无机胶凝材料在加固混凝土结构中的性能研究
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摘要
目前结构粘结用胶多是环氧树脂,由于其软化点较低、热稳定性、耐疲劳性等缺点,无法发挥出纤维布的全部特性,因此配制出一种兼容性更好,性能更优越的粘结用胶,对FRP复合材料在混凝土结构修复和加固中的广泛应用有很大的促进作用。MPC(磷酸镁胶凝材料Magnesium Phosphate Cementitious)具有以下比较突出的性能:①快凝快硬;②早期强度高;③低温凝结速度快;④与旧混凝土的粘接强度高;⑤耐磨性及抗冻性好,干缩小;等等。本文主要针对磷酸镁无机胶在加固混凝土结构中的性能进行研究,主要研究工作和创新成果有:
(1) MPC以往采用的磷酸盐原料磷酸二氢铵,在反应过程中会放出氨气,有异味,并污染环境,所以本课题采用了磷酸镁二氢钾及磷酸氢二钠。由于加固施工条件的需要,原料配比必须满足流动度在200mm,初凝时间在30min的要求。本课题通过调整MgO/KH2PO4比值、水灰比大小、粉煤灰及缓凝剂的含量,调配出4组较合理的配料比。
(2)通过磷酸镁无机胶的砂浆抗压、抗折试验,磷酸镁无机胶粘结砂浆试块的三点弯曲试验、粘结混凝土试块的劈拉试验,根据其粘结强度及破坏模式,对上述配料比进行对比分析,选出较优的配料比进行加固试验。并从中选出最优的配料比,测量其有效粘结长度为150mm-180mm。
(3)通过棱形梁和圆柱的加固试验,得出磷酸镁无机胶加固有良好的破坏模式。其用于玄武岩纤维加固的基体时,对于素混凝土梁四点弯曲试验时的抗弯强度的提高模量达到57.5%;对于圆柱体轴压试验的极限轴压力的模量提高达到45.4%。
(4)将磷酸镁无机胶加固,环氧树脂加固,环氧树脂加固外表面涂上磷酸镁无机胶3类方法加固的梁。测量其高温后的加固效果,有机胶EP的提高模量为50%,只有自然环境下的一半;无机胶P3-B10的提高模量为57.5%,由于梁本身强度的降低,其加固效果不明显,但还是有所提高,并且好于EP在高温下的效果。
At present, epoxy is widely used as structural adhesive glue. But there exist many disadvantages of it, like lower softening point, bad thermal stability and poor fatigue resistance, makes the FRP cloth can’t play well. Therefore, we need to produce a adhesive with better compatibility and better performance to promote the affection of FRP composite materials when they are used in repairing and reinforcing concrete structures. MPC(Magnesium Phosphate Cementitious) has many good properties:○1 Curdling and stiffening rapidly;○2 High early strength;○3 Fast condensation in low-temperature;○4 high bonding strength with the old concrete;○5 Well wear resistance and good frost resistance,little shrinkage. This project is working on researching the properties of MPC when use it reinforcing concrete, mainly tests and results as below:
(1) MPC usually made by ADP (Ammonium Dihydrogen Phosphate) as Phosphate raw material, the reaction will consist with ammonia, bringing peculiar smell and polluting the surroundings. So this project changes raw material from ADP to Potassium Dihydrogen Phosphate Disodium hydrogen phosphate. Thinking about the needs of reinforcement construction conditions, the ratio of raw materials must fulfill the requirements of MPC products as fluidity of 200mm and initial setting time of 30 min. This project worked out four rational ratio of raw materials by adjusting the ratio of MgO and KH2PO4, water-cement ratio, and the content of fly ash and retarder.
(2) After the tests of mortar compressive and mortar flexural of MPC, the three point bending tests of mortar test blocks and the splitting test of concrete blocks after bonding by MPC, analyzing the strength and failure mode of there 4 ratio of raw materials. And then choose the better one and put them into reinforcement test. Meanwhile choose the best one to test the effective bond length, and found it between 150mm and 180mm.
(3) Found out the MPC reinforcement’s failure mode is good, through the tests of reinforcement of prism beams and columns. When it used as the base of basalt FRP reinforcement, the increased modulus of bending strength for plain concrete beams showed by four-point bending test could be 57.5%; the increased modulus of ultimate axial for columns showed by axial compression test could be 45.4%.
