November 27, 2020

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Brittle Matrix Composites 10

Brittle Matrix Composites 10
Author : A M Brandt,M A Glinicki,J Olek,C K Y Leung
Publisher : Elsevier
Release Date : 2012-11-12
Category : Technology & Engineering
Total pages :350
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The subjects of the symposia are on composite materials behaving as brittle, normal and special conditions of exploitation. Brittle matrix composites are applied in various domains and the series of symposia are closely related to their applications in civil engineering. In the last decades their importance is increasing along with their variety and the use of most advanced methods of testing. Papers include concretes, fibre concretes and ceramics, particularly their composition, microstructure and fracture processes. Various new and advanced engineering problems are presented in the papers.

Brittle Matrix Composites 7

Brittle Matrix Composites 7
Author : A M Brandt,V C Li,I H Marshall
Publisher : Elsevier
Release Date : 2003-10-01
Category : Technology & Engineering
Total pages :564
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The International Symposium in Brittle Matrix Composites October 13-15, 2003 covers a wide spectrum of topics including cement based composites, ceramic composites and brittle polymer matrix composites. In the papers various topics and issues are considered such as: analytical and numerical studies related to the design of composites, prediction of behaviour and verification of strength and stability, testing methods, manufacturing processes and repair, environmental effects and durability assessment. The present volume of 55 papers proves that there are still many problems in the field of brittle matrix composites deserving theoretical and experimental investigations and that new solutions to these problems are needed for practical application in civil engineering, industrial structures, machinery and other domains.

Brittle Matrix Composites

Brittle Matrix Composites
Author : Kim Van Tittelboom,Manuel Dierick,Nele De Belie
Publisher : Elsevier Inc. Chapters
Release Date : 2012-11-12
Category : Technology & Engineering
Total pages :350
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Concrete is one of the most widely used construction materials due to its excellent mechanical properties and relatively low cost. However, concrete is prone to crack formation. These cracks do not impair the structural integrity, but they endanger the durability of the structure as aggressive liquids and gasses may enter via these cracks and cause degradation. Therefore, crack repair is needed but these repair works increase the cost of concrete structures by 50 % as they are labour intensive and because the structure becomes in disuse during repair. Accordingly, in this research it was investigated whether cementitious materials can be modified so that cracks heal themselves. Therefore, healing agents were encapsulated by brittle capsules and embedded inside the cementitious matrix in the zones where cracks were expected. When the matrix starts cracking, the capsules break and release their content, leading to crack repair. Water absorption measurements were performed to evaluate the healing efficiency. The amount of absorbed water was determined by gravimetrical measurements and visualized by X-ray radiography. When samples with untreated cracks were placed with their cracked surface in a water reservoir, it was noticed from the radiographs that water penetrated very fast into the cracks. For samples with self-healing properties no water entered into the cracks. Moreover, even in the zone alongside the crack no water entry was noticed. Therefore, it can be concluded that self-healing of concrete cracks can be used to prevent the ingress of liquids and to prevent subsequent damage to the matrix.

Brittle Matrix Composites

Brittle Matrix Composites
Author : Agnieszka J Klemm,Paul Baker,Karol Sikora
Publisher : Elsevier Inc. Chapters
Release Date : 2012-11-12
Category : Technology & Engineering
Total pages :350
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Construction industry like any other area of economic and social life undergoes continuous alterations and improvements in order to successfully comply with the requirements of sustainable development. Consumers demand more durable, less labour and service intensive materials at a competitive price. To meet these expectations numerous new composite materials have been developed over the last couple of decades, including cementitious materials modified by superabsorbent polymers (SAP). The paper presents part of the larger research project on the performance of cementitious mortars containing two types of superabsorbent polymers (SAP) as the internal curing agent.SAP A is a copolymer of acrylamide and acrylic acid and SAP B is a polymer based on acrylic acid. Research work presented in this paper involves macro and micro scale characterisation of polymer modified mortars. The microstructural features were studied with application of the Mercury Intrusion Porosimetry and the Scanning Electron Microscopy techniques. Analyses of pore size distribution in mortars of different ages are accompanied by the analyses of strength and autogenous shrinkage development as well as early density changes in immature mortars by the X-ray absorption method. The investigations confirmed the positive effect of SAP A on the reduction of autogenous shrinkage and microcrack propagation. Limited absorption/desorption abilities of SAP B cannot reassure continuous supply of water and hence the performance of SAP B mortars was comparable with the reference samples. The effect of both SAPs on strength development proved to be negligible.

