On August 18th, 2021, China Concrete and Cement-based Products Association organized the scientific and technological achievement appraisal meeting for the project entitled as “Development and engineering application technology of a series of new mineral admixtures for concrete", which was completed by China Academy of Building Research, China Road & Bridge Corporation, and YCIC Highway Construction Co., Ltd.

As one of the most important building materials, the annual consumption of concrete of the world has exceeded 5 billion m3. Due to large construction project, in some regions there is always a shortage of raw materials and the traditional high-quality mineral admixtures such as fly ash and GGBS for concrete. Highway, railway and water conservancy projects are often located in remote regions or underdeveloped countries, where are always lack of these traditional high-quality mineral admixtures above. And the transport duration of the mineral admixtures is quite long and the delivery cost is relative high. Adding appropriate mineral admixtures into concrete is an important way to improve the workability and durability. The development of new mineral admixtures for concrete to prepare high-performance concrete is not only the objective need of engineering construction, but also the inevitable trend of technology development.

To solve the problems of shortage of traditional mineral admixtures such as fly ash, silica fume and GGBS, the scientific research team of this project carried out the following research:

l Development of the characteristics of natural materials as mineral admixtures for concrete and the relative concrete proportion technology;

l Development and utilization technology of typical industrial waste residue as concrete admixture;

l Development and application of composite and functional concrete admixtures.

After 10 years of experimental research, engineering practice, the project team has the following technological innovations:

l In the situation of the increasing shortage of traditional mineral admixtures such as fly ash and GGBS, but the growing demand of high performance of concrete, a variety of single mineral admixtures, composite mineral admixtures and functional composite mineral admixtures are systematically studied. A theoretical system of mineral admixture composite is formed, and a series of standardized technical indexes are established.

l As single mineral admixtures, the technical characteristics of natural materials and industrial waste residues are revealed, such as natural pozzolanic materials, limestone rock powder, gneiss stone powder, granite stone powder, ferronickel slag and phosphorus slag. The key quality control indexes, such as effective alkali content of pozzolanic ash, adsorption characteristics of rock powder, activity and stability of ferronickel slag, P₂O₅ content in phosphorus slag, and their testing and evaluation methods are established.

l Based on the theory of induced activation and particle dense packing of mineral admixtures, the synergistic effect between different kinds of mineral admixtures is clarified, and the methods of improving the activity of mineral admixtures and optimizing the powder particle gradation are proposed, which provides theoretical guidance for the targeted design of various functional composite mineral admixtures.

l The functional composite mineral admixtures such as viscosity reducer, anti-corrosion viscosity reducer and steam curing early strength agent are developed. The standardized evaluation methods and indexes such as viscosity ratio and steam curing compressive strength ratio are established, which provides technical solutions for the preparation and construction of concrete in different conditions.

Mombasa–Nairobi Railway in Kenya

The first 120m concrete wind power tower in China

The research results of the project are widely used in international projects such as Mombasa–Nairobi Railway and Nariobi-Malaba Railway in Kenya and a lot of major domestic projects. The result provides technical support for engineering construction in areas lacking traditional mineral admixtures, has great significance to ensure the quality of concrete engineering, and remarkable social benefits. At the same time, mineral admixtures can take partial place of cement, which could reduce carbon emission and have remarkable environmental benefits.

China Academy of Building Research welcomes cooperation with foreign enterprises. If interested, please contact CCPA Science and Technology Department at chenyu@ccpa.com.cn for further information.