Preparation And Properties Of Polycarboxylate Superplasticizer For Desert Sand Concrete

With the rise of the concept of “ new infrastructure ” that represents the era of smart economy and the continuous advancement of the national strategy of western development,the scale of national infrastructure projects is expanding.Especially the surge in the number of construction projects in the western region will inevitably lead to the shortage of raw materials required for the project.The surge in the number of projects will inevitably lead to the shortage of raw materials required for the project.In this paper,the sand aggregate is taken as the starting point.The natural sand resources are being continuously consumed,and the quality of the existing sand resources is gradually declining.However,the western region has a large number of desert sand resources.How to reasonably use desert sand resources,take local materials and reduce transportation costs is a problem worth thinking.Based on the most widely used polycarboxylate superplasticizer in concrete engineering is easily affected by the quality of sand and stone aggregate,and the properties and characteristics of desert sand and the existing research case analysis,a polycarboxylate superplasticizer with good adaptability to small impurities such as clay is studied and prepared,so that it still has good water reduction performance when the clay content is too high,and has unadversely affect the working performance of concrete.A polycarboxylate superplasticizer was synthesized by free radical polymerization using OXAB-501 and acrylic acid as main raw materials,ammonium persulfate,mercaptoethanol,methacrylic acid,styrene and other raw materials,so that it has high adaptability to clay minerals and can be applied in desert sand.The effects of reaction temperature,acid ether ratio,initiator content and chain transfer agent content on the performance of water reducing agent were studied.The results showed that the the reaction temperature was 65 ℃,the ratio of acid to ether was 4 : 1,the dosage of initiator was 1 %,the dosage of chain transfer agent was 0.4 %,the reaction time was 2 h,and the holding time was 1 h,the synthesized polycarboxylate superplasticizer had good water-reducing property.The 4-3 water reducing agent obtained by single factor analysis experiment was compared with the water reducing agent and Xika water reducing agent of Heilongjiang Shenglong Science and Technology Company.Adding styrene and methacrylic acid to change the molecular side chain functional group structure of polycarboxylate superplasticizer makes polycarboxylate superplasticizer have better adaptability to clay minerals.It was found that when the substitution amount of styrene was 5 % and the substitution amount of methacrylic acid was 10 %,the water reducer had high adaptability to clay.Subsequently,the effects of styrene content,acrylic acid content,reaction temperature,initiator content and chain transfer agent content on the performance of the synthesized polycarboxylate superplasticizer were analyzed by orthogonal test,and two kinds of water reducers with better effects were obtained.The cement mortar test was carried out to explore the change rule of the properties of the two water reducers under different clay contents.Using No.19 water reducing agent to test the rheological properties of concrete,it is found that No.19 water reducing agent is suitable.Using 11,15,19 water reducing agent and Mu Us desert sand mortar performance testing,found in the desert sand particle diameter is too fine,large specific surface area,need a lot of cement cementitious materials for mixing.When the cement-sand ratio is 48 %,water-cement ratio is 50 %,and the amount of water reducing agent is0.18 %,the effect of No.19 water reducing agent is the best,the fluidity is 208 mm,and the 7 d compressive strength is 30.16 MPa.It is proved that No.19 water reducing agent has good adaptability to desert sand and provides technical support for the application of desert sand.