Nghiên cứu chế tạo gạch xây không nung hệ geopolymer từ bùn đỏ tân rai lâm đồng tt

MINISTRY OF EDUCATION AND TRAINING MINISTRY OF CONSTRUCTION VIETNAM INSTITUTE OF BUILDING SCIENCE AND TECHONOLOGY QUANG LE VAN RESEARCH ON MANUFACTURING GEOPOLYMER UNBAKED BRICK BASED ON RED MUD OF TAN RAI LAM DONG SUMMARY OF DOCTORAL THESIS Specialization: Materials engineering Code: 9520309 HA NOI-2019 THE DISSERTATION IS COMPLETED AT: VIETNAM INSTITUTE FOR BUILDING SCIENCE AND TECHONOLOGY Academic supervisor: Doctor HOANG MINH DUC INSTITUTE OF CONCRETE TECHONOLOGY - VIETNAM INSTITUTE FOR BUILDING SCIENCE AND TECHONOLOGY Associate Professor Doctor DO QUANG MINH HO CHI MINH CITY UNIVERSITY OF TECHNOLOGY Reviewer 1: Asso.Prof Dr Ngoc Nguyen Minh Reviewer 2: Asso.Prof Dr Long Luong Duc Reviewer 3: Dr Dai Bui Danh This dissertation is defended by Academy Doctoral Examination Boar at Institute of Building Science and Techonology, 81 Tran Cung street, Nghia Tan, Cau Giay District, Ha Noi at …… on the day of 2019 The dissertation may be read at: - National Library of Vietnam - Library of Vietnam Institute of Building Science and Techonology INTRODUCTION Rationale of the Study Red mud is the name of waste generated from bauxite hydrated alumina by Bayer technology Tan Rai Aluminum Factory has the amount of red mud discharged into the environment during the operation process of 80÷90 million m3, causing environmental pollution, significant impact on ecosystems and society In the composition of red mud containing alkali, easy to soak into the soil, polluting water sources, degradation of arable land or in the composition may have radioactive substances very difficult to store and preserve Utilizing the typical residual components, silicon oxide, aluminum oxide in red mud combined with the addition of silicon oxide from other waste sources such as fly ash and appropriate curing methods to fabricate geopolymer materials The demand for unbaked construction bricks in Vietnam as well as environmental treatment is essential Research subject and scope The object of the dissertation is geopolymer using Tan Rai Lam Dong red mud to meet the requirements for making unburnt bricks The scope of the study includes: properties of component materials Effect of alkaline concentration, curing conditions on the solubility of silicon oxide and aluminum oxide in raw materials Effect of materials, curing conditions on intensity, softening coefficient, pH and excess alkalinity of geopolymer The properties of geopolymer and economic efficiency Scientific significance Having argued and proved experimentally on the following issues: - The ability to make geopolymer from red mud depends on the amount of silicon oxide dissolved in the alkaline solution, thanks to curing at high pressure and high temperatures or supplemented from materials such as fly ash, silica fume - Clarified the influence of material and technology parameters on the properties of geopolymer from red mud From there set the technological parameters for production Practical significance - Based on the research results that have contributed to the market a new product, geopolymer unburnt bricks from Tan Rai red mud, meeting technical requirements for use in construction works - Method of making geopolymer unburnt bricks from red mud by autoclave technology allows effective treatment of red mud waste, contributing to environmental protection New contributions of dissertation - Using red mud waste of Tan Rai Aluminum factory and fly ash of Tan Rai internal thermal power plant, successfully manufacturing unbaker geopolymer bricks with autoclave technology to meet the requirements of construction - Clarifying the influence of several factors on the solubility ratio of silicon oxide in red mud and fly ash including alkaline solution concentration, temperature, pressure and curing time Under autoclave conditions, silicon oxide in red mud can be dissolved in alkaline solution and can participate in geopolymerization reaction - Contributing data on the properties of geopolymer from red mud and mixture of red mud and fly ash curing in autoclave conditions When autoclaving can improve the ratio of dissolved silicon oxide under low alkaline concentration Thus, it is possible to improve the softening coefficient, reduce the excess alkalinity and the pH of geopolymer Structure of the dissertation The dissertation includes introduction, five chapters (15 periods), conclusions and recommendations, list of references and appendices CHAPTER OVERVIEW OF RESEARCH ISSUES OF USING RED MUD IN CREATING GEOPOLYMER 1.1 Red mud emission and treatment direction 1.1.1 The process of red mud emissions Red mud is a waste of bauxite alumina production by Bayer technology Nowadays, there are about 90% of alumina in the world is manufactured using Bayer technology (invented by Bayer in 1887) Red mud consists of insoluble, inert and quite stable components in weathering conditions such as Hematite, Natrisilicat, Aluminate, Calcium-titanate, Mono-hydrate aluminum and especially contains a amount of caustic soda, a type of Highly toxic alkaline excess from the manufacturing process 1.1.2 Characteristics of the red mud - Solid phase of red mud: characterized by main factors such as chemical composition, minerals, particle size ; + Chemical composition: as reported by UNIDO, the solid phase chemical composition of red mud includes Al2O3, SiO2, Fe2O3, Na2O, CaO, TiO2, L.O.I + Mineral composition: similar to the composition of bauxite and has two new phases, namely Na2O.Al2O3.2SiO2.nH2O and compounds with oscillating components of CaO with Al2O3, Na2O and SiO2 components + Particle size: red mud usually has a fine to very fine particle size Most of them have a grain grade of 100%