Hygric Properties of Lime-cement Plasters with the Addition of a Pozzolana

AbstractThere are more than seven billion people currently living on the Earth and the demands of population are rising. Lime and cement are parts of most building materials, so their global consumption grows. Therefore, it is necessary to think both economically and ecologically, and search for a suitable alternatives and replacements. This study is aimed at an investigation of the influence of pozzolana as the third binder component on basic physical characteristics and hygric properties of lime-cement plasters. Results show that with the increasing amount of pozzolana in the mixture the open porosity goes down. This is accompanied by a liquid water absorption decrease. Also diffusion parameters are somehow worsened, as the water vapour diffusion resistance factor increases

Thermophysical and mechanical properties of fiber‐reinforced composite material subjected to high temperatures

The bulk density, open porosity, matrix density, tensile strength, bending strength, thermal diffusivity, specific heat capacity, thermal conductivity and linear thermal expansion coefficient of high‐density glass fiber reinforced cement composite are determined as functions of temperature up to 1000 °C. The basic physical parameters and mechanical parameters are found to exhibit the most important changes between the reference state and 600 °C pre‐heating where the increase of porosity is as high as 40% and both the tensile strength and bending strength decrease to about one third of their original values. The measured dependences of thermal diffusivity and thermal conductivity on temperature indicate that the heat transfer in the studied material is accelerated once temperature achieves 500–600 °C but the change in heat storage expressed by the specific heat capacity is less important. The linear thermal expansion coefficient is not found to be affected by high temperatures in a negative way; it is either lower or comparable to its low‐temperature values. Santrauka Tiriama, kaip kinta tankiojo stiklo pluoštu armuoto cementinio kompozito tankis, atvirasis poringumas, matricinis tankis, tempiamasis bei lenkiamasis stipris, terminis laidumas, savitasis šilumos imlumas, savitasis šilumos laidumas ir tiesinis terminio pletimosi koeficientas, kai šia medžiaga veikia temperatūra, kylanti iki 1000 °C. Rasta, kad pagrindiniai fiziniai ir mechaniniai parametrai daugiausia keičiasi temperatūrai kylant nuo pradines iki 600 °C. Šioje temperatūros kilimo atkarpoje poringumas išaugo iki 40 %, o tempiamasis ir lenkiamasis stipriai sumažejo maždaug trečdaliu, palyginti su pradinemis reikšmemis. Išmatuotoji terminio laidumo ir savitojo šilumos laidumo priklausomybe nuo temperatūros rodo, kad šilumos perdavimas tiriamoje medžiagoje pagreiteja temperatūrai pasiekus 500–600 °C, tačiau šilumos kaupimas, išreikštas savituoju šilumos imlumu, yra ne toks svarbus. Nenustatyta, kad tiesinis terminio pletimosi koeficientas būtu neigiamai veikiamas aukštos temperatūros. Šio koeficiento reikšmes yra mažesnes arba maždaug lygios reikšmems, išmatuotoms žemoje temperatūroje. First Published Online: 10 Feb 2011 Reikšminiai žodžiai: stiklo pluoštu stiprinti cemento kompozitai, aukšta temperatūra, tempiamasis stipris, lenkiamasis stipris, terminis laidumas, savitasis šilumos imlumas, savitasis šilumos laidumas, tiesinis terminio pletimosi koeficienta

Application of Ceramic Powder as Supplementary Cementitious Material in Lime Plasters

In this paper, the properties of plasters based on lime – brick powder binder of varying composition (ceramics content from 0 to 80 %) are studied. The plasters are prepared with a constant water amount. The pore size distribution is thus influenced in a positive way; the total porosity increases with the ceramics content but the volume of capillary pores is reduced. It results in lower water vapor diffusion resistance factor while the apparent moisture diffusivity coefficient increases just moderately. The influence of ceramic on strength of plasters is not found very important. The thermal conductivity of plasters containing ceramics is lower than those with the pure lime what is again in agreement with the pore size distribution. It can be concluded that fine brick powder can be used as pozzolanic admixture in lime based plasters with a positive influence on its functional parameters

Thermal Properties of High-Performance Concrete Containing Fine-Ground Ceramics as a Partial Cement Replacement

