Development of compressed block and green mortar using loess (hwangto)

DEVELOPMENT OF COMPRESSED BLOCK AND GREEN MORTAR USING LOESS (HWANGTO) by LE, ANH TUAN DISSERTATION Presented to the Faculty of the Graduate School of Yeungnam University in Partial Fulfillments of the Requirements for the Degree of DOCTOR OF PHILOSOPHY YEUNGNAM UNIVERSITY December 2008 DEVELOPMENT OF COMPRESSED BLOCK AND GREEN MORTAR USING LOESS (HWANGTO) APPROVED BY DISSERTATION COMMITTEE: ACKNOWLEDGEMENTS First of all, I have nothing but the ultimate respect for my supervisors, Prof Kwon, Hyug-Moon, for his great guidance and encouragement throughout the work of this thesis I am very thankful to Prof Shin, Young-Shik; Prof Kwon, YoungBong; Prof Woo, Kwang-Sung; Prof Lee, Jae-Hoon for their classes, especially, to Prof Park, Sung-Moo and Prof Park, Yeong-Mok for dedicating their time and effort on participating in my dissertation committee I also would like to thank Mr Ju, Hag-Don; Mr Kim, Chang-Dong ; Mr Kwon, Jung-Ki, Mr Lee, Sam-Yong; Mr Kim, Sang-Won; Mr Chae, Chul-Ho; Mr Ko, Jin-Seok; Mr Shin, Sung-Jin; Dr Do, Dai Thang, Dr Nguyen, Ninh Thuy for their help throughout the work I also wish to thank Vietnamese friends in Yeungnam University for their patient advice and assistance during my study My deep appreciation goes to Jean Christophe, who spent and enjoyed the time I would also thank my parents, my wife and two daughters for their love which has given me courage and strength, encouraging me to my best, and supporting me to complete my goal Finally, I wish to thank Ho Chi Minh University of Technology and Yeungnam University support during my study i CONTENTS Acknowledgements i Contents ii List of Tables iv List of Figures vii CHAPTER 1.1 1.2 1.3 1.4 INTRODUCTION Motivation Objectives and scope Methodology Organization of dissertation CHAPTER 2.1 2.2 2.3 2.4 LITERATURE REVIEWS Green construction materials Compressed earth block and earth mortar 13 Stabilization mechanism 22 Summary 25 CHAPTER 3.1 3.2 3.3 EXPERIMENTS 26 Materials 26 Specimen preparation and curing condition 34 Test methods 35 CHAPTER COMPRESSED LOESS BLOCK 39 4.1 Influence of moisture content 40 4.2 Influence of binder and compaction pressure 43 ii 4.3 4.4 4.5 Influence of sand 73 Influence of curing condition 93 Summary 98 CHAPTER 5.1 5.2 5.3 GREEN LOESS MORTAR 100 Influence of binder and water content 101 Influence of sand 127 Summary 139 CHAPTER 6.1 6.2 6.3 6.4 DURABILITY AND ENVIRONMENT 141 Weather resistance 142 Acid resistance 154 Environmental impact 169 Summary 178 CHAPTER 7.1 7.2 7.3 7.4 CONCLUSIONS 180 Compressed loess block 182 Green loess mortar 180 Durability and environment 183 Future study 184 REFERENCES 185 ABSTRACT 197 iii List of Tables Table 2- Recommendation concerning contents of the different soil fractions 17 Table 2- Comparison compressed earth blocks and other materials 21 Table 3- Physical properties of Ordinary Portland cement 26 Table 3- Chemical composition of cement 27 Table 3- Physical properties of Natural Hydraulic Lime 27 Table 3- Chemical composition of silica sand 28 Table 3- Physical properties of silica sand 29 Table 3- Physical properties of blast furnace slag 29 Table 3- Chemical composition of blast furnace slag 30 Table 3- Chemical composition of Rice Husk Ash 31 Table 3- Physical properties of admixture 31 Table 3- 10 Physical properties of loess 33 Table 3- 11 Clay content of different loess groups 33 Table 3- 12 Chemical composition of loess 34 Table 4- Effect of compaction pressure on dry density 40 