Slump Retainer and Properties
AEOR CHEMICAL
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According to the standard, PCE slump retainers are divided into 3 types：Type 1 is when the slump of concrete changes over 1h by not more than 10mm
Type 2: 2h slump loss not more than 10mm
Type 3: 3h slump loss is not more than 10mm
The slump retention agent of the synthesis process, the PCE process formula with the first acid to ether ratio (1.3-2.0) was used in the early stage, which roughly corresponds to the type 1 slump retention agent. When this type of PCE has poor adaptability to cement or poor ground quality, it is necessary to compound other retarding components to basically meet the construction requirements. After a sufficient amount of hydroxyethyl ester/hydroxypropyl ester monomer is used to participate in the polymerization reaction, the slump-preserving type 1 quality can be easily achieved. It has been reported that after adding NP-10 (alkylphenol polyoxyethylene ether) and methyl methacrylate to the polymerization reaction, the performance of PCE slump retention and viscosity reduction is better than that of type 1 slump retention agent.
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At present, amide phosphates are promoting the use of substituted hydroxy esters. The amount used in the polymerization reaction is as low as 5-35kg/ton. The slump retention performance can fully reach the type 2 slump retention agent, and the applicability to cement is wider. In other words, When adjusting the workability and slump retention of concrete, it is easier to achieve the goal, so that the performance of the slump retention agent has risen to a new level.
Type 3 slump retention agent with vinyl methyl butyl ether polyoxyethylene ether as the starting agent has also come out. In some cases, the surface slump retention effect can reach 4-6 hours, and it has been successfully applied to the construction of high-throw self-compacting concrete. However, although the polymer in the 4+2 method (HPEG plus ethylene oxide) has low viscosity, high water reduction rate and slightly improved slump, it still has a gap with type 3 slump retention agent or high-efficiency water retention agent.
Most of the concrete slump retention agents made by composite technology are composed of at least two retarder components or three or more retarder components. For example, type 1 slump retention agent has zinc sulfate plus sodium sulfite, type 2 slump retention agent has sodium gluconate, white granulated sugar and sodium metabisulfite, and type 3 slump retention agent uses type 1 PCE slump retention agent plus glycerin and phosphate tribasic. Compounds of carboxylic acids, etc.