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The influence of the mud content of sand on the polycarboxylate superplasticizer is often fatal, which is more obvious than the naphthalene series and aliphatic superplasticizers. When the mud content increases, the workability of concrete is improved by increasing the amount of polycarboxylate superplasticizer, sometimes with half the effort, and sometimes bleeding begins before the fluidity is reached. When the mud content of the fine aggregate exceeds 5%, the water reduction rate of the concrete mixed with polycarboxylate superplasticizer will decrease, and even the 

 fluidity will be completely lost, and the slump retention performance will also be poor. For the content of stone powder, it is also necessary to carry out on-site tests several times to reasonably control the content of stone powder, so that the sensitivity can be effectively controlled, the fluidity of concrete can be guaranteed, and the performance of concrete can be optimized.

 

For the current problem of mud content, there are several conventional solutions:

there are several

(1) Increase the dosage or increase the proportion of slow-release slump-retaining agent, but control the amount to prevent the problems of yellowing, bleeding, segregation, bottom grabbing and concrete retarding time being too long;

(2) Adjust the sand rate or increase the air-entraining amount. On the premise of ensuring good workability and strength, reduce the sand rate or increase the air-entraining amount to achieve the purpose of increasing the free water and slurry amount of the concrete system. to adjust the properties of concrete;

(3) Appropriately add or change the components to solve the problem. Experiments have shown that adding an appropriate amount of sodium metabisulfite, sodium thiosulfate, sodium hexametaphosphate, and sodium sulfate to the water reducer can reduce the influence of mud content on concrete to a certain extent.

Of course, the above methods cannot solve all the problems of mud content, and the effect of mud content on concrete durability needs further research, so the fundamental solution is to reduce the mud content of raw materials.

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Post time: May-18-2022