Research On Material Performances Of Self-sensing ECC Board

With the development of society and the progress of technology,people have put forward higher requirements on the quality and safety of concrete structures.In order to prepare materials that meet the requirements of high toughness structures such as plates,bridge decks and pavement,engineering cement-based composite materials(ECC)with ultra-high toughness emerged at the right moment.ECC is composed of reinforced fibers,cementified materials and fine aggregate and has superior mechanical and durability properties than traditional concrete.In ECC micromechanical reinforcement system,fiber plays a key role in establishing ultra-high tensile ductility and controlling self-crack width.Fly ash is one of the important cementitious materials in the matrix,and sand is the only aggregate in the matrix.In order to achieve largescale promotion and application of ECC in engineering,it is necessary to consider the economy of materials and make full use of local resources to save costs.Therefore,it is necessary to study low-cost materials to achieve large-scale application.But the structure always degrades over time due to the self-destruct of concrete materials.Due to the complex interaction between materials and their use environment,external mechanical impact,poor workmanship,etc.,concrete will be slowly destroyed.Although structural deterioration is expected over time,there is a lack of modern tools available to assess structural safety.Therefore,in order to monitor the health status of the structure in real time,carbon black was added into the matrix to study the electrical properties of specimens under cyclic loading and unloading.To this end,this paper has done the following work:(1)At first,to understand the raw material of ECC,at the same time in order to achieve the purpose of material mass use,under the premise that meet the needs of engineering practice,easy material instead of looking for more economy,study each component’s influence on concrete mechanics performance,design experiments with the response surface method,and analyzed the influence of various factors on the mechanical properties,The relationship between the factors and the response is obtained by analyzing the factors that have great influence on each response.(2)For the preparation of the awareness of ECC,the first step in the experiment,on the basis of selecting the two largest correlation factor,with carbon black content as the third factor,design test with the response surface method,and to analyze the impact on the mechanical properties,to explore the impact of the addition of carbon black on mechanical properties and determine whether to meet engineering needs.(3)The self-sensing performance of specimens was studied.According to the mix ratio of the first step experiment,relevant self-sensing performance test is conducted,and the response surface method is used to find the appropriate dosage that can realize both bending sensitivity and pressure sensitivity.At the same time,combining with the first step test,the dosage that can meet both self-sensing performance and mechanical properties can meet the needs of engineering is found.The relation equation between the factor and the response is obtained,which is convenient for selecting the dosage in practical engineering.