By use of ASTM C1202, this paper studied the influence of mineral admixtures on the chloride ions penetration resistance of the new-old concrete compound system. The results indicate that the performance of new-old concrete exert significant influence on the new-old concrete compound system. The addition of mineral admixtures improve the permeability properties of new-old concrete. Adding fly ash(FA) require a relatively longer time to get its beneficial effect. When 30% weight of cement is replaced by 10% FA and 20% ground blast furnace slag(GGBFS), the inclusion of 30% mineral admixtures significantly improve the chloride ions penetration resistance properties of the new-old concrete compound system at 28 days and 180 days.

The harmful chloride ion in sea sand concrete is the main issue that hinders its application, proposing a method using fly ash the active mineral, chloride ion content of harmful curing of sea sand concrete, to improve the durability of sea sand concrete. The experiment studies the influence of sand in the chlorine ion and fly ash on the strength of concrete, and analyzes microscopic structure and hydration products of concrete. Research results show that: the sea sand concrete with 20% fly ash prepared has good mechanical properties and durability; the existence of Cl- on the early strength of sea sand concrete has a positive promoting role, but has negative effective on the later development.

The objective of this research was to develop a new composite material/system in structural civil engineering. To use of mechanical properties of bamboo-based panel and cold-formed steel, this study composite two kind of materials above-mentioned together utilizing structural adhesives. The research developed various of bamboo/steel composite members, such as composite slabs, composite walls, composite beams and composite columns. And the paper emphasized mechanical performance of bamboo/steel composite slabs and composite beams. Experimental studies on flexural behavior of 6 composite slabs and 9 composite beams were carried out and the failure process, failure modes and failure mechanism were investigated. Experiment results indicates that the bamboo plywood and cold-formed steel can form an excellent composite cross-section; Load vs. mid-span deflection curves of composite slabs and composite beams show linear on serviceability limit state. The maximum ultimate strength of composite slabs and beams have reached 30.0 kN•m and 36.13 kN•m respectively. The study shows that bamboo-steel composite members have good prospects in building structures of China.

Sea sand concrete is a kind of concrete in which mixed sea sand as fine aggregate, which is large-scale application in the coastal areas in recent years, especially in Ningbo area. The sea sand solves the problem of river sand shortage, coupled with cheaper price, most of the ready-mixed concrete companies are willing to use desalted sea sand instead of river sand. Many companies even are using sea sand without any treatments.In Ningbo sea sand concrete using wide range of usage is not optimistic. This survey and analysis in Ningbo area physical characteristics of concrete using sea sand and sea-sand. On this basis, chloride simulating sea sand, mixed with desalted sea sand, not desalted sea sand mortar strength measurement, the concrete strength rule were analyzed, and discovered the early strength for the sea sand concrete by the presence of chloride.

In precast concrete elements manufacturing, steam-cured concrete incorporating 30% fly ash encountered the problem of a too low demoulding compressive strength. To resolve it, this paper developed a new steam-cured concrete (AFSC) incorporating fly ash and a chemical activator. Experiments were conducted to investigate the mechanical properties of AFSC. The corresponding mechanism was also discussed by testing the microstructure of concrete. Results indicate that the demoulding compressive strength of AFSC can meet production requirements, and compressive and flexure strength of AFSC at later ages increase well. Compared with that of ordinary steam-cured concrete, AFSC has a higher tensile strength, and the capability of AFSC to resist cracks is enhanced remarkably. At an early age, addition of the chemical activator can distinctly accelerate the extent of hydration of the fly ash cement systems, and thus the microstructure of concrete becomes denser.