Generally, it is 12 months, which is one year. The shelf life of early-strength superplasticizers produced by some manufacturers will be two years, depending on the manufacturer of the product.
You can add a small amount of preservatives (such as formaldehyde, acetone) to extend the shelf life by a few months. Remember that the shelf life will become shorter after early strength compounding (especially It is an admixture containing sugar or alcohol).
The shelf life of early strength mother liquor is only 12 months, and it must be stored in a cool and ventilated condition. If it is a compound product, it can be up to 6 months. It is best to have the product tested and qualified before use if it has exceeded the shelf life.
According to the different main chain structures, early-strength high-efficiency superplasticizer products can be divided into two categories: one is mainly acrylic acid or methacrylic acid chain, grafting polyethers with different side chain lengths. The other type is polyethers with maleic anhydride as the main chain grafted with different side chain lengths. Based on this, a series of high-performance water reducing agent products with different characteristics have been derived.
Before the emergence of early strength admixtures, there were lignin sulfonate admixtures, naphthalene sulfonate formaldehyde condensates, melamine formaldehyde condensates, and acetone Sulfonate formaldehyde condensate, sulfamate formaldehyde condensate, etc. In the early 1980s, Japan took the lead in successfully developing early-strength superplasticizers. The new generation of early-strength high-efficiency water-reducing admixture has overcome some of the shortcomings of traditional water-reducing admixtures. It has low dosage, good slump retention performance, low concrete shrinkage, strong adjustability in molecular structure, great potential for high performance, and production process. Outstanding advantages include not using formaldehyde.
In many concrete projects, traditional high-efficiency concrete such as naphthalene series is increasingly unable to meet project needs due to limitations in technical performance. The new generation of water-reducing agent that has attracted much attention at home and abroad, the early-strength high-performance water-reducing agent, has truly designed an effective molecular structure based on the mechanism of dispersed cement. It has a super-dispersed type and can prevent the loss of concrete slump. It does not cause obvious retardation, exerts a high plasticizing effect at low dosage, has good fluidity retention, has a large degree of freedom in cement adapting to a wide range of molecular structures, has many synthesis technologies, and has great room for high performance, and has a great effect on concrete reinforcement. Significantly, it can reduce the shrinkage of concrete and has extremely low harmful substance content and other technical performance characteristics, which gives the concrete excellent construction workability, good strength development, excellent durability, early-strength series high-performance water-reducing agent with good comprehensive technology Performance advantages and environmental protection characteristics meet the needs of modern concrete projects. Therefore, early-strength high-performance water-reducing admixtures are gradually becoming the first choice admixtures for formulating high-performance concrete. According to reports, the use of early strength admixtures in Japan accounts for more than 80% of all high-performance admixture products, and North America and Europe also account for more than 50%. In my country, early-strength water reducing agents have been successfully used in large-scale water conservancy, bridges, nuclear power, and railway projects such as the Three Gorges Dam, Sutong Bridge, Tianwan Nuclear Power Station, and Beijing-Shanghai High-speed Railway, and have achieved remarkable results.
At the same time, there are also some problems with early-strength superplasticizer:
1. In high temperature environment Insufficient slump retention;
2. It is highly temperature sensitive. If the same early-strength water-reducing agent is constructed in different seasons, the slump retention of concrete will be very different;
3. There are few functional products, which are difficult to meet the needs of ultra-high and ultra-long distance concrete pumping, negative temperature construction, preparation of ultra-early strength concrete and high concrete Durability and other requirements;
4. High viscosity. In the preparation of concrete with high admixture materials and low water-cement ratio, the viscosity of concrete is high, which is not conducive to construction;
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5. It is highly sensitive to the mud content of sand and gravel aggregates.
6. It is also poorly adapted to machine-made sand and is sensitive to the dosage, which affects construction. </p
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