Wood fibre - cement composites by extrusion

2000 ◽  
Vol 27 (3) ◽  
pp. 543-552 ◽  
Author(s):  
Yixin Shao ◽  
Shylesh Moras ◽  
Nilgun Ulkem ◽  
George Kubes
Keyword(s):  
Cement Composite ◽  
Temperature Cycling ◽  
Wood Fibre ◽  
Flexural Behavior ◽  
Cement Composites ◽  
Building Product ◽  
Toughness Index ◽  
Composites Materials ◽  
Fibre Cement ◽  
Hardwood Pulp

Wood fibres derived from both hardwood and softwood, being relatively inexpensive and in ample supply, have gained increasing popularity in the fibre-cement building product industry. Presently, the manufacture of most wood fibre - cement composites employs the Hatschek process. The purpose of this paper is to examine the feasibility of using extrusion technology for the production. Wood fibre - cement sheets, composed of both hardwood and softwood fibres of different fibre contents, were fabricated using an auger-type extruder. The flexural behavior, moisture content, water absorption, and density of all batches were evaluated. To investigate the weathering durability of the extruded composites, materials were also subjected to a temperature-cycling test and a natural exposure weathering test. With a relative ease of manufacture and a much cleaner production, extrusion was found to be a suitable means for making cement composite thin sheets with up to 8% fibres by weight. The extruded composites exhibited a performance comparable to or even better than that of the Hatschek products. Hardwood fibres, which are cheaper and more available than the softwood fibres, were found to be more suitable for extrusion production in terms of the extrudability, finished surface, and long-term mechanical properties.Key words: wood fibre - cement composites, hardwood pulp, softwood pulp, extrusion, strength, toughness index, temperature cycling, natural weathering.

scholarly journals CEMENT COMPOSITES REINFORCED WITH TEOS-TREATED WOOD FIBRES

2021 ◽  
Vol 55 (1-2) ◽  
pp. 141-147
Author(s):  
ALESSANDRA BUSS TESSARO ◽  
RAFAEL DE AVILA DELUCIS ◽  
SANDRO CAMPOS AMICO ◽  
DARCI ALBERTO GATTO ◽  
MARGARETE REGINA FREITAS GONÇALVES
Keyword(s):  
Mechanical Properties ◽  
Treated Wood ◽  
Cement Composite ◽  
Tetraethyl Orthosilicate ◽  
Wood Fibre ◽  
Cement Composites ◽  
Hygroscopic Properties ◽  
Wood Fibres ◽  
Fibre Cement ◽  
Fibre Cement Composite

In this study, wood fibres were extracted from eucalyptus and pine woods, treated by immersion in tetraethyl orthosilicate (TEOS) and incorporated into a cementitious matrix at three weight contents (2 wt%, 5 wt% and 10 wt%). The fibres were characterized using chemical and morphological analyses and the cement-based composites were evaluated using chemical, hygroscopic, mechanical and morphological tests. The morphological and spectroscopic results satisfactorily justified the physical-mechanical properties. The wood fibre-cement composites reached similar water uptake and apparent porosity to those of the neat mortar, but exhibited higher mechanical properties. Furthermore, all treated fibres yielded composites with improved mechanical and hygroscopic properties compared to those with pristine fibres. Overall, the best performance (based on hygroscopic and mechanical results) was obtained for the wood fibre-cement composite with 2 wt% pine fibres.

Bonding in wood fibre-cement composites

1984 ◽  
Vol 19 (10) ◽  
pp. 3355-3359 ◽  
Author(s):  
R. S. P. Coutts ◽  
P. Kightly
Keyword(s):  
Wood Fibre ◽  
Cement Composites ◽  
Fibre Cement

scholarly journals Flexural Behavior of Extruded DFRCC Panel and Reinforced Concrete Composite Slab

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Chang-Geun Cho ◽  
Bang Yeon Lee ◽  
Yun Yong Kim ◽  
Byung-Chan Han ◽  
Seung-Jung Lee
Keyword(s):  
Reinforced Concrete ◽  
Cement Composite ◽  
Extrusion Process ◽  
Flexural Behavior ◽  
Composite Slab ◽  
Flexural Performance ◽  
Cracking Control ◽  
Rc Slab ◽  
Reinforced Cement ◽  
Deformation Hardening

This paper presents a new reinforced concrete (RC) composite slab system by applying an extruded Ductile Fiber Reinforced Cement Composite (DFRCC) panel. In the proposed composite slab system, the DFRCC panel, which has ribs to allow for complete composite action, is manufactured by extrusion process; then, the longitudinal and transverse reinforcements, both at the bottom and the top, are placed, and finally the topping concrete is placed. In order to investigate the flexural behavior of the proposed composite slab system, a series of bending tests was performed. From the test results, it was found that the extruded DFRCC panel has good deformation-hardening behavior under flexural loading conditions and that the developed composite slab system, applied with an extruded DFRCC panel, exhibits higher flexural performance compared to conventional RC slab system in terms of the stiffness, load-bearing capacity, ductility, and cracking control.

