Research And Application Of Reinforced Concrete Anticorrosive Admixture

The problem of corrosion resistance and durability of reinforced concrete is a worldwide problem that plagues the whole world.At present,assembled reinforced concrete members are lack of multi-level durability protection measures.Based on the method of molecular structure design,a rust-inhibiting polycarboxylic water reducer was synthesized,and a rust-inhibiting composite liquid corrosion inhibitor was further compounded.It is of great practical significance for the sustainable development of assembled concrete members to discuss the mechanism of corrosion resistance of steel bars and concrete.Arginine was used as modifier of functional Polycarboxylic Water Reducer and p-toluene sulfonic acid as releasing agent of arginine structural carboxylic acid.The ratio of arginine to p-toluene sulfonate was 1:2,and the ratio of arginine to p-toluene sulfonate to Methylallyl alcohol polyoxyethylene ether was 3.75:1.The esterification reaction lasted for 3 hours at120 ?.Free radical polymerization was used to synthesize HPEG-AT with ammonium persulfate as initiator and mercaptopropionic acid as chain transfer agent.A rust-inhibiting polycarboxylic acid water reducer ZX-PCE was synthesized by controlling the reaction temperature from 40 to 45 ?,reaction dripping time from 2.5 to 3.0 h,thermal insulation reaction for 1 h and neutralization of polyethylene polyamine alkaline organic compounds.The weight loss rate of steel bar soaked in 5% ZX-PCE solution for 90 days was only 1.121‰,while that of steel bar soaked in water for 90 days was 18.957‰.The 28-day compressive strength ratio of concrete mixed with ZX-PCE is 120%.There is no corrosion of reinforcing bars in concrete under the condition of random multiple dry-wet cycles of one-year-old.Under the same conditions,steel bars in concrete mixed with ordinary Polycarboxylic Water Reducer have serious corrosion,while exposed steel bars have serious corrosion,which indicates that ZX-PCE has better corrosion resistance to steel bars in concrete.A series of FS series composite liquid corrosion inhibitors were prepared by using rust-inhibiting polycarboxylic acid water reducer as penetration promoter and compounding with water-soluble Nano-organosilicon materials,aluminium sulfate,organic alkanolamine,hydroxycarboxylate and other components.The results show that the optimum dosage of anti-corrosive agents FS-1 and FS-2 is 1%,while the optimum dosage of anti-corrosive agents FS-3 and FS-4 is 2%.The flexural strength of 28-day cement mortar with FS corrosion inhibitor increased by 11.6%~13% compared with the reference group,and the compressive strength of 28-day concrete increased by 14%~15%.Compared with the blank concrete,the carbonization rate decreased by 13.0%~21.7%,and the electric flux decreased by 23%~32%in 6 h.For concrete with 100 freeze-thaw cycles,the mass loss of 2% FS-4 group is only0.3%,and the relative dynamic modulus of elasticity is 79.5%,which improves the frost resistance of concrete obviously.The molecular structure of anti-rust polycarboxylic superplasticizer is comb-like rocking claw structure.There are dispersing carboxyl groups in the main chain and amino sulfonic acid groups in the end of the branch chain.GPC test showed that the number-averagemolecular weight was 30887 and the polydispersity index was 1.76.Zeta potential on the surface of cement particles mixed with ZX-PCE is-20.3 mV,and that on the surface of cement particles in blank group is-3.1 mV.The analysis shows that the polar groups in the structure of the rust-inhibiting Polycarboxylic Water Reducer form coordination bonds with metal iron,deposit on the surface of steel bar by chemical adsorption and form a stable and insoluble protective film to protect steel bar from corrosion.Composite liquid corrosion inhibitor uses rust-resistant polycarboxylic acid water reducer as penetration accelerator,nano-silicone with penetration and waterproofing effect,sulphoaluminate with micro-expansibility activator,organic alkanolamine with complexation activation effect and hydroxyl carboxylate with adjusting setting time effect,which can effectively improve the durability of prefabricated components.In summary,the anti-corrosion additives studied in this paper can be applied to concrete with anti-corrosion requirements and prefabricated components for assembly building.