Preparation And Properties Of Geopolymer Coating By Machine-sprayed For ALC Plate Steel Anticorrosion

With the widespread application of prefabricated buildings,the demand for autoclaved aerated concrete panels(ALC panels)has greatly increased,However,due to its porous structure and the production process,it is cured under the conditions of 180?-200? and 1.0MPa.Autoclaved curing makes ALC have a natural disadvantage in preventing corrosion of steel bars.Coating materials can isolate steel bars from corroded substances,and are currently the most commonly used method for preventing corrosion of steel bars.According to the performance requirements of anti-corrosion coating materials for ALC plate steel bars,geopolymer materials have good performance in bonding strength,impermeability,heat resistance,and chemical resistance,but they have weaknesses such as poor flexibility and shrinkage cracking.Organic anticorrosive coating has good toughness,but poor heat resistance and durability.It is planned to develop a new type of anticorrosive coating material for ALC plate steel bar with excellent performance through the combination of geopolymer and organic material,and carry out construction by mechanical spraying.The main research contents of this article are as follows:First,the preparation and performance of composite coatings that meet the requirements of mechanical spraying construction are studied.The results show that for the small mechanical spraying equipment built in this study,the construction parameters are obtained through repeated practice: the nozzle diameter of the spray gun is 1 mm,the air pressure is 4-6 KPa,and the working distance is 10-20 cm.Under the above spraying conditions,the coating The yield stress of the freshly mixed material is 20-80 Pa,the plastic viscosity is 1.2-2.0 Pa·s,and the fluidity is not less than 180 mm,which is more suitable for construction and shows good working performance.Alkali-activated metakaolin soil polymer is mixed with styrene-acrylic emulsion.When the mixing amount is 6%?8%,the newly mixed slurry of the coating material meets the requirements of spraying construction;in the ALC production process,the temperature is about 180?-200?,1.0 MPa Under autoclaved curing conditions,the coating structure is denser and does not crack;thermal stability,no structural damage caused by decomposition;all indicators meet the requirements of the national standard GB15762-2008 "Autoclaved Aerated Concrete Slab".Then the anti-rust performance of the coated steel bars was studied.The results show that in the simulated hole solution coupling chloride ion anti-corrosion test,compared with the uncoated steel bar and the current commercially available coated steel bar M3,the open circuit potential correction,impedance arc radius and phase of the metakaolin base polymer composite coated steel bar The angle is larger,the current density measured around the steel bar is smaller,and the anti-corrosion efficiency can reach 92.75% after 28 days.In the ALC carbonization anti-rust test,after 60 days ALC has been fully carbonized,the corrosion area of the metakaolin base polymer composite coated steel M1 is less than 5%,showing good anti-corrosion ability.At the same time,it is found that the coating material has also been carbonized after 60 days.Although the composition of the coating material has not changed fundamentally,the surface is enriched with NaCO3,and its pH value drops from 13.17 to 9.13,which cannot maintain the stable existence of the passive film of the steel bar.As a result,its protective effect in this environment is worse than that of the commercially available rust inhibitor coating M3.The anti-rust effect of the metakaolin base polymer composite coating mainly comes from the stable structure of the coating composition and its own high alkalinity,as well as the small accumulation and small volume of rust products.The anti-rust effect of commercially available coated steel M3 mainly comes from the barrier effect and hydrophobicity of the coating.Finally,the life cycle assessment(LCA)and life cycle cost(LCC)models are established around the metakaolin base polymer composite coating material,and it is concluded that the metakaolin base polymer composite coating material has low energy consumption;it will not be generated during the production process.Severe environmental acidification and eutrophication of water bodies is an environmentally friendly material;raw materials have a wide range of sources and low prices,which are extremely competitive.