scholarly journals DESIGN OF CEMENT COMPOSITES WITH INCREASED IMPERMEABILITY

Vestnik MGSU ◽  
2016 ◽  
pp. 72-81
Author(s):  
Roman Sergeevich Fedyuk
Keyword(s):  
Composite Materials ◽  
Cement Composite ◽  
Vapor Permeability ◽  
Cement Stone ◽  
Cement Composites ◽  
Hydrated Cement ◽  
Body Density ◽  
Scale Levels ◽  
Positive Effect ◽  
Improved Characteristics

The paper deals with the development of composite binders for producing concrete with improved characteristics of gas, water and vapor permeability. The authors investigate the processes of composite materials formation in order of decreasing scale levels from macro to nanostructures. The criteria for optimization of the volume of dispersed additives in concrete are offered. The authors theoretically studied the technological features of the formation of hydrated cement stone structure. A positive effect of nanodispersed additives on the structure and physico-mechanical properties of cement composite materials are predicted. Thanks to its improved features, such as good ratio of strength and body density, high density and lifetime, the modified concrete may be used when solving various practical tasks of the construction branch.

scholarly journals Using scanned images to estimate salt formation on the surface of cement composites

Vestnik MGSU ◽  
2020 ◽  
pp. 1523-1533
Author(s):  
Vladimir T. Erofeev ◽  
Victor V. Afonin ◽  
Tatiana F. Elchishcheva ◽  
Marina M. Zotkina ◽  
Irina V. Erofeeva
Keyword(s):  
Building Materials ◽  
Control Sample ◽  
Cement Composite ◽  
Operating Conditions ◽  
Cement Composites ◽  
High Humidity ◽  
Grayscale Image ◽  
Salt Formation ◽  
Scanned Images ◽  
Composite Samples

Introduction. An engineering method is proposed for assessing salt formation on the surface of cement composites exposed to adverse operating conditions. The technique is based on the histogram method used to determine the dominant brightness of the half-tone image of scanned cement composites. The criterion for ranking composites is a relative dimensionless value –– a metric obtained by comparing the brightness of a grayscale image with the brightness level of white. Materials and methods. We selected three types of compositions of composites in the amount of 21 items; each of them contains three samples –– a control sample and samples exposed to high humidity and positive temperatures for 15 and 45 days. Each composition is represented by a scanned raster image of the sample surface. The images are further subjected to digital processing using a software program written in the C++ programming language and the OpenCV technical vision library. This allows you to use the available methods and classes to develop algorithms to solve the problem in question and to convert a full-color RGB image to a grayscale image. Such images are used to analyze histograms, which determine the dominant level of brightness to determine the numerical metric for quantifying the salt formation on the surface of cement composite samples on the basis of their scanned images. Results. A description of the software algorithm, used to detect salt formation on the surface of cement composite specimens that have passed performance tests under high humidity conditions at positive temperatures, is presented. The method of ranking cement composite samples using the values of their dominant brightness relative to the brightness of control samples is shown. The comparative analysis of the study is presented in the form of numerical data and explanatory diagrams. Conclusions. Software modeling is employed to demonstrate the expediency of the methodology for the assessment of salt formation on the surface of cement composites and other building materials prone to salt formation.

scholarly journals EXPERIENCE OF APPLICATION HIGH PERFORMANCE CEMENT COMPOSITES FOR CREATING DURABLE SCULPTURAL ELEMENTS

2017 ◽  
Vol 3 ◽  
pp. 286
Author(s):  
Genadijs Sahmenko ◽  
Sandis Aispurs ◽  
Aleksandrs Korjakins
Keyword(s):  
Water Absorption ◽  
High Performance ◽  
Cement Composite ◽  
Cement Composites ◽  
Freezing And Thawing ◽  
Initial Water ◽  
Good Potential ◽  
Freezing And Thawing Cycles ◽  
Material Ductility ◽  
And Control

Traditionally, sculptural and decorative elements of building facades are created from mortar mixes based on lime, gypsum or Portland cement. Generally these materials have porous and permeable structure, which determines their accelerated degradation, especially in the aggressive environment of modern cities. High performance cement composites (HPCC) have been considered for production and restoration of sculptural elements in historical buildings. For this purpose, fine-graded, multi-component and highly workable mixes were elaborated. Mix compositions were modified with micro-fillers, plasticizing and stabilizing admixtures, as well as fibers to improve material ductility and control shrinkage cracking. Basic mechanical properties and durability (such as water absorption, frost resistance) were determined and two types of HPCC were compared (>50 MPa: HPCC and >120 MPa: UHPCC). It has been confirmed that cement composite mixes are characterized by self-consolidating effect, high compressive strength, extremely high resistance versus freezing and thawing cycles and low water absorption. Surface quality was evaluated and initial water absorption (tube tests) were performed for laboratory samples and real sculptural elements after 5 years of exploitation. The results confirmed good potential for using HPCC for creating more attractive and durable architectural shapes and façade elements compared to elements made using traditional cement and lime mortar.

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