Table 4- Effect of loess group on optimum moisture content 41 Table 4- Mix proportion of compressed loess block 43 Table 4- Effect of cement on developed compressive strength 44 Table 4- Effect of cement and compaction pressure on dry density, tensile strength and water absorption 45 Table 4- Mix proportion with different loess groups 52 Table 4- Properties of compressed loess with different loess groups 53 Table 4- Strength developed with NHL on natural size group 61 Table 4- Mix proportion with Blast furnace slag 67 iv Table 4- 10 Mix proportion with Rice husk ash 68 Table 4- 11 Mix proportion of natural size group with sand 74 Table 4- 12 Mix proportion of P16 group with sand 75 Table 4- 13 Mix proportion of P30 group with sand 76 Table 4- 14 Mix proportion of P50 group with sand 77 Table 4- 15 Mix proportion of P100 group with sand 78 Table 4- 16 Effect of sand grading on strength 90 Table 4- 17 Effect of curing condition on 28-day strength 94 Table 5- Mix design for green loess mortar 101 Table 5- Water content and water-binder ratio on green loess mortar 101 Table 5- Effect of water-cement ratio on flow of green loess mortar 102 Table 5- Effect of water content on ultimate drying shrinkage 106 Table 5- Effect of water content on compressive strength 107 Table 5- Effect of water content on tensile strength 108 Table 5- Effect of water content on water absorption 110 Table 5- Mix proportion with different loess groups 112 Table 5- Effect of water content and loess particle on mortar 113 Table 5- 10 Effect of NHL on loess mortar 116 Table 5- 11 Mix proportion of mortar with BFS and RHA 120 Table 5- 12 Effect of BFS and RHA on properties of mortar 121 Table 5- 13 Mix proportion with chemical admixture 124 Table 5- 14 Effect of admixture on properties of green loess mortar 124 Table 5- 15 Mix proportion of green loess mortar with sand 128 Table 5- 16 Properties of mortar of natural size group 129 Table 5- 17 Properties of mortar of the P16 group 129 Table 5- 18 Properties of mortar on of P30 group 130 Table 5- 19 Properties of mortar of the P50 group 130 v Table 5- 20 Properties of mortar of the P100 group 131 Table 5- 21 Properties of green loess mortar with different sand grades 136 Table 6- Mass reduction of natural size group after cycle of slake durability, with 2.5 MPa pressure 143 Table 6- Mass reduction of loess mortar with natural size group after cycle of slake durability 143 Table 6- Slake durability of compressed loess block 146 Table 6- Effect of different binders on slake durability 147 Table 6- Effect of compaction pressure on slake durability 151 Table 6- Effect of different loess groups on slake durability 152 Table 6- Effect of cement on HCl solution 155 Table 6- Effect of compaction pressure on HCl solution 155 Table 6- Effect of different binders on durability on HCl solution158 Table 6- 10 Effect of sand on durability on HCl solution 160 Table 6- 11 Effect of sand and loess group on durability on HCl solution 160 Table 6- 12 Effect of cement and pressure on H2SO4 solution 162 Table 6- 13 Effect of compaction pressure on H2SO4 solution 163 Table 6- 14 Effect of different binders on durability on H2SO4 solution 166 Table 6- 15 Effect of sand on durability on H2SO4 solution 166 Table 6- 16 Effect of sand and loess group on durability on H2SO4 solution 167 Table 6- 17 Effect of cement content on pH with curing time 170 Table 6- 18 Effect of cement and loess groups on pH after 450 days 171 Table 6- 19 Effect of different binder on pH value 174 Table 6- 20 Effect of sand on