Recycled concrete is a kind of green and new material. With the application of construction, more research should be carried on its carbonization performance, not only focusing on its mechanical properties. Recycled concretes with different W/C (0.45、0.55 and 0.65) and recycled aggregate mix proportions (0、30%、50%、70%and 100%) are made to test their carbonation depth. The results show that water-cement ratio and recycled aggregate mix proportions have interactive influence on carbonization performance of recycled concrete. Influence of recycled aggregate on carbonation depth depends on two conflicting aspects: one is beneficial effect due to high water absorption; another is harmful effect caused by damage structure. A new model of RAC carbonation depth is suggested based on the study.

Water treatment ceramic particles were prepared using dewatered life sludge in Huainan No.1 Sewage treatment plant and power plant fly ash as main materials and clay as the bond. Through the L9 (43) orthogonal test, we obtained the best conditions of the preparing process. The product can be used as water treatment packing ceramic particles and simulated adsorption experiment with the wastewater including Pb2 + was conducted. The results indicate that ceramic particles (used as wastewater treatment filler) bibulous rate is 25.0%, the loose density is 690kg/m3, the particle density is 1240kg/m3, specific surface area is 5.997m2/g, the compressive strength is 9.40MPa and the adsorptive performance is excellent. The toxic metal leaching experimental result shows that the concentration of toxic heavy metals in leaching solution is in the range of GB specification and the performance of product is stable which will not cause second pollution.

Performing the superposition effect of multi-elements mineral admixtures, high performance concrete (HPC) with 3% of silicon fume, 20% of fly ash and 40% of ground granulated blast-furnace slag (GGBS) was prepared, and its physical and mechanical properties and durability were studied systematically. The compressive strength and tensile strength of HPC are better than those of ordinary concrete. HPC has high compactness with smaller gas diffusion coefficient and relative permeability coefficient. Adding volume stabilizer and controlling the contents of SO3 in the GGBS and volume stabilizer at 3%, can reduce dry shrinkages effectively. Large mount of mineral admixture was used to make the concentrations of K+ and Na+ in the pore solution and the expansion caused by alkali-silica reaction depress greatly. So the alkali-silica reaction gets controlled markedly. The effective diffusion coefficient of chloride ion is 1.96×10-12 m2/s, which means HPC has a favorable chloride ion penetration resistance. After 15 times of wet-dry cycle, the rates of the rust area and quality loss of the reinforcing steel bars in HPC are only 4.1% and 0.05% respectively, so HPC has better performance of steel protection. The mortar bar did not expand in corrosive sodium sulfate solution, and it means HPC has better performance of sulfate resistance. The performances of frost resistance and carbonation resistance of HPC are also favorable. It’s proved in tests that the superposition effect of multi-elements mineral admixtures can enhance the physical and mechanical properties and durability of concrete greatly.

This paper presents results of impermeability and frost resistance tests of a series of high strength concrete which will be used in Yuncheng coal mine shaft lining. And the shaft is one of the most difficult to construct using freezing method because of the extreme thick overburden soil. The results show the impermeability and frost resistance of the selected concrete mix proportion options can meet the special requirements of the shaft construction. It’s due to the low water-cement ratio, admixture and water-reducing agent decreases void caused by excess water. And the composite mineral admixture forms bubbles to cut off the tiny water permeable channels in cement stone. Also the filling effect and pozzolanic effect caused by fly ash contribute a lot. The research on high strength concrete used in shaft of coal mine with thick overburden soil is still rare worldwide.

Physical characteristics (including unit weight, dry unit weight and submarine rest angle) and motion characteristics (including settlement characteristics, incipient velocity and resistance characteristics) of bamboo powder model sediment were studied by test in this paper. Experimental study on physical characteristics showed that particle size variation had little effect on unit weight, dry unit weight increased with the particle size,submarine rest angle increased with the decrease in particle size and an empirical formula for calculating submarine rest angle of bamboo powder model sediment was proposed. Experimental study on motion characteristics found that the single particle settling velocity of bamboo powder model sediment increased with particle size, the relative settling velocity initially increased and then decreased with sediment concentration, the incipient velocity increased with the particle size and water depth, the roughness decreased with water depth and increased with the flow velocity and an empirical formula for calculating the incipient velocity of bamboo powder model sediment is proposed.