scholarly journals Evaluation of external sulfate attack (Na2SO4 and MgSO4): Portland cement mortars containing fillers

2020 ◽  
Vol 13 (3) ◽  
pp. 644-655 ◽  
Author(s):  
D. J. DE SOUZA ◽  
M. H. F. MEDEIROS ◽  
J. HOPPE FILHO
Keyword(s):  
Portland Cement ◽  
Linear Expansion ◽  
Sulfate Attack ◽  
Hardened Cement ◽  
X Ray Diffraction ◽  
Limestone Filler ◽  
Sulfate Ions ◽  
X Ray ◽  
Cement Mortars ◽  
Physical And Chemical

Abstract Sulfate attack is a term used to describe a series of chemical reactions between sulfate ions and hydrated compounds of the hardened cement paste. The present study aims to evaluate the physical (linear expansion, flexural and compressive strength) and mineralogical properties (X-ray diffraction) of three different mortar compositions (Portland Cement CPV-ARI with limestone filler and, with a quartz filler, in both cases with 10% replacement of the cement by weight) against sodium and magnesium sulfate attack (concentration of SO4 2- equal to 0.7 molar). The data collected indicate that the replacing the cement by the two fillers generate different results, the quartz filler presented a mitigating behaviour towards the sulfate, and the limestone filler was harmful to Portland cement mortars, in both physical and chemical characteristics.

scholarly journals Evaluation of external sulfate attack (Na2SO4 and MgSO4): Portland cement mortars containing siliceous supplementary cementitious materials

2020 ◽  
Vol 13 (4) ◽  
Author(s):  
Diego Jesus de Souza ◽  
Marcelo Henrique Farias de Medeiros ◽  
Juarez Hoppe Filho
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Cementitious Materials ◽  
Sulfate Attack ◽  
Supplementary Cementitious Materials ◽  
Hardened Cement ◽  
X Ray Diffraction ◽  
Sulfate Ions ◽  
Cement Mortars ◽  
Physical And Chemical

ABSTRACT: Sulfate attack is a term used to describe a series of chemical reactions between sulfate ions and hydrated compounds of the hardened cement paste. The present study aims to evaluate the physical (linear expansion, flexural and compressive strength) and mineralogical properties (X-ray diffraction) of three different mortar compositions (Portland Cement CPV-ARI containing silica fume and rice husk ash, in both cases with 10% replacement of the cement by weight) against sodium and magnesium sulfate attack (concentration of SO42- equal to 0.7 molar). The data collected indicate that the replacing the cement by the two siliceous supplementary cementitious materials (SCMs) generate similar results, both SCMs were able to mitigate the effects of the sodium sulfate attack in both physical and chemical characteristics, however, both materials increase the deterioration (i.e. compressive strength) when exposed to MgSO4 solution.

scholarly journals Influence of Cement Type and Water-to-Cement Ratio on the Formation of Thaumasite

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Ailian Zhang ◽  
Linchun Zhang
Keyword(s):  
Portland Cement ◽  
Cement Mortar ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Strength Development ◽  
X Ray Diffraction ◽  
Limestone Filler ◽  
Visual Appearance ◽  
Cement Ratio ◽  
Water To Cement Ratio

Cement mortar prisms were prepared with three different cement types and different water-to-cement ratios plus 30% mass of limestone filler. After 28 days of curing in water at room temperature, these samples were submerged in 2% magnesium sulfate solution at 5°C and the visual appearance and strength development for every mortar were measured at intervals up to 1 year. Samples selected from the surface of prisms after 1-year immersion were examined by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The results show that mortars with sulfate resisting Portland cement (SRC) or sulphoaluminate cement (SAC) underwent weaker degradation due to the thaumasite form of sulfate attack than mortars with ordinary Portland cement (OPC). A lower water-to-cement ratio leads to better resistance to the thaumasite form of sulfate attack of the cement mortar. A great deal of thaumasite or thaumasite-containing materials formed in the OPC mortar, and a trace of thaumasite can also be detected in SRC and SAC mortars. Therefore, the thaumasite form of sulfate attack can be alleviated but cannot be avoided by the use of SAC or SRC.

