| With the low-carbon development of society,concrete as the largest amount of construction materials faces the problem of sustainable development.The development direction of concrete is transforming into green,high performance,and multi-functional.According to the characteristics of concrete as a ground material and the regional characteristics of solid waste in Jiangxi Province,grounded ceramic waste tile were used as cementitious materials and fine aggregates,copper-coated fibers as reinforcing fibers,for the preparation of green multi-functional high-performance concrete(HPC).However,it has been shown that the high volume of ceramic waste tile powder and tile aggregates will reduce the mechanical properties of HPC from the available studies.As a cheap nano filler,nanocalcium carbonate(NC)has been proven to improve the mechanical properties and piezoresistivity of concrete.Therefore,the mechanisms and effect of NC on the mechanical properties of HPC with high volume ceramic waste tile powder and tile aggregates were firstly investigated in this paper.Then,the effect of NC on the electrical and piezoresistive of HPC with high volume ceramic waste tile powder and tile aggregates was investigated,and the stress-electricity model was developed.The mainly research content and results are as follow:(1)NC modified HPC with high-volume ceramic waste tile powder/tile aggregate was prepared using two particle sizes of NC(NC1:40~50nm and NC2:70~80nm).And the effects of different contents and particle sizes of NC on the workability and the mechanical properties of the HPC were tested.The mechanisms were explored using X-ray diffraction,scanning electron microscopy,thermogravimetric and mercury compression analysis methods.The results show that both different particle sizes of NC can improve the fluidity of ceramic waste tile powder/ aggregate high-performance concrete due to the ball effect and displacement effect of NC.The appropriate amount of NC can effectively improve the flexural strength,fracture toughness,compressive strength,compressive toughness,and flexural to compressive ratio of HPC with high-volume ceramic waste tile powder/tile aggregate.And the strength and toughness of HPC with high-volume ceramic waste tile powder/tile aggregate both tend to increase and then decrease with the increase of NC content.Compared with the NC in smaller particle size,NC in larger size has a more significant improvement in the early compressive and flexural strength.Moreover,NC can improve the mechanical properties of HPC with high-volume ceramic waste tile powder/aggregates by reducing the selective orientation and size of calcium hydroxide,promoting hydration reducing the width of the interfacial transition zone,and improving the pore structure.(2)The direct current and alternating current resistivities of HPC with high volume ceramic waste tile powder and aggregates were tested,along with the piezoresistive properties of concrete specimens under cyclic and ultimate loads.And the stress-electricity model of HPC with a large dose of tile powder/tile aggregate was established.The results show that the incorporation of NC raises the direct current/alternating current resistivity of HPC with highvolume ceramic waste tile powder and aggregates.Both direct current/alternating current resistivity tended to increase and then decrease with the increase of NC content.The two size of NC modified tile high-performance concrete both showed good pressure sensitivity under different load types and loading amplitudes.And the improvement of the piezoresistive of the tile high-performance concrete specimens was more obvious for NC1.This is attributed to the fact that the incorporation of NC affects the distribution of steel fibers in the matrix,the size,number,and distribution of hydration products,resulting in changes in the electrical conductivity and piezoresistive of the concrete.The force-electric model is established by polynomial fitting,which can be used to describe and describe the force-electric relationship. |
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