| Ecological Porous Concrete(EPC)is a new type of concrete structure material,which can achieve plant growth,regulate ecological balance timely,beautify the environment,and realize the human with natural ecological system coordinated symbiosis.In order to realize chemical compatibility between EPC and plant growth characteristics,and put forward a scientific and effective method of reducing alkali control of EPC,in this thesis,the technology of EPC alkali reduction was systematically discussed based on the material science,ecology,botany,chemistry,other basic theories and professional knowledge,and the method for controlling alkali reduction of EPC by reference to alkali absorption,alkali reduction,alkali sealing and solid alkali.Besides,the morphological characteristics of EPC hole were discussed by means of CT scanning technique.The main conclusions are as follows:1.The effects of cement varieties,type and content of mineral admixture and acid modified materials on the pH value of EPC paste were studied.The pH value of cement paste made by sulphoaluminate cement and aluminate cement was lower than that of ordinary portland cement by 2 to 3 units;mineral admixtures can reduce EPC alkalinity to a certain extent,in addition,the pH value decreased with the increase of mineral admixture,and the effect of silicified alkali was the best;acid modified material is very limited to alkalinity reduction.2.The effect on strength and alkalinity of EPC with single alkalinity-reduced treatment,such as oxalic acid soaking,oxalic acid spraying,DPS(deep penetrating sealer)spraying and rapid carbonization were studied.The results show that:compared with the standard group,the strength of EPC was reduced by 0.5?2MPa after oxalic acid soaking;the strength of EPC treated with oxalic acid or DPS was reduced 1?2MPa,and the influence of oxalic acid spraying on the strength of EPC is greater than that of DPS;compared to the natural carbonation,the strength increased slightly and more stable after the rapid carbonization.The EPC pH value can be reduced by 0.5?2 units after oxalic acid immersion;the EPC pH decreased 1?2 units after using oxalic acid and DPS to surface spraying,and the best results both achieved after spraying two times,last,the pH value was stable at about 10.3;the EPC value of pH after rapid carbonization decreased by about 1.7 units compared with the natural pH value after carbonization.Therefore,the project with high requirements to the EPC strength and alkalinity can be treated with a single alkali reduction method.3 The results of the study on the strength and alkalinity of EPC by adding silica fume and ferrous sulfate,adding permanent gel spraying and rapid carbonization technology showed that:using 10%silica fume and 4%ferrous sulfate,and the rapid carbonization technology,then,the use of permanent gel spray sealing compound alkali reduction process.Finally,the compressive strength can reach 8.3MPa after 28d,pH value decreased to 9.71;56d compressive strength up to 8.8MPa,pH value can be reduced to 9.82.Therefore,the EPC can meet the design strength and alkaline environment for plant growth.4.Based on the criterion of EPC and vegetation chemical compatibility,the matching degree between EPC and Bermuda grass was higher in the five kinds of plants.Eventually,the corresponding rules were provided for EPC to optimize the corresponding plant varieties.5.Depend on the CT scanning technology and fractal theory,the calculation method of ecological porous concrete section is analyzed.Besides the correlation between section fractal dimension and porosity is established,and the relativity is good.Finally,the relationship between the fractal dimension of pore structure and its macro and micro structural properties was established. |
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