检索结果-南通市图书馆

Characterization of Mixed mortars with Partial Replacement of Sand with Sugarcane Bagasse Ash (SCBA)

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Open Journal of Civil Engineering 2016年第3期6卷 410-419页

作者： Carlos Humberto Martins Tainara Rigotti de Castro Camila Colhado Gallo StateUniversityof Maringá Maring&aacute Brazil StateUniversityof Paraná Campo Mour&atilde o Brazil

This paper analyzes the effect of partial sand replacement by sugarcane bagasse ash in mixed mortars utilizing a 1:2:9 mix proportion by volume for cement, lime and fine aggregate. The ash is characterized by its particle distribution, pozzolanic activity, chemical composition, bulk density, moisture content and loss on ignition. The mortars are then produced with a constant water/cement ratio of 2.64 and a partial replacement of sand with sugarcane bagasse ash using different substitution percentages (0%, 5%, 10%, 15% and 20%). The mortars are characterized in the plastic state: water retention, bulk density and air content, and in the hardened state: capillary coefficient, tensile strength by bending test, axial compressive strength and flexural and longitudinal Young’s modulus. The statistical analysis of the results showed that the ash can be incorporated into mortars without causing significant alterations in its properties.

关键词： mortars Sugarcane Bagash Ash

Corrosion Behavior of Reinforcement Steel Embedded in Cement mortars Using Different Protection Systems

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Materials Sciences and Applications 2019年第6期10卷 461-474页

作者： Evgenia Voulgari Aggeliki Zacharopoulou Nikolaos Chousidis George Batis Department of Chemical Engineering National Technical University of Athens Athens Greece Department of Civil and Environmental Engineering University of Cyprus Nicosia Cyprus

Although reinforced concrete structures are able to withstand towards a variety of adverse environmental conditions, reinforcement corrosion could lead to concrete structure deterioration. The present study examines four different ways of using corrosion inhibitors against pitting corrosion. In particular, it was investigated the chloride penetration resistance of reinforced cement mortars using corrosion inhibitor applied in three different ways. The corrosion behavior of the specimens was evaluated by electrochemical methods such as Linear Polarization Resistance and Halfcell Potential Resistance. In addition, the mass loss of steel rebars against time of partially immersion in sodium chloride (NaCl) solution was carried out in the lab. The experimental results showed that the corrosion systems examined in the study provide anticorrosion protection on steel rebars against chlorides comparing with the reference group.

关键词： Cement mortars Reinforcement Steel Pitting Corrosion Corrosion Inhibitors Chloride Ions Electrochemical Measurements Mass Loss

Effect of Waste Oil-Cracking Catalyst Incorporation on Durability of mortars

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Materials Sciences and Applications 2014年第13期5卷 905-914页

作者： Carla Costa M. Sofia Ribeiro Nuno Brito Department of Civil Engineering High Institute of Engineering of Lisbon (ISEL) Lisbon Portugal Materials Department National Laboratory for Civil Engineering (LNEC) Lisbon Portugal

This paper presents research on transport properties and alkali-silica reaction (ASR) susceptibility of mortars containing a pozzolanic waste generated in the fluid catalytic cracking (wFCC) unit by the Portuguese oil-refinery. For this purpose, two series of mortars were prepared by partially replacing cement with 5%, 10% and 15% of wFCC catalyst. The main difference between the two series of mortars is the sand reactivity used in their composition. The results revealed that wFCC catalyst blended cement mortars exhibit an increased resistance against capillary water absorption and chloride migration, as well as a considerable inhibition effect on deleterious ASR expansion. However, under the adopted experimental conditions the incorporation of wFCC catalyst in mortars decreases their carbonation resistance.