(4) Put beams which reinforced by MPC into the oven 240min with the temperature of 100 o C, and take other three groups (EP reinforced beams, beams which are reinforced by EP first and then brush MPC on the surfaces, nude beams) as compare. Then take the test of four-point bending and found out the bending strength as below: Ep’s increased modulus is 50%, just as the half under normal conditions; MPC’s (P3-B10) increased modulus is 57.5%. Because of the declination of strength happened on beams selves, though the affection of reinforcement isn’t obvious, it still has improvement spaces, and better than EP under high temperature.
(1) MPC以往采用的磷酸盐原料磷酸二氢铵,在反应过程中会放出氨气,有异味,并污染环境,所以本课题采用了磷酸镁二氢钾及磷酸氢二钠。由于加固施工条件的需要,原料配比必须满足流动度在200mm,初凝时间在30min的要求。本课题通过调整MgO/KH2PO4比值、水灰比大小、粉煤灰及缓凝剂的含量,调配出4组较合理的配料比。
(2)通过磷酸镁无机胶的砂浆抗压、抗折试验,磷酸镁无机胶粘结砂浆试块的三点弯曲试验、粘结混凝土试块的劈拉试验,根据其粘结强度及破坏模式,对上述配料比进行对比分析,选出较优的配料比进行加固试验。并从中选出最优的配料比,测量其有效粘结长度为150mm-180mm。
(3)通过棱形梁和圆柱的加固试验,得出磷酸镁无机胶加固有良好的破坏模式。其用于玄武岩纤维加固的基体时,对于素混凝土梁四点弯曲试验时的抗弯强度的提高模量达到57.5%;对于圆柱体轴压试验的极限轴压力的模量提高达到45.4%。
(4)将磷酸镁无机胶加固,环氧树脂加固,环氧树脂加固外表面涂上磷酸镁无机胶3类方法加固的梁。测量其高温后的加固效果,有机胶EP的提高模量为50%,只有自然环境下的一半;无机胶P3-B10的提高模量为57.5%,由于梁本身强度的降低,其加固效果不明显,但还是有所提高,并且好于EP在高温下的效果。
At present, epoxy is widely used as structural adhesive glue. But there exist many disadvantages of it, like lower softening point, bad thermal stability and poor fatigue resistance, makes the FRP cloth can’t play well. Therefore, we need to produce a adhesive with better compatibility and better performance to promote the affection of FRP composite materials when they are used in repairing and reinforcing concrete structures. MPC(Magnesium Phosphate Cementitious) has many good properties:○1 Curdling and stiffening rapidly;○2 High early strength;○3 Fast condensation in low-temperature;○4 high bonding strength with the old concrete;○5 Well wear resistance and good frost resistance,little shrinkage. This project is working on researching the properties of MPC when use it reinforcing concrete, mainly tests and results as below:
(1) MPC usually made by ADP (Ammonium Dihydrogen Phosphate) as Phosphate raw material, the reaction will consist with ammonia, bringing peculiar smell and polluting the surroundings. So this project changes raw material from ADP to Potassium Dihydrogen Phosphate Disodium hydrogen phosphate. Thinking about the needs of reinforcement construction conditions, the ratio of raw materials must fulfill the requirements of MPC products as fluidity of 200mm and initial setting time of 30 min. This project worked out four rational ratio of raw materials by adjusting the ratio of MgO and KH2PO4, water-cement ratio, and the content of fly ash and retarder.
(2) After the tests of mortar compressive and mortar flexural of MPC, the three point bending tests of mortar test blocks and the splitting test of concrete blocks after bonding by MPC, analyzing the strength and failure mode of there 4 ratio of raw materials. And then choose the better one and put them into reinforcement test. Meanwhile choose the best one to test the effective bond length, and found it between 150mm and 180mm.
(3) Found out the MPC reinforcement’s failure mode is good, through the tests of reinforcement of prism beams and columns. When it used as the base of basalt FRP reinforcement, the increased modulus of bending strength for plain concrete beams showed by four-point bending test could be 57.5%; the increased modulus of ultimate axial for columns showed by axial compression test could be 45.4%.
(4) Put beams which reinforced by MPC into the oven 240min with the temperature of 100 o C, and take other three groups (EP reinforced beams, beams which are reinforced by EP first and then brush MPC on the surfaces, nude beams) as compare. Then take the test of four-point bending and found out the bending strength as below: Ep’s increased modulus is 50%, just as the half under normal conditions; MPC’s (P3-B10) increased modulus is 57.5%. Because of the declination of strength happened on beams selves, though the affection of reinforcement isn’t obvious, it still has improvement spaces, and better than EP under high temperature.
引文
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[4]王文炜,赵国藩. FRP加固混凝土结构技术及应用[M].北京:中国建筑工业出版社, 2007.
