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

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

Determination of Pozzolanic Activity of Thermally Activated Brick Loam

Supplementary cementing materials (SCM) present of one of possible ways how to reduce the energy consumption and related CO2 emissions from Portland cement production. There is number of more or less stablished SCM. These may be by-products of another production technologies (blast furnace slag, coal fly ash), natural materials (certain volcanic rocks) or produced materials (calcined clays).Metakaolin (MK) – thermally activated kaolin – belongs to the widely studied SCM. Its main drawback is relatively high price, caused partially by the rather “exclusive” raw material – kaolin. The research on thermal activation of more abundant clay raw materials to SCM may raise the application potential of clay-based SCM. This paper deals with thermal activation of a brick loam. The loam under study contains all principle clay minerals (kaolinite, illite, montmorillonite) accompanied by quartz and feldspars. The loam was characterized by thermogravimetry and XRD. Then it was activated at three temperature levels (500, 550 and 600 °C) and the pozzolanic activity was determined by Saturated Lime Test. It was found that all three materials are fixing considerable amount of Ca 2+ ions, but probably not only by pozzolanic reaction, but also adsorption on clay minerals plays a role

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

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

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

Water Vapor Diffusion and Adsorption of Sandstones: Influence of Rock Texture and Composition

The term sandstone is used for wide range of rocks containing quartz clasts which can be cemented by secondary precipitated quartz or calcite; moreover the space between clasts can be filled by matrix. These facts result in existence of numerous rocks having highly various properties. Sandstones have been used as construction materials due to their good accessibility and workability. Since most of sandstones are porous, water vapor can penetrate through sandstone constructions. The rate of water vapor diffusion, as well as the vapor sorption isotherm, was determined for range of sandstone types. The diffusion resistance factor was found to be dependent on the total porosity of sandstone but the sorption behavior was strongly influenced by nature of the particular sandstone; the specific surface area of stone and presence of clay matrix are determining its sorption isotherm. The published data enable estimating (i) diffusion resistance factor of a sandstone via knowledge of its total porosity and (ii) the sorption isotherm via knowledge of the stone’s nature and specific surface area. This approach can significantly reduce the time necessary to acquire vapor-related properties of a sandstone

Treated Coconut Coir Pith as Component of Cementitious Materials

The presented paper deals with utilization of raw and treated coir pith as potential component of cementitious composites. The studied material is coir pith originating from a coconut production. Its applicability as cement mixture component was assessed in terms of the physical properties of concrete containing different amount of coir pith. Basic physical properties, compressive and bending strength, and hygric transport characteristics as well as thermal properties belong among the studied characteristics. It was proved that the concrete with 5% (by mass of cement) of this waste material shows appropriate physical properties and it gives rise to an applicable material for building structures. Generally, the coir pith can be regarded as lightening additive. When 10% of coir pith was added, it has led to higher deterioration of properties than what is acceptable since such dosing is greatly increasing the total porosity. The influence of chemical treatment of coir pith was evaluated as well; both tested treatment methods improved the performance of cementitious composites while the acetylation was somewhat more effective the treatment by NaOH