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«A1 Bauinstandsetzen Restoration und Baudenkmalpflege of Buildings and Monuments 19. Jahrgang, Heft 2/3, 2013 Vol. 19, No. 2/3, 2013 Contents / Inhalt ...»

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Restoration of Buildings and Monuments Bauinstandsetzen und Baudenkmalpflege Vol. 19, No. 2/3, 117–124 (2013) Hydration of Cement in the Presence of SAE Dispersion and Powder R. Wang*, L. J. Yao and P. M. Wang Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, School of Materials Science and Engineering, Tongji University, 4800 Cao’an Road, Shanghai 201804, China *Corresponding author: R. Wang, E-mail: ruwang@tongji.edu.cn Abstract In this paper, styrene-acrylate copolymer (SAE) dispersion and powder were used to modify Portland cement paste. The effect of the SAE dispersion and powder on cement hydration including the heat evolution, the calcium aluminate hydrates, the calcium silicate hydrates and the interaction between polymer and cement were investigated. The results show that SAE dispersion and powder delay the cement hydration, and the effect of the dispersion is much more evident than the powder. Both the dispersion and powder of SAE facilitate the formation, enhance the stability of AFt and inhibit the formation of C4AH13 in cement paste, but in different levels; the effect of the SAE dispersion is much more evident than the SAE powder. Both the dispersion and powder of SAE delay the formation of Ca(OH)2, and the difference between SAE dispersion and powder is not significant. FTIR and the acid-base proton theory analysis indicate that Ca2+-carboxyl complexes form in cement pastes modified with SAE dispersion and powder.

Keywords: Styrene-acrylate copolymer (SAE); Cement; Hydrates; Hydration heat; XRD.

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Restoration of Buildings and Monuments Bauinstandsetzen und Baudenkmalpflege Vol. 19, No. 2/3, 125–134 (2013) Effect of TiO2 Addition on the Properties of Macro Defect Free Cement-Polymer Composites O. Ekincioglu1*, M. H. Özkul2, S. Patachia3 and G. Moise3 Okan University, Faculty of Engineering and Architecture, Civil Engineering Department, Tuzla, Istanbul, Turkey 2Istanbul Technical University, Faculty of Civil Engineering, Maslak, Istanbul, Turkey Transilvania University of Brasov, Materials Science and Engineering Faculty, Brasov, Romania *Corresponding author: O. Ekincioglu, E-mail: ozgur.ekincioglu@okan.edu.tr Abstract Macro-defect free (MDF) cement is a cement-polymer composite with superior flexural strength although produced by mixing cement with small amounts of polymer and water. Special production technique and the crosslinking occurred between cement and polymer are important factors for obtaining such high strengths.

However, MDFs lose considerable strength when exposed to water. The objective of this study was to explore the effects of TiO2 addition on flexural strength and water sensitivity of MDF. In this study, MDF cements were produced by adding up to 4 % TiO2 by weight of cement. Biaxial flexural test as well as Atomic Force Microscopy (AFM) and Fourier Transform Infrared Spectroscopy (FTIR) tests were conducted in order to investigate the effect of TiO2 addition. TiO2 addition improved the water resistance of MDF cements in some batches, especially with 2 % addition possibly due to the CPVA–O–Ti–O–CPVA bond and this cross-linking mechanism together with CPVA–O–Al–O–CPVA bonds cause a more stable polymer network.

Keywords: MDF composites; PVA, TiO2; Calcium aluminate cement; Water sensitivity.

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Restoration of Buildings and Monuments Bauinstandsetzen und Baudenkmalpflege Vol. 19, No. 2/3, 135–146 (2013) Recent Development and Application of Concrete-Polymer Composites in Korea K. S. Yeon1, Y. S. Choi1, J. H. Yeon2* and M. Kawakami3 Dept. of Regional Infrastructure Engineering, Kangwon National University, Korea Center of Transportation Research, The University of Texas at Austin, USA Graduate School of Engineering and Resource Science, Akita University, Japan *Corresponding author: J. H. Yeon, E-mail: jyeon@utexas.edu Abstract This study examines and analyzes the R&D and field applications of concrete-polymer composites conducted in the past 5 years in Korea by reviewing related patents, new technologies and technical research articles.