pH value 176 Table 6- 21 Effect of sand and loess group on pH 176 vi List of Figures Fig 2- Recommended area of dry density and moisture content for adobe, rammed earth and compressed earth blocks following Houben and Guillard 19 Fig 3- Sand grading 28 Fig 3- Rice Husk Ash 30 Fig 3- Loess groups 32 Fig 3- Particle size of loess on the P100 group 32 Fig 3- Loess grading 33 Fig 3- Compressed loess specimen with static compaction 34 Fig 3- Flow test for loess mortar 36 Fig 3- Measurement changes in length of loess 37 Fig 3- pH tested equipments 38 Fig 4- Relationship between dry density and moisture content 41 Fig 4- Relationship between moisture content and loess groups 42 Fig 4- Effect of cement on strength after and 28 days 46 Fig 4- Increasing strength ratio to compare to strength of 2.5 MPa compaction pressure 46 Fig 4- Increasing strength of 90, 180, 360, and 450 days compared with 28 days 48 Fig 4- SEM of compressed sand cement after 450 days 49 Fig 4- SEM of compressed loess cement after 450 days 49 Fig 4- Effect of cement on 28-day tensile strength 51 Fig 4- Effect of compaction pressure on strength with 10% cement 54 Fig 4- 10 Relationship between cement and dry density of natural size group 55 vii Fig 4- 11 Relationship between strength and density of natural size group with various compaction pressures 56 Fig 4- 12 Effect of compaction pressure on compactive effect ratio 57 Fig 4- 13 Water absorption and cement content with various pressures 58 Fig 4- 14 Water absorption of different loess groups with 10 % cement 59 Fig 4- 15 Relationship between strength and NHL content at 28 days 62 Fig 4- 16 SEM of NHL loess after 450 days curing in air condition 63 Fig 4- 17 Effect of NHL on 28-day tensile strength 65 Fig 4- 18 Effect of NHL on 28-day water absorption 65 Fig 4- 19 Effect of BFS on strength of loess 69 Fig 4- 20 Effect of BFS on water absorption of loess 70 Fig 4- 21 Effect of RHA on strength of loess 71 Fig 4- 22 Effect of RHA on water absorption of loess 72 Fig 4- 23 Influence of clay content on strength of natural size group 79 Fig 4- 24 Influence of clay content on strength in the P16 group 80 Fig 4- 25 Influence of clay content on strength in the P30 group 81 Fig 4- 26 Influence of clay content on strength in the P50 group 81 Fig 4- 27 Influence of clay content on strength in the P100 group 82 Fig 4- 28 Relationship between dry density and strength 84 Fig 4- 29 Relationship between tensile and compressive strength 85 Fig 4- 30 Influence of clay content on water absorption with 2.5 MPa pressure 87 Fig 4- 31 Influence of clay content on water absorption with MPa pressure 87 Fig 4- 32 Influence of clay content on water absorption with 10 MPa pressure 88 viii References [43] [44] [45] [46] [47] [48] [49] [50] [51] H Ahnberg and S.-E Johansson, “Increase in strength with time in soil stabilized with different types of binder in relation to the type and amount of reaction products”, Dry Deep Mix Methods for Deep Soil Stabilisation, 13-15 October, Stockholm, 2005 V Rigassi, “Compressed Earth Blocks: Manual of Production”, Vol CRATerre-EAG Vilefontaine Cedex, France, 1995 SENCICO, “Norma Tecnica Edificacion NTE E 0.80 Adobe, Reglamento Nacional de construcciones”, Lima: SENCICO, 2000 Standards Australia and P Walker, HB 195: The Australia earth building handbook Sydney (Australia): Standard Australia, 2000 ILO/UNIDO, “Small-scale Brick making”, Technology Series, Memorandum No.6 International Labour Organisation Geneva, Switzerland, Jimenez, 1984 M.C Jimenez Delgado and I.C Guerrero, “The