scholarly journals Cellulose ethers as water-retaining agents in natural hydraulic lime mortars

2019 ◽  
Author(s):  
Martin Vyšvařil ◽  
Patrik Bayer
Keyword(s):  
Water Absorption ◽  
Liquid Water ◽  
Frost Resistance ◽  
Water Retention ◽  
Point Of View ◽  
Cellulose Ethers ◽  
Water Absorption Coefficient ◽  
Hydraulic Lime ◽  
Air Content ◽  
Natural Hydraulic Lime

Cellulose ethers (CEs) are commonly used as viscosity enhancing, water retaining agents in cement-based mortars. Nevertheless, studies about the effect of CEs on the properties of natural hydraulic lime-based mortars (NHL) are absent, although the use of mortars with hydraulic lime is often preferred for renovation purposes. In this study, the behavior of NHL mortars modified by four different CEs is assessed. The fresh state of mortars was characterized by water retention, air content, density a consistency. Hardened mortars were submitted to strength determination, study of pore size distribution, and thermogravimetric analyses. Transport of liquid water in the studied materials was characterized by water absorption coefficient, sorptivity, and liquid water diffusivity. Durability of the prepared mortars was monitored by frost-resistance tests. The results revealed elevated air content and water retention in mortars with increasing dose of CEs resulting in decreased density of fresh mortars. The strengths of modified mortars surpassed the reference ones at age of 180 d despite the fact that the mortars showed higher open porosity and water absorption. Enhanced porosity of mortars resulted in improvement of their frost resistance and faster carbonation. From a practical and economical point of view, the CEs dosage of 0.5% by weight of the binder appears to be sufficient.

Influence of Cellulose Ethers on Fresh State Properties of Lime Mortars

2018 ◽  
Vol 276 ◽  
pp. 69-74 ◽  
Author(s):  
Martin Vyšvařil ◽  
Michaela Hegrová ◽  
Tomáš Žižlavský
Keyword(s):  
Water Retention ◽  
Guar Gum ◽  
Relative Yield ◽  
Point Of View ◽  
Rheological Parameters ◽  
Cellulose Ethers ◽  
Air Content ◽  
Flow Table ◽  
Lime Mortars ◽  
Fresh State

Cellulose ethers (CEs) are widely used as viscosity enhancing, water retaining additives in cement based mortars. Nevertheless, studies about the effect of cellulose ethers on the properties of aerial lime-based mortars are very lack. The use of water retaining additives in lime mortars can influence not only their fresh state properties but also the pore structure and strength of hardened mortars. In this work, four different commercial cellulose ethers were added to lime mortars in order to test their influence on properties of mortars in the fresh state. Mortar rheological parameters (relative yield stress, consistency coefficient and fluidity index) were correlated with flow table tests, relative density measurements, water retention and air content in the mortars. It was found that CEs reduce the spread of lime mortars and increase air content in the mortars. The CEs are not so effective in water retention compared with other types of water retention agents. Most dosages of CEs change the behaviour of mortars from pseudoplastic to dilatant. In contrast to the effect of CEs in cement-based materials, their viscosity enhancing behavior in lime mortars is denied, due to the presence of large amounts of calcium hydroxide. From this point of view, the CEs are not so suitable to use as viscosity enhancing admixtures in lime mortars like derivatives of chitosan or guar gum.

scholarly journals Bond Properties of NHL-Based Mortars with Viscosity-Modifying Water-Retentive Admixtures

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 685
Author(s):  
Tomáš Žižlavský ◽  
Patrik Bayer ◽  
Martin Vyšvařil
Keyword(s):  
Water Content ◽  
Adhesive Strength ◽  
Water Retention ◽  
Minor Role ◽  
Clay Brick ◽  
Hydraulic Lime ◽  
Natural Hydraulic Lime ◽  
Binder Ratio ◽  
Paste Viscosity ◽  
A Minor

This article studies the influence of biopolymeric viscosity-modifying admixtures with water-retentive function on the physico-mechanical properties of natural hydraulic lime-based mortars and their adherence to the traditional fired-clay brick substrate. The use of admixtures increases the water/binder ratio, which in turn leads to a decrease in the strength of the mortars. The viscosity-modifying function improves the adhesive strength between mortar and pre-wetter brick by increasing the binder paste viscosity, while the water-retentive function along with increased water content may lead to a decrease in adhesive strength. On the contrary, water retention and increased water content are beneficial on a dry surface, while paste viscosity plays only a minor role. When subjected to temperature-varying cycles, the mortars are more prone to in-mortar failure during the pull-off test. The air-entraining function of some admixtures improves the frost resistance of the mortars; however, it would negatively affect the adhesive strength by incorporating pores into the contact zone between the mortar and brick substrate. This study showed that the use of some of the studied admixtures may improve the adhesion of mortar to the brick substrate.

