| Ancient architectures are important carriers for the inheritance of human history and culture.There are a lot of cultural relics and ancient architectural resources in China.For thousands of years,due to the destruction of natural creativity and human activities,ancient buildings have suffered from weathered pastries,defects,hollows,cracks and saltpetering,which have seriously endangered their structural safety.To strengthen the protection of ancient buildings,it is necessary to scientifically manage the disease,so the choice of disease repair materials is crucial.Lime-based cementitious materials are the main materials of ancient architectures.In view of the principle of "repairing as old" for the protection of cultural relics,in this paper,volcanic ash-lime is used as the matrix material,and four kinds of alkyl chain length silane coupling agent modified pastes were prepared,which were used to study the performance and modification mechanism;in addition,the properties of the silane modified mortars were studied with the mortar ratios and the amount of silane;finally,the use of octyltriethoxysilane for polypropylene powder(PP),carbon fiber powder(CF)and metakaolin(MK)were pretreated to obtain carrier silane,which was used to modify pozzolan-lime mortar and analyze the properties of the modified mortar.1.The study found that hexyl-silane,octyl-silane and dodecyl-silane caneffectively reduce the volume shrinkage and mass loss rate of the pastes in the early stage of curing,and the softening coefficient of the modified pastes is greater than 0.85,which meets the standard of high water resistance materials.The modification effect of propyl-silane is poor;in addition,the flexural strength and compressive strength of the four modified pastes have been significantly improved.Analysis and testing shows that silane can combine with the paste matrix in the form of chemical bonds to play the role of cross-linking and coupling.Silane delays the hydration reaction in the early stage of curing,and then promotes the formation of CSH.However,it will adversely affect the carbonization reaction during the whole curing period.2.When the mortar ratio is 1:3,the properties of the mortar are the best;silanes with shorter alkyl chain lengths are beneficial to the fluidity,volume stability,and quality stability of the mortar,while silane with a longer alkyl chain has a stronger cross-linking coupling effect and hydrophobic property,which is more beneficial to the bending strength,waterproof and water resistance of the mortar.M-Octyl and M-Dodecyl specimens have the best waterproof,water resistance and durability performance.When the silane content is 1.5%,the volume stability and mass loss rate of the mortar are better modified,and when the dosage is lower,the mechanical properties of mortar are better.3.Compared with octyl-silane modified mortars,the carrier silane modified pozzolan-lime mortars are further improved in terms of setting time,mechanical properties and water resistance.Among them,MK carrier silane has the best modification effect on setting time,linear shrinkage,water absorption and water content,and the optimal content is 5%.The PP and CF carrier silane modification effect is slightly worse,and the performance is best when the dosage is 3%.Besides,CF and MK carrier silane shows the best modification effect on the flexural strength and compressive strength respectively. |
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