Research On Performance Of Graphene Oxide Modified Cement Composite Material

With the development of society and the rise of prefabricated buildings,high-performance ceramsite concrete has good application prospects and huge development potential.As the main coarse aggregate of ceramsite concrete,due to its low mechanical properties,ceramsite concrete limits the development of high-performance ceramsite concrete.A large number of researchers have solved this problem by adding functional materials to cement composites.The nano-material graphene oxide(GO)has unique mechanical properties,nano-size effects,and excellent reinforcement effects in cement composite materials.It is currently the most potential material to improve the performance of cement-based materials.In this study,the LC30 ceramsite concrete was prepared according to relevant specifications as the experimental basis,and the ceramsite concrete was modified by GO to improve the mechanical properties of the ceramsite concrete.The gel system,colloidal sand system and ceramsite concrete system were respectively studied to the influence of GO on the performance of ceramsite concrete is comprehensively discussed.The microscopic analysis clearly characterizes the mechanism of GO on the mechanical properties of cement-based materials.The main content and results are as follows:(1)With the increase of the amount of GO,the compressive strength of cement slurry first increased and then decreased.The compressive strength of the additive group was higher than that of the blank control group.In addition,the highest increase in compressive strength of GO content is 0.02 wt.%.The maximum increase for the 3-day age is 64%;the maximum increase for the 7-day age is 51%;the maximum increase for the 28-day age is 21%.(2)GO can promote the hydration process of cement,accelerate the dissolution of silicate minerals in the raw materials,and increase the content of CSH as a hydration product.GO leads to formation of more CH and reduced the production of acicular mineral ettringite(Aft)during early hydration of the cementitious system.The low dosage of GO nanosheets can effectively regulate the formation and distribution of cement in the cement slurry,and promote the transformation of cement hydration products to coarse columnar crystals with more strong chemical bonds.(3)With the increase of GO content,the water retention and fluidity of cement mortar showed an increasing trend.The maximum water retention increased by 11.9%,and the maximum fluidity increased by about 28%.The 3-day,7-day and 28-day compressive strength of cement mortar firstly increased and then decreased with the increase of GO content.In the3-day curing age,the maximum increase was 43.8%,in the 7-day curing age,63.2%,and in the 28-day curing age,The maximum increase was 32.6%.The change in bending strength is consistent with the change in compressive strength.In the 3-day healing age,the maximum increase was 26.7%,41.7% in the 7-day curing age and 40.4% in the 28-day curing age.(4)GO-ceramsite concrete has good workability,the minimum slump of GO-ceramsite concrete is 180 mm,and the minimum expansion degree is 385 mm.The addition of GO can effectively improve the compressive strength of ceramsite concrete,and the maximum improvement rate is 35.6% in the 3-day age.In the 7-day age,the maximum lifting rate was10.5%,and in the 28-day age,the maximum lifting rate was 14.8%.With the increase of GO content,the splitting tensile strength of ceramsite concrete first increases and then decreases,the maximum increase is 52.5%.In addition,Due to too little GO content,it has little effect on the elastic modulus of ceramsite concrete.(5)GO aggregates around the ceramsite through the water-absorbing effect of the ceramsite,and the micropores on the surface of the ceramsite provide a smaller spatial size for the aggregation of GO.In addition,the rough surface of the ceramsite provided adhesion points for the GO agglomeration,leading to the GO agglomeration around the ceramsite in the concrete system,which resulted in the formation of micro-cracks between the ceramsite and the gel,thus reducing the direct engagement effect between the ceramsite and the gel.(6)The cost of graphene oxide modified ceramsite concrete increased to 8.4 yuan/m3.And the benefit of improving its mechanical properties is far greater than the increase of its cost,which has strong economic feasibility.