Study On The Interaction Mechanism Between Polycarboxylic Superplasticizers And Stone Powders In Ledong And Haikou In Hainan Province

In recent years,natural sand resources have been rapidly reduced,and machine-made sand is widely used in concrete as a substitute for natural green sand.The mechanism sand contains a certain amount of stone powder(SP),and the SP can play a filling effect and a crystal nucleus effect in the concrete,but when the amount of the SP exceeds a certain range,the work performance of the concrete will be reduced.Polycarboxylate superplasticizer(PCE)is the most widely used and studied concrete admixture at present,and it is an indispensable component in concrete.It can make concrete reduce the mixing water consumption and improve the strength of concrete under the condition of maintaining the same fluidity and durability.It was found that when the amount of PCE is the same,the workability of the concrete mixed with SP produced in Ledong and Haikou of Hainan Province is significantly different,which makes it difficult to control the workability of concrete through PCE.To develop a PCE that is insensitive to stone powder production,namely SP-type PCE.This article studied the mobility of carboxylate density and side chain length of PCE to SP-cement paste.The effects of rheology,adsorption,etc.,combined with the physicochemical properties such as particle size distribution,micromorphology,and mineral composition of two kinds of SPs,explored the interaction between PCE and SP in Ledong and Haikou of Hainan Province.The mechanism provides theoretical basis for further research and development of new anti-stone powder PCE.In this paper,the particle size distribution,micro-morphology and mineral composition of stone powder(LDSP)produced in Ledong quarry and stone powder(HKSP)in Haikou quarry are analyzed and compared.It has been found that there are major differences in the properties of SP produced in different regions.Studies have shown that the performance difference between LDSP and HKSP in engineering applications is mainly due to the fact that LDSP is dominated by large particles with a high degree of circularity and contains a layered muscovite structure,which is easy to interlayer adsorption and ion exchange.The particles of HKSP are fine,with many corners,irregular shapes,and poor circularity.They mainly contain chain-like structure of augite,and the PCE is mainly adsorbed on the surface of SPRSecondly,in this paper,PCEs with different side-chain lengths and different carboxylate densities were synthesized by aqueous solution polymerization.The interaction effects of PCE with side chain length,carboxylate density,and different lithology characters and volume of SP were investigated.The study found that:long side chain PCE has strong steric hindrance,and the fluidity of cement paste is better than short side chain.The PCE with a low carboxyl density maintains a large space and works well on the dispersion.After adding SP,the long side chain PCE can make the initial fluidity of the SP cement paste reach 26cm under low dosage;under the saturation dosage,the short side chain PCE can obtain better flowability.The long-chain PCE is easy to insert into the LDSP layer under large dosage,resulting in less adsorption of the PCE on the cement surface,and the dispersion effect is worse than that of the short side chain.From the results of flow loss,the PCEs generally have poor adaptability to LDSP,and the loss rate over time is large and changes with the PCE content.The retention of PCE-L1 with 2.5:1 ratio of acid to ether in the long side chain PCE was optimal.In this study,SP was used as an admixture to partially replace the cement,and the effect of the addition of SP and the molecular structure of PCE on the yield stress and plastic viscosity of the cement paste with SP was observed.By measuring the rheological parameters of the cement paste,the effects of the amount of SPs and the structure of PCEs can be determined.The results show that the cement paste exhibits shear thinning as a pseudo plastic fluid.PCE-L1 showed better flow properties,the value of initial viscosity was lowest of the PCEs with long side chain at an acid-ether ratio of 2.5:1.The viscosity of 5%LDSP is lower than that of paste,and the plastic viscosity at 20%is obviously higher.It can be achieved to the best yield stress and plastic viscosity with PCE-L1,while the viscosity of HKSP is slightly lower than that of PCE-L1.This experiment has guiding significance on the practical application of cement concrete.The results of the discussion of the interaction between SPand PCE show that the adsorption capacity of PCE on LDSP is significantly higher than that on cement particles and HKSP.As the carboxylate density increases and the length of the side chains decreases,the amount of PCE adsorbed increases.The potential values of cement,LDSP,and HKSP in PCE solutions were lower than those in water.The mass loss of the LDSP and PCE solution after interaction is greater than that of the blank LDSP,indicating that the decomposition of the polymer caused a significant decrease in quality,verified the inference of the intercalating effect of PCE in the LDSP layer.