Design and evaluation of restoration mortars for historic masonry using traditional materials and production techniques

2002 ◽  
Vol 712 ◽  
Author(s):  
Antonia Moropoulou ◽  
Asterios Bakolas ◽  
Petros Moundoulas ◽  
Eleni Aggelakopoulou ◽  
Sofia Anagnostopoulou
Keyword(s):  
Mechanical Strength ◽  
Water Absorption ◽  
Mechanical Tests ◽  
Hydraulic Lime ◽  
Historic Masonry ◽  
Natural Hydraulic Lime ◽  
Total Percentage ◽  
Lime Mortars ◽  
Production Techniques ◽  
Absorption Measurements

ABSTRACTCement based mortars used for historic masonry restoration presented unsatisfactory results, due to their chemical and physico-mechanical incompatibility to original buildings. In the present research, several syntheses of restoration mortars are produced using traditional techniques and materials such as binders (aerial and natural hydraulic lime), pozzolanicadditives (natural and artificial pozzolanas) and aggregates (sand and crushed brick). The technical characteristics of the mortars were determined using mechanical tests (compressive and flexural) and mercury intrusion porosimetry measurements at the time of 1, 3, 9, 15 months of curing. Water absorption measurements were performed at the time of 9 and 15 months curing, in order to evaluate mortars microstructural characteristics, their rate of water absorption and the total percentage of absorbed water. The aerial lime - artificial pozzolana mortar presented the best mechanical and microstructural performance. Hydraulic mortars acquired the maximum of the mechanical strength in 1 month, lime - pozzolana mortars in 3 months while aerial lime mortars continue to gain mechanical strength even in 15 months curing. Furthermore, the use of ceramic aggregates produces lightweight and elastic mortars, compatible to historicones.

scholarly journals Thermo-mechanical Characterization of Insulating Bio-plasters Containing Recycled Volcanic Pyroclasts

2020 ◽  
Vol 14 (1) ◽  
pp. 66-77
Author(s):  
Loredana Contrafatto ◽  
Salvatore Gazzo ◽  
Antonio Purrazzo ◽  
Antonio Gagliano
Keyword(s):  
Thermal Properties ◽  
Volcanic Ash ◽  
Mechanical Characterization ◽  
Construction Material ◽  
Sustainable Construction ◽  
Mechanical And Thermal Properties ◽  
Water Absorption Coefficient ◽  
Hydraulic Lime ◽  
Natural Hydraulic Lime

Aim: The research proposes the reuse of volcanic wastes in the production of lightened and insulating bio-plasters. Introduction: The goal is the production of a novel sustainable construction material that reduces the environmental impact. Methods: Four mixtures were designed. The recycled Volcanic Ash was used in combination with two bio-compatible binders; basically Natural Hydraulic Lime (NHL) or calcium hydroxide blended with a commercial Portland cement (CH-CEM). To improve thermal properties, CH-CEM mixtures were treated with an Air Entraining Agent (AEA) in two different percentages and a breathable resin (R). The main physical, mechanical and thermal properties were experimentally determined. Results: The results of such analysis indicate that the mixture NHL, realized using hydraulic lime as a binder, do not satisfy the threshold of the water absorption coefficient, exceeding the limit established by UNI EN 998-1 standard. Conclusion: On the contrary, one of the mixtures CH-CEM, containing both AEA and R, is suitable for use as lightweight plastering mortar and also satisfies the requirements for insulating mortars.

scholarly journals Volumetric strains of cement-based mortars caused by ice formation in terms of frost resistance diagnostics

