1. Research for Recycled concrete
According to statistics, in 2015, China's commodity concrete has reached 1.6 billion m3, sand aggregate demand reached more than 12 billion tons, the consumption has leapt to the world's first. The production of raw materials of concrete, such as aggregate, water resources, binding materials consumed a large amount of natural resources; on the other hand, mining, transporting and manufacturing raw materials brought large influence on the environment.
The recycled concrete aggregate is the aggregate of waste concrete block being broken and graded and mixed in a certain proportion. The recycled concrete is the concrete which using recycled aggregate as part or all aggregate. Recycled concrete technology has accomplished the recycling of waste concrete and formed new building materials products, which has remarkable economic, social and environmental benefits.
The research group has always regarded the research of recycled concrete as the most important research and has achieved fruitful results in this field. It has been in the leading position both at home and abroad on the research of recycled concrete. Study on recycled concrete of the research group has following fields: life cycle assessment of recycled concrete; reliability analysis model of modified recycled concrete; modeled recycled concrete; time-dependent reliability of recycled concrete structure; shear interlocking mechanism of recycled concrete; impact and dynamic performance of concrete, etc..
2. Fire Resistance of High Performance Concrete
Fire is one of the most common, dangerous and devastating disasters in disasters that cause damage to civil engineering. High temperature (fire) has a significant influence on the properties of structural materials. Therefore, fire can easily lead to deterioration of material, component damage, structural damage, and even collapse.
The fire resistance of concrete structures is a highly comprehensive interdisciplinary subject, involving fire science, fire engineering, building materials, engineering thermal physics, structural engineering and other fields. The main goal of the research is to improve the understanding of the structure and characteristics of building fire effect, establish fire resistance theory and design method, provide economic, reasonable and effective technical measures to reduce the fire losses.
The former research mainly aims at the ordinary concrete, and the high performance concrete is the inevitable trend of the development of structural concrete in the future. In recent years, high performance concrete with high strength, high workability and high durability has been developing vigorously. However, the research on the high temperature performance and structural fire resistance of high performance concrete materials is not enough and systematic.
The research group has always focused on the study of fire resistance of high performance concrete, and has achieved great results. The main research directions in this field are: shear properties, thermal conductivity, bond slip performance, thermal parameters and the mechanical properties of concrete after high temperature; fire response of high-strength concrete concrete-steel composite shear wall and seismic performance of after fire high-strength concrete-steel composite shear wall; fire response of high performance concrete frame and seismic performance of after fire high performance concrete frame, etc..
3. Prefabricated Concrete Structure
Precast concrete technology is an industrialized way of building construction. The construction method of precast concrete structure, in brief, is a kind of construction technology that combines prefabricated concrete components by cranes and other carrying construction machinery. The construction could be divided into two stages: the first stage, prefabricate the components in the factory; the second stage, install the components on the site. The process of construcion of precast concrete structures are designing, manufacturing, transporting, installing, decorating, etc..
The prefabricated concrete structure can realize fully automated production and modern control in the process of construction, with short construction period and fast construction speed, and can also make full use of industrial waste in the process of design and production and turn waste into treasure. The prefabricated concrete structure is easier to be demolished than the cast-in-place structure, therefore the reuse of the concrete structure can be realized. The combination of prefabricated structure and recycled concrete can improve the sustainability of concrete.
The research of prefabricated concrete structure is of great significance to the research group. Through the unremitting efforts in recent years, the research group has made many breakthroughs in prefabricated concrete structure. There are some main research directions in this field: the seismic performance of full-scale beam column joints of precast recycled aggregate concrete frame; analysis of cast-in-situ exterior joints of precast recycled aggregate concrete frame; shaking table test on precast recycled aggregate concrete frame structure model; BIM-based framework of concrete structure reuse.
4. Sea Water Sea Sand Concrete
In actual engineering applications, the acquisition of concrete raw materials is largely limited by geographical location. China's coastal and island areas lack fresh water and river sand resources, but have rich sea water and sea sand in resource storage. To utilize seawater and sea sand resources for the construction of concrete islands and coastal engineering reasonably and effectively is of great benefit whether in economic or environmental aspects.
In recent years, the research group has carried deep research on the sea water sea sand concrete, and made a lot of progress. The main research directions are: the durability of high performance concrete with desalinated sea sand; bonding properties of seawater sand concrete and FRP bars; the seismic performance of sea sand high performance concrete shear wall, etc..
5. Make Construction Waste into Resources
According to the statistics, China produces more than 20 tons of construction waste every year, and Germany produces about 2 tons of construction waste every year, Japan produces less than 1 tons, South Koreas’ is about 70 million tons, Spains’ is about 40 million tons. The construction waste in China is higher than the total amount of Germany, Japan and Korea. But the comprehensive utilization rate of construction waste in China is much lower than those in other countries. It is estimated that in the next 10 years, China will still produce more than 20 tons of construction waste on average every year, therefore the construction waste siege will be intensified. Under such a severe background, considering the energy saving, environmental protection and sustainable development, the recycling and utilization of construction waste in China is imperative.
Making construction waste into resources means that we should fully excavate the potential value of construction waste, the establish good collection system of construction waste, specify the relevant legal system, improve the relevant industry standards, and come up with incentive measures to support the construction waste recycle and reuse.
To make recycled concrete aggregate from concrete construction waste is an important part of building waste recycling Therefore, the construction waste recycling has always been the focus of the research group.
