基于分形理论的废弃纤维再生混凝土碳化深度模型
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摘要
为改善再生混凝土由于骨料自身缺陷产生的性能不稳定,通过掺入废弃聚丙烯纤维的方式探讨其对再生混凝土碳化深度的影响,同时将分形理论引入到废弃纤维再生混凝土孔隙结构的评价体系中,为定性或定量评定废弃纤维再生混凝土孔结构的复杂性及孔结构与宏观性能的关系开辟新的思路。通过快速碳化试验,以再生骨料掺入量、废弃纤维掺入量、水灰比等为影响因素,结合分形理论对废弃纤维再生混凝土的碳化深度进行研究。结果表明:水灰比、再生骨料掺入量的减小及纤维掺入量的增大均会减小碳化深度;废弃纤维再生混凝土孔隙体积分形维数越小,碳化深度越大。利用孔隙体积分形维数与碳化深度的关系,建立了废弃纤维再生混凝土碳化深度预测模型,模型预测结果与试验值吻合良好。
In order to improve the performance instability of recycled concrete due to the defects of aggregate itself, the influence of waste polypropylene fibers on the carbonation depth of recycled concrete was discussed by adding waste polypropylene fibers. At the same time, fractal theory was introduced into the evaluation system of pore structure of recycled concrete with waste fibers to qualitatively or quantitatively evaluate the pore structure complexity and pore structure of recycled concrete with waste fibers. Through rapid carbonization test, taking the amount of recycled aggregate, waste fiber and water cement ratio as influencing factors, fractal theory was used to study the depth of carbonization performance of recycled concrete with waste fiber. The results show that the carbonization depth decreases with the decrease of water cement ratio, recycled aggregate content and the increase of fiber content, and the smaller the fractal dimension of pore volume of waste fiber recycled concrete, the larger the carbonization depth. Based on the relationship between fractal dimension of pore volume and carbonation depth, a prediction model of carbonation depth of recycled waste fiber concrete was established. The predicted results of the model were in good agreement with the experimental values.
In order to improve the performance instability of recycled concrete due to the defects of aggregate itself, the influence of waste polypropylene fibers on the carbonation depth of recycled concrete was discussed by adding waste polypropylene fibers. At the same time, fractal theory was introduced into the evaluation system of pore structure of recycled concrete with waste fibers to qualitatively or quantitatively evaluate the pore structure complexity and pore structure of recycled concrete with waste fibers. Through rapid carbonization test, taking the amount of recycled aggregate, waste fiber and water cement ratio as influencing factors, fractal theory was used to study the depth of carbonization performance of recycled concrete with waste fiber. The results show that the carbonization depth decreases with the decrease of water cement ratio, recycled aggregate content and the increase of fiber content, and the smaller the fractal dimension of pore volume of waste fiber recycled concrete, the larger the carbonization depth. Based on the relationship between fractal dimension of pore volume and carbonation depth, a prediction model of carbonation depth of recycled waste fiber concrete was established. The predicted results of the model were in good agreement with the experimental values.
引文
[1] 李检保.混凝土碳化及其碳化后力学性能试验与分析[D].上海:同济大学,1997.
[2] YINGYU L,GUIDONG W.The mechanism of carbonation of mortar and the dependence of carbonation on pore structure[C]//Proc Katharine and Bryant Mather Int Conf on Concrete Durability.Atlanta,1987:1915-1943.
[3] HOUST Y F,WITTMANN F H.Influence of porosity and water contenton the diffusivity of CO2 and O2 through hydrated cement paste[J].Cement and Concrete Research,1994,24(6):1165-1176.
[4] 叶绍勋.混凝土碳化反应的热力学计算[J].硅酸盐通报,1989,8(2):15-19.
[5] PAPADAKIS V G,VAYENAS C G,FARDIS M N.Physical and chemical characteristics affecting the durability of concrete[J].A C I Materials Journal,1991,88:363-372.
[6] JI X,GHAN S Y N,FENG N.Fractal model for simulating the space-filling process of cement hydrates and fractal dimensions of pore structure of cement-based materials[J].Cement and Concrete Research,1997,27(11):1691-1699.
[7] 唐明,李晓.多种因素对混凝土孔结构分形特征的影响研究[J].沈阳建筑大学学报(自然科学版),2005,21(3):232-237.
[8] ZHANG B,LIU W,LIU X.Scale-dependent nature of the surface fractal dimension for bi- and multi-disperse porous solids by mercury porosimetry[J].Applied Surface Science,2006,253:1349-1355.
[9] 牛荻涛.混凝土结构耐久性与寿命预测[M].北京:科学出版社,2003:25-27.
[10] NIMA G.Corrosion control in underground concrete structures using double waterproofing shield system[J].International Journal of Mining Science and Technology,2013,23(4):603-612.
[11] SIM J S,PARK C.Compressive strength and resistance tochloride ion penetration and carbonation of recycledaggregate concrete with varying amount of fly ash and fine recycled aggregate[J].Waste Management,2011,31(11):2352-2360.
[12] TAN Y Q,XU H N,ZHOU C X,et al.Temperature distribution characteristic of subgradein seasonally frozen regions[J].Journal of Harbin Institute of Technology,2011,43(8):98-102.
[13] 王新栋.废弃纤维再生混凝土分形特征研究[D].沈阳:沈阳建筑大学,2015:40-50.
[2] YINGYU L,GUIDONG W.The mechanism of carbonation of mortar and the dependence of carbonation on pore structure[C]//Proc Katharine and Bryant Mather Int Conf on Concrete Durability.Atlanta,1987:1915-1943.
[3] HOUST Y F,WITTMANN F H.Influence of porosity and water contenton the diffusivity of CO2 and O2 through hydrated cement paste[J].Cement and Concrete Research,1994,24(6):1165-1176.
[4] 叶绍勋.混凝土碳化反应的热力学计算[J].硅酸盐通报,1989,8(2):15-19.
[5] PAPADAKIS V G,VAYENAS C G,FARDIS M N.Physical and chemical characteristics affecting the durability of concrete[J].A C I Materials Journal,1991,88:363-372.
[6] JI X,GHAN S Y N,FENG N.Fractal model for simulating the space-filling process of cement hydrates and fractal dimensions of pore structure of cement-based materials[J].Cement and Concrete Research,1997,27(11):1691-1699.
[7] 唐明,李晓.多种因素对混凝土孔结构分形特征的影响研究[J].沈阳建筑大学学报(自然科学版),2005,21(3):232-237.
[8] ZHANG B,LIU W,LIU X.Scale-dependent nature of the surface fractal dimension for bi- and multi-disperse porous solids by mercury porosimetry[J].Applied Surface Science,2006,253:1349-1355.
[9] 牛荻涛.混凝土结构耐久性与寿命预测[M].北京:科学出版社,2003:25-27.
[10] NIMA G.Corrosion control in underground concrete structures using double waterproofing shield system[J].International Journal of Mining Science and Technology,2013,23(4):603-612.
[11] SIM J S,PARK C.Compressive strength and resistance tochloride ion penetration and carbonation of recycledaggregate concrete with varying amount of fly ash and fine recycled aggregate[J].Waste Management,2011,31(11):2352-2360.
[12] TAN Y Q,XU H N,ZHOU C X,et al.Temperature distribution characteristic of subgradein seasonally frozen regions[J].Journal of Harbin Institute of Technology,2011,43(8):98-102.
[13] 王新栋.废弃纤维再生混凝土分形特征研究[D].沈阳:沈阳建筑大学,2015:40-50.
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