Effect of Mixed Material on Sulphoaluminate Cement Sulfate Attack Resistance

2011 ◽  
Vol 306-307 ◽  
pp. 1101-1105
Author(s):  
Gui Yun Wang ◽  
Ling Chao Lu ◽  
Shou De Wang ◽  
Pi Qi Zhao
Keyword(s):  
Calcium Carbonate ◽  
Mechanical Performance ◽  
Resistance Coefficient ◽  
Sulfate Attack ◽  
Hardened Cement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sulfate Resistance ◽  
Composition And Structure ◽  
Mixed Material

In order to enhance the ability of sulfate resistance of the coastal engineering, the effects of hydroxyapatite, shell and calcium carbonate on the mechanical performance and sulfate attack resistance were studied. The composition and structure of hardened cement paste were analyzed by means of X-ray diffraction and scanning electron microscopy. The experimental results showed that with the increase of mixed material contents, the compressive strength decreased, while the content of hydroxyapatite was 5%, the strength reached highest. The ability of sulfate resistance was improved as appropriate amounts of hydroxyapatite, shell and calcium carbonate were added into the cement. When the content of hydroxyapatite was 5%, the corrosion resistance coefficient was1.24, reaching the best resistance to sulfate attack.

scholarly journals CO2 Sequestration in the Production of Portland Cement Mortars with Calcium Carbonate Additions

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 875
Author(s):  
Marius-George Parvan ◽  
Georgeta Voicu ◽  
Alina-Ioana Badanoiu ◽  
Adrian-Ionut Nicoara ◽  
Eugeniu Vasile
Keyword(s):  
Electron Microscopy ◽  
Calcium Carbonate ◽  
Portland Cement ◽  
Setting Time ◽  
Carbonate Content ◽  
X Ray Diffraction ◽  
Limestone Filler ◽  
Transmission Electron ◽  
Cement Mortars ◽  
Mechanical Strengths

The paper presents the obtention and characterization of Portland cement mortars with limestone filler and nano-calcite additions. The nano-calcite was obtained by the injection of CO2 in a nano-Ca(OH)2 suspension. The resulted nano-CaCO3 presents different morphologies, i.e., polyhedral and needle like crystals, depending on the initial Ca(OH)2 concentration of the suspension. The formation of calcium carbonate in suspensions was confirmed by X-ray diffraction (XRD), complex thermal analysis (DTA-TG), scanning electron microscopy (SEM) and transmission electron microscopy (TEM and HRTEM). This demonstrates the viability of this method to successfully sequestrate CO2 in cement-based materials. The use of this type of nano-CaCO3 in mortar formulations based on PC does not adversely modify the initial and final setting time of cements; for all studied pastes, the setting time decreases with increase of calcium carbonate content (irrespective of the particle size). Specific hydrated phases formed by Portland cement hydration were observed in all mortars, with limestone filler additions or nano-CaCO3, irrespective of curing time. The hardened mortars with calcium carbonate additions (in adequate amounts) can reach the same mechanical strengths as reference (Portland cement mortar). The addition of nano-CaCO3 in the raw mix increases the mechanical strengths, especially at shorter hardening periods (3 days).

