In the development of polycarboxylate superplasticizers, many research scholars are also conducting research on many aspects.
In this paper, we have made a brief summary of the development of polycarboxylate water reducers in recent years, focusing on the latest research results of different types of polycarboxylate water reducers.With the continuous improvement of technical requirements for engineering construction, polycarboxylate superplasticizers have evolved from the initial high water reduction and high moisture retention types, and then different types of polycarboxylate water reducers have emerged today, but mainly the following Kind.
1 Guaranteed and super-protected polycarboxylate water reducer
The synthesis of such water reducing agents is carried out in the process of synthesizing the water reducing agent by introducing an active unsaturated monomer having a valence-protecting function.Thus, a slow release guaranteed polycarboxylic acid water reducing agent having excellent slump retention ability and a certain dispersing property was developed.The birth of such water-reducing agents originates from the higher mud content or powder content of sand-stone materials, and is most commonly used in areas where the mechanism sand is more frequent.Commonly used non-saturated monomers are hydroxyethyl acrylate (HEA) and hydroxypropyl acrylate (HPA).Such water-reducing agent can reduce the slump of concrete for 2~3h in concrete with general mud content (methylene blue value less than 2.0), and the concrete slump loss is faster after more than 3h.In super high-rise buildings or construction sites with long distances of transportation, the concrete slump is generally required to have no loss for 4~6h.And the concrete setting time and the late strength are not affected,The water reducing agent that satisfies this requirement is called a super-protected polycarboxylic acid water reducing agent.
2 functional polycarboxylate water reducer
In the actual construction process, sometimes there is a situation in which water reduction and protection cannot be achieved. Generally, the water reducing agents sold on the market are mainly water-reducing type and moisture-proof type.The water-reducing type has poor moisture retention, and the water-saving type has a low water-reducing rate, which needs to be used in proportion.In areas with good sand and gravel materials, the combination of the two water reducers not only increases the complexity of the production process, but also easily causes fluctuations in production quality.The water reducing agents generally used in these areas have both high water reduction rate and good moisture retention, and are called functional water reducing agents.
3 slow release polycarboxylate water reducer
The sustained-release polycarboxylic acid water reducing agent is a polycarboxylic acid product which is slowly released in a short time.Compared with other water reducing agents, the water reducing agent has a good effect of improving the post-protection performance and early strength of the concrete.Moreover, the water reducing agent is improved to some extent in terms of workability and dispersibility compared to ordinary water reducing agents.
Different from the Baogan type polycarboxylate water reducing agent, the concrete slump will be quickly lost after the water reducing agent releases the water reducing effect in a short time.Unlike the Paul type, the slump retention ability is better.