关键词： Waste Oil-Cracking Catalyst Blended Cement mortars Water Absorption Chloride Migration Resistance to Carbonation Alkali-Silica Reaction Durability

Dynamic Modulus of Elasticity of Some mortars Prepared from Selected Jordanian Masonry Cements

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Composite Materials 2019年第2期9卷 199-206页

作者： Hamadallah Al-Baijat Civil Engineering Department College of Engineering Tafila Technical University Tafila Jordan

In light of the highly demanding cement market in Jordan, comprehensive studies should be undertaken to investigate the properties of the different cement types. This paper studies the Dynamic modulus of elasticity (DME) at 2, 7 and 28 days in mortars using six cement Jordanian types with CaO contents less than that of the ordinary Portland cements. It was found that the DME has strong relation with compressive strength. At the age of 28 days the mortars had some different values of DME. One important result of our work is that DME at the age of 28 days can be derived from those of the two days mixes. To account for the differences in dynamic modulus of elasticity with time, it is highly recommended to study in detail the mortars petrography under the light microscope. Using the scanning electron microscope (SEM), usually with attachment for chemical analysis at the crystal scale, in addition to X-ray diffraction technique may help characterization of the cement phases qualitatively and quantitatively.

关键词： Jordan Masonry Cement mortars Dynamic Modulus of Elasticity

Effect of the Mineralogical Composition of Limestone on the Properties of mortars

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science and Chemical Engineering 2016年第5期4卷 16-24页

作者： Carla Macie Arão Manhique Rodrigues Manjate Carvalho Madivate Laboratório de Engenharia de Mo?ambique Maputo Mo?ambique Departamento de Química da Universidade Eduardo Mondlane Maputo Mozambique

Limestone has been used as a partial substitute for cement, due to its beneficial effect on mechanical properties of mortars and concretes. In the present research, we studied the effect of the mineralogical composition in mortars produced from limestone samples collected in different areas of Mozambique, using two cement types (Portland cement 32.5N and 42.5N). Additions of 10 to 25% limestone gave, in general and for the 32.5N cement, good results of the compressive strength for all limestone samples, while for the 42.5N only the Massinga samples performed well. Effect of the limestone additions on the flexural strength showed a beneficial effect for all samples and at all compositions studied, when using the 42.5N cement, while for the 32.5N cement only additions of 10% limestone gave values of the flexural strength higher than the reference material, with the exception of the Magude samples.

关键词： mortars Concrete Limestone Filler

Advanced cement based nanocomposites reinforced with MWCNTs and CNFs

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Structural and Civil Engineering 2016年第2期10卷 142-149页

作者： Emmanuel E. GDOUTOS Maria S. KONSTA-GDOUTOS Panagiotis A. DANOGLIDIS Surendra P. SHAH Department of Civil Engineering Democritus University of Thrace GR 671 O0 Xanthi Greece Northwestern University Evanston IL 60208 USA

Cementitious materials reinforced with well dispersed multiwall carbon nanotubes （MWCNTs） and carbon nanofibers （CNFs） at the nanoscale were fabricated and tested. The MWCNTs and CNFs were dispersed by the application of ultrasonic energy and the use of a superplasticizer. Mechanical and fracture properties including flexural strength, Young＇s modulus, flexural and fracture toughness were measured and compared with similarly processed reference cement based mixes without the nano-reinforcement. The MWCNTs and CNFs reinforced mortars exhibited superior properties demonstrated by a significant improvement in flexural strength （106%）, Young＇s modulus （95%）, flexural toughness （105%）, effective crack length （30%） and fracture toughness （120%）.

关键词： multi-walled carbon nanotubes carbon nanofibers mortars toughness Young's modulus

Valorization of Pozzolans as Partial Additive of Portland Cement: A Case of Pozzolans from the Localities of Foumbot, Penja and Tombel (Cameroon)

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Journal of Minerals and Materials Characterization and Engineering 2019年第1期7卷 18-33页

作者： Mambou Ngueyep Luc Leroy Njimboum Aboubakar Sidiki Tchakouteu Mbakop Théophile Mache Jacques Richard Laboratory of Materials Science Department of Physics Faculty of Science University of Yaoundé 1 Yaoundé Cameroon Department of Mining & Extractive Metallurgy School of Geology & Mining Engineering University of Ngaoundéré Ngaoundéré Cameroon Laboratory of Applied Inorganic Chemistry Faculty of Science University of Yaoundé I Yaoundé Cameroon Laboratory of Materials Local Materials Promotion Authority MINRESI/MIPROMALO Yaoundé Cameroon

