| With the development of the society,the traffic volume and load of the road are increasing.Cement based concrete pavement,as a rigid pavement with high stability and good bearing capacity,will inevitably produce cracks,holes and holes in the course of its use due to repeated actions of load and environmental factors.If the local disease does not get effective and timely repair,it will eventually lead to irreversible damage.The pavement repair materials used on the market are now expensive and can't be green.Geopolymer is a new type of cementitious material.The geopolymer is characterized by three dimensional network structure.It is excite by excite territory,aluminate mineral or industrial waste residue and so on.Its structure unit is[AlO4]and[SiO4]tetrahedron.It has the characteristics of ceramic and polymer materials.Geopolymers are generally considered to be a new type of cementitious material that can replace Portland cement.The main purpose of this paper is to prepare geopolymer based repair materials,which is economical,green and environmental friendly,and applied to repair concrete pavement.Using slag and fly ash and other industrial wastes as the main raw material,using water glass and NaOH as activator of geopolymer mortar preparation,study the effect of oxide content in raw material and raw material ratio on the performance of mortar,the effects of various factors on the law of the repair mortar and the best ratio.The effect of silica fume,sulphoaluminate cement and gypsum on the performance of mending mortar was then studied.In the repair experiment of concrete pavement,water reducer,retarder and fiber are added to improve the performance of repaired mortar,so as to meet the mechanical strength,setting time and construction performance requirements of pavement repair materials.The results of the study show that:Using fly ash as main raw material and adding different amounts of slag and silica fume can promote the mechanical properties of geopolymer mortar,but slag has greater influence on strength than silica fume.By analyzing the composition of raw material in oxide containing CaO showed:in the system,the compressive strength and the flexural strength with CaO/(Al2O3+SiO2)increases in calcium free Geopolymer mortar system,geopolymer mortar strength with n(SiO2)/n(Al2O3)increase and when n(SiO2)/n(Al2O3)reaches about 3.8,the mortar strength has no obvious change,so the geopolymer mortar system most suitable for n(SiO2)/n(Al2O3)ratio is about 3.8.The ratio of liquid to solid,slag and fly ash,water glass content and NaOH concentration and other factors on the performance of mortar to obtain the factors the optimal level,and by optimizing the ratio of L1656,and the influence of various factors on the performance of mortar was small.Through single factor and orthogonal test,the best proportion of repair mortar is as follows:slag content is 0.8,liquid to solid ratio is 0.35,water glass content is30%,NaOH molar concentration is 3.2mol/L.Through the incorporation of silica fume in the activator that can significantly improve the mechanical strength of mortar,and the optimum content is 2%;by the incorporation of sulphoaluminate cement,the mechanical strength of repair mortar have no effect,but can play a retarding effect;by adding gypsum gypsum that blended obviously prolong the setting time of mortar,when the content is 4%,the setting time can be extended to 50min.Through the road repair experiment of mending mortar,it has the following shortcomings:poor fluidity,short setting time,and easy to crack.By adding naphthalene superplasticizer,retarder and basalt fiber to modify it,the best dosage of water reducer is 1%,retarder 0.6%and basalt fiber 0.4%.Through laying test section,it is found that the 1d compressive strength of modified geopolymer based mortar can reach more than 30MPa,and the flexural strength can reach 6MPa,and the setting time is 20-60min.It can meet the construction performance and fast traffic requirements of the repair works of various areas. |
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