The Study Of Preparation And Properties Of High-strength Metakaolin-based Geopolymer

Geopolymer,a high silicon aluminium natural minerals or industrial waste as raw materials,form a new type of inorganic polymeric material through chemical excitation.It can change from amorphous to semi-crystalline,belonging to non-metallic materials.Due to the low cost of raw material,simple production process,low energy consumption,low pollution,good mechanical performance,heat-resistant,corrosion resistance and durability,the geopolymer not only can replace the building materials but can be a solid nuclear solid waste material,repairing materials,heat-resistant materials and drug supporters.Which is a research hotspot in material industry.The formation of the Geopolymer is affected by many other factors,include the nature of the raw material,the characteristics of the alkali activator,the alkali concentration,the water content,the curing conditions and the additives.In this paper,In this paper,geopolymeric polymers was prepared from kaolinite,mineral powder,NaOH and water glass,and the effect of the oxide mole ratio?Na₂O/Al₂O₃,H₂O/Na₂ O,SiO₂/Al₂O₃?of the geopolymer mixtures,the curing conditions?temperature,time?and mineral powder?specific surface area,dosage?on the properties of metakaolinite-based geopolymer.were mainly discussed.The aim is to prepare high strength geopolymers.The specific results are listed as follows:?1?The oxide mole ratio of the mixed batch?Na₂O/Al₂O₃?H₂O/Na₂O?SiO₂/Al₂O₃?is a key factor for the compressive strength of geopolymer.,and The optimum mixtures oxide molar ratio were: the mole ratio of SiO₂ to Al₂O₃ was 3.6,Na₂ O to Al₂O₃ was 1.0 and the H₂ O to Al₂O₃ was 9.0,and obtanied the compressive strength of 3 d,7 d and 28 d were 48.7,67.4 and 78.6 MPa,respectively.?2?The curing conditions had significantly influenced on compressive strength of the metakaolin-based geopolymer.The best curing conditions are at 60 ? for 6 h,and obtanied the compressive strength of 1 d,3 d,7 d and 28 d were 52.5,79.7,97.4 and 117 MPa,respectively.?3?There are two types of gels of hydrated silicon?aluminum?calcium?C-?A?-S-H?and alkali aluminosilicate?N-A-S-H?in the mineral powder-metakaolin system geopolymers.Hydrogenated silicon?aluminum?calcium?C-?A?-S-H?gel is beneficial to improve the early strength of geopolymer.The optimum specific surface area and content of the slag were 519 m²/kg and 30%,respectively.The initial-set and final-set time of as-synthesized mineral powder-metakaolin system geopolymer were 310 min and 395 min,respctively,and the compressive strength of 1 d,3 d,7 d and 28 d were 52.8,73.9,87.1 and 98.8 MPa,respctively.