Rock-fill Concrete Experiments On Comprehensive Properties And Studies On Thermal Stress

Rock-filled Concrete (RFC) technology is a new mass concrete construction method. Firstly, large-size rocks (maximum particle size can reach more than 1m) are put into mould directly. Afterwards, self-compacting Concrete (SCC) with high fluidity is poured to mould to fully fill the gaps among the rocks. Finally, high dense massive concrete with high strength and durability can be achieved.As the development of Rock-fill Concrete, compared with compactness, engineers and researches pay more attention to the comprehensive performance of RFC.In this thesis, a series of experiments are conducted focusing on thermal properties, mechanical properties, durability properties and shrinkage deformation properties. This paper is organized as follows:In Chapter 2, based on the results of adiabatic temperature rising tests of RFC and SCC, adiabatic temperature rising regularity and corresponding formula are obtained. By taking into account the temperature characteristics of RFC, the accuracy of the heat balance equation is derived with the conclusion that the exponent constant in the formula has nothing to do with rate of rockfill. Meanwhile, thermal expansion coefficients of rock, RFC and SCC are measured by thermal expansion coefficient tests and their relationship are formulized. In Chapter 3, mechanical properties of RFC are researched by compression tests and splitting tensile tests.In Chapter 4, the relationship between shrinkage deformation properties and age of concrete are studied by shrinkage deformation tests. Shrinkage rate formula is derived and the relationship between the dry shrinkage value of RFC and SCC and the volume rate of rock is obtained. In Chapter 5, permeability coefficient and grade, as well as permeability rate are achieved by impermeability test, permeability coefficient and water pressure test. The reasons for differences between permeability properties of RFC and SCC are analyzed. Good relationship of permeability coefficient and permeability rate is found by comparing the results of permeability coefficient and permeability rate.In Chapter 6, in the stages of construction and operation, thermal and mechanical behaviors of ChangKeng gravity dam are analyzed with numerical simulation. The stress and temperature fields are obtained. The results indicate that, in the mass concrete constructions, RFC has good performance. Because of low cement content, temperature rise of concrete is relatively low, and tensile stress in later stage of concrete structure is effectively reduced. Besides, the safety of the RFC structures is ensured by high tensile strength of RFC.