A series of ultra-fine fly ash composite powder (CUFAⅡ) products for rapid repair are researched and developed successfully with the ultra-fine fly ash as matrix. CUFAⅡ can replace cement equivalently more than 30%....A series of ultra-fine fly ash composite powder (CUFAⅡ) products for rapid repair are researched and developed successfully with the ultra-fine fly ash as matrix. CUFAⅡ can replace cement equivalently more than 30%. High performance rapid repair concrete (HPRRC) can meet the requirements for opening traffic within 12 - 48 h, which solves the problem of opening traffic as soon as possible after damaged Portland cement concrete pavement are repaired for a whole plate, and the engineering cost is lowered greatly.1) Based on the systematical study on the physical properties, particle morphologies and micro-mechanism of ultra-fine fly ash, CUFAⅡ products are successfully developed by means of optimizing the particle gradation and activation technique. HPRRC composed of CUFAⅡproducts and with the strength grade no less than 32.5R ordinary Portland cement can meet the minimum strength index demands for opening traffic within (12 - 48) h.2) By extensive experiments and research, in consideration of the requirements of durability to chemical composition, referring to "High Strength High Performance Concrete Mineral Admixture" (draft report) and correlative standards abroad, the first Technical Specification (Q/DBAA001-2002) of ultra-fine fly ash mineral admixture in China has been put forward.3) Numerical model is established by finite element method. The stress of new-old concrete is simulated under the condition of standard axle loading. The critical bond strength of new-old concrete interface is obtained. According to Chinese standard and referring to foreign research results, the key parameters for repaired concrete to open traffic are put forward.(1) The minimum flexural strength of repaired concrete is no less than 70% of the design strength. That is to say, the flexural strength of repaired concrete arrives at 3.5 Mpa (the design strength of original slab is 5 MPa) or 3.15 MPa (the design strength of original slab is 4.5 MPa).(2) The bond strength of the old-new concrete interface is greater than 1.15 MPa.(展开更多
文摘A series of ultra-fine fly ash composite powder (CUFAⅡ) products for rapid repair are researched and developed successfully with the ultra-fine fly ash as matrix. CUFAⅡ can replace cement equivalently more than 30%. High performance rapid repair concrete (HPRRC) can meet the requirements for opening traffic within 12 - 48 h, which solves the problem of opening traffic as soon as possible after damaged Portland cement concrete pavement are repaired for a whole plate, and the engineering cost is lowered greatly.1) Based on the systematical study on the physical properties, particle morphologies and micro-mechanism of ultra-fine fly ash, CUFAⅡ products are successfully developed by means of optimizing the particle gradation and activation technique. HPRRC composed of CUFAⅡproducts and with the strength grade no less than 32.5R ordinary Portland cement can meet the minimum strength index demands for opening traffic within (12 - 48) h.2) By extensive experiments and research, in consideration of the requirements of durability to chemical composition, referring to "High Strength High Performance Concrete Mineral Admixture" (draft report) and correlative standards abroad, the first Technical Specification (Q/DBAA001-2002) of ultra-fine fly ash mineral admixture in China has been put forward.3) Numerical model is established by finite element method. The stress of new-old concrete is simulated under the condition of standard axle loading. The critical bond strength of new-old concrete interface is obtained. According to Chinese standard and referring to foreign research results, the key parameters for repaired concrete to open traffic are put forward.(1) The minimum flexural strength of repaired concrete is no less than 70% of the design strength. That is to say, the flexural strength of repaired concrete arrives at 3.5 Mpa (the design strength of original slab is 5 MPa) or 3.15 MPa (the design strength of original slab is 4.5 MPa).(2) The bond strength of the old-new concrete interface is greater than 1.15 MPa.(
