Introduction. Raw materials and experimental methods

Transcription

1 Key Engineering Materials Submitted: ISSN: , Vols , pp Revised: doi: / Accepted: Trans Tech Publications, Switzerland Online: Research on the Proportion of Inorganic Binder Stabilize Materials with Soda Residue Guo Wenying 1,a, Zheng Meiru 1,b, Yang Yibo 1, 2, c, Wang Hengchang 1, d 1 School of Civil Engineering and Transportation, South China University of Technology, Guangzhou China; 2 State Key Laboratory of Subtropical Architecture Science, South China University of Technology, Guangzhou, China a wyguo@scut.edu.cn, b @qq.com, c yangyibo@scut.edu.cn, d cthcwang@scut.edu.cn Keywords:Soda residue; cement; inorganic binder stabilize materials; mineral admixtures Abstract. The soda residue pollutes the environment because of high contents of alkali ion and chloride ion in it. So how to treat the soda residue is an urgent problem to be solved. The mineral admixtures are added in traditional inorganic binder, and the strength performance and the negative effect of inorganic binder stabilized materials with soda residue is studied. And the results as follows: (1) Soda residue has different activated effect on mineral admixture; (2) Mineral admixture replace the cement with same dosage can improve the unconfined compressive strength greatly to meet the requirement of standard; (3) The chloride ion leaching rates of cement-mineral admixture-soda residue stabilized stone chip decrease with time. Mineral admixture has a better immobilization effect on the chloride ion except fly ash before 90d; (4) Ground granular blast-furnace slag is the best material to improve the strength performance of inorganic binder stabilized materials and decreases the negative effect of soda residue. Introduction Soda residue is the by-production of soda, and over 3000 thousand tones of soda residue are produced per year in China. Soda residue is a white paste material with high water content, and the main chemical content of soda residue are calcium carbonate, calcium sulfate, silica dioxide, magnesium hydroxide, magnesium chloride, sodium chloride, etc [1, 2]. The soda residue pollutes environment because of the high contents of alkali ion and chloride ion in it. So many researches about soda residue are focus on application of it. And soda residue can be used in agriculture and industry, such as to prepare the compound cementitious materials [3], inorganic binder [4~7], etc. But the negative effect of soda residue is not studied. Many researches were shown that the alkali material can react with the mineral admixture to generate strength. Because soda residue is a high alkali material, and the ph of soda residue is higher than 12, that is to say soda residue may react with the mineral admixture. The mineral admixtures are added in traditional inorganic binder to decrease the negative effect of soda residue was studied. Raw materials and experimental methods Raw materials. The soda residue was the reproduction of soda produced by Nanfang Soda Plant, and the main chemical components of soda residue are shown in table 1. The content of soluble choleric ion is 11.93%, water content is 92%, and the ph value is All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans Tech Publications, (ID: , Pennsylvania State University, University Park, USA-19/02/16,18:45:01)

2 482 High Performance Concrete Innovation & Utilization Table 1 The main chemical components of soda residue(%) Loss on CaO MgO Cl SO 3 SiO 2 Al 2 O 3 Fe 2 O 3 Na 2 O MnO Ignition The "Yuexiu band" P II.42.5R cement produced by Guangzhou Pear River Limited was used. Class I slaked lime powder produced by Guangzhou Huixiang Environmental Protection Material Co., Ltd., S95 slag produced by Fujian province, class II fly ash produced by Guangzhou Huangpu Power Plant, silica fume with specific surface area of 19200m 2 /kg produced by Beijing Jianghan Science and Technology Company and the metakaolin produced by Kaifeng Qiming Refractory Material Co., Ltd. were also used in the experiment. Besides, the stone chip with fineness modulus 2.75 was also used in experiment and the sieving result was shown in table 2. Table 2 Sieving result of stone chip Nominal size/mm <0.15 Fineness modulus Stone chip Proctor compaction test. The samples were tested according to the proctor compaction test method in Test Methods of Materials Stabilized with inorganic Binders for Highway Engineering (JTG E ). Unconfined compressive strength test. The samples were tested according to the unconfined compressive strength test method in Test Methods of Materials Stabilized with inorganic Binders for Highway Engineering (JTG E ). Chloride ion leaching test. The samples were curing for 7d, 28d, 56d, 90d, 180d at 20 士 2, R.H.>95%. Then crush the sample and pick out the aggregate. 40g sample is stirred 5min and put in 400ml dilled water for 24h. Then test the chloride ion content by PXSJ-216 type ion meter. Results and analysis Physical performances of soda residue. The results of figure 1 show that the best water content of soda residue is 54% and the biggest dry density of soda residue is 1.10g/cm 3. Because the water content of untreated soda residue is higher than 90%, the soda residue should be dried before use Biggest dry density/g/cm Water content/% Fig. 1 Relationship between water content and biggest dry density of soda residue

