scholarly journals EVALUATION OF SALT RESISTANCE OF LOW HEAT PORTLAND CEMENT USING WITH CHLORIDE IONS IMMOBILIZED MATERIAL AND EXPANSIVE ADDITIVE

2015 ◽  
Vol 69 (1) ◽  
pp. 221-227 ◽  
Author(s):  
Shinya ITO ◽  
Minoru MORIOKA ◽  
Takafumi ITO ◽  
Takeshi IYODA
Keyword(s):  
Portland Cement ◽  
Salt Resistance ◽  
Chloride Ions ◽  
Expansive Additive

The Durability Study of Concrete in Sulfate Environment

2012 ◽  
Vol 204-208 ◽  
pp. 3137-3141
Author(s):  
Hong Xia Qiao ◽  
Yu Li ◽  
Zhong Mao He ◽  
Jin Mei Dong
Keyword(s):  
Portland Cement ◽  
High Performance ◽  
Elastic Moduli ◽  
High Performance Concrete ◽  
Salt Resistance ◽  
Fine Aggregate ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Sulfate Solutions ◽  
Better Than

Aiming at determining the durability of concrete in very salty regions, this study examines the performance of various high performance fine aggregate concretes in a sulfate environment, such as high performance concrete inside a composite additive, and Portland cement concrete and sulfate resistant cement concrete, all of which experienced dry-wet cycles in sodium sulfate solutions. By examining the changes of elastic moduli and analyzing the SEM of the concrete, this paper has found that the salt resistance of sulfate resistant cement concrete is no better than that of Portland cement concrete in the extremely aggressive dry-wet cycle environment but high performance concrete containing a composite additive has better resistance in a sulfate environment. Besides, the composite additive can create the environment for a second hydration to reduce the amount of Ca(OH)2 inside the concrete, and build additional C-S-H gel to reform the microstructure of concrete effectively. Finally, the paper offers some advice for mixing concrete in salt regions.

Evaluation of shrinkage and cracking in concrete of ring test by acoustic emission method

2015 ◽  
Vol 29 (06n07) ◽  
pp. 1540033
Author(s):  
Takeshi Watanabe ◽  
Chikanori Hashimoto
Keyword(s):  
Acoustic Emission ◽  
Portland Cement ◽  
Drying Shrinkage ◽  
Length Change ◽  
Ring Test ◽  
Emission Method ◽  
Expansive Additive ◽  
Free Body ◽  
Lime Stone ◽  
Methods Of Measurement

Drying shrinkage of concrete is one of the typical problems related to reduce durability and defilation of concrete structures. Lime stone, expansive additive and low-heat Portland cement are used to reduce drying shrinkage in Japan. Drying shrinkage is commonly evaluated by methods of measurement for length change of mortar and concrete. In these methods, there is detected strain due to drying shrinkage of free body, although visible cracking does not occur. In this study, the ring test was employed to detect strain and age cracking of concrete. The acoustic emission (AE) method was adopted to detect micro cracking due to shrinkage. It was recognized that in concrete using lime stone, expansive additive and low-heat Portland cement are effective to decrease drying shrinkage and visible cracking. Micro cracking due to shrinkage of this concrete was detected and evaluated by the AE method.

scholarly journals Evaluation of Chloride Resistance of Early-Strength Concrete Using Blended Binder and Polycarboxylate-Based Chemical Admixture

2020 ◽  
Vol 10 (8) ◽  
pp. 2972 ◽  
Author(s):  
Taegyu Lee ◽  
Jaehyun Lee
Keyword(s):  
Compressive Strength ◽  
Diffusion Coefficient ◽  
Portland Cement ◽  
Chloride Ion ◽  
Strength Criterion ◽  
Chloride Ions ◽  
Chloride Diffusion ◽  
Chloride Diffusion Coefficient ◽  
Characteristic Strength ◽  
Early Strength

