| In recent years,with the release of the carbon peak plan,my country’s energy development has gradually shifted from fossil energy to clean energy.This measure has great positive significance for building an environment-friendly,resource-saving modern society and addressing global warming.My country is rich in offshore wind energy resources,and we can vigorously build offshore wind turbines to realize the full development and utilization of wind energy resources.In the construction of offshore generating units,the grouting connection is an important connection between the upper fan and the lower foundation.The use of grouting materials with excellent performance is particularly important for the stability of the fan structure.During on-site construction,too low a water-binder ratio makes the fluidity of the grouting material poor,resulting in greater construction difficulty.Therefore,the offshore wind power grouting material must meet certain fluidity requirements while meeting high strength.The viscosity-reducing polycarboxylate superplasticizer not only meets the strength requirements of offshore wind power grouting materials,but also improves its fluidity and effectively reduces viscosity to ensure durability.Viscosity-reducing polycarboxylate superplasticizers can play an important role in the construction of offshore wind turbines,improve the stability of the turbines,and promote the development of the offshore wind power industry to achieve the goal of reducing the use of fossil energy.Firstly,the synthesis process and basic ratio of viscosity-reducing polycarboxylate superplasticizer were determined through experimental research.Cement mortar viscosity and cement paste viscosity were used as test indices,and single-factor tests and orthogonal tests were conducted to optimize the synthesis process.Ethylene glycol monovinyl polyethylene glycol ether(EPEG)was chosen as the macromonomer,with a dropping time of 60 minutes and a holding time of 60 minutes.The reaction concentration was determined to be 46%,and the p H of the bottom kettle was 6.The acid ether ratio(n(AA):n(EPEG)),sodium methallyl sulfonate(SMAS),sodium hypophosphite(LZ),and methacryl tartaric acid(MJ)were then varied in single-factor tests to determine their effect on cement mortar fluidity and cement paste apparent viscosity.A response surface optimization was then used to find the best ratio of n(AA):n(SMAS):n(LZ):n(MJ):n(EPEG)= 4.84:0.44:4.9:1.13:1,with a predicted cement mortar fluidity of 257 mm and a predicted apparent viscosity of cement paste of 1029 MPa·s.The average measured cement mortar fluidity was 255.3 mm and the average cement paste apparent viscosity was 1015 MPa·s,with a relative error of 0.58% for cement mortar fluidity and 1.38%for cement paste apparent viscosity between the predicted values and the average measured values of the three tests.The response surface optimization achieved the desired effect.Secondly,the microstructure and action mechanism of the synthesized polycarboxylate superplasticizer were studied through infrared spectroscopy(FTIR),surface tension,Zeta potential,and total organic carbon(TOC)adsorption tests.The research results show that the synthesized polycarboxylate superplasticizer PC-A contains various functional groups such as hydroxyl,carboxyl,ether,methyl,and sulfonic acid groups,and the synthesis meets expectations.Compared with two commercially available polycarboxylate superplasticizers PCQ and PC-M,PC-A introduces hydrophobic polar groups such as methyl groups,which reduces the hydrophilic-lipophilic balance(HLB)value,and the solution shows a lower surface tension can better wet the cement,thereby improving the fluidity of the slurry.Compared with PC-Q and PC-M cement slurry,the Zeta potential of the cement slurry mixed with PC-A is significantly lower,and it has stronger electrostatic repulsion,which makes more free water between cement particles and improves the dispersion effect.PC-A introduces hydrophobic rigid groups during the synthesis process to increase the exposed area of carboxyl groups.The introduction of dicarboxylic acids during the synthesis process increases the density of carboxyl groups.Polyether reduces steric resistance and increases the degree of freedom of side chains.adsorption of cement.The greater the adsorption amount of PC-A on the surface of cement particles,the thicker the adsorption layer,the thinner the water diffusion layer,the more free water,resulting in a lower viscosity for the slurry.Thirdly,experiments were carried out in the offshore wind power grouting material to determine the optimal dosage of the synthetic viscosity-reducing polycarboxylate superplasticizer PC-A,which was found to be 0.45%.Subsequently,PC-A was tested for cement adaptability and mineral admixtures,along with two commercially available viscosity-reducing polycarboxylate superplasticizers,PC-Q and PC-M.The results revealed that PC-A exhibited good adaptability to different cements and relatively low sensitivity to silica fume.Furthermore,scanning electron microscopy(SEM)showed that the addition of PC-A,compared with PC-Q and PC-M,improved the compactness inside the test block,thereby increasing the strength.Finally,the frost resistance performance of the offshore wind power grout was tested in the freeze-thaw cycle test.The test block of the offshore wind power grout prepared with PC-A has better compactness and better frost resistance.The quality loss and dynamic elastic modulus decrease of the offshore wind power grouting material test block prepared by PC-A are better than those of PC-Q and PC-M.The results show that by reducing the viscosity of the offshore wind power grouting material and improving the fluidity of the offshore wind power grouting material,the pore volume in the offshore wind power grouting material test block can be reduced,the expansion of the internal pore volume under the action of freeze-thaw cycles can be reduced,and the penetration of cracks can be hindered,which improves frost resistance. |
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