Polycarboxylic superplasicizer is the 3 generation of high performance water reducer. In order to meet different requirements of concrete technical performance, it is often used after compounding with a small amount of retarder, air entraining agent, defoaming agent, viscosity modifier, etc. However, due to the high temperature in summer, the superplasticizer added with retarding components (such as sodium gluconate and sucrose) is prone to deterioration, which seriously affects the use effect.
1) Deterioration and causes
The modification of Polycarboxylic superplasicizer is mainly caused by the compound sodium gluconate. In industrial production, Aspergillus niger is widely used to produce sodium gluconate. After the fermentation of Aspergillus niger, a lot of residue of Aspergillus niger will be produced. Under suitable natural conditions (nutrients, temperature, humidity, oxygen, pH value), "mould explosion" appears. The blackening of the modified water reducing agent is caused by the fermentation of Aspergillus niger in the unqualified sodium gluconate product.
The mildew of polycarboxylic superplasticizer is also related to its storage environment. Higher temperature will aggravate the movement of macromolecular chains, which will lead to faster degradation of polymers. Similarly, the higher the temperature, the greater the activity of macromonomers, and the faster the mildew rate of water reducer.
2) Prevention and solution of deterioration
The quality of polycarboxylate superplasticizer will be affected by mildew, which will lead to concrete quality accidents. The following measures are recommended.
(a) Choosing high quality sodium gluconate as retarding component
(b) Mixed with a certain amount of preservative
In the production process of Polycarboxylic superplasticizer, a certain amount of preservative is compounded. Among which isothiazolinone is a kind of more extensive, high-efficiency, low toxicity, non oxidative bactericide, which is suitable for a wide range of pH value, so it is ideal to be used for mold and sterilization of water reducing agent. The dosage of preservative is 0.5-1.5 kg per ton of polycarboxylic water reducer.
(c) Pay attention to storage environmentTry to store polycarboxylate superplastcizer in a cool, ventilated place without direct sunlight.In addition, non-metallic materials should be used as much as possible for Polycarboxylic Water reducing agent storage containers, otherwise the corrosion of metallic materials will cause discoloration or even deterioration of water reducing agent.
(d) Reasonable prediction of Polycarboxylic Water reducing agent used in Engineering
It is suggested that before delivery, the manufacturer should communicate with the project department about the product use progress and cycle, so as to achieve the planned use and ensure the dynamic balance of the consumption and supplement of polycarboxylic water reducer.
(e) Reduce the use of formaldehyde, nitrite and other preservatives.
Shijiazhuang City Horizon Chemical Industry Co., Ltd. has research and production and application of polycarboxylate superplasiticizer for a long time. We can provide high quality product and onsite technique support. Meanwhile, the raw materials-HPEG2400, TPEG2400 for polycarboxylate superplasiticizer are avaliable too.