scholarly journals Influence of nanosilica and binary oxide systems on the selected physical and mechanical properties of cement composites

Author(s):  
Agnieszka Ślosarczyk ◽  
Izabela Klapiszewska ◽  
Łukasz Klapiszewski
Author(s):  
Viola Hospodarova ◽  
Nadezda Stevulova ◽  
Vojtech Vaclavik ◽  
Tomas Dvorsky ◽  
Jaroslav Briancin

Nowadays, construction sector is focusing in developing sustainable, green and eco-friendly building materials. Natural fibre is growingly being used in composite materials. This paper provides utilization of cellulose fibres as reinforcing agent into cement composites/plasters. Provided cellulosic fibres coming from various sources as bleached wood pulp and recycled waste paper fibres. Differences between cellulosic fibres are given by their physical characterization, chemical composition and SEM micrographs. Physical and mechanical properties of fibre-cement composites with fibre contents 0.2; 0.3and 0.5% by weight of filler and binder were investigated. Reference sample without fibres was also produced. The aim of this work is to investigate the effects of cellulose fibres on the final properties (density, water absorbability, coefficient of thermal conductivity and compressive strength) of the fibrecement plasters after 28 days of hardening. Testing of plasters with varying amount of cellulose fibres (0.2, 0.3 and 0.5 wt. %) has shown that the resulting physical and mechanical properties depend on the amount, the nature and structure of the used fibres. Linear dependences of compressive strength and thermal conductivity on density for plasters with cellulosic fibres adding were observed.


2020 ◽  
Vol 322 ◽  
pp. 01001
Author(s):  
Dana Konakova ◽  
Eva Vejmelkova ◽  
Lenka Scheinherrova ◽  
Martin Keppert ◽  
An Cheng ◽  
...  

Basic physical and mechanical properties of several cement composites are determined as functions of thermal load and the results are compared with reference materials. Bulk density, matrix density, and open porosity are measured using the water vacuum saturation method. Compressive and bending strengths are determined according to the European standard. High-temperature coefficient of thermal expansion is obtained using a comparative measurement. Experimental results show that composites based on Portland cement do not resist high temperatures well. Their applicability is limited to 400 °C, due to the damage caused by hydrates decomposition. On the other hand, composites based on calcium aluminate cement exhibit a better thermal stability and retain residual strength even after being exposed to 1000 °C.


2010 ◽  
Vol 24 (5) ◽  
pp. 777-785 ◽  
Author(s):  
Flávio de Andrade Silva ◽  
Romildo Dias Toledo Filho ◽  
João de Almeida Melo Filho ◽  
Eduardo de Moraes Rego Fairbairn

2014 ◽  
Vol 897 ◽  
pp. 165-170 ◽  
Author(s):  
Lucia Kidalova ◽  
Nadežda Števulová ◽  
Anton Geffert

Sustainable building materials are based on the use of renewable materials instead of non-renewable. A large group of renewable raw materials are materials of plant origin containing cellulosic fibres which are used as filler into building material with reinforcement function of composite. This study aimed to establish the mechanical and physical properties of cement composites with organic filler, such as wood pulp. Pulp derived from wood pulping process is very interesting material as reinforcement in cement which contributes to a reduction of pollutants. In this paper, utilization of unbleached and bleached wood pulp in combination with cement matrix with emphasis on the physical and mechanical properties is studied. Varying the producing technology (wood pulp and cement ratio in mixture) it is possible to obtain composites with density from 940 to 1260 kg.m-3 and with compressive strength from 1.02 to 5.44 MPa after 28 days of hardening. The experimental results of mechanical properties indicate that cement composites with using unbleached wood pulp reaches higher values than composites based on bleached wood pulp. The percentage of water uptake increased with increasing the volume ratio of unbleached wood pulp in composite.


2020 ◽  
Vol 3 (5) ◽  
pp. 34-42
Author(s):  
A. Kozin ◽  
R. Fedyuk ◽  
Yu. Il'inskiy ◽  
S. Yarusova ◽  
P. Gordienko ◽  
...  

Improvement of the physical and mechanical properties of cement composites should be accompanied by the disposal of industrial waste of various generation. Therefore, the paper proposes the principles of controlling the strength properties of concrete, which consist in the complex effect of wollastonite obtained from boron production waste on the processes of structure formation of the cement matrix. When this introduced in an amount of 2-8 wt. % wollastonite has a dual function as a mineral filler and a reinforcing fiber. It has been proven that in the presence of wollastonite, the concrete mix becomes lighter without reducing its physical and mechanical properties. It was revealed that the early strength for all the developed compositions with the addition of wollastonite increases due to the acceleration of hydration processes. Calcium silicate, which is wollastonite CaSiO3, has a close chemical composition with cement clinker, especially with Ca2SiO4 belite and Ca3SiO5 alite. This leads to the formation of a chemically homogeneous and, as a result, hardened microstructure. Elongated wollastonite fibers with good adhesion to the cement stone provide effective micro-reinforcement of the concrete composite. Using the results will lead to the possibility of designing high-strength concretes, including for special structures


2012 ◽  
Vol 7 (4) ◽  
pp. 155892501200700 ◽  
Author(s):  
Roohollah Bagherzadeh ◽  
Hamid Reza Pakravan ◽  
Abdol-Hossein Sadeghi ◽  
Masoud Latifi ◽  
Ali Akbar Merati

The influence of polypropylene fibers has been studied in different proportioning and fiber length to improve the performance characteristics of the lightweight cement composites. Fibers used in two different lengths (6mm and 12mm) and fiber proportions (0.15% and 0.35%) by cement weight in the mixture design. Hardened concrete properties such as: 7- and 28-day compressive strength, splitting tensile strength, flexural strength, water absorption, and shrinkage were evaluated. Fiber addition was seen to enhance the physical and mechanical properties of lightweight concrete. Compared to unreinforced LWC, polypropylene (PP) reinforced LWC with fiber proportioning 0.35% and 12 mm fiber length, caused 30.1% increase in the flexural strength and 27% increase in the splitting tensile strength. Increased fiber availability in the LWC matrix, in addition to the ability of longer PP fibers to bridge on the micro cracks, are suggested as the reasons for the enhancement in mechanical properties.


2019 ◽  
Vol 1 (2) ◽  
pp. 153-163 ◽  
Author(s):  
Temidayo E. Omoniyi

This study was designed to evaluate the physical and mechanical properties of cement-bonded composite made from oil palm (Elaeisguineensis) empty fruit bunch (OPEFB) fibres. The production variables investigated were pre-treatment of fibres with water at varying temperatures (cold, 60°C and 100°C), five chemical additive (NaOH) concentrations (2%, 4%, 6%, 8%, and 10%), OPEFB fibres ash content at three cement replacement levels (10%, 20%, and 30%) and three fibre contents (5%, 10%, and 15%) by weight of cement. The composites were tested for modulus of elasticity (MOE), modulus of rupture (MOR), internal bonding strength (IBS), compressive strength, density, thickness swelling (TS), and water absorption (WA). The pre-treatment of fibre with water at a temperature of 60°C and a NaOH concentration of 8% significantly enhanced and modified the performance of the composites. It increased MOE (from 5.5 to 8.9GPa) and MOR (from 3.6 to 7.3MPa), and decreased WA (from 26.2 to 12.8%) and TS (from 2.5 to 0.5%). The results revealed that pre-treatment of fibres, partially replacing cement with OPEFB fibre ash and fibre contents had a marked influence on the properties of the composite board produced (p< 0.05). It was concluded that pre-treatment of OPEFB fibres, when optimised, enhanced the sorption resistance and some mechanical properties of the cement composite.


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