The Design Of Alkali-activated Coating Materials And The Characterization And Evaluation Of Its Solid-liquid Interface

Alkali-Activated Materials(abbreviated as AAMs)are a kind of cementitious materials with spatial three-dimensional network structure which is obtained through appropriate treatment processes and chemical reactions by mineral admixtures and alkaline activators.In this paper,the contact angle(CA)of the AAMs’ solid-liquid interface which is characterized by the new bubble method was used to calculate the surface energy and adhesion of AAMs based on the Young equation derivation.Meanwhile,Alkali-activated coating materials(AACMs)with hydrophobic properties were prepared through the optimization and modification of AAMs.In addition,the technical indexes and performances of the prepared AACMs were evaluated as well.Finally,the critical surface energy curve was used to further evaluate the wetting behaviour of AACMs.First of all,the influencing factors of the solid-liquid interfacial properties between AAMs and deionized water were researched in this paper.These factors include water-solid ratio,mineral admixtures,activator species,and age.The results show that the solid-liquid two-phase contact angle of AAMs is about 29° and belongs to hydrophilic materials.Besides,AAMs with different mineral admixtures have similar solid-liquid interface properties.However,the properties of different AAMs are slightly different,the red mud-based AAMs have insufficient adhesive strength and strength,the fly ash-based AAMs are powdered off which makes it difficult to collect data,the slag-based AAMs have high strength but are easily basified,the metakaolin-based AAMs have moderate strength and are not susceptible to cracking.Therefore,the AAMs of the blending ratio from slag(S)and metakaolin(MK)are more appropriate to utilize;the AAMs of S and MK mixed bases have higher strength and are not easy to crack;the water-solid ratio has little effect on the surface energy of the material;AAMs activated by Na OH are brittle and have severe efflorescence,but its sodium silicate excitation is fantastic.Hence,using AAMs with the optimal ratio of 0.4 for W/S(S)and the mixture of ore and metakaolin(S and MK)could lead to the best results.Next,in the research,an alkali-activated coating material which contains hydrophobic water repellent properties were prepared by using a modified method.The modified method includes adding penetrating crystalline materials PTB,SY and brushing surface modifiers OSW,MSO etc.The results reveal that the contact angle of AAMs between solid and liquid condition increases from 29° to 100° after modification.In addition,the surface of AAMs changes from hydrophilic to hydrophobic as well.Using the surface modifier OSW achieves the best brushing effect because Silicone’s own hydrophobicity makes better material hydrophobic effects.The effect of adding permeation-type crystalline material as modifier is slightly lower than using OSW,but the manner of addition modification not only meet the hydrophobic requirement but also allow AACMs be denser with raw materials,thereby enhancing the compactness of the substrate and improving the durability.In addition,in this research,the newly developed AACMs were evaluated and optimized through a series of technical indicators.This process includes the adjustment of AACMs’ stability and appearance,the determination of AACMs’ setting time and their flexural and compressive strength.Also,Hardness test and bond strength test of AACMs were conducted in this paper.Besides,the AAMs’ hydrophobicity at the solid-liquid interface under a chloride concentration of 1%-4% and their durability to the depth of chloride ion erosion were tested as well.The results reveal that all indicators meet the requirements.Finally,the critical surface energy curve(CS curve)was used to evaluate the wettability of AACMs before and after modification.Studies show that calculating the CS difference between the given material and the specific liquid which is ? γ value can obtain the size of the CA.After comparison,the AACMs’ contact angle is the largest after modification,the tests from the beginning to the end have verified the accuracy of the results.The comparability between Data testing and theoretical derivation is favourable.In conclusion,an alkali-activated coating material was designed and prepared in this research which is suitable for coastal environment.Meanwhile,a new bubble method was used to characterize and evaluate its solid-liquid interface properties.Also,the paper explores the effects by various factors on AAMs’ hydrophobicity.In addition,this research discusses the solid-liquid interface properties of AACMs in different environments and provides a theoretical basis for AAMs’ performances in coastal environments.