The Effect of Fly Ash on TSA of Cementitous Material: Based on Three Years Results

2013 ◽  
Vol 539 ◽  
pp. 139-144
Author(s):  
Ben Wan Liu ◽  
Chang Hui Yang ◽  
Xiao Bin Xiang ◽  
Lin Wen Yu ◽  
Jing Zhang
Keyword(s):  
Fly Ash ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Hardened Cement ◽  
Hydration Reaction ◽  
X Ray Diffraction ◽  
Hardened Cement Paste ◽  
X Ray ◽  
Ft Ir ◽  
Secondary Hydration

The thaumasite form of sulfate attack of cementitous material (TSA) is a new kind of sulfate attack and it is more harmful than traditional sulfate attack. By means of Fourier transform infrared (FT-IR) and X-ray diffraction (XRD), the effect of dosage and fineness of fly ash on TSA of cementitous material were investigated in this paper. The specimens had been immersed in magnesium sulfate solution of 5% mass concentration at 5±2° C for three years. The results showed that fly ash could not restrain the formation of thaumasite but it delayed the occurrence of TSA in cementitous material when 30% fly ash takes place of cement. Fly ash could enhance the resistance of cementitous material to TSA through secondary hydration reaction to optimizing the pore structure of hardened cement paste and lowering the C/S of C-S-H gel.

Deterioration of Cement Pastes Containing Limestone Powder with Different Fineness Exposed to Sulfate Environment at Low Temperature

2013 ◽  
Vol 423-426 ◽  
pp. 1076-1080
Author(s):  
Feng Chen Zhang ◽  
Ruo Yu Tang ◽  
Yun Zhao
Keyword(s):  
Fourier Transform ◽  
Low Temperature ◽  
Sulfate Attack ◽  
Limestone Powder ◽  
Test Results ◽  
X Ray Diffraction ◽  
Limestone Filler ◽  
Cement Pastes ◽  
Cement Production ◽  
X Ray

Limestone filler and aggregates are used widely in cement production and concrete mixing nowadays, which could be connected with thaumasite formation, and lead to a lack of durability further in sulfate environment. This work deals with the deterioration of cement pastes containing 35% w/w limestone powder with different fineness immersed in MgSO4 solution at 5°C±2°C for 15 weeks by. Erosion phases are discussed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD). Test results show that visual deterioration of three kinds of cement pastes containing 400-mesh, 800-mesh and 1250-mesh limestone powders has little distinction, and erosion phases are all compound of ettringite, thaumasite, gypsum and brucite. Limestone powders with fineness of 400-mesh could supply enough carbonate needed for thaumastie formation. Increase of limestone fineness further could not accelerate deterioration of cement paste during the external magnesium sulfate attack at low temperature.

Erosion Phases in Two Types of Cement Pastes Containing Limestone Exposed to Sulfate Attack

2014 ◽  
Vol 584-586 ◽  
pp. 1182-1187 ◽  
Author(s):  
Feng Chen Zhang ◽  
Yun Zhao ◽  
Fu Wan Zhu
Keyword(s):  
Portland Cement ◽  
Cement Paste ◽  
Limestone Powder ◽  
Test Results ◽  
X Ray Diffraction ◽  
Limestone Filler ◽  
Cement Pastes ◽  
Cement Production ◽  
X Ray ◽  
Gypsum Formation

Limestone filler and aggregates are used widely in cement production and concrete mixing nowadays, which could be connected with thaumasite formation, and lead to a lack of durability further. This work deals with the sulfate minerals including of thaumasite, ettringite and gypsum in two types of cement pastes containing 35% w/w limestone powder immersed in MgSO4 solution at 5°C±2°C for 15 weeks by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD). Two types of cements were used: (i) ordinary Portland cement (P·O), (ii) typeII Portland cement (P·II). Test results show that thaumasite is present in two types of cement pastes, amount of thaumasite as well as amount of portlandite reacted with external SO42- in P·II cement paste are more than those in P·O cement paste. It indicates that P·II cement is more susceptible to thaumasite formation than P·O cement containing the same amount of limestone powder, and more gypsum formation could contribute to thaumasite formation possibly during the external MgSO4 attack at low temperature.

scholarly journals Effect of Mineral Composition and w/c Ratios to the Growth of AFt during Cement Hydration by In-Situ Powder X-ray Diffraction Analysis