Among the materials, polymer cement concrete (mortar) was used the most for patent application followed by geopolymer concrete (mortar) and polymer concrete (mortar). As for the uses, pavement overlay took the most for field application followed by repair and waterproof, and bricks were used the most for precast products followed by sewerage products and interior materials. The main subjects of the published research papers were repair of concrete pavement, manufacturing of polymer concrete using recycled wastes, and production of polymer cement concrete with improved performance. Most of the commercialized new technologies were related with the rehabilitation of concrete pavement using polymer concrete or polymer cement concrete and various precast products using polymer concrete. Based on the results of the examination and analysis, in respect of materials, the R&D activities in Korea focused on geopolymer concrete as a new item while few research studies were conducted on polymer impregnated concrete. Regarding field application, the mainstream was the R&D on overlay and repair, and the development of precast products.

Keywords: Concrete-polymer composites; Polymer concrete; Polymer cement concrete; Geopolymer concrete; Field application.





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Restoration of Buildings and Monuments Bauinstandsetzen und Baudenkmalpflege Vol. 19, No. 2/3, 147–154 (2013) Effects of Substitution Degree of Cellulose Ethers on the Properties of Tile Cement Mortars N. Choi* Green Materials Development Team, Samsung Fine Chemicals R&D, Ulsan, Korea *Corresponding author: N. Choi, E-mail: nakwoon.choi@smasung.com Abstract Cellulose ethers are functional additives which are widely used in drymix mortar industries such as tile adhesive, gypsum plaster, cement plaster, etc. The three most important functions of the cellulose ethers in mortars are water retention, thickening and air entraining. In this study, the effects of substitution degree [i.e., MeO % (Methoxyl %), HPO % (Hydroxyprophoxyl %), HEO % (Hydroxyethoxyl %)] of cellulose ethers on the properties of the fresh tile cement mortars such as viscosity, air content, slip, wetting capability, etc., and the adhesion strength and open time strength of hardened mortars were investigated. As a result, the viscosity is increased with increasing MeO % and with decreasing HPO % or HEO %. The air content and slip are decreased with an increase in the MeO %, and with a decrease in the HPO % or HEO %. The effect of the substitution degree on the adhesion strengths is resulted in different according to the curing period. The open time strength is increased with increasing wetting capability of the mortar. An interesting result that the adhesion strength of the mortars is increased with increasing air content is discussed also.

Keywords: Tile Adhesive, Methylcellulose; Thickener; Drymix Mortar; Adhesion strength.

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Restoration of Buildings and Monuments Bauinstandsetzen und Baudenkmalpflege Vol. 19, No. 2/3, 155–162 (2013) Factors Influencing Durability of Bond of Ceramic Tiles in Swimming Pools D. Van Gemert* Triconsult n.v., KU Leuven *Corresponding author: D. Van Gemert, E-mail: dionys.vangemert@triconsult.be Abstract Finishing of the walls and floors in swimming pools is frequently realized by means of ceramic tiles, bonded to the substrate with polymer-modified cement mortar. This paper discusses debonding of tiles in the pool, as well as on the platform and on the building walls. An experimental program was carried out to investigate the possible causes of the debonding phenomena. The experimental program dealt with different layouts of the system, different exposure, different application procedure of the tile on the adhesive mortar. The experiments showed that the bond strength greatly depends on the waiting time between spreading of the mortar and placing of the tile on the mortar. The paper presents experimental results, as well as guidelines for an improved application and performance.

Keywords: PCC; Adhesion; Ceramic tile; Swimming pool; Debonding.