selection of soils for unstabilised earth building: A normative review”, Construction and building materials, Vol 21, pp.237-251, 2007 MOPT, “Bases para el Diseno y Construcion Tapial Madrid”, Spain: Centro de Publicaciones, Secretaria General Tecnicia, Ministerio de Obras Punicas y Transportes, 1992 E.W Smith and G.S Austin, “Adobe, pressed-earth and rammed earth industries in New Mexico”, Bulletin No 159, Socrorro, NM: New Mexico Bureau of Mines and Mineral Resources, 1996 M Olivier and A Mesbah, “Influence of Different Parameters on the Resistance of Earth used as a Building Material”, Proceeding of the Mud Architecture International Conference organised in Bangalore, 1987 189 References [52] [53] [54] [55] [56] [57] [58] [59] [60] [61] [62] [63] B.V Venkatarama Reddy and K.S Jagadish, “Influence of soil composition on the strength and durability of soil-cement block”, Indian concrete journal, Vol 69 (9), pp 517-524, 1995 H Houben and H Guillaud, “Traitéde construire en terre: l’encyclopédie de la construction en terre”, CRATERRE, Vol Edition Parenthèse, Paris, 1989 G Torraca, “Air Pollution and the Conservation of Building Materials”, Durability of Building Materials, Vol 53(4), pp 383-392, 1988 J Glanville and A Neville, “Prediction of concrete durability”, E&FN Spon, London, 1997 Orhan Reman, “Increasing the strength of soil for adobe construction”, Architectural Science Review, Vol 47, 2004 O.G Ingles, “Soil Stabilization - Principles and Practice”, Butterworths Publications, Sydney, Australia, 1972 G Allen, J Allen, N Elton, M Farey, S Holmes, P Livesey and M Radonjic, “Hydraulic lime mortar for stone, brick, block masonry”, Donhead publishing Ltd., 2003 S Holmes and M Wingate, “Building with lime”, Published by ITG, 2003 BS EN 451:2001, Building limes: part Definitions, specifications and conformity criteria, published by BSI, 2001 ASTM C136, Standard Test Method for Sieve Analysis of Fine and Coarse Aggregates, 1996 F.C Lanning, “Silicon in rice”, Agricultural and Food Chemistry, Vol 11, pp 435–437, 1963 C.L Hwang and D.S Wu, “Properties of cement paste containing Rice Husk Ash”, ACI SP114-35, Proceeding of the Third CANMET/ACI International conference, Norway, ed V.M Malhotra, pp.733-762, 1989 190 References [64] [65] [66] [67] [68] [69] [70] [71] [72] [73] [74] [75] D.J Cook, “Rice Husk Ash”, Concrete technology and design, Vol.3, Cement replacement materials, ed R.N Swamy, published by Surrey University Press, pp.171-196, 1986 ASTM C109-99, Standard Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in or [50mm] Cube Specimens), 1999 ASTM C1437, Standard Test Method for Flow of Hydraulic Cement Mortar, 1999 ASTM D1633, Standard Test Methods for Compressive Strength of Molded Soil-Cement Cylinders, 2000 ASTM 496-96, Standard test method for splitting tensile strength of cylindrical concrete specimens, 1996 ASTM C596-96, Standard test method for drying shrinkage of mortar containing hydraulic cement, 1996 ASTM C1403, Standard Test Method for Rate of Water Absorption of Masonry Mortars, 2006 ASTM D559, Standard Test Methods for Wetting and Drying Compacted Soil-Cement Mixtures, 1996 ASTM C267-1, Standard Test Methods for Chemical Resistance of Mortars, Grouts, and Monolithic Surfacing and Polymer Concretes, 2006 J.E Eades and R.E Grim, “A quick test todetermine lime requirements for lime stabilization”, Highway Research Board, Record No 139, pp.61–72, 1963 J K Weng, B W Langan, and M A Ward, “Pozzolanic reaction in Portland cement, silica fume, and fly ash mixtures”, Canadian