2015 ◽  
Vol 63 (1) ◽  
pp. 35-41
Author(s):  
Z. Rusin ◽  
P. Świercz
Keyword(s):  
Phase Transformation ◽  
Water Absorption ◽  
Frost Resistance ◽  
Cement Mortar ◽  
Volumetric Strain ◽  
Vacuum Treatment ◽  
Ice Formation ◽  
Test Results ◽  
Air Content ◽  
Degree Of Filling

Abstract The paper presents the volumetric strain test results of differently composed cement mortar samples during the phase transformation of water into ice, and juxtaposes the results with other relevant indicators, such as the water absorption and the degree of filling pores with water. It also presents the possibility of using these observations in terms of frost resistance diagnostics. The investigation covered non-airentrained mortars, which were also subjected to the vacuum treatment and vibration to reduce the air content. It was found experimentally that the volumetric strain of mortar samples soaked in water under vacuum at ΔV/V < 2‰ means the mortar of high frost resistance. ΔV/V > 4‰ indicates that the mortar requires air-entraining regardless of the microstructure and kind of cement.

Accurate Liquid Water Path Retrieval from Low-Cost Microwave Radiometers Using Additional Information from a Lidar Ceilometer and Operational Forecast Models

2007 ◽  
Vol 24 (9) ◽  
pp. 1562-1575 ◽  
Author(s):  
Nicolas Gaussiat ◽  
Robin J. Hogan ◽  
Anthony J. Illingworth
Keyword(s):  
Water Vapor ◽  
Water Absorption ◽  
Liquid Water ◽  
Liquid Water Path ◽  
Absorption Coefficients ◽  
Additional Advantage ◽  
Water Absorption Coefficient ◽  
Water Path ◽  
Additional Information ◽  
Microwave Radiometers

Abstract Water clouds have an important impact on the radiative balance of the earth. The use of ground-based dual-frequency microwave radiometers to derive both liquid water path (LWP) and water vapor path (WVP) is well established, but uncertainties over the dry, water vapor, and liquid water absorption coefficients and the radiometric calibration can lead to errors in the retrieved LWP. A method in which additional information from a lidar ceilometer is used to identify the presence of liquid water clouds and their altitude is described. When such clouds are absent, the radiometric calibrations of the two frequencies are optimally adjusted so that the retrieved LWP is forced to zero; when they are present the calibrations are interpolated from the nearest clear-sky periods before and after, and the temperature of the cloud is used to refine the liquid water absorption coefficient (with the temperature profile taken from a forecast model). This procedure is insensitive to the choice of absorption model, removes the troublesome negative values of LWP that can be retrieved, and provides more accurate values of low LWP in thin clouds. Analysis shows that LWP as low as 10 g m−2 can be reliably retrieved, 90% of the time the error being less than 50%, and for LWP greater than 20 g m−2 the error is less than 10%. An additional advantage is that the retrieval can tolerate uncertainties in the various absorption coefficients and is unaffected by slow drifts in brightness temperature errors of up to 5 K. Previous techniques have required that these temperatures be accurate to 0.5 K or better, which entails careful calibration and can be quite difficult to achieve.

Tunable Diode Laser Spectrophotometry: Measurement of Liquid Water Absorption Coefficients

1981 ◽  
Vol 35 (1) ◽  
pp. 111-112 ◽  
Author(s):  
C. G. Venkatesh ◽  
R. S. Eng ◽  
A. W. Mantz
Keyword(s):  
Absorption Coefficient ◽  
Water Absorption ◽  
Diode Laser ◽  
Liquid Water ◽  
Nonlinear Least Squares ◽  
Tunable Diode Laser ◽  
Refractive Indices ◽  
Multiple Reflections ◽  
Water Absorption Coefficient ◽  
Double Beam

A very accurate measurement of the absorption coefficient of liquid water using a tunable diode laser double beam spectrometer is presented. The water absorption coefficient is 123 ± 1.8 cm−1 at 2590 cm−1 obtained by nonlinear least squares fitting to an exact transmittance formula including the effect of multiple reflections at all four window surfaces, using only the nominal values of the refractive indices of water and window of ZnSe.

scholarly journals Zeolite Lightweight Repair Renders: Effect of Binder Type on Properties and Salt Crystallization Resistance