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Restoration of Buildings and Monuments Bauinstandsetzen und Baudenkmalpflege Vol. 19, No. 2/3, 163–170 (2013) Use of Biopolymers to Improve the Reinforced Concrete Sustainability S. Roux1*, B. Tribollet2, N. Serres3, A. Lecomte1 and F. Feugeas3 IJL/CP2S-207, Université de Lorraine, UMR 7198, IUT de Nancy-Brabois, Villers-lès-Nancy Cedex, France UPR15 CNRS, LISE, UPMC, Paris Cedex 05, France ICube, INSA de Strasbourg, CNRS; Strasbourg Cedex, France * Corresponding author: S. Roux, E-mail: sebastien.roux@iutnb.uhp-nancy.fr

Abstract

Corrosion of the steel rebars is a frequent pathology of reinforced concrete structures and can highly affect the sustainability of the civil engineering works. This study aims to develop an eco-friendly corrosion inhibitor admixture whose active principle is the EPS180 biopolymer. CEMI and CEMV cement pastes reinforced with carbon steel and containing EPS180 admixture were immersed in natural seawater. The influence of the EPS180 on the C15 steel rebars corrosion was studied after open circuit potential stabilization using electrochemical impedance spectroscopy (EIS). These tests confirmed the steel corrosion inhibition due to EPS180 presence in the specific surrounding that the cement-based materials are. The EIS tests showed that, whatever the EPS180 admixture rate, corrosion inhibition is due to the slowdown of the cathodic reaction kinetic rather than modifications of the passive layer composition. To check the compatibility of the EPS180 admixture with the mechanical resistances development, compression and bending tests were performed using standard mortars containing different EPS180 admixture rates. These tests highlighted a decrease about 10 % of both bending and compression resistances after 90 days hardening in standard cure.

Keywords: Concrete; Mortar; Bioadmixture, Rebars corrosion; Mechanical resistance.

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Restoration of Buildings and Monuments Bauinstandsetzen und Baudenkmalpflege Vol. 19, No. 2/3, 171–178 (2013) Thermal Mortars with Incorporation of PCM Microcapsules S. Cunha1*, J. B. Aguiar1, M. Kheradmand1, L. Bragança1 and V. M. Ferreira2 University of Minho, Department of Civil Engineering, Campus de Azurém, Guimarães, Portugal 2University of Aveiro, Department of Civil Engineering, Campus Universitário de Santiago, Aveiro, Portugal *Corresponding author: S. Cunha, E-mail: sandracunha86@gmail.com Abstract The main purpose of this work is the production of a mortar with incorporation of Phase Change Materials (PCM) microcapsules, which must have a compromise between workability, mechanical strength and aesthetic appearance. The mortars studied in this work are mixed mortars of lime and gypsum. The proportion of PCM is 0 %, 10 %, 20 % and 30 %. In order to minimize some problems associated with shrinkage and consequent cracking of the mortars, the incorporation of nylon fibers, superplasticizer and gypsum was tested. A study of mechanical characteristics and some sensitivity tests for qualify the shrinkage of the fifteen compositions was realized. In this way, one composition for the application in tests cells was selected, with the aim of studying the thermal behaviour of these mortars. The test performed on test cells includes the study of a standard mortar without addition of PCM and a mortar with incorporation of an ideal percentage of PCM. Based on the obtained results it was possible to conclude that the incorporation of PCM microcapsules in the studied mortars causes an increase in mechanical strengths and shrinkage. The tests performed on test cells allowed to verify a time lag in maximum and minimum temperatures, as well as a slight attenuation in the temperature variation. It can be concluded that the use of PCM microcapsules in mixed mortars of lime and gypsum can be assumed as a viable solution for applications in the construction industry once these present a compromise between their resistance, aesthetic appearance and thermal behaviour.

Keywords: Mortars; Lime; Gypsum; Phase Change Material.

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