Journal of Civil Engineering, Vol.24 (5), pp 754–760, 1997 Science Report, “Review of scientific literature on the use of stabilisation/solidification for the treatment of contaminated soil, solid waste and sludge”, Environment Agency, UK, 2004 191 References [76] [77] [78] [79] [80] [81] [82] [83] [84] [85] J.C Morel, Abalo Pkla and P Walker, “Compressive strength testing of compressed earth blocks”, Construction and Building Materials, Vol.21 (2), pp.303-309, 2007 B.V Venkatarama Reddy, A Gupta, “Characteristic of soilcement blocks using highly sandy soils”, Materials and structures 38, (July), pp.651-658, 2005 G.P Broderick and D.E Daniel, “Stabilisation compacted clay against chemical attack”, ASCE, Geotechnical Engineering, Vol 116, pp.1549–1567, 1990 B.V Venkatarama Reddy, Richardson Lal and K.S Nanjunda Rao, “Enhancing bond strength and characteristics of soilcement block masonry”, Journal of Materials in Civil Engineering, ASCE, Vol 19(2), pp 164 – 172, 2007 TRB State of the Art report 5, “Lime stabilization”, 1987 G Veith, “Essay competition green, ground and great: soil stabilization with slag”, Building research and information, Vol 28(1), pp.70–72, 2000 M.A Mustapha, “Effect of Bagasse Ash on Cement Stabilized Laterite”, Seminar Department of Civil Engineering, Ahmadu Bello University, Zaria, Nigeria, 2005 K.J Osinubi and V.Y Katte, “Effect of elapsed time after mixing on grain size and plasticity characteristics; soil lime mixes”, NSE technical Transactions, Nigeria, Vol 32(4), pp 65-76, 1997 E.B Oyetola and M Abdullahi, “The Use of Rice Husk Ash in Low-Cost Sandcrete Block Production”, Leonardo Electronic Journal of Practice and Technologies, Vol.8, pp 58-70, 2006 P Walker and T Stace, “Properties of some cement stabilized compressed earth blocks and mortar”, Materials and structures, Vol 30(November), pp 545-551, 1997 192 References [86] [87] [88] [89] [90] [91] [92] [93] [94] [95] R.J.S Spence and D.J Cook, “Building Materials in Developing Countries”, John Wiley & Sons Ltd Chichester, England, 1983 BS 8007:1987, Code of practice for design of concrete structures for retaining aqueous liquids, 1987 C Anderson and L.C Held, “The effect of sand grading on mortar properties and tensile bond strength of brickwork specimens”, Proc Br Mason Soc., Vol.1, pp.1-6, 1986 J Hu and K Wang, “Effects of Aggregate on Flow Properties of Mortar”, Proceedings of the 2005 Mid-Continent Transportation Research Symposium, Ames, Iowa, 2005 S Kenai, Y Benna and B Menadi, “The effect of fines in crushed calcareous sand on properties of mortar and concrete”, Infrastructure regeneration and rehabilitation improving the quality of life through better construction-International conference, Sheffield, Royaume-Uni, pp 253-261, 1999 B.V Venkatarama Reddy and A Gupta, “Characteristics of cement-soil mortars”, Materials and structures, Vol 38, Number / July, pp 639-650, 2005 R Hanley and S Pavia, “A study of the workability of natural hydraulic lime mortars and its influence on strength, Materials and structures, Vol 41, pp 373-381, 2008 L.R Baker, “Some Factors Affecting the Bond Strength of Brickwork”, Fifth International Brick Masonry Conference, Washington, 1979 Japan Concrete Institute JCI), “Autogenous shrinkage of concrete”, Proceedings of the International Workshop Organized by JCI, Hiroshima, Japan, London and New York, 411 pp., 1998 P.K Mehta and P.J.K Monteiro, “Concrete: Structure, Properties, and Materials”, 2nd Edition, Prentice Hall, Englewood Cliffs, N J., 548 pp., 1993 193 References [96] [97] [98] [99] [100] [101] [102] [103] [104] Joachim Schulze, “Influence of water-cement ratio and cement content on the properties of polymer-modified mortars”, Cement and concrete research, Vol 29 (6), pp 909915, 1999 I Soroka, “Portland Cement Paste and Concrete”, Chemical Publishing & Co, New York, 1980 J Eibl, “Beton Kalender Teil 1”, Verlag Ernst & Sohn Wiesbaden, Germany, 1990 F Lange, N Mörtel and V Rudert, “Dense Packing of Cement Pastes and Resulting Consequences on Mortar Properties”, Cement and Concrete Research, Vol.27 (10), pp.1481-1488, 1997 C.F Ferraris and J.M Gaidis, “Connection between the rheology of concrete and rheology of cement paste”, ACI Materials Journal, Vol 89 (4), pp 388, 1992 O Cizer, K Van Balen and D Van Gemert, “Carbonation and hydration of mortar with calcium hydroxide and calcium silicate binders”, Proc International Conference on Sustainable Construction Materials and Technologies, International Conference on Sustainable Construction Materials and Technologies location: Coventry, UK, pp 611621, 2007 S Chandra and J Björnström, “Influence of cement and superplasticizers type and dosage on the fluidity of cement mortars—Part I”, Cement and Concrete Research, Vol 32 (10), pp.1605– 1611, 2002 S Chandra and J Björnström, “Influence of superplasticizer type and dosage on the slump loss of Portland cement mortars ─ part II”, Cement and Concrete Research, Vol 32 (10), pp 1613─1619, 2002 H Ai and J.F Young, “Mechanisms of shrinkage reduction using a chemical admixture”, Proceedings of the 10th 194 References [105] [106] [107] [108] [109] [110] [111] [112] International Congress on the Chemistry of Cement, vol.3, 3iii018, Gothenburg (Sweden), p 8, 1997 V.S Ramachandran, “Concrete Admixtures Handbook: Properties, Science and Technology”, Noyes Publications, 1995 K Van Balen and D Van Gemert, “Modeling lime mortar carbonation”, Materials and Structures, Vol 27, pp.393-398, 1994 B.V Venkatarama Reddy, and A Gupta, “Influence of sand grading on the characteristics of mortars and soil-cement block masonry”, Construction and Building Materials, Vol 22(8), pp 1614-1623, 2008 Baker et al., “Durability of Building Materials and Components”, Proceedings of the Fifth International Conference held in Brighton, 7-9 November, England, 1990 Sjostrom et al., “Durability of Building Materials and Components 7: Testing, Design and Standards”, Proceedings of the Seventh International Conference on Durability of Building Materials and Components, DBMC held in Stockholm, Sweden 19-23 May 1996, Vol 2, May 1996 E & FN SPON London, England, 1996 J Glanville and A Neville, “Prediction of Concrete Durability”, Proceedings of STATS 21st Anniversary Conference, The Geological Society, London, 16 November 1995 E & FN SPON London, England, 1997 D.M Roy, “Hydration, microstructure, and chloride diffusion of slag-cement pastes and mortars”, ACI SP-114, Vol 2; pp 1265–1282, 1989 R Siddique, “Waste Materials and By-Products in Concrete”, Springer Berlin Heidelberg, 2008 195 References [113] [114] [115] [116] [117] [118] D Hunter, “Lime induced heave in sulfate-bearing clay soils”, Journal of Geotechnical and Geoenvironmental Engineering ASCE 114, pp 150–167, 1988 D.T Bergardo, L.R Anderson, N Miura and A.S Balasubramaniam, “Soft ground improvement in lowland and other environments”, ASCE Press, New York pp 234–304, 1996 F.G Bell, “Cement Stabilisation and Clay Soil, with examples”, Environmental and Engineering Geoscience, Vol.1, pp 139-151, 1995 A.M.O Mohamed and H.E Antia, “Geoenvironmental