Study On Preparation And Performance Of Graphene Oxide Recycled Mortar

Since the 21st century,with the continuous development of urbanization in China,the demolition of old buildings will produce a lot of construction waste.According to statistics,China’s construction waste output reached 19.87 billion tons in 2019,while concrete consumption reached27.38 billion cubic meters in 2019.The amount of sand and gravel used makes up 70 percent of the concrete’s weight.However,China’s construction treatment is still dominated by filling,which not only causes waste of resources but also causes secondary pollution to the environment.Therefore,the recycling of construction waste is one of the most reasonable,environmentally friendly,and economically beneficial methods to improve the utilization rate of construction waste and reduce the extraction rate of sand and gravel.In this paper,the replacement rate of recycled fine aggregate,water-cement ratio,and the amount of polycarboxylic acid water-reducing agent on the mechanical properties of recycled mortar were analyzed through the preparation of reclaimed sand to partially replace standard sand.Basic performance,to improve the regeneration of slurry by adding oxidized graphene（GO）to promote the cement hydration,improve the regeneration of mortar stick relay,analysis of graphene oxide content of recycled cement mortar flexural,compressive,freeze resistance,weather resistance,and through the analysis of the microscopic mechanism of GO mortar,the basic principle of the comprehensive performance of enhanced regeneration.The specific content is summarized as follows:（1）The physical performance test analysis of the recycled fine aggregate and standard sand shows that:the recycled fine aggregate has many edges and corners,the surface is rough,there are a large number of microcracks and contains a large amount of fine powder,resulting in its apparent density,bulk density,The porosity,and water absorption are higher than those of standard sand,and the water absorption of recycled fine aggregate is 4.55 times that of standard sand.（2）The analysis of the mechanical properties of recycled cement mortar shows that its flexural and compressive strength decreases as the replacement rate of recycled fine aggregate increases.When 30%recycled fine aggregate was added to replace standard sand and the curing age of recycled cement mortar was 28 days,the flexural and compressive strength decreased by 16%and18%,respectively.Changing the water-cement ratio and the amount of water-reducing agent has no obvious effect on the mechanical properties of recycled cement mortar.（3）Add GO to recycled cement mortar,and conduct flexural and compressive tests,freeze-thaw resistance,and weather resistance performance analysis.Compared with recycled mortar without GO:the flexural and compressive strength of the 7-day recycled mortar modified by adding0.03%GO is increased by 16%and 21%,respectively;the flexural strength of the recycled mortar with 28-day strength modified by adding 0.02%GO The compressive strength was increased by13.7%and 13.6%respectively,and the resistance to freeze-thaw cycles for 25 and 50 times,and the weather resistance of 7 days were all significantly improved.（4）Through scanning electron microscopy,thermal analysis,and X-ray diffraction analysis,GO can promote cement hydration products,making ettringite（AFt）and hydrated calcium silicate（C-S-H）denser.At the age of 7d and 28d,the content of calcium hydroxide（CH）increased by 2.1%and-1.6%,respectively,confirming that GO has an inhibitory effect on the formation of CH,the product of cement hydration in the later stage.（5）Environmental radioactivity detection and chloride ion content detection and analysis were carried out on recycled mortar.The chloride ion content of recycled mortar was less than 0.06%.The internal and external exposure index of the mortar was I_Ra≤1.0 and I_r≤1.3,which reached the standard of Class A decorative material and can be used in reinforced concrete.Any internal and external surfaces of fields and building structures are harmless to the human body.Figure[44]table[25]reference[87]...