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4963
Author(s):  
Bo Chen ◽  
Yongming Zhang ◽  
Qing Chen ◽  
Fei Yang ◽  
Xianping Liu ◽  
...  
Keyword(s):  
Portland Cement ◽  
Cement Hydration ◽  
Hardened Cement ◽  
X Ray Diffraction ◽  
Cement Pastes ◽  
X Ray ◽  
Hardened Cement Pastes ◽  
Maximum Content ◽  
Very High

AFt is one of the major products at the early stage of cement hydration. It is an important product that influences the performance of the fresh and hardened cement pastes such as the setting time. However, there is a lack of detailed investigation on the growth of AFt in the cement pastes with a long-time scale. In this work, we reported a detailed analysis by using in-situ powder X-ray diffraction (XRD) on the growth of AFt in the cement pastes during hydration. Samples of the hydrated ordinary Portland cement (OPC) and another locally produced Portland cement with very high tricalcium silicate (C3S) content with different water–cement (w/c) ratios were investigated continually till they were hydrated for about 270 days by powder XRD. The work shows that during Portland cement hydration, the AFt reaches its maximum content with very high speed within about 24 h, which is influenced by the content of C3S in the raw cement samples and the w/c ratios of the cement pastes. Once the maximum content of AFt was reached, it decreases very fast within the following couple of days, and then decreases slowly and finally reaches a stable level at the late stage of hydration. The results also present that a lower w/c ratio is beneficial to the formation of AFt and the conversion of AFt to AFm as well. While higher w/c ratios are favorable for the AFt to remain stable in the hardened cement pastes.

scholarly journals Evaluation of the SR Portland cement against sodium and magnesium sulfate attack: a physical and comparative analysis of mortars

2018 ◽  
Vol 11 (5) ◽  
pp. 1053-1075 ◽  
Author(s):  
D. J. de SOUZA ◽  
M. H. F. MEDEIROS ◽  
J. HOPPE FILHO
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Comparative Analysis ◽  
Chemical Composition ◽  
Magnesium Sulfate ◽  
Linear Expansion ◽  
Sulfate Attack ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Sulfate Ions

Abstract Sulfate attack is a term used to describe a series of chemical reactions between sulfate ions and hydrated compounds of the hardened cement paste. Thus, the chemical composition of the binders used is important for the durability of the structure against this aggressive agent. The objective of the present research is to evaluate the influence of sodium and magnesium sulfates on physical properties (linear expansion, flexure tensile strength, and compressive strength) of mortars composed by SR cement (CP V - ARI RS), as commercially sold in Brazil. The results indicate that SR cement complies the requirements established by Brazilian standards, as to chemical composition and resistance to sodium sulfate. However, for magnesium sulfate, SR cement was harmful to mortars mainly in mechanical.

scholarly journals Physical and chemical effects of limestone filler on the hydration of steam cured cement paste and mortar

2020 ◽  
Vol 10 (2) ◽  
pp. 191-205
Author(s):  
Mohmmad Aqel ◽  
Daman Panesar
Keyword(s):  
Thermal Analysis ◽  
Material Properties ◽  
Dilution Effect ◽  
Heat Of Hydration ◽  
Inert Material ◽  
X Ray Diffraction ◽  
Limestone Filler ◽  
X Ray ◽  
Chemical Effects ◽  
Physical And Chemical

The aim of the paper is to decouple the physical and chemical effects of limestone filler (LF), when used as a cement replacement. The effects were decoupled using LF and a chemically inert material (brucite Mg(OH)2). Paste, and mortar specimens were steam cured for 16 hours at 55°C. The heat of hydration, thermal analysis, x-ray diffraction, and compressive strength, were evaluated at 16 hours and at 28 days. LF can adversely affect the properties through dilution effect. However, heterogeneous nucleation compensates for the dilution effect at 16 hours while the production of mono-carboaluminate compensates for the dilution effect at 16 hours and 28 days. The study could be broadened by considering a wider temperature range. The originality lies in the method of decoupling the physical and chemical effects. Measurable effects of the physical and chemical contribution of LF are evident on the mechanical and transport material properties.

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