Engineering”, Elsevier, Amsterdam, 1998 V Ouhadi, “The role of marl components and ettringite on the stability of stabilized marl”, Ph.D Thesis, McGill University, Montreal, Canada, 1997 A.M.O Mohamad, J.F Boily, M Hossein, M and F.P Hassani, “Ettringite formation in lime remediated mine tailings: I thermodynamic modeling”, Canadian Institute of Mining, Metallurgy, Petroleum (CIM) Bull., Canadian Mineral Processors Division, Vol.88, pp 69–75, 1995 196 Abstract Ph.D Dissertation Development of compressed block and green mortar using loess (Hwangto) Le, Anh Tuan Department of civil Engineering Graduate School Yeungnam University (Advised by Prof Kwon, Hyugmoon) 요약 세계적으로 천연자원으로부터 만들어진 모든 건축물은 건강한 실내환경과 환경적인 충격을 줄인다 건설에서 천연건설재료는 다른 재료와 같이 사용할 수 있다 토류제품은 사용 후에 재사용을 위해 거의 에너지를 사용하지 않고 흙의 모체로 되돌아가므로 토류제품의 사용은 안전하고, 197 Abstract 경제적이고, 에너지 효율적이다 한국에서 황토라고 불리어지는 Loess는 누런색의 흙으로 알려져 있다 황토는 높은 흡수성, 자정작용과 원적외선을 가진 전형적인 건강하고 친환경적인 재료 중 하나이며 아토피, 여드름, 습진과 같은 피부의 문제에 효과적이다 건축재료로서 황토를 개발하는 목적은 재료비를 낮추고, 인류의 건강을 지켜주는 것이다 현실적으로 황토의 성공적인 적용은 경제력이 낮은 개발도상국 특히, 베트남에 장점을 가져다 줄 수 있다 본 연구에서는 황토몰탈과 그의 성능을 화학적, 기계적, 물리적 방법 및 이들의 조합에 의하여 연구하였다 토류제품에 대한 경험 지식에 근거하여 공장에서 생산되는 건설재료로서 황토의 사용성에 대하여 연구를 수행하였다 본 연구로부터 얻은 결과를 요약하면 다음과 같다 시멘트와 천연수경성석회는 황토의 작업성, 건조수축, 압축강도, 인장강도 및 내구성뿐만 아니라 흡수율을 개선하는데 사용될 수 있지만, 이들은 황토에서 pH값을 증가시킨다 10%이상의 시멘트를 사용한 황토건설재료는 내구성을 요하는 건설에 사용될 수 있다 황토몰탈에서 천연수경성석회의 사용은 양생을 위하여 시멘트보다 긴 시간과 많은 양을 필요로 한다 결합재에서 고로슬래그분말 50% 치환, 왕겨재 20%의 치환은 결합재의 양을 줄일 수 있고, 내구성과 황토의 pH 뿐만 아니라 건조수축, 흡수율, 강도특성을 개선시킨다 결합재의 무게에 비하여 1%유동화제의 198 Abstract 사용은 주어진 반죽질기에 대하여 수량을 감소시킬 수 있고, 몰탈의 특성을 개선할 수 있다 황토입자 크기의 증가와 더불어 황토량의 증가는 황토몰탈의 특성과 내구성에 크게 영향을 미친다 배합에서 황토의 양을 줄이기 위해 모래가 추가된다 본 연구에서, 최적의 황토량은 4.75mm이하인 황토입자를 가압다짐한 토류블록에 대하여 5~30%인 것으로 나타났다 이때 최대 다짐압력은 10MPa이고, 황토입자를 4.75mm~0.15mm로 줄이면 최적의 황토량은 30%이상 증가시킬 수 있다 가압다짐압력을 20MPa로 증가시키면 황토제품의 강도는 증가하지만, 가압다짐력의 증가는 모래의 입자크기를 줄여야한다 입자의 크기를 변형시킨 황토는 황토제품의 특성을 개선할 뿐만 아니라 배합에서 황토의 양을 줄일 수 있다 몰탈에서 황토량을 줄이면 작업성, 건조수축, 강도특성, 건조밀도 및 흡수율을 개선할 수 있다 모래입도(조립율)를 큰 것에서 작은 것으로 변화시키면 작업성과 강도특성은 감소하지만 건조수축은 증가한다 가압다짐에 의한 황토제품의 28일 압축강도는 증기양생과 기중양생보다 수중양생에서 더 크게 나타났다 일반적으로 황토입자와 모래, 적당한 양의 결합재로 구성된 황토몰탈은 수량에 따라 시멘트 몰탈 및 콘크리트와 비슷한 특성을 가지지만 낮은 pH 값을 갖는 몰탈과 압축된 황토블록을 생산할 수 있다 199 Abstract Ph.D Dissertation Development of compressed block and green mortar using loess (Hwangto) Le, Anh Tuan Department of civil Engineering Graduate School Yeungnam University (Advised by Prof Kwon, Hyugmoon) Abstract In the world, every building product from natural resources is a healthy indoor environment and a low environmental impact Using natural building materials in construction can be incorporated with another structure Moreover, using of earth products is safe, cost effective, energy efficient because the products will return to Mother 200 Abstract Earth after using, causing almost free-spending energy to solve the problem of recycling wastes In Korea, loess, which is named Hwangto, is known as an orange soil It is one of the representative healthy and eco-friendly materials with the properties of high absorbency, self-purification, and radiation of infrared rays Therefore, loess has good effectiveness for healing skin troubles such as atopic skin, pimple and eczema The purposes to develop loess as building materials are to reduce cost of building materials, to protect and maintain good health for human beings The successful application of loess in practice can bring benefits to Less Economically Developed Countries, especially Vietnam In this study, loess materials and their performances are studied by the methods