The objective of this study is to analyze the effects of using surfactant(CTAB)and cellulose nanofibers(NFC)as an admixture in cement mortars.We examined composite properties as porosity,compression energy,thermal con...The objective of this study is to analyze the effects of using surfactant(CTAB)and cellulose nanofibers(NFC)as an admixture in cement mortars.We examined composite properties as porosity,compression energy,thermal conductivity and hydration.The results showed that with the addition of 0.7%by weight of NFC per emulsion in the presence of a cationic surfactant(CTAB).The new material produced presented a dry porosity between 4.7%and 4.4%,compressive strength between 9.8 and 22.9 MPa,and thermal conductivity between 0.95 and 2.25 W·m^(−1)·K^(−1).Thus we show better mechanical and thermal performance than that traditional Portland cement mortar with a density similar.In addition,the mortar made by emulsion of ordinary portland cement,cellulose nanofiber and organophilic clay(OC)treated with cetyltrimethylammonium bromide(CTAB)obtained has good resistance under high temperature and water,as well as excellent thermal insulation performance under high temperature and humidity conditions.This study verified that the presence of NFC promotes hydration,leading to the production of more calcium silicate and portlandite gel.展开更多
Development of macro and micro cracks on plastered walls and floors have been studied at different sites under site investigation whereby building inspections, construction history, engineering properties of soil and ...Development of macro and micro cracks on plastered walls and floors have been studied at different sites under site investigation whereby building inspections, construction history, engineering properties of soil and building surroundings assessment were conducted. We did revision of structural calculations and laboratory experiment to find out the source of cracks. Micro and macro cracks have no structural problems on the structure so long as the developed cracks are within the serviceability limit state [1]. There are two main causes of cracks in the structure that are structural and nonstructural sources [2]. The first task was to identify whether the source of cracks are structural or non structural. During site investigation the modes of crack formation, depth and length of crack, crack patterns and direction were studied at different sites in Ngara. Theoretical calculations of crack width and particles size distribution of sand from three main sources were analyzed after performing both sieve analysis and decantation tests. In depth site investigation, literature review and laboratory tests result showed that the causes of cracks are nonstructural and all three reliable sources of sand in Ngara contain more quantities of fines than that specified in BS 882. This paper is looking for the causes of cracks on structures and recommending further research on new idea of using simple technology and low cost methods that is affordable by both the government of Tanzania and local community of Ngara to overcome the problem of structures that develop micro and macro cracks.展开更多
文摘The objective of this study is to analyze the effects of using surfactant(CTAB)and cellulose nanofibers(NFC)as an admixture in cement mortars.We examined composite properties as porosity,compression energy,thermal conductivity and hydration.The results showed that with the addition of 0.7%by weight of NFC per emulsion in the presence of a cationic surfactant(CTAB).The new material produced presented a dry porosity between 4.7%and 4.4%,compressive strength between 9.8 and 22.9 MPa,and thermal conductivity between 0.95 and 2.25 W·m^(−1)·K^(−1).Thus we show better mechanical and thermal performance than that traditional Portland cement mortar with a density similar.In addition,the mortar made by emulsion of ordinary portland cement,cellulose nanofiber and organophilic clay(OC)treated with cetyltrimethylammonium bromide(CTAB)obtained has good resistance under high temperature and water,as well as excellent thermal insulation performance under high temperature and humidity conditions.This study verified that the presence of NFC promotes hydration,leading to the production of more calcium silicate and portlandite gel.
文摘Development of macro and micro cracks on plastered walls and floors have been studied at different sites under site investigation whereby building inspections, construction history, engineering properties of soil and building surroundings assessment were conducted. We did revision of structural calculations and laboratory experiment to find out the source of cracks. Micro and macro cracks have no structural problems on the structure so long as the developed cracks are within the serviceability limit state [1]. There are two main causes of cracks in the structure that are structural and nonstructural sources [2]. The first task was to identify whether the source of cracks are structural or non structural. During site investigation the modes of crack formation, depth and length of crack, crack patterns and direction were studied at different sites in Ngara. Theoretical calculations of crack width and particles size distribution of sand from three main sources were analyzed after performing both sieve analysis and decantation tests. In depth site investigation, literature review and laboratory tests result showed that the causes of cracks are nonstructural and all three reliable sources of sand in Ngara contain more quantities of fines than that specified in BS 882. This paper is looking for the causes of cracks on structures and recommending further research on new idea of using simple technology and low cost methods that is affordable by both the government of Tanzania and local community of Ngara to overcome the problem of structures that develop micro and macro cracks.