【作者】 梁丽敏；

【导师】 余红发；

【作者基本信息】 南京航空航天大学 ， 道路与铁道工程， 2010， 博士

【摘要】 旧城区改造、粘土砖生产和工程施工等过程产生的废弃粘土砖碎块垃圾严重占用了场地、污染环境。利用废弃粘土砖生态种植型混凝土既可以解决废弃粘土砖造成的污染,又可以解决天然骨料生产生态种植混凝土吸率不高的问题。而且利用生态种植型混凝土上的植物进行伪装,拥有与背景完全一致的外貌和特性,当植物达到一定密度时,可有效地对抗光学、红外和雷达侦察。在资源再生和循环利用及降低环境负荷方面和工程伪装方面,生态种植型混凝土具有重要的意义。本文主要对碎砖集料生态混凝土的制备工艺、pH控制、吸水性和保水性进行讨论和研究;研究生态种植型混凝土的内部结构、三维结构仿真重建;分析生态种植型混凝土吸收电磁波特性以及吸波剂对其吸波性能的影响;探讨生态种植混凝土种植的原则,植被生长以后对光学伪装性能、红外伪装性能、电磁波吸收性能进行分析。本文取得的主要结论如下:1、针对碎砖集料吸水率高、强度低的特点,提出了生态种植型混凝土搅拌工艺应该采用净浆裹石法。2、矿物掺合料的加入有利于生态种植型混凝土内部空隙pH值的降低,粉煤灰降低pH的效果优于粉煤灰与矿渣混掺的效果。浆集比直接决定生态种植型混凝土的渗透系数,渗透系数混凝土随着浆集比的增加而降低。相同空隙率时,而透水系数越高,表明生态种植型混凝土的连通性越好。随着集灰比的增加,生态种植型混凝土的保水能力下降,吸水率随集灰比增加而增。3、孔结构采用MATLAB软件对图像进行增强、分割等处理,利用Image-Pro Plus软件分析法测量生态种植型混凝土孔的孔结构参数。生态种植型混凝土的平均孔直径随着集料粒径的增加而增加,而且呈指数关系。采用MATLAB软件对图像进行增强、分割等处理,采用体重建的方法实现了基于真实细观结构的生态种植混凝土三维重建。重构的三维结构模型接近真实的生态种植型混凝土,可以直观地分析混凝土内部的多孔结构和孔的连通性。4、生态种植型混凝土的多孔结构可以改善其表面阻抗与自由空间阻抗的匹配,使电磁波易于进入材料内部,进而增加其损耗衰减;同时多孔结构能够对入射电磁波进行多次的反射和散射,电磁波在材料内部迅速衰减,使生态种植型混凝土具有良好的电磁波吸收性能。在8GHz~18GHz内对电磁波反射率小于-10 dB,平均反射率均小于-20 dB,而吸波剂铁氧体和铁矿粉改善生态种植型混凝土的吸波性能和拓宽吸收频段。5、草的种植密度合理,可以完全覆盖生态种植型混凝土,形成的生态伪装面,用光学相机不能区分植物下方的物质与土壤,可以对抗光学侦察。6、在晴天通过红外热像仪检测到生态种植型混凝土上草的平均辐射温度比土壤上草的辐射温度高0.96℃,在雨天生态种植型混凝土上草的辐射温度与土壤上草的辐射温度相同。生态种植型混凝土只要能覆盖合理厚度的客土,保证植物合理的种植密度,就可以与周围植被达到一致的环境协调性,可以对抗热红外侦察。7、生态种植型混凝土种草后,对电磁波同时具有吸收和散射作用,而且植草密度电磁波吸收效果有影响,植草密度为100%时,对电磁波的最大值反射率为-20.16 dB,最小值反射率为-42.87 dB,平均值反射率为-29.91 dB,能对抗雷达的侦察。更多还原

【Abstract】 The focus of the paper is green-growing porous concrete with broken bricks. Preparation and pH control of it were discussed,and water absorption and water retention of it were researched, and the internal structure of porous concrete and three-dimensional simulation of the construction were studied. Electromagnetic wave absorption properties of porous concrete and influences of absorbing agents on the absorbing properties were analysised. Principles of plant cultivation on green-growing porous concrete were studied. Optical camouflage, infrared camouflage and electromagnetic wave absorption properties of porous concete with plant were researched.It is an important significance from renewable resources, reducing environmental load, and multi-level development application of porous concrete, etc..To use massive waste bricks and improve water absorption of porous concrete, porous concrete was made with the entire broken brick as aggregate. In view of the broken brick aggregate’s low hardness and the high water-absorption, preparation process and the physical mechanics performance of porous concrete were studied. Net slurry stone process was used.Mineral admixtures can reduce pH value of ecological planting type concrete Soil pH, and the effect is better than fly ash and slag mix mixed results. Cement paste– aggregate ratio directly determine waterhead and permeability coefficient of ecological planting concrete, with a logarithmic relation coefficient.Cement paste– aggregate ratio creasing,waterhead increases with the positive function relation, but permeability coefficient decreases with inverse function relation. Relation of permeability coefficient and porosity also is the logarithmic relationship,with the same pore ratio, permeability coefficient is taller, shows that the ecological planting concrete has better connectivity. Green-growing porous concrete with broken bricks has better water absorption capacity and water-holding capacity than with gravel. Along with the increase of aggregate-cement ratio, water-holding capacity drops, but water absorption capacity creases.With modern image analysis technique, aggregate size and cement-aggregate ratio on the pore structure parameters were analysised. Used the principles of industrial three-dimensional reconstruction of CT image, adopted digital grapHic process and MATLAB program to achieve three-dimensional reconstruction of the porous concrete.The results showed that the reconstruction view of three-dimensional structure was similar to the real structure of porous concrete, and the inner porous structure and the connectivity of concrete can be analyzed intuitively. It provided an effective model for porous structure, mechanic property and penetrability of porous concrete using finite element method.Porous structures of porous concrete can improve the matching ability of surface impedance and free space impedance, this means that the electromagnetic wave is prone to enter into the internal of it, moreover the reflection loss of electromagnetic wave decreased. Incident wave had undergone multiple reflection and scatter, so the energy loss increased. In 8GHz~18GHz brand, average reflectivity of the sample is less than -20dB. Moreover, influences of iron ore, ferrite and steel fibers on absorbing properties of porous concrete were studied.Green-growing porous concrete can be completely covered with reasonable density grass, the picture with optics cameras can’t distinguish between Green-growing porous concrete and soil, tand can escape the optical reconnaissance.With infrared thermograpHy, temperature of grass on green-growing porous concrete is high 0.96℃than that on soil in sunny day, and temperature is same in rainy day. as long as green-growing porous concrete is covered with reasonable thickness out-soil, ensure plant rational planting density, can achieve consistently harmony with environment, can avoid thermal infrared reconnaissance.Ecological planting grass type concrete covered with reasonable density grass can absorpt and scatter electromagnetic wave. And grass density influences electromagnetic wave absorption, when plant grass density of 100%, the minimum, maximum and average reflectivity of the sample is -42.87 dB, -20.16dB and -29.91 dB, respectively. Green-growing porous concrete completely covered with reasonable density grass and can escape the radar reconnaissance.更多还原