including chemical, mechanical, physical and a combination of these three methods Based on the background of knowledge about earth products, the research is carefully undertaken to investigate the ability to use loess materials produced by manufactory process as building materials in the construction The results from this investigation can be summarized as below Cement and natural hydraulic lime can be employed to improve the workability, the ultimate drying shrinkage, the compressive and tensile strength, and the water absorption as well as the durability of loess However, they caused an increase in a pH value on loess Loess products containing cement more than 10% can be used in the construction Using natural hydraulic lime in loess materials requires 201 Abstract long-term effect and higher quantity as compared with cement The replacement of either 50% blast furnace slag or 20% rice husk ash on binder can reduce a quantity of binder, and can improve the strength properties, the drying shrinkage, the water absorption as well as the durability and the pH value of loess materials Moreover, 1% superplasticizer-based admixture by weight of binder can reduce the water content to achieve a given consistency, and improve the properties of green loess mortar The amount of clay, which increases with an increase in the fineness of loess grading, significantly affects on the property and the durability of loess In order to reduce clay content in mixture, sand additive is used In this research, the optimum clay content is corresponding to the recommendation of 5-30% clay in the literatures for compressed earth blocks with loess grading less than 4.75 mm and its maximum compaction pressure of 10 MPa The optimum clay content is increased over 30% by decreasing maximum particle size of loess from 4.75 to 0.15 mm On the other hand, the mega pressure of 20 MPa can be employed to produce high strength loess blocks Hence, modification particle size of loess can increase the amount of clay content in mixture as well as improve the properties of loess materials Moreover, the increase in compaction pressure requires a decrease in grading of sand For a green loess mortar, the reduction on clay content can improve workability, ultimate drying shrinkage, strength properties, dry density and water absorption In addition, when sand 202 Abstract size varies from coarse to fine grade, the workability and the strength properties are reduced, whereas the drying shrinkage is increased Loess materials can increase their strength properties by watercuring condition greater than by steam-curing, which produced better strength than air-curing after 28 days Generally, depending on water content of loess, which contained loess particles, sand and suitable amount of binder should be employed to produce compressed loess block or green loess mortar with the characteristics that are similar to cement mortar and concrete, but with a low pH value   203 ... particle size of loess, and amount and type of binders on workability and characteristics of mortar Chapter reports the results of durability of compressed loess block, green loess mortar and their... admixture on flow of green loess mortar 125 Fig 5- 18 Effect of admixture on drying shrinkage of green loess mortar 125 Fig 5- 19 Effect of admixture on strength of green loess mortar 126... proportion of green loess mortar with sand 128 Table 5- 16 Properties of mortar of natural size group 129 Table 5- 17 Properties of mortar of the P16 group 129 Table 5- 18 Properties of mortar