Effect Of Nano-alumina Content On Permeability And Mechanical Properties Of Metakonlin Geopolymer Mortar

Because metakaolin and other geopolymers have relatively high porosity and low interfacial binding force and other shortcomings.In order to promote the use of geopolymers,these properties must be further improved.Among them,adding nanomaterials to geopolymers is a direction to improve these properties.Because nanoparticles have the characteristics of high specific surface area and small particle size,they have the ability to promote early hydration reaction and fill the micropores of the matrix.In this paper,the geopolymer mortar with different nano alumina content（0%,1%,2%,3%）is taken as the research object,and the physical properties,impermeability（gas permeability,liquid permeability and chloride ion permeability）and mechanical strength of geopolymer mortar with different nano alumina content are tested.The change rules of permeability and physical and mechanical properties of geopolymer mortar with different nano alumina content were analyzed from various angles,including the change rules of physical and mechanical properties of geopolymer mortar with different nano alumina content,the change rules of gas permeability,liquid permeability and anti chloride ion permeability.The main results are as follows:（1）The nitrogen adsorption capacity of gaogaoling polymer mortar increases exponentially with P/P₀.The average pore size of geopolymer mortar samples with0%and 3%nano alumina content is obviously larger than that of geopolymer mortar samples with 1%and 2%nano alumina content,and the porosity of geopolymer mortar samples with 1%and 2%nano alumina content is obviously smaller than that of geopolymer mortar samples with 0%and 3%nano alumina content;With the increase of nano alumina content,the specific surface area of geopolymer mortar first increases and then decreases.The specific surface area of geopolymer mortar with 1%and 2%nano alumina content is significantly larger than that without nano alumina content;With the change of nano alumina content,the pore volume distribution of geopolymer mortar also changes,and the change trend is first decreased,then increased.Among them,the pore volume of geopolymer mortar with nano alumina is the largest.（2）It can be seen from the experimental results of gas and liquid permeability that the liquid permeability experimental data and the gas permeability experimental data reflect basically the same trend law,which fully illustrates the validity of the gas permeability experimental data.This permeation experiment method can play a very complementary role.（3）Under the same curing time,with the increase of nano alumina content,the electric flux of geopolymer mortar first decreases and then increases.When the content of nano-alumina is 2%,the electric flux of geopolymer mortar is the smallest,and the mortar without nano-alumina is the largest.The results show that the electrical flux of mortar decreases after adding 2%nano alumina,which improves the resistance of geopolymer to chloride ion penetration.Moreover,the anti-gas permeation and anti-liquid permeation ability is also improved after adding 2%nano alumina.It can be seen that the incorporation of an appropriate amount of nano alumina will have a beneficial effect on the compactness and connectivity of the geopolymer mortar.（4）The strength of geopolymer mortar mixed with ganamide alumina metakaolin increases with the increase of curing time,which is due to the continuous hydration inside the geopolymer mortar,which increases the mechanical strength of geopolymer mortar.The compressive flexural strength of geopolymer mortar at 7d is more than80%of that at 28d,which indicates that geopolymer mortar has obvious high early strength.Under the same curing time,the geopolymer mortar specimens with the addition of 2%nano-alumina have the best mechanical properties,while the mechanical properties of the specimens with the addition of 0%,1%and 3%nano-alumina mortar are all lower than those with the addition of 2%nano-alumina geopolymer mortar specimens.