The objective of this study is to find alternative materials that can be used as an addition in cement in order to produce ecological and economical cement. Three pozzolans coming from different volcanic regions of Cameroon (Penja, Tombel and Foumbot) were sampling. Mechanical compressions on 40 × 40 × 160 mm3 mortar specimens were made with partial replacements of 2%, 4%, 6% and 8% of the pozzolans in Portland cement and physical analyzes on the mortar powders were carried out. The values of the activity indices of different pozzolans obtained are in the normative range. The compressive strength of motars decreases at all ages with the proportion of cement substitution. The compressive strength values up to 40 Mpa are obtained for a substitution of 6% for the pozzolans from Penja, Tombel and 8% for the pozzolan from Foumbot. Pozzolan from Foumbot which contains the highest percentage of SiO2 offers a maximum substitution rate and therefore optimally reduces the production costs of Portland cement. Physical tests show that specific surfaces increase with an additions of pozzolans from Tombel and Penja.

关键词： Pozzolan mortars Compressive Strength Tensile Strength

Efficiency of Amino Alcohols as Corrosion Inhibitors in Reinforced Concrete

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Civil Engineering 2013年第2期3卷 1-8页

作者： Ioannis Vyrides Eleni Rakanta Theodosia Zafeiropoulou George Batis Department of Chemical Engineering and Chemical Technology Imperial College London UK School of Chemical Engineering National Technical University of Athens Athens Greece

The objective of this paper is to investigate the behaviour of amino alcohol corrosion inhibitors when they are used in reinforced cement mortars either as admixtures in the cement paste or as coating applications on the surface of the rebars. The reinforced cement mortars were exposed to both partial and full immersion in 3.5 wt% NaCl solution. Electrochemical measurements such as half-cell potential and linear polarization technique, as well as weight loss of the embedded rebars were performed in order to obtain information on the corrosion behaviour of the reinforcing steel in cement mortar. Results demonstrate that the amino alcohol corrosion inhibitors offer protection against rebar corrosion in cement mortars.

关键词： Steel Corrosion Concrete Durability Amino Alcohols Corrosion Inhibitors Cement mortars

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

世界钞票防伪技术的发展趋势

中国钱币 1993年第4期 71-73页

作者：刘晖

世界钞票防伪技术的发展趋势刘晖随着高科技的发展，复制技术日新月异，许多国家的钞票被不法之徒仿造，因此必须采取强有力的措施对付此类伪造犯罪活动。目前，世界各国政府均认为，在钞票防伪技术的研究开发方面，必须保持先进性，高... 详细信息

世界钞票防伪技术的发展趋势刘晖随着高科技的发展，复制技术日新月异，许多国家的钞票被不法之徒仿造，因此必须采取强有力的措施对付此类伪造犯罪活动。目前，世界各国政府均认为，在钞票防伪技术的研究开发方面，必须保持先进性，高效率和延续性。为此，也开展了大量卓有成效的工作。美国、英国、加拿大和澳大利亚组织的四国集团先进防伪技术委员会、太平洋印钞会议成员国和欧洲印钞会议成员国在钞票防伪技术的研究和开发方面走在了前列。特别在新版钞票上应用最先进的防伪技术，已形成一股潮流。现将其主要防伪技术介绍如下：一、钞票印刷的承印物从传统的钞票防伪技术来讲，承印物始终采用特种纤维配比的纸张，固定式、半固定式和满版水印及有色纤维一直是较为有效的防伪措施。为了更有效地防范钞票的伪造，澳大利亚国家银行在澳大利亚国庆２００周年之际发行了世界上第一张以特种塑料为承印物的面值１０澳元的塑料钞票，开创了钞票印刷的新纪元。英国最注重钞票印刷专用纸张上安全线的研究。英国新近发行的Ｅ系列钞票，采用了最先进的开窗式透射安全线──ＳＴＡＲＤＵＳＴ宽幅安全线。该项防伪技术将使利用现代复制技术伪造钞票者陷入束手无策的境地。英国还研制出一种光学可变安全线。

关键词： latex floating bead cement latex modified mortars