Some types of industrial waste can be used in concrete as a partial replacement of a cement binder. One such material is fine-ground ceramics, which is a waste produced during brick cutting. The ground ceramic can be used as a pozzolana active material which can improve final properties of concrete. This fine powder was used in this study as a partial replacement of the cement binder up to 60 mass% and its thermal and mechanical properties were studied using the differential scanning calorimetry, thermogravimetry, and thermodilatometry. It was shown that the differential scanning calorimetry is a suitable method for observing thermal changes in concrete samples containing such additives at the microstructural level. In particular, it allows one to investigate the hydration and pozzolanic reaction in the studied concrete. The investigation was performed in the temperature range from 25 °C to 1000 °C.DOI: http://dx.doi.org/10.5755/j01.ms.21.3.7160</p

Rheological and mechanical properties of alkali-activated brick powder based pastes: effect of amount of alkali activator

The rheological behaviour and mechanical properties of alkali-activated materials prepared by activation of a brick powder by alkaline solution (alkali + water glass) is presented in this paper. The effect of quantity of alkaline activator on the rheological and mechanical properties of brick pastes prepared from two types of brick dust was monitored. The rheological investigation included the characterization of flow properties and viscoelastic properties of the fresh mixtures. Compression and bending strengths were determined at 7, 28, 56 and 90 days. These materials have a low yield stress and a high viscosity strongly influenced by the amount of alkali activator. The fresh brick pastes become liquid more easily with increasing amount of alkali activator. The rising amount of alkali activator leads to a decrease of the material cohesion. The results of rheological and mechanical properties investigation showed considerable differences in behaviour of particular types of brick dust

Omítky z ternárních směsí s vylepšenými tepelně izolačními schopnostmi

New kind of plasters with improved thermal insulating ability are presented in this article. Improvement was reached by utilization of lightweight expanded perlite with high porosity. The second used aggregate was silica sand. Regarding the binder, three kind were combined for the reason of better plaster performance. Pure lime, Portland cement and pozzolanic ceramic powder were employed. Basic physical properties and thermal characteristics were determined. The porosity of plasters reached desired higher value about 50% and the thermal conductivity in dry state was lower than 0.16 Wm1K1.New kind of plasters with improved thermal insulating ability are presented in this article. Improvement was reached by utilization of lightweight expanded perlite with high porosity. The second used aggregate was silica sand. Regarding the binder, three kind were combined for the reason of better plaster performance. Pure lime, Portland cement and pozzolanic ceramic powder were employed. Basic physical properties and thermal characteristics were determined. The porosity of plasters reached desired higher value about 50% and the thermal conductivity in dry state was lower than 0.16 Wm1K1

Transport of gadolinium in a cement composite

Development of cement based composites suitable for radionuclide immobilization is of great interest for secure containment of nuclear waste. This requires, in particular, detailed knowledge of how radionuclides are transported in such composites. In this paper we investigate the transport of gadolinium in a dry cement composite. Experimental data are obtained in a non-destructive way by neutron imaging. Their theoretical interpretation is based on a diffusion-advection model in which sorption is included

Pore structure and hygric properties of composite materials for radionuclide protection barriers

Many practical applications of concrete require adjustment of its properties. If concrete is used as casing for radioactive waste deposits, its main purpose is to mitigate radionuclide release and the mix design must conform to this requirement. In this article bentonite as a material with great sorption capacity is used as a concrete component. The main issue is to assess durability of designed mixtures. Therefore, the pore structure and hygric properties are investigated. The experimental results show that bentonite utilization in concrete mixtures leads to a significant growth of pore amount in the range of 0.01 to 1 μm and increase of water transport ability

Mechanical properties of concrete for radioactive waste repositories

Concrete casing for radioactive repositories have to meet many strict requirements. One of the most important is a radiation protection and a radionuclide inhabitation. Bentonite, with a great sorption capacity, seems to be a suitable material for this purpose. Therefore, the main aim of this study was to assess an impact of the bentonite utilization as a component in concrete mixtures. For this reason, basic physical properties and mechanical parameters of concretes containing different amount of bentonite were determined. Bentonite applications led to the open porosity growth, while the matrix densities were not influenced. Regarding the mechanical parameters, the compressive strengths as well as the flexural strengths were significantly deteriorated by the bentonite application. Despite the presented negative effect, the obtained results seems to prove a possible applicability of a lower percentage of bentonite in concrete structures not as a cement replacement, but just as a component