Concrete is the most widely used building material in the world. China is one of the countries with the largest amount of concrete. Reducing the carbon emission and resource consumption of concrete, and improving the recycling and utilization of waste, is the one of the method to develop green concrete. However, there are still internationally recognized problems in the basic theoretical research of concrete in environmental protection, mechanics and rheology, such as the contradiction between concrete environmental protection and performance, the influence mechanism of high brittleness and low toughness of concrete, concrete logistics and so on.

This project has carried out systematic and exploration around the relevant problems of green concrete, and achieved a number of representative research results, which provides some new methods, models and theories for the basic theoretical research of green concrete.

The project jumped out of the traditional way of solid waste as cement replacement or aggregate replacement, took solid waste as slurry substitute, and invented "cementitious paste replacement method", which opened up a new direction for the research of solid waste utilization. The mechanical model and constitutive equation of elastic particles concrete are established, which provides a new reference for the design of recycled rubber concrete. The "water film thickness theory" is developed, which contributes a new theory to the progress of rheology of cement-based materials and the application of self compacting concrete.

Research achievements and scientific research value of the project are as follows.

Research achievement- Adding solid waste as cementitious paste replacement

The "cementitious paste replacement" method of solid waste is invented, which realizes the efficient utilization of solid waste and the significant reduction of cement consumption. The concrete with synergistic improvement of performance and environmental protection is successfully developed, which opens up a new direction for the resource utilization of solid waste and the research and development of green high-performance concrete.

"Cementitious paste replacement" for solid waste solves the problems of poor practicability of the traditional "cement replacement" and "aggregate replacement" without reducing cement consumption and performance, realizes the efficient utilization of solid waste and significantly reduces cement consumption, and improves the performance of concrete at the same time. This plays an important role in solving the problem of solid waste pollution, realizing the transformation and upgrading of building materials products, and developing a low-carbon sustainable economy.

Cement replacement-aggregate replacement-cementitious paste replacement

Research achievement- Mechanical model of recycled rubber concrete

The theoretical system of elastic particles concrete is put forward, the mechanical analysis model and constitutive equation of recycled rubber concrete under different forces are established, and the environmental friendly recycled concrete with impact resistance and fatigue resistance is designed, which provides important guidance for the reuse of waste rubber and the design of elastic particles concrete. 

The design theory and analysis model of elastic particle concrete provide important theoretical guidance for the development of concrete solid mechanics. The environmental friendly recycled rubber concrete with impact resistance and fatigue resistance not only provides a method for dealing with "black pollution", but also provides an important technical support for solving the stubborn disease of high brittleness and low toughness of concrete.

Fatigue resistance-impact resistance-constitutive model

Research achievement- water film thickness

It is proved that the key factor affecting the rheological properties of cement-based materials is "water film thickness". A "water film thickness" theory of rheology of cement-based materials is developed, which lays an important theoretical foundation for the optimal design of self compacting concrete. The proved key factor "water film thickness" reveals the influence mechanism of rheological properties of cement-based materials, and effectively promotes the development of rheological research. The "water film thickness" theory provides important theoretical guidance for the optimal design and engineering application of self compacting concrete

Water film thickness theory