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[6] Hamid Saadatmanesh, M R Ehsani. Fiber Composite Plates Can Strengthen Concrete Beams[J]. Concrete International, 1990, 3:65-71.
[7] Hamid Saadatmanesh. Fiber Composites for New and Existing Structures[J]. ACI Structural Journal, 1994, 91(3):346-354.
[8] Luc Taerwe, Stijn Matthys. FRP for Concrete Construction Activities in Europe[J]. ACI Concrete International, 1999, 21(10):33-36.
[9]付东升,朱光明,韩娟妮.环氧树脂的改性研究进展[J].中国胶粘剂, 2003, 12(3):51-54.
[10]张凯,黄渝鸿,郝晓东,等.环氧树脂改性技术研究进展[J].化学推进剂与高分子材料, 2004, 2(1):12-14.
[11]谢海安,陈汉全,王伟.环氧树脂改性研究进展[J].塑料科技, 2007, 35(1): 82-85.
[12]胡家朋,熊联明,唐星华,等.环氧树脂改性研究新进展[J].工程塑料应用, 2005, 33(5):73-76.
[13] BAO-LONG ZHANG. Modification of EP by Acrylic Copolymers with side chain mesogenic units[J]. J Appl Polym Sci, 1999(71):177-184.
[14] AOPUODON. The action of alkalis on bast-furnace slag[J]. J soc Chem Ind, 1940(59):191.
[15] Malone Philip G., Randall Charlie A., Kirkpatrick Thaddeus. Potential Applications of Alkali-Activated Alumino-Silicate Binders in Military Operations [J]. Defense Technical Information Center, 1985:103-111.
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[20] D. A Hall., R Stevens., B El-Jazairi. The effect of retarders on the microstructure and mechanical properties of magnesia-phosphate cements mortar[J]. Cement and Concrete Research, 2001, 31:455-465.
[21]汪宏涛,钱觉时,王建国.磷酸镁水泥的研究进展[J].材料导报, 2005, 19(12): 46-48.
[22]丁铸,邢锋,李宗津.高早强磷硅酸盐水泥修复性能的研究[J].工业建筑, 2008, 38(09):77-81.
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[24]郑文忠,陈伟宏,徐威,等.用碱激发矿渣耐高温无机胶在混凝土表面粘贴碳纤维布试验研究[J].建筑结构学报; 2009; 30(4):138-144.
[25]汪宏涛,钱觉时,曹巨辉等.粉煤灰对磷酸盐水泥基修补材料性能的影响[J].新型建筑材料,2005(12):41-43.
[26] Van Jaarsveld J. G. S., Van Deventer J. S. J., Lorenzeni L. The potential use of geopolymeric materials to immobilize toxic metals: part I. Theory and applications [J]. Minerals Engineering, 1997, 10(7): 659-669.
[27]刘继江,刘文彬,王超,等.磷酸盐基胶粘剂的研究与应用[J].化工科技, 2007, 15(01):55-58.
[28]林志明,张雄.钢筋混凝土建筑物修复补强技术[J].建筑材料学报, 2003, 6(01):61-65.
[29]胡静宇.新型无机胶凝材料及添加剂改性砂浆强度试验研究[J].交通建设与管理, 2009(08);72-75.
[30]徐威,粘贴CFRP片材用耐高温无机胶的制备及应用研究, 2007,哈尔滨工业大学:哈尔滨.27-28.
[31]彭斌,顾祥林.灰缝砂浆在圧剪状态下的破坏准则[J].2005年全国砌体结构基本理论与工程应用学术会议论文集,2005:22-28.
[32]王述红.砌体开裂过程数值试验方法及其工程应用[J].2005年全国砌体结构基本理论与工程应用学术会议论文集,2005:141-145.
[33]谢丽丽,刘立新与薛鹏飞.改性砂浆砌体抗剪强度的试验研究[J].2005年全国砌体结构基本理论与工程应用学术会议论文集,2000:158-163.
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[43]郑文忠,陈伟宏等.用碱激发矿渣耐高温无机胶在混凝土表面粘结碳纤维布试验研究[J].建筑结构学报,2009,30(4):138-144.
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[2] Teng J. G. FRP-strengthened RC structures[M]. Bei Jing: China Architecture & Building Press,2005.
[3]李隽,刘宏伟.既有混凝土结构加固技术研究现状及新进展[J].山西建筑, 2008, 34(26):99-100.
[4]王文炜,赵国藩. FRP加固混凝土结构技术及应用[M].北京:中国建筑工业出版社, 2007.
