Hydraulic concrete is seriously damaged by poor construction quality, cracks, alkali-aggregate reaction, corrosion of reinforcement bars, and chemical erosion, resulting in giant economic losses. China is currently planning, designing and constructing many large-scale hydraulic engineering, and the investment of hydraulic projects in the 13th National Five-Year Plan Period keeps steady growth. As the international hydropower market quickly develops and the domestic hydropower enterprises speed up their “Going out” paces taking the advantage of the Belt and Road initiative, higher and higher requirements on hydraulic engineering construction, especially on hydraulic concrete materials, have been forwarded due to the foreign and domestic development tendency of increasingly large hydraulic engineering construction, complex engineering conditions, rapid construction pace and high durability. Therefore, there is an urgent need to conduct the research of key control technology of hydraulic concrete performance in order to satisfy the major strategic demands on large modern hydraulic engineering construction quality and safe operation.
Because of the particularity of hydraulic concrete materials, structure and function and the complexity of process control of concrete pouring and service environment of concrete structures, many challenges are faced in regard of the key control technology of concrete performance so that the existing results are difficult to meet the practical needs of concrete engineering. Thus it is necessary to do a lot of in-depth and meticulous theoretical and test research in order to obtain the ideal engineering application effects of hydraulic concrete performance control technology in view of construction, anti-cracking and durability.
Based on the above background and analysis of hydraulic concrete properties under harsh conditions of long distance transportation in high temperature, aggregates with high concentration of mud, low-glue concrete pumping, high alkali activity of aggregates, chemical erosion, supervolumetric structure, and action of high velocity flow, the effective key control technology of hydraulic concrete performance has been proposed from the perspective of chemical admixture technology, mineral admixture technology, evaluation methods and theoretical models with the research focuses on technical difficulties of construction behavior of hydraulic concrete, alkali-aggregate reaction, anti-erosion, anti-crack and anti-abrasion in typical large-scale hydraulic engineering practices. The technology is of great significance for engineering smooth construction, safety operation and service life extension.
1.Major Innovative Achievements
1.1 The mechanism of molecular association, dissociation and complexation of polycarboxylic acid has been disclosed, and a series of construction performance control additives of hydraulic concrete invented, overcoming the technical challenges of concrete construction performance control under the harsh conditions of high temperature, high mud content, long time delivery and quick support under the high risk of rock burst.
1.2 A quick risk evaluation method of actual alkali-aggregate reaction of hydraulic concrete has been established, the physical and chemical factors for evaluating the effect of fly ash on the inhibition of alkali-aggregate reaction constructed, the self-immunity effect of alkali-aggregate reaction disclosed, Technical Specifications for Hydraulic Concrete Durability compiled, and the final criterion of alkali reactivity of hydraulic concrete aggregates forwarded for the first time.
1.3 The multi-path pore structure transfer theory has been raised, the quantitative calculation method of ion transport in nonlinear multiphase reaction and multi-ion interaction and fracture density calculation method based on multiphase reaction product volume change set up, the numerical model of concentration distribution of corrosive ions including chloride ion and sulfate ion and prediction model of damage evolution constructed, the prediction theory and method of hydraulic concrete durability life under complex erosion conditions perfected, and a series of functional ecological concrete rust inhibitor and corrosion inhibitor invented.
1.4 The test and evaluation methods for temperature-stress crack resistance of hydraulic concrete have been proposed for the first time based on actual working conditions, and crack prevention techniques of hydraulic concrete like coarse grinding cement - fine grinding slag, expansion aging and hydration process control developed to effectively reduce the high cracking risk of hydraulic concrete in alpine regions and super high dams.
1.5 The test devices and methods have been created for high-velocity underwater ball grinding and rotary scaling type abrasion-cavitation coupling, Test Code for Hydraulic Concrete revised, the prediction model of anti-abrasion life of hydraulic concrete established, and the anti-abrasion coating material of multinano-interpenetrating network epoxy resin concrete invented
2. Academic Outputs
51 national invention patents were authorized, and 303 papers, including 100 collected by SCI and EI, and 5 books published. The research findings have been adopted by 18 national or industrial standards. And a batch of high-level talents have been fostered and selected in Jiangsu Province, and more than 40 students for master and doctor degrees educated.
3.Application Promotion and Comprehensive Benefits
The research findings have been successfully applied in the construction and operation of major foreign and domestic hydraulic engineering, such as Neelum-Jhelum Hydropower Project in Pakistan, South-to-North Water Diversion Project, Jinping First-Cascade Hydropower Project and Jinping Second-Cascade Hydropower Project, Guangzhao Hydropower Project, etc., and extended to over 100 similar project construction. Typical engineering applications are as following.
3.1 The key construction performance control techniques, such as collapse prevention of concrete over long time in high temperature and with high mud content, low-glue concrete pumping and bleeding control, self-regulation of high temperature retarding, etc., have been successfully applied in Neelum-Jhelum Hydropower Project in Pakistan, Jinping Second-Cascade Hydropower Project, Guangzhao Hydropower Project, Houziyan Hydropower Project, and Yanglin Ship Lock.
3.2 The key alkali-aggregate reaction control techniques including inhibitting additives and evaluation method have been successfully applied South-to-North Water Diversion Project and Jinping First-Cascade Hydropower Project.
3.3 The key anti-corrosion techniques of new materials, based on the new theories of chloride ion and sulfate corrosion and fresh water corrosion damage and new mix design idea, have been successfully applied in South-to-North Water Diversion Project, Water Diversion from Mainland to Zhoushan Island, and Beilun Port.
3.4 The core crack control techniques of slight expansion, shrinkage reduction, hydration heat reduction and postponing exothermic peak have been successfully applied in Jinping First-Cascade Hydropower Project, hekoucun Hydropower Project, and Kalasuke Hydraulic Project.
3.5 The key anti-abrasion techniques of new test methods and nanometer coating have been successfully applied in Wuluwati Hydraulic Project and Baihetan Hydropower Project.
The research findings have played an important support role in engineering construction quality improvement and cost saving, and safeguarding engineering safe operation. The core techniques have generated direct economic benefits of 1 billion Yuan and indirect economic benefits of 20 billion Yuan in respect of reduction of maintenance and rehabilitation, crack repair and extension of engineering service life. In addition, the findings can meet the social demand of green development by energy saving and carbon emission reduction of cement grinding or clinkering and resource utilization of low quality aggregates. Relevant findings may provide important technical support for the scientific decision-making of major engineering and effective help for promoting the scientific and technological progress of the industry and the economic and social sustainable development, which will produce huge and far-reaching social benefits.
