Influence Of Water Binder Ratio On Natural Hydraulic Lime Mortar And Its Modification

Natural hydraulic limes（NHL for short）,with the characteristics of both hydraulic and pneumatic properties,are characterized by moderate mechanical strength,good permeability,low water-soluble salt content,good compatibility,and the ability to repair and reduce environmental pollution.In recent years,they have been given received extensive attention in the field of restoration of immovable cultural relics.However,in the actual use process,NHL has great room for improvement in early strength,durability and cost.In order to study the effect of water on the nhl,this paper studies the influence on the performance of natural hydraulic lime mortar by controlling the water binder ratio,and studies the composite modification of natural hydraulic lime by adding silica fume,glutinous rice pulp,paper fiber and water reducer,which are all materials with better performance for the restoration of immovable cultural relics.The following are the main contents and conclusions:In this paper,four kinds of natural hydraulic lime mortar with different water binder ratio are used as the research object.The results show that the water binder ratio can effectively improve the working performance of mortar,which is convenient for construction,but has adverse effects on the water absorption and shrinkage of mortar.When the water binder ratio increases from 0.5 to 0.8,the flexural and compressive strength is 50%and 40%of the original.Through comparison,The effect of water binder ratio on compressive strength of natural hydraulic lime mortar is greater than that on flexural strength.The optimum softening coefficient exists in different water binder ratios,and the maximum softening coefficient is 0.76 when the water binder ratio is 0.6,which can meet the environment with light moisture.During the durability test,the water absorption of mortar specimens with different water binder ratios showed a downward trend,in which the mass loss rate and strength loss rate decreased during the dry wet cycle and the acid resistant solution corrosion process,The higher the water binder ratio is,the lower the loss rate is.The higher the content of hydration products is,the greater the impact of corrosion is;In the process of salt resistant solution corrosion,The loss rate of quality and strength is negative because the salt fills the internal pores,but the absorption of too much salt will lead to serious cracking of the mortar specimen;The higher the water binder ratio,the lower the hydration and carbonization reaction,and the more dispersed the micro morphology.Organic and inorganic composite modification of natural hydraulic lime was carried out by using organic additive glutinous rice pulp,inorganic additive silica fume and paper fiber,and the effect of water reducer on the performance of composite modified mortar was explored.The results show that the hydration and hardening speed of the modified mortar is accelerated,the flexural and compressive strength are increased by 141.03%and 424.36%respectively,and the durability of the modified mortar is improved in varying degrees.The main reasons are:the pozzolanic reaction of silica fume with Ca（OH）₂ will increase the content of hydration products;The hydrophobicity of glutinous rice paste can effectively improve the water resistance;The effect of paper fiber and silica fume filling.The performance of mortar added with water reducing agent is further improved,the workability of mortar is optimized,The water absorption is reduced,and the softening coefficient is 0.87,meeting the requirements of waterproof materials.The strength of water reducing mortar is similar to that of the original brick,which can ensure the requirements of actual project use.This research content can provide reference for subsequent tests and projects.Figure[68]Table[12]Reference[72]...