Metamorphic rock applications

Project Overview:

The primary mineral resources in the Qiandongnan region of Guizhou Province are low-grade metamorphic rocks. The risk of alkali-aggregate reaction in concrete severely limits their application in construction projects. This project addresses common challenges associated with the use of low-grade metamorphic rocks in concrete, overcoming key technical hurdles both domestically and internationally—including the mechanism of alkali-aggregate reaction in these rocks, rapid characterization and efficient inhibition of alkali activity, refined preparation of mechanism aggregates from low-grade metamorphic rocks, and the design, production, and application of high-performance concrete made from such aggregates. As a result, it has achieved the resourceful utilization of locally available materials and is leading the way in the large-scale engineering applications of low-grade metamorphic rocks. This project represents an important initiative for Guizhou Province’s implementation of key tasks such as building a “transportation powerhouse” and ensuring “oil roads connecting every township and paved roads connecting every village.” It also serves as an effective approach for poverty alleviation and rural revitalization in Guizhou Province.

Project Highlights:

A set of technologies has been developed for characterizing the alkali reactivity of shallow metamorphic rocks, as well as for their rapid detection and highly efficient inhibition. Addressing the challenging issue of effectively inhibiting the latent alkali reactivity of shallow metamorphic rocks, this research has elucidated the distribution characteristics of such rocks in the southeastern Guizhou region, revealed the potential alkali reactivity features and reaction mechanisms underlying the slow-expansion type of alkali-aggregate reaction in these rocks, and developed a rapid detection method for the latent alkali reactivity of shallow metamorphic rocks based on electrochemical impedance spectroscopy. Furthermore, a multi-path, highly efficient, and synergistic inhibition technology has been established, grounded in the understanding of the destruction mechanism of the slow-expansion type of latent alkali-aggregate reaction in shallow metamorphic rocks. This breakthrough has resolved the longstanding challenge of comprehensively applying shallow metamorphic rocks in concrete by achieving an over 95% reduction in the alkali-aggregate expansion rate of these rocks.
A highly efficient production method and process for mechanism aggregates based on the characteristics of slightly metamorphosed rocks have been proposed. Addressing the critical challenge of difficulty in controlling the quality of mechanism aggregates from slightly metamorphosed rocks, this work elucidates the mechanisms by which the characteristics of such aggregates influence concrete performance and introduces a novel, rapid method for evaluating the sphericity similarity of mechanism aggregates derived from slightly metamorphosed rocks. Furthermore, an efficient production process and equipment for mechanism aggregates from slightly metamorphosed rocks have been invented, thereby establishing a high-quality, green, and intelligent production system for these aggregates.
We have pioneered technologies for the design and preparation of high-performance concrete using mechanism aggregates derived from low-grade metamorphic rocks. Addressing the critical issues of insufficient quantitative design theories and lack of preparation techniques for high-performance concrete incorporating mechanism aggregates from low-grade metamorphic rocks, we have developed a theoretical framework and methodology for mix-design of high-performance concrete based on the particle morphology and lithological characteristics of these aggregates. This breakthrough overcomes the current limitation in mix-design approaches, which fail to quantitatively account for aggregate properties. Furthermore, we have established design principles and construction guidelines for multiple categories and grades of high-performance concrete made with mechanism aggregates from low-grade metamorphic rocks, tailored to various service environments—including large-volume applications, ultra-high pumping requirements, self-compacting concrete, underwater placement, and shotcrete—based on multi-scenario service conditions. We have also proposed performance optimization and control technologies for high-performance concrete incorporating mechanism aggregates from low-grade metamorphic rocks, ensuring the long-term durability and reliable performance of such concrete under diverse environmental conditions.
We have innovated key technologies for the engineering application of mechanism aggregate concrete made from slightly metamorphosed rocks. Based on the characteristics and distribution patterns of slightly metamorphosed rocks in the Qiandongnan region, and in response to the diverse functional requirements of different structural components in engineering projects, we have developed a set of critical technologies for controlling alkali-aggregate reactions as well as a series of key technologies for the engineering application of mechanism aggregates from slightly metamorphosed rocks, tailored to various application fields and performance demands. This has enabled innovative large-scale applications of slightly metamorphosed rocks in transportation infrastructure projects across the entire region. We have also established a comprehensive system of technical standards for the engineering application of mechanism aggregates from slightly metamorphosed rocks, designed to meet service performance requirements, address diverse application needs, and promote in-situ resource utilization.

Honored Achievements:

Second Prize, Guizhou Province Science and Technology Achievement Transformation Award
Second Prize, Standard Technology Innovation Award, China Engineering Construction Standardization Association
First Prize, Building Materials Science and Technology Award, China National Building Materials Federation and Chinese Society of Ceramics – Silicate Materials
Second Prize, China Highway Society Science and Technology Award, China Highway Society
Local Standard “Technical Code for Preventing Alkali-Aggregate Reaction in Concrete for Highway Engineering” DB52/T 1704-2022
Group Standard “Technical Specification for Concrete Alkali-Aggregate Reaction Suppression in Highway Engineering” T/CECS G:D69-01—2020