I. Development status of concrete admixture industry

1. Development of admixture products

At present, the country has a complete range of admixtures, and the total output of concrete admixtures is 7.2225 million tons. The output of various synthetic water reducing agents is about 4,846,800 tons, and various high-efficiency water reducing agents (naphthalene, melamine, sulfamate, aliphatic and lanthanide water reducing agents) account for 67% of the total synthetic water reducing agent. Polycarboxylate high performance water reducer accounted for 26%, ordinary water reducer (lignin sulfonate water reducer) accounted for 7%. In 2009, the output of other admixtures was 1.6317 million tons of air entraining agent, expansion agent 1,263,600 tons, quick-setting agent 100,71 tons (including solid accelerators accounted for 74.32%, liquid accelerators accounted for 25.68%), retarders (sodium gluconate, sugar calcium, molasses, etc.) 91,500 tons. It is estimated that the sales value of the above admixtures reached 27.78 billion yuan.

(1) Superplasticizer

Superplasticizer is an admixture with high water-reducing rate when the workability of concrete is about the same. In 2009, the total output of the country was 3,227,900 tons, of which naphthalene accounted for 82.53% of the total production of superplasticizer. The family accounted for 12.85%, the sulfamate accounted for 2.85%, the lanthanide accounted for 1.32%, and the melamine system accounted for 0.45%. The naphthalene production accounted for 55% of the total synthetic water reducer production, which decreased compared with 2007; The carboxylic acid-based water reducing agent accounts for 26% of all synthetic water reducing agents, and has increased compared with 2007, but the naphthalene system is still a widely used variety of water reducing agents. In 2009, the output of aliphatic water reducer increased by 293,300 tons compared with 2007, which increased more. This is because the price of aliphatic water reducer is relatively cheap, mainly used for the compounding of admixtures, and the aliphatic provinces of Henan and Zhejiang provinces are reduced. A large province of water production.

(2) High performance water reducing agent

The high-performance water-reducing agent with polycarboxylate as the main component has a certain air-entraining property, a high water-reducing rate and a good slump retention performance, and is an environmentally-friendly additive zirconium silicon micropowder . It was used in foreign countries in the 1990s. The current usage rate in Japan accounts for 60% to 70% of high-efficiency water reducing agents, and Europe and America account for about 20%.

From around 2000, China's concrete engineering community gradually recognized polycarboxylate water reducers. In recent years, driven by the construction of high-speed railways, high-performance water reducing agents have developed rapidly and have been widely promoted and applied. In 2007, the annual domestic output was 414,300 tons. In 2009, according to the cumulative production of polycarboxylate admixtures in various provinces, the output was 1,268,300 tons, with a growth rate of 206%. The provinces and cities with large polycarboxylate admixture production are Shanxi. Province, Jiangsu Province and Zhejiang Province.

GB50119 "Technical Specifications for Application of Concrete Admixtures" compiled a survey of the sales volume of raw materials for the seven major polycarboxylate raw material producers in the country. The seven companies sold about 150,000 tons of polycarboxylic acid raw materials in 2009, which is equivalent to polycarboxylate. The acid water reducing agent mother liquor is about 800,000 tons. In addition, some foreign companies also produce and sell zirconium silicon powder of polycarboxylic acid admixture raw materials.

The admixture for high-speed railway engineering is mainly a polycarboxylic acid-based water reducing agent. The admixture will conduct detailed statistics on the amount of polycarboxylic acid admixtures for 26 railway trunk lines under construction from 2008 to 2009. The survey shows that the total mileage of these 26 routes is 11,243.56 km, with a total investment of 1,019.796 billion yuan. Or the actual use (already completed) polycarboxylate superplasticizer totaled 1,492,267 tons.

In 2007, the bidding amount for these polycarboxylate superplasticizers was 123,200 tons, in 2008 it was 329,900 tons, and in 2009 it was 523,100 tons. Even if the polycarboxylic acid-based water reducing agent is estimated at a higher price of 7,000 yuan/ton in a certain period, the output value of polycarboxylate-based water reducing agent in the three years from 2007 to 2009 is about 1,104,458,900 yuan (1.044 billion yuan). It only accounts for 1.03% of the total railway investment. One problem that is particularly worthy of attention at present is that the price of polycarboxylate admixtures in the high-speed railway bidding process has the lowest bid, and the lowest bid price in 2009 is about 3,450 yuan/ton. From the perspective of ensuring the quality of the project, we should encourage the continuous improvement of the quality of polycarboxylate superplasticizers, strengthen the theoretical and applied basic research of new varieties of polycarboxylate water reducers, strengthen engineering on-site services, and oppose malicious price competition.

(3) Expansion agent

The main characteristic of the expansion agent is to resist cracking and seepage after being mixed into the concrete. Its expansion property can compensate the shrinkage during the hardening process of the concrete and become self-stressing concrete under the limited conditions. The main varieties of expansion agents in China are: U-type expansion agent (raw, cooked alum, anhydrite, etc.), composite expansion agent (CEA), calcium aluminate expansion agent (AEA-high-strength clinker, natural alum, gypsum) , EA-L expansion agent (small vermiculite, gypsum, etc.), FN-M expansion agent (sulfur aluminate concrete expansion agent), CSA micro-expansion agent (sulfur aluminate, etc.), lipid film lime expansion agent (lime , stearic acid, etc.). In 2009, the annual output of expansion agent was about 1,263,600 tons, and there were more than 100 production enterprises. Some large-scale enterprises have an annual output of 30,000 to 50,000 tons, and a few manufacturers have an annual output of 100,000 tons or even 200,000 tons. Production enterprises are concentrated in Hubei, Anhui, Jiangxi, Tianjin, Shanxi and other provinces and cities.

