Study On Conductivity And Strain Sensitivity Of Steel-slag Concrete

Concrete is the most widely used material in construction, while concrete often rupture with brittleness as a result of weathering , environmental eroding and human interference, which may leading to a disastrous outcome. Therefore, it is necessary to conduct a research on the safety inspection and self-adaptive control system for big civil establishment, which is important scientific and technical issue bearing upon the sustainable development of our country. During the past few years, many academicians had conducted studies on the electrical performance of concrete. The latest study showed that electrical performance could be used for self-inspected in concrete structure. While little knowledge have been got yet, thus, it is indispensable to study the electrical performance with system before we can use electricity test as a non-destructive evaluation of concrete successfully. The study of electrical performance and strain sensing would serve theoretical and experimental foundation for the smart concrete which could be integrated with the performance of loading, sensing and transmission. The study was a great offshoot of smart material and structure research.This thesis reviewed papers on the electrically conductive concrete and strain sensing concrete inside and outside the country and studied the electrical performance and strain sensing of steel-slag concrete systemically by test analysis. The paper studied the prepare craftwork, parameter optimization, electrical performance, strain sensing and the factors affected. The mechanisms of conductivity and strain sensing were discussed as well. The gain was listed as following:(1) A new kind of electrically conductive concrete has been prepared with steel slag. The new concrete decreased the cost largely while with good performance in conductivity and mechanics, cut a new way of utility for steel slag, achived notable economic , society and nature benefit.(2) By compared the performance of concrete with different proportion of concrete, the better mix was found between 1~4 by cement to steel slag. Afterwards, many factors that affected the conductivity had been concerned.(3 ) The paper revealed that steel-slag concrete had good strain sensing and that there was a corresponding relation between strain and the fraction change ofelectrical resistivity. It was pointed out that the trend for the change of resistivity during loading was accorded with quadratic equation, which could be used for forecast the real-time resistivity. Therefore, strain sensing could be used for stress evaluation in concrete, and then cut a new way for the realization of smart structure.(4) The factors that affected the strain sensing were studied based on the study of the conductivity of steel-slag concrete.(5) The paper showed that strain sensing had "size effect". With the increase of size of specimen, resistivity is more sensitive with strain. Resistivity of specimen also had size effect, which would be related with the contact resistivity between electrode and concrete.(6) The study showed that resistivity became more sensitive to strain after integrated with fly ash or silica fume, which would be resulted by the melioration of aggregate interface.(7) Curing under hot water would speed up hydration, which would resulted in that the resistivity increased, by the way, the strain sensing, while the mechanism needed further discussion.( 8 ) The mechanism that resistivity was affected by temperature and moisture was revealed from micro vision. The paper analyzed the effect of capillary water and gel water on the resistivity and put forth on strain sensing and the ratio of tunnel penetration of electron.