3 Key Engineering Materials Vols Mineral admixture-soda residue stabilized stone chip. The results of mineral admixture-soda residue stabilize stone chip are shown in Table 3. Table 3 Proportion and unconfined compressive strength of mineral admixture-soda residue stabilized stone chip No. Slag Fly ash Proportion(%) Silica fume Metakaolin Soda residue Stone chip 7d unconfined compressive strength/mpa D D D D D D D D Fig. 2 Unconfined compressive strengths of mineral admixture-soda residue stabilized stone chip The results showed that soda residue can react with mineral admixture, and the soda residue has different activated effect on mineral admixture. The unconfined strengths of samples with ground granulated blast-furnace slag and silica fume are bigger than others. But the confined compressive strengths of mineral admixture-soda residue stabilized stone chip are smaller than 0.7MPa, which is much lower than 1.5MPa. No mineral admixture-soda residue stabilized stone chip can meet the strength requirement of cement stabilized material used in sub base in Technical Specification for Construction of Highway Road bases (JGJ ). Cement-mineral admixture-soda residue stabilized stone chip. The results of cement-mineral admixture-soda residue stabilized stone chip are shown in Table 4.

4 484 High Performance Concrete Innovation & Utilization No. Table 4 Results of cement-mineral admixture-soda residue stabilized stone chip Cement Slag Fly ash Proportion(%) Silica fume Metakaolin Soda residue Stone chip Best water content/% Biggest dry density/ g/cm 3 7d unconfined compressive strength/mpa E E E E E E E E E Fig. 3 Unconfined compressive strengths of cement-mineral admixture-soda residue stabilized stone chip The unconfined compressive strengths of cement-mineral admixture-soda residue stabilized stone chip increase sharply when the mineral admixture replaces cement with same dosage. And all the unconfined compressive strengths can meet the strength requirement of sub base in Technical Specification for Construction of Highway Road bases (JGJ ). The effects of mineral admixture on the unconfined compressive strength of cement-mineral admixture-soda residue stabilized stone chip are silica fume > metakaolin > ground granular blast-furnance slag > fly ash. Chloride ion leaching rate of cement-mineral admixture-soda residue stabilized stone chip. The results of chloride ion leaching rate of cement-mineral admixture-soda residue stabilized stone chip are shown in Table 5. Table 5 Chloride ion leaching rate of cement/mineral admixture stabilized stone chip No. Chloride ion leaching rate/g/kg 7d 56d 90d 180d E E E E E Note: the chloride ion leaching rate is the ratio of the weight of leaching chloride ion to that of the dry soda residue.

5 Key Engineering Materials Vols The chloride ion leaching rates of cement-mineral admixture-soda residue stabilized stone chip decrease sharply with time. Cement can immobile the chloride ion, but the mineral admixture has a better immobilization effect on the chloride ion except fly ash before 90d. Before 56d the ground granular blast-furnace slag and silica fume are the better than the others, and after 90d ground granular blast-furnace slag and fly ash are the better than the others. Fig. 4 Chloride ion leaching rates of cement-mineral admixture-soda residue stabilized stone chip For the four kinds of mineral admixture the ground granular blast-furnance slag is the best material to improve the strength performance of inorganic binder stabilized materials and decrease the negative effect of soda residue by considering the strength of inorganic binder stabilized materials, chloride ion leaching rate, and ecomony. Conclusions The following conclusions can be drawn through the above results: (1) Soda residue has different activated effect on mineral admixture. (2) Mineral admixture replace the cement with same dosage can improve the unconfined compressive strength greatly to meet the requirement of standard. (3) The choleric ion leaching rates of cement-mineral admixture-soda residue stabilized stone chip decrease with time. Mineral admixture has a better immobilization effect on the chloride ion except fly ash before 90d. (4) Ground granular blast-furnance slag is the best material to improve the strength performance of inorganic binder stabilized materials and decreases the negative effect of soda residue. Acknowledgements This work was supported by a grant from the State Key Lab of Subtropical Building Science, South China University of Technology (No. 2012ZC25).

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