Combined with strain gauge measurement method, the modified split Hopkinson pressure bar was adopted to investigate the behavior of normal concrete and steel fiber reinforcement concrete exposed to 400°C and 800°C under axial impact compressive loading. The experimental results show that compared with normal temperature, the compressive strength and elasticity modulus of normal concrete exposed to 400°C and 800°C decrease obviously. The transformation of concrete exposed to high temperature in microstructure is analyzed by SEM. The influence of high temperature on macro mechanics performance is discussed.

Graphite, stainless steel and brass were selected as electrode materials in the chloride migration test. The diffusion coefficients were calculated from the steady state of chloride flux by the Nernst-Planck equation. X-ray diffraction was used to characterise the corrosion products in the chloride migration tests. The results show that the types of electrodes have significant effects on the diffusion coefficient calculated from the migration test. The diffusion coefficient may trend closely to the real value when graphite electrodes are used. Graphite is a suitable electrode material used in the chloride migration test.

According to the theory of dense packing of particle, the theoretical particle size distribution of raw materials of RPC (Reactive Powder Concrete) was calculated. On the basis, the ratio of raw materials with different range of particle sizes of the RPC was determined by mechanical experiments. According to the determined ratio, a new type RPC was prepared by using flying ash and slag to replace part of cements and quartz flour, respectively. The workability, mechanical properties of the new RPC with different mix proportion and its shrinkage, cured at the normal temperature and 60°C, respectively, were studied. The results show that when water-binder ratio is 0.23, fly ash replaces 30% cements, slag replaces 50% quartz flour and superfine steel fibers percentage in volume is 2%, the compressive and flexural strength of prepared RPC are 160.1MPa and 25.3MPa, respectively, and after 3days heat curing (60°C), the dry shrinkage of it in 28days age reaches 299um/m. In addition, the fluidity of the new RPC is 258mm and meets requirements of workability of the pump concrete.

In order to monitor corrosion risk in cover-zone concrete, an integrated tower type sensor (TTS) was developed to obtain the electrochemical parameters such as concrete resistance, macro-cell current and the corrosion potential of built-in electrodes. To obtain valid macro-cell current value, specialized short-circuit acquisition time equal to 30 s has been defined in present cement mortar. The results indicate that the macro-cell current increases and cement mortar resistance decreases meanwhile with the content of chloride ions increase in imported chloride cement mortar. The effective measurement of the macro-cell current and cement mortar resistance allows TTS to be used as a corrosion risk monitoring system in cover-zone concrete.