Brittle Matrix Composites

Brittle Matrix Composites
Author : Tomasz Ponikiewski,Jacek Gołaszewski
Publisher : Elsevier Inc. Chapters
Release Date : 2012-11-12
Category : Technology & Engineering
Total pages :350
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The paper presents results of tests on self-compacting mixtures with the addition of steel fibres (Steel Fibre Reinforced Self-Compacting Concrete). Four types of steel fibres at 3 levels of the volume ratio are considered. The results include studies on samples belonging to classes of slump flow SF, classes of viscosity T500, and rheological tests. The studies were based on application of two rheometers for rheological properties of concrete mixtures - BT2 Rheometer and Viskomat XL. Additionally, a study of compressive strength fcm,28 and flexural strength f was carried out on concrete SFRSCC. These studies have confirmed the possibility of using steel fibres in concrete SCC while maintaining the assumed technological parameters for concrete mixtures and, above all, their workability.

Brittle Matrix Composites

Brittle Matrix Composites
Author : Maria Kaszyńska,Adam Zieliński
Publisher : Elsevier Inc. Chapters
Release Date : 2012-11-12
Category : Technology & Engineering
Total pages :350
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This paper presents a part of the results from a broader study dealing properties of lightweight self-consolidating concrete. Various self-consolidating mixtures were considered by replacing a part of fine and coarse aggregate with light-weight aggregate. The workability of SCC was evaluated using the slump flow test, V-fimnel test and J-ring test. For verification of concrete segregation the concrete specimens were cutting and a visual evaluated of the distribution of coarse aggregates. Free shrinkage of concrete has been investigated using beam specimens 50×50×250mm on Graf-Kaufman test. Restrained shrinkage cracking performance was tested using ring specimens (ASTM CI581), which had an inner steel ring instrumented with an electrical strain gauge to monitor stress rise in the concrete due to drying shrinkage under restrained conditions.

Brittle Matrix Composites

Brittle Matrix Composites
Author : Zbigniew Ranachowski,Daria Jóźwiak - Niedźwiedzka,Mariusz Dąbrowski,Jolanta Wołowicz,Maciej Sobczak,Tomasz Dębowski,Michał A. Glinicki
Publisher : Elsevier Inc. Chapters
Release Date : 2012-11-12
Category : Technology & Engineering
Total pages :350
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In the paper a new method of determination of cement paste microhardeness is presented. It includes the procedure of systematic indentation with a Vickers tip and a statistical processing of population of obtained results. The tested specimens were cast with different kinds of blended cements, containing high calcium fly ash (HCFA) as one of major components. Differences in values of microhardeness obtained for six series of tested specimens mixes are discussed and compared with compressive strength of investigated materials.

Brittle Matrix Composites

Brittle Matrix Composites
Author : Tareq S. Al-Attar,Ahmed S. Ali,Bayan S. Al-Nu'man
Publisher : Elsevier Inc. Chapters
Release Date : 2012-11-12
Category : Technology & Engineering
Total pages :350
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Reactive powder concrete, RPC, demonstrates greatly ultra-high strength and improved durability characteristics compared with traditional or even high performance concrete. The main purpose of the present investigation is to modify RPC by adding styrene butadiene rubber, SBR, as a polymer in percentages 6, 12, 14, and 18 by weight of cement to the original mixture. An experimental work had carried out to investigate the behavior and durability of the polymer modified reactive powder concrete, PMRPC, exposed to two types of oil products (gas oil and kerosene) in comparison with the original RPC. Metakaolin was used as a pozzolanic material. Teasing program was designed to include compression, initial surface absorption, total absorption, and permeability tests. The test period was extended to 180 days. Moreover, drying shrinkage strain was measured up to the age of 90 days. Tested specimens were grouped in three series after the age of 28 days. The first continued to be cured with water, meanwhile, the second cured with gas oil and the third with kerosene. The experimental results showed that, the PMRPC mixes exhibited superior performance in all tested properties than the original RPC, especially when exposed to oil products. This behavior could be related to the role of the polymer in filling the pores and cracks and thus improving the surface condition. It was concluded that the optimum percentage of added SBR was 14%. In addition, it was found experimentally that SBR could totally replace the highrange water reducing admixture in PMRPC. Finally, the main conclusion reached was that PMRPC could be used to construct durable oil storage tanks or at least be used as lining layers for storage tanks.

Brittle Matrix Composites

Brittle Matrix Composites
Author : Dominik Logoń
Publisher : Elsevier Inc. Chapters
Release Date : 2012-11-12
Category : Technology & Engineering
Total pages :350
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The paper presents the methods of controlling sedimentation of cement mix using D-cube flow, slump, cone immersion and electrical resistance tests. These methods make it possible to control the sedimentation of aggregates and fibers, the optimization of different admixtures and additives and the rheological properties of cement mixes. The electrical resistance test for cement composites was modified. The cube (150x 150x 150mm) was equipped with two electrodes to measure the resistance of the mix. For sedimentation measurement electrodes were placed in the upper and bottom part of the mix. Measured changes of the resistance at different depths of the mix give the information about the sedimentation of components. The main advantage of the D-cube (150x150x150 mm) flow, slump and cone immersion tests is the ability to do it without advanced measuring devices and the fact that one method is sufficient to compare the rheological properties of cement pastes, mortars and concretes.