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3760
Author(s):  
Milena Pavlíková ◽  
Adéla Kapicová ◽  
Adam Pivák ◽  
Martina Záleská ◽  
Michal Lojka ◽  
...  
Keyword(s):  
Water Vapor Permeability ◽  
High Water ◽  
Salt Crystallization ◽  
Vapor Permeability ◽  
High Porosity ◽  
Water Absorption Coefficient ◽  
Hydraulic Lime ◽  
Technical Parameters ◽  
Natural Hydraulic Lime ◽  
High Sorption

Rendering mortars with lightweight zeolite aggregates were designed and tested. The effect of the type of binder used was also researched. For the hardened mortars, macrostructural parameters, mechanical characteristics, hygric and thermal properties were assessed. Specific attention was paid to the analysis of the salt crystallization resistance of the developed rendering mortars. Quartz sand was fully replaced in the composition of mortars with zeolite gave materials with low density, high porosity, sufficient mechanical strength, high water vapor permeability and high water absorption coefficient, which are technical parameters required for repair rendering mortars as prescribed in the WTA directive 2-9-04/D and EN 998-1. Moreover, the zeolite enhanced mortars exhibit good thermal insulation performance and high sorption capacity. The examined rendering mortars were found to be well durable against salt crystallization, which supports their applicability in salt-laden masonry. Based on the compatibility of the repair materials with those originally used, the lime and natural hydraulic lime zeolite mortars can be used as rendering mortars for the repair of historical and heritage buildings. The cement-lime zeolite render is applicable for repair purposes only in the case of the renewal of masonry in which Portland cement-based materials were originally used.

scholarly journals An Improved Liquid Water Absorption Model at Microwave Frequencies for Supercooled Liquid Water Clouds

2016 ◽  
Vol 33 (1) ◽  
pp. 33-44 ◽  
Author(s):  
D. D. Turner ◽  
S. Kneifel ◽  
M. P. Cadeddu
Keyword(s):  
Water Absorption ◽  
Liquid Water ◽  
Optimal Estimation ◽  
Supercooled Liquid ◽  
Field Observations ◽  
Absorption Model ◽  
Water Absorption Coefficient ◽  
Microwave Frequencies ◽  
Empirical Coefficients ◽  
Microwave Radiometers

AbstractAn improved liquid water absorption model is developed for frequencies between 0.5 and 500 GHz. The empirical coefficients for this model were retrieved from a dataset that consists of both laboratory observations of the permittivity of liquid water (primarily at temperatures above 0°C) and field observations collected by microwave radiometers in three separate locations with observations at temperatures as low as −32°C. An optimal estimation framework is used to retrieve the model’s coefficients. This framework shows that there is high information content in the observations for seven of the nine model coefficients, but that the uncertainties in all of the coefficients result in less than 15% uncertainty in the liquid water absorption coefficient for all temperatures between −32° and 0°C and frequencies between 23 and 225 GHz. Furthermore, this model is more consistent with both the laboratory and field observations over all frequencies and temperatures than other popular absorption models.

Effect of Aggregate Type on Properties of Natural Hydraulic Lime-Based Mortars

2017 ◽  
Vol 908 ◽  
pp. 35-39 ◽  
Author(s):  
Martin Vyšvařil ◽  
Tomáš Žižlavský ◽  
Štěpán Zimmermann ◽  
Patrik Bayer
Keyword(s):  
Frost Resistance ◽  
Total Porosity ◽  
Hydraulic Lime ◽  
Limestone Aggregate ◽  
Natural Hydraulic Lime ◽  
Detailed Characteristic ◽  
Restoration Practice ◽  
Limestone Fines ◽  
Mechanical Strengths

In the current restoration practice, the mortars based on aerial or hydraulic lime with siliceous aggregate are used on repair / reconstruction of historical plasters. The resulting properties of lime mortars do not depend only on the type of aggregate, but also on its contamination, origin and a degree of hardening. For this reason, it is needed to know a detailed characteristic of the aggregate and the results obtained for the particular aggregate cannot be generally applied for the similar type of aggregate. This work presents the applicability of Czech local crushed limestone aggregate and limestone fines as a filler to natural hydraulic lime-based mortars. The role of aggregate and limestone fines on the properties of mortars is examined by comparing the mechanical strengths, porosity and frost resistance of the mortars with pure quartz sand and limestone aggregate and its quantity in the mortar. It was found that the limestone aggregate has produced lower strengths, higher total porosity of natural hydraulic lime-based mortars. It has resulted in low frost resistance of the mortars.

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