(4) Accelerator

Accelerators are admixtures that regulate the setting and hardening speed of concrete (or mortar). They accelerate the hydration of cement and significantly reduce the setting time for shotcrete construction. According to the product form, the quick-setting agent can be divided into solid and liquid; according to the content of the alkali, it can be divided into alkali, alkali and low alkali. In 2009, the annual output of national quick-setting admixture was about 1,007,100 tons, and there were more than 60 production plants, mainly distributed in North China, East China and Central South. In 2009, due to the large-scale growth of the railway, highway and coal industries, the production of accelerators increased significantly compared to 2007. In particular, the demand for liquid alkali-free quick-setting admixtures for high-speed railways has led to the production of liquid quick-setting admixtures in 2009 reaching 258,600 tons, which has become one of the highlights of the development of admixtures.

(5) lignin sulfonate water reducing agent

The lignosulfonate water reducing agent is a commonly used common type water reducing agent, and its water reducing rate is 8% to 10%, which can be used directly or as one of the raw materials of the composite admixture, because the price is relatively cheap, and the use is still More extensive. The production of lignosulfonate superplasticizer in 2009 was about 356,600 tons, and the products included wood calcium, magnesia, and sodium. From the application of lignosulfonate water reducer in China, the localities are unbalanced, and the south is used more. For example, Shanghai uses it to make medium-efficiency pumping agent, which is widely used in commercial concrete; Calcium production has increased significantly. The lignosulfonate water reducing agent is a common water reducing agent produced by the papermaking waste liquid of the paper mill, which turns waste into treasure and solves the problem of environmental pollution; the product quality is stable, the price is moderate, and the application range is wide. An admixture product that should be widely promoted.

(6) retarder

Currently, the main retarder products used are calcium calcium, molasses, sodium gluconate, and citric acid. Also useful as retarders are hydroxycarboxylic acids (tartaric acid, gluconic acid, salicylic acid, acetic acid, maleic acid, tannic acid, hexose, etc.), carbohydrates (sucrose) or some other compound. In 2009, the total production of retarder has reached 91,500 tons. Sichuan Miyi and Inner Mongolia Jining have professional production plants for sugar and calcium.

(7) air entraining agent

The air entraining agent is an admixture capable of introducing a large amount of uniformly distributed, closed microbubbles into the mortar and concrete while stirring, and allowing the bubbles to remain in the hardened concrete. The air entraining water reducing agent is an admixture with both air entraining and water reducing functions. The air entraining agent and the air entraining water reducing agent are mainly used to improve the workability of plastic mortar and concrete, reduce bleeding and segregation, and at the same time Improve the durability of mortar and concrete. At present, the air entraining agent with a large amount of application in the country is a rosin thermal polymer. Saponins air-entraining agents have good performance and are currently produced in factories in Shanghai and Hangzhou. In 2009, the total output of air-entraining agents nationwide was 16,300 tons, an increase of 12,900 tons compared with 2007.

(8) Composite admixture

The compound admixture is mainly composed of the above various components according to the engineering needs, and then added with other components, such as antifreeze, early strength water reducer, pumping agent, waterproof agent, air entraining agent , retarding water reducing agent, retarding high-efficiency water reducing agent, admixture for underwater concrete, grouting agent, etc. These composite admixture production equipments are relatively simple, with low investment and good benefits. A large part of admixture plants in China is producing this type of admixture. Most of the concrete admixtures are added to the concrete as a composite admixture.

2. Development of admixture enterprises

At present, the overall development of China's concrete admixture enterprises has the following four characteristics.

1. The variety of concrete admixtures is continuously improved, the product performance is continuously improved; the scale of synthetic admixture production enterprises is large, and the annual output value of large enterprises exceeds 1 billion yuan; automated production is receiving more and more attention, and some enterprises have realized full automation production, and SMEs also It pays great attention to the automation control of key processes; there are already synthetic admixture manufacturers in Hainan and Tibet, but the problem of uneven distribution is more prominent.

2. Similar to other industries in the field of building materials (cement, commercial concrete), the concrete admixture industry has problems such as overcapacity, low industry thresholds, and market chaos. According to incomplete statistics, there are more than 1,500 existing additive production enterprises, including more than 350 chemical synthesis plants. There are more than 100 polycarboxylic acid water reducing agent manufacturers, and 53 admixture enterprises are currently certified by the Ministry of Railways and have high-speed railway supply qualifications. The development of the concrete admixture industry lacks unified planning and industrial policies, and industry management and market supervision need to be strengthened. After the number of concrete admixture plants exceeds the market demand, it is necessary to strictly control the qualification approval of new concrete admixture enterprises, and cannot blindly develop and repeat construction, resulting in new malicious competition.

3. The environmental protection level of concrete admixture production enterprises has yet to be further improved. Most compounding admixture plants have not been closed, and there are odors in the process of synthesizing naphthalene-based manufacturers. Some admixture plants are compounded in the workshop. The ground cleaning was not clean, and the people walked and raised a lot of dust.

4. Foreign companies are very concerned about the development of China's concrete admixture industry, on the one hand to increase and expand investment in China, and on the other hand to accelerate the pace of acquiring domestic concrete admixture manufacturers.