |
2 | Gas content | > 3.0% | Inspection according to GB8076 |
3 | Atmospheric bleeding ratio | <70% | Inspection according to GB8076 |
4 | 1h gas content changes over time | -1.5% ~ + 1.5% | Inspection according to GB8076 |
| | 3d | > 95% | Inspection according to GB8076 |
5 | Compressive strength ratio | 7d | > 95% | Inspection according to GB8076 |
| | 28d | > 90% | Inspection according to GB8076 |
6 | Set time difference | Final coagulation | -90min ~ "+ 120min | Inspection according to GB8076 |
Initial setting | Inspection according to GB8076 |
7 | Shrinkage ratio | <125% | Inspection according to GB8076 |
8 | Relative durability index (200 times) | > 80% | Inspection according to GB8076 |
9 | 28d Hardened Concrete Bubble Spacing Coefficient | <300 ^ m | Appendix E of "Construction Quality Acceptance Standards for Railway Concrete Engineering" (TB10424-2010) |
Naphthalene series superplasticizer
Naphthalene-based superplasticizers can be divided into high-concentration products, medium-concentration products, and low-concentration products according to the content of Na2SO4 in their products. Most naphthalene-based superplasticizer synthesis plants have the ability to control the Na2SO4 content Capability below 3%, and some advanced companies can even control it below 0.4%. Na2SO4 content is 15% ~ 20% for low concentration type, and less than 5% for high concentration type. [12]
Water reducing agent abroad
In the 1930's, it was found that mixing concrete with sulfite pulp waste liquid can improve the workability, strength and durability of the mixture.
Can be improved. In 1935, the American EWScripture was first developed as a water reducing agent with lignin sulfonate as the main component. It was patented in 1937} s}. In the 1950s, it was obtained in the United States from slipform concrete, dam concrete and winter construction concrete. Used heavily. In 1962, Japan's Kao Shijian Company took the first part of the health department, first developed a water-reducing agent with R-tea sulfonic acid formaldehyde condensate sodium salt as the main component, referred to as tea-based water reducing agent. This type of water reducing agent has the characteristics of high water reducing rate, and is suitable for preparing high strength (compressive strength of 100 MPa) or slump of up to 20 [more than two concrete. Then in 1964, the Federal Republic of Germany successfully researched the sulfonated melamine formaldehyde resin water reducer. This type of water reducer has the same characteristics as tea-based water reducer with high water reduction rate, good early strength, and low air entrainment. The products and cement products with high aluminate (mainly C3A) content have better adaptability and can prepare high-strength or high-flow concrete. In this way, Germany invented fluid concrete, which developed the concrete from the original manual pouring or hanging pot pouring to pumping construction, saving manpower, improving work efficiency, ensuring quality, eliminating noise, and greatly improving the level of concrete technology and construction. leap.
Due to the important contribution of the superplasticizer to the modification of concrete, its application became the third major breakthrough in the development history of concrete after reinforced concrete and prestressed concrete. With the development and application of high-efficiency water reducing agent as the mark, the concrete technology has entered the third generation from plastic, dry and rigid to fluidized.
In the early 1990s, the United States first proposed the concept of high-performance concrete (HPC), which requires concrete to have high strength, high fluidity, high durability and other properties. High-performance concrete has put forward higher requirements for water reducing agents and requires high performance. Water reducing agent has the characteristics of high water reduction rate, large flow and small slump loss over time. Some new high-efficiency water-reducing agents have been rapidly developed and applied, such as polysuccinic acid and sulfamic acid-based superplasticizers. [13]
Water reducing agent domestic
China's admixture started a little later than abroad, but it developed rapidly. In the 1950s, research and application of lignin sulfonate and air-entraining agents began; after the 1970s, tea-based superplasticizers and onion-based superplasticizers reduced water Agents and other products have been independently developed; in the late 1990s, modified melamine, sulfamate, and aliphatic superplasticizers developed rapidly; since 2006, driven by the construction of high-speed railways, polysuccinic acids have high performance Water reducing agents have also developed rapidly. Water reducing agent has promoted the development of new concrete technology in China, and promoted the application of industrial by-products in the cementitious material system. It has gradually become an essential material for high-quality concrete. [14]