Brittle Matrix Composites

Brittle Matrix Composites
Author : Daria Jóźwiak-Niedźwiedzka
Publisher : Elsevier Inc. Chapters
Release Date : 2012-11-12
Category : Technology & Engineering
Total pages :350
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The influence of high calcium fly ash as clinker replacement in blended cements on the resistance of concrete structures to the carbonation is presented. The paper concerns of five blended cements made with different contents of supplementary cementitious materials: high and low calcium fly ash and ground granulated blastfurnance slag and one reference cement – Portland cement. The aim was to study the carbonation depth on several concretes designed with a constant water to binder ratio and with various blended cements. Additionally, the prediction of the maximum carbonation depth was proposed. The evaluation of the microstructure was performed using optical microscopy on thin sections in transmitted light. The best results according to the resistance to carbonation achieved the concretes made with Portland-fly ash cement where 14.3 % of high calcium fly ash was used. CEM II/A-W can be used to prove the fc28 and resistance to carbonation for XC3 class.

Analysis of the Progressive Failure of Brittle Matrix Composites

Analysis of the Progressive Failure of Brittle Matrix Composites
Author : David J. Thomas
Publisher : Unknown
Release Date : 1995
Category :
Total pages :120
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Brittle Matrix Composites 9

Brittle Matrix Composites 9
Author : A M Brandt,J Olek,I H Marshall
Publisher : Elsevier
Release Date : 2009-11-30
Category : Technology & Engineering
Total pages :600
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The subjects of the symposia are on composite materials with matrices behaving as brittle in normal or special conditions. Brittle matrix composites are applied in various domains (civil engineering, mechanical equipment and machinery, vehicles, etc.) and in the last decades their importance is increasing together with their variety. Papers include: aggregate-binder composites (concretes, fibre concretes, rocks); sintered materials (ceramics); high strength composites with brittle matrices. In principle, the general problems of structures made of composite materials are not included in the papers. Various approaches to the material engineering problems are presented in the papers.

Brittle Matrix Composites

Brittle Matrix Composites
Author : Christopher K. Y. Leung,Dongwei Hou
Publisher : Elsevier Inc. Chapters
Release Date : 2012-11-12
Category : Technology & Engineering
Total pages :350
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Steel corrosion is a major problem with concrete structures. For concrete structures exposed to chlorides, once a critical chloride concentration is reached at the steel surface, corrosion starts to occur. For a given cover thickness, the corrosion initiation time depends on the chloride diffusivity. For different kinds of concrete, the diffusivity Do at the un-cracked state has been measured. However, in reinforced concrete design, concrete members are allowed to crack in tension. Once cracking occurs, chloride can also diffuse through the crack at a faster rate governed by the crack diffusivity Dcr. Recent experiments have shown that Dcr is a function of the crack width. In the present study, finite element analysis is performed to study the effect of cracking on corrosion initiation in concrete with different values of Do. For various crack width and cover thickness, the time for critical chloride concentration to be reached at steel intersected by the crack is determined. Based on the simulation results, we will derive the empirical equation for an effective diffusion coefficient (Deff) which can be employed directly in the solution of the one-dimensional diffusion equation to calculate the corrosion initiation time. The study will provide a convenient but accurate approach for predicting corrosion initiation under real world situations where cracks are present in a concrete structure.

Brittle Matrix Composites

Brittle Matrix Composites
Author : M. Maalej,S.T. Quek,J. Zhang,V.W J. Lin
Publisher : Elsevier Inc. Chapters
Release Date : 2012-11-12
Category : Technology & Engineering
Total pages :350
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This paper reviews the results of recent laboratory research studies focusing on the behavior of hybrid fiber Engineered Cementitious Composite (ECC) panels subjected to low- and high-velocity projectile impact. The reviewed laboratory studies include high-velocity (300-700m/s) small-size projectiles impact tests conducted on 0.30×0.17m hybrid fiber ECC prismatic panels of various thicknesses (representing a section of a door or wall), low-velocity large projectile impact tests conducted on both full scale hybrid fiber ECC blast/shelter panels (2.0×1.0×0.05-0.1m), and 1/3 scale hybrid fiber ECC strengthened masonry wall panels (1.0 x 1.0 x 0.1m). Recent results obtained from dynamic tensile tests of hybrid fiber ECC coupon specimens are also reviewed to assess the effect of strain rate on the material uniaxial tensile behavior. The reviewed test results demonstrate the potential value of hybrid fiber ECC for providing better functionality as protective material in aspects such as increased shatter resistance with damage reduction due to scabbing and spalling, as well as significantly-improved cracking behavior, resistance against multiple impacts, and energy absorption associated with distributed microcracking in comparison to concrete.

The Mechanical Behavior of a Fiber-reinforced Brittle Matrix Composite

The Mechanical Behavior of a Fiber-reinforced Brittle Matrix Composite
Author : Ellice Yeng Luh
Publisher : Unknown
Release Date : 1988
Category :
Total pages :214
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