Application of Crumb Rubber in Cement-Matrix Composite

Many studies have used rubber as an additive to form a cement-matrix composite (rubcrete). However, rubcrete has a lower mechanical strength than standard concrete. To improve the properties of rubcrete, this study performed surface modifications on crumb rubber through a partial oxidization reaction. The optimal ratio of air to nitrogen was determined by experiments to be 1:4. Fourier transform infrared spectroscopy (FT-IR) was used to identify the functional groups on the surface of the crumb rubber. A colloidal probe of calcium silicate hydrate (C–S–H) was prepared, and the intermolecular interactions between the rubber and the C–S–H were measured using an atomic force microscope (AFM). The experimental results showed that the partially oxidized crumb rubber contained more hydrophilic S–O bonds. The intermolecular force between C–S–H and treated rubber increased by 23% compared to the force between the original rubber and C–S–H. The compressive strength of the hardened cement paste (56 days) with the treated crumb rubber increased 50% in comparison with that of the hardened cement paste with the as-received crumb rubber.

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On Developing a Hydrophobic Rubberized Cement Paste

Materials ◽

10.3390/ma14133687 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3687

Author(s):

Chi-Yao Chen ◽

Zih-Yao Shen ◽

Maw-Tien Lee

Keyword(s):

Cement Paste ◽

Crumb Rubber ◽

Cement Matrix ◽

Infrared Spectrometry ◽

Hardened Cement ◽

Pyrolysis Oil ◽

X Ray Diffraction ◽

Atomic Force ◽

Static Contact ◽

Ft Ir

It is well known that most cement matrix materials are hydrophilic. For structural materials, hydrophilicity is harmful because the absorption of water will induce serious damage to these materials. In this study, crumb rubber was pretreated by partial oxidation and used as an additive to develop a hydrophobic rubberized cement paste. The pretreated crumb rubber was investigated using Fourier-transform infrared spectrometry (FT-IR) to understand the function groups on its surface. The pyrolysis oil adsorbed on the surface of the crumb rubber was observed by FT-IR and nuclear magnetic resonance (NMR) spectroscopy. A colloid probe with calcium silicate hydrate (C–S–H) at the apex was prepared to measure the intermolecular interaction forces between the crumb rubber and the C-S-H using an atomic force microscope (AFM). Pure cement paste, cement paste with the as-received crumb rubber, and cement paste with pretreated crumb rubber were prepared for comparison. FT-IR, X-ray diffraction (XRD), and scanning electron microscopy (SEM) were used to understand the microstructure of the pastes. The static contact angle was used as the index of the hydrophobicity of the pastes. Experimental results showed that the hardened cement paste containing partially oxidized crumb rubber had excellent hydrophobic properties with an insignificant reduction in the compressive strength.

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Einfluss der elektrochemischen Doppelschicht auf die Sorption und den Transport von Chlorionen im Zementstein / Influence of the electrochemical double layer on sorption and transport of chlorides in hardened cement paste

Restoration of Buildings and Monuments ◽

10.1515/rbm-2000-5490 ◽

2000 ◽

Vol 6 (4) ◽

pp. 415-428

Author(s):

O. Wowra ◽

M.J. Setzer

Keyword(s):

Double Layer ◽

Cement Paste ◽

Building Materials ◽

Pore Solution ◽

Chloride Ions ◽

Transport Processes ◽

Cement Matrix ◽

Hardened Cement ◽

Hardened Cement Paste ◽

Electrochemical Double Layer

Abstract Besides the formation of Friedel salt the transport and binding of chlorides in concrete is mainly defined by the electrochemical double layer at the interface between cement matrix and pore solution. Due to the alkaline pore solution the surface of hardened cement paste is negatively charged which may change to positive values by the potential regulating calcium ions. Inverting of the surface charge leads to an attraction of anions and therefore, to an adsorption of chloride ions in the diffuse part of the electrochemical double layer. Influence from outside like sulphates and carbon dioxide may lead to a decomposition of Friedel salt. Apart from these effect temperature, pH-value and certain environmental conditions affects the electrochemical double layer as well. The chloride equilibrium is mainly controlled by adsorbed ions in the electrochemical double layer. The model presented here is relevant for the assessment of ion transport processes in mineral building materials. Continuing investigations may lead to optimize transport models and a better evaluation of the critical chloride threshold value in reinforced concrete.

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Thermal analysis of water confined in fully and partially saturated cement paste

E3S Web of Conferences ◽

10.1051/e3sconf/202017217008 ◽

2020 ◽

Vol 172 ◽

pp. 17008

Author(s):

Dalia Bednarska ◽

Marcin Koniorczyk

Keyword(s):

Thermal Analysis ◽

Cement Paste ◽

Pore Solution ◽

Cement Matrix ◽

Complex Nature ◽

Hardened Cement ◽

Hardened Cement Paste ◽

Scanning Calorimetry ◽

Partially Saturated ◽

Different Temperatures

The main object of the presented research is to apply thermal analysis in order to investigate microstructure of hardened cement paste. The test is conducted by means of differential scanning calorimetry on samples stored in various relative humidity levels as well as the fully saturated ones. The obtained results describe water solidification beginning at several different temperatures, which implies complex nature of cement paste microstructure. The recorded thermograms consist of two main peaks, which clearly indicate the division into capillary and gel pores. Additionally, the thermodynamic properties of actual pore solution confined in cement matrix are investigated. The obtained results indicate ions present in the liquid strongly affects its phase transition temperature as well as amount of ice formed during such the phase change.

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The Structure and Properties of Sulfo-Butylated Celluluse Ether (SBC) Based Water-Reducing Agents

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.556-562.433 ◽

2014 ◽

Vol 556-562 ◽

pp. 433-440

Author(s):

Halidan Maimaiti ◽

Xuekelaiti Aerken

Keyword(s):

Cement Paste ◽

Water Soluble ◽

Crystalline Cellulose ◽

Cellulose Ether ◽

Hardened Cement ◽

Structure And Properties ◽

Hardened Cement Paste ◽

Sem Images ◽

H Nmr ◽

Ft Ir

Abandoned cellulose was treated with acid to prepare Micro-Crystalline Cellulose (MCC) holding affirmative polymerization, which was then treated with 1,4–butanesultone (BS) to synthesize water-soluble Sulfo-Butylated Cellulose ether (SBC). The structure of the SBC was characterized by means of FT-IR, 1H NMR, SEM, and XRD, and its relationship to function was investigated based on the polymerization of MCC and Degree of Substitution (DS). SEM images of hardened cement were also studied. The results indicated that when the polymerization of the MCC was smaller than 96 and the DS greater than 0.375, SBC exhibited water-reduction. When sulfonated cellulose was mixed into the cement paste, its retarding effect slowed hydration early in the aging process, so that later the structure of hardened cement paste became more uniform and compact than that of control.

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