Effect Of Aluminium Ion On The Expansibility Of Alkali-silica Reaction

Alkali-aggregate reaction （ASR） is a key factor of the damage of the concretestructure. The concrete structures damaged by ASR reaction are difficult to repair, sohow to stop the ASR is being or has occurred caused for worldwide concern. This issuestudied the affection and mechanism of Al³⁺in preventing the ASR reaction has occurred,by treating the specimens have occurred ASR reaction with Al（NO₃）₃solution.Compared the inhibition of ASR reaction with different Al³⁺concentrations,different curing time in Al（NO₃）₃solution, and Al³⁺and Li+using the method of quickmortar bar. Using SEM/EDS analysis and other testing methods analyzed the morphologyand the composition of the products of the interface between cement paste and glass. Theresults show: when Al（NO₃）₃concentration is3.5%, and curing time is14d, the inhibitoryeffect is the best; the minimum Al（NO₃）₃concentration can effectively inhibit the ASRreaction is1.5%; Al³⁺and Li+have a synergistic effect and the mixed solution has abetter inhibitory effect.Studying the laws of Al³⁺diffusion under conditions of natural and the electric field,combined with aluminon method and EDS analysis, revealed the quantitative relationshipbetween the Al³⁺content and the penetration depth at different infiltration time, and theirconcentration equation model has been derived, The theory values calculated with thehuge have a big difference with the actually measured value, and the error due to thecomplexity of the concrete and the situation far from the ideal.Exploring the synthesis method of ASR gel, the results showed that: the bestreaction condition for preparation of ASR gel is:10ml1mol/L NaOH and0.02g glasspowder reacted for3d under80℃. Adding different concentrations of Al（NO₃）₃solutionin the ASR gel, with the prolonging of reaction time, the gel gradually changed from theparticles into the state of aggregation, and the contents of Al³⁺and Na+had a tendency torise. The mechanism is the ASR gel with Al³⁺strengthens the adsorption capacity, so thatthe product changes from the expansive substance into non-expansive zeolite minerals.