[5] Vicki L Brown, Charles L Bartholomew. FRP Reinforcing Bars in Reinforced Concrete Members[J]. ACI Materials Journal, 1993, 90(1):34-39.
[6] Hamid Saadatmanesh, M R Ehsani. Fiber Composite Plates Can Strengthen Concrete Beams[J]. Concrete International, 1990, 3:65-71.
[7] Hamid Saadatmanesh. Fiber Composites for New and Existing Structures[J]. ACI Structural Journal, 1994, 91(3):346-354.
[8] Luc Taerwe, Stijn Matthys. FRP for Concrete Construction Activities in Europe[J]. ACI Concrete International, 1999, 21(10):33-36.
[9]付东升,朱光明,韩娟妮.环氧树脂的改性研究进展[J].中国胶粘剂, 2003, 12(3):51-54.
[10]张凯,黄渝鸿,郝晓东,等.环氧树脂改性技术研究进展[J].化学推进剂与高分子材料, 2004, 2(1):12-14.
[11]谢海安,陈汉全,王伟.环氧树脂改性研究进展[J].塑料科技, 2007, 35(1): 82-85.
[12]胡家朋,熊联明,唐星华,等.环氧树脂改性研究新进展[J].工程塑料应用, 2005, 33(5):73-76.
[13] BAO-LONG ZHANG. Modification of EP by Acrylic Copolymers with side chain mesogenic units[J]. J Appl Polym Sci, 1999(71):177-184.
[14] AOPUODON. The action of alkalis on bast-furnace slag[J]. J soc Chem Ind, 1940(59):191.
[15] Malone Philip G., Randall Charlie A., Kirkpatrick Thaddeus. Potential Applications of Alkali-Activated Alumino-Silicate Binders in Military Operations [J]. Defense Technical Information Center, 1985:103-111.
[16]张策.硅酸钠无机高分子建筑涂料[J].涂料工业, 1988(02):19-21.
[17] Van Jaarsveld J. G. S., Van Deventer J. S. J., Lorenzen L. The potential use of geopolymeric materials to immobilise toxic metals :Part .I Theory and applications[J]. Minerals Engineering, 1997, 10(7):659-669.
[18] Van Jaarsveld J. G. S., Van Deventer J. S. J., Schwartzman A. The potential use of geopolymeric materials to immobilise toxic metals Part II. Material and leaching characteristics[J]. Minerals Engineering, 1998, 12(1):75-91.
[19]马鸿文,杨静,任玉峰,等.矿物聚合材料研究现状与发展前景[J].地质前缘, 2002, 9(4):397-407.
[20] D. A Hall., R Stevens., B El-Jazairi. The effect of retarders on the microstructure and mechanical properties of magnesia-phosphate cements mortar[J]. Cement and Concrete Research, 2001, 31:455-465.
[21]汪宏涛,钱觉时,王建国.磷酸镁水泥的研究进展[J].材料导报, 2005, 19(12): 46-48.
[22]丁铸,邢锋,李宗津.高早强磷硅酸盐水泥修复性能的研究[J].工业建筑, 2008, 38(09):77-81.
[23]李品科覃维祖.碱激发偏高岭土粘结剂的粘结界面性能研究[J].施工技术, 2008, 37(12):18-19.
[24]郑文忠,陈伟宏,徐威,等.用碱激发矿渣耐高温无机胶在混凝土表面粘贴碳纤维布试验研究[J].建筑结构学报; 2009; 30(4):138-144.
[25]汪宏涛,钱觉时,曹巨辉等.粉煤灰对磷酸盐水泥基修补材料性能的影响[J].新型建筑材料,2005(12):41-43.
[26] Van Jaarsveld J. G. S., Van Deventer J. S. J., Lorenzeni L. The potential use of geopolymeric materials to immobilize toxic metals: part I. Theory and applications [J]. Minerals Engineering, 1997, 10(7): 659-669.
[27]刘继江,刘文彬,王超,等.磷酸盐基胶粘剂的研究与应用[J].化工科技, 2007, 15(01):55-58.
[28]林志明,张雄.钢筋混凝土建筑物修复补强技术[J].建筑材料学报, 2003, 6(01):61-65.
[29]胡静宇.新型无机胶凝材料及添加剂改性砂浆强度试验研究[J].交通建设与管理, 2009(08);72-75.
[30]徐威,粘贴CFRP片材用耐高温无机胶的制备及应用研究, 2007,哈尔滨工业大学:哈尔滨.27-28.
[31]彭斌,顾祥林.灰缝砂浆在圧剪状态下的破坏准则[J].2005年全国砌体结构基本理论与工程应用学术会议论文集,2005:22-28.
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