The mixing proportions of concrete were examined with regard to the durability performance and early strength in coastal areas. Research was conducted to improve the C24 mix (characteristic strength of 24 MPa). C35 concrete (characteristic strength of 35 MPa) was selected as a comparison group, as it exhibits the minimum proposed strength criterion for concrete in the marine environment. To secure the early strength of the C24 concrete, 50% of the total ordinary Portland cement (OPC) binder was replaced with early Portland cement (EPC); and to provide durability, 20% was substituted with ground granulated blast-furnace slag (GGBS). In addition, a polycarboxylate (PC)-based superplasticizer was used to reduce the unit water content. The compressive strength, chloride ion diffusion coefficient, chloride penetration depth, and pore structure were evaluated. After one day, the compressive strength improved by 40% when using EPC and GGBS, and an average increase of 20% was observed over 91 days. EPC and GGBS also reduced the overall porosity, which may increase the watertightness of concrete. The salt resistance performance was improved because the rapid early development of strength increased the watertightness of the surface and immobilization of chloride ions, decreasing the chloride diffusion coefficient by 50%.

Freeze-Thaw and De-Icing Salt Resistance of Concrete Containing Mineral Admixtures and Air-Entraining Agent

2010 ◽  
Vol 163-167 ◽  
pp. 3122-3127 ◽  
Author(s):  
Xiao Lu Yuan ◽  
Bei Xing Li ◽  
Shi Hua Zhou
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Chloride Ion ◽  
Salt Resistance ◽  
Mineral Admixtures ◽  
Ion Diffusion ◽  
Chemical Corrosion ◽  
Freeze Thaw ◽  
Loss Of Mass

The effect of mineral admixtures and air-entraining agent on freezing-thawing and de-icing salt resistance of concrete has been studied. Concrete specimens made with ordinary Portland cement or ordinary Portland cement incorporating fly ash with the replacement of 10% or 20%, or 0.7/10000 air-entraining agent and fly ash with the replacement of 20%, or ground blast furnace slag with the replacement of 15% or 30%, were made and exposed to 500 cycles of freeze-thaw and de-icing salt environment. Concrete properties including loss of mass, relative dynamic elastic modulus, compressive strength, flexural strength and chloride ion diffusion coefficient were measured. Phase composition of samples was determined by means of x-ray diffraction (XRD). Results indicate that concrete exposed to freeze-thaw and de-icing salt environment is subjected to both physical frost action and chemical corrosion. Incorporation of mineral admixtures and air-entraining agent possesses more effect on internal deterioration, mechanical properties and permeability of concrete than on the scaling of concrete.

scholarly journals Evaluation of salt resistance of concrete combined with chloride-ion immobilizer and expansive additive

◽  
2019 ◽  
Author(s):  
Shinya Ito ◽  
◽  
Akihiro Hori ◽  
Takeshi Iyoda ◽  
◽  
...  
Keyword(s):  
Chloride Ion ◽  
Salt Resistance ◽  
Expansive Additive

scholarly journals Investigating the Effects of Polyaluminum Chloride on the Properties of Ordinary Portland Cement

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3290
Author(s):  
Taewan Kim ◽  
Choonghyun Kang ◽  
Sungnam Hong ◽  
Ki-Young Seo
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Chloride Ions ◽  
Aluminum Silicate ◽  
Microstructural Properties ◽  
Sem Images ◽  
Polyaluminum Chloride ◽  
Friedel’S Salt ◽  
Mechanical And Microstructural Properties

This study investigates the mechanical and microstructural properties of paste comprising ordinary Portland cement (OPC) added with polyaluminum chloride (PACl). The properties of the resulting mixture are analyzed using compressive strength, X-ray diffraction, scanning electron microscopy (SEM), mercury intrusion porosimetry, and thermogravimetric analysis. The results show that the addition of PACl improves the mechanical properties of OPC paste, that calcium-(aluminum)-silicate-hydrate (C-(A)-S-H) gel and Friedel’s salt are the major products forming from the reaction with the aluminum and chloride ions in PACl, and that the portlandite content decreases. Moreover, the size and number of micropores decrease, and compressive strength increases. All these phenomena are amplified by increasing PACl content. SEM images confirm these findings by revealing Friedel’s salt in the micropores. Thus, this work confirms that adding PACl to OPC results in a mixture with superior mechanical and microstructural properties.

Chloride Ion Diffusion of Phosphoaluminate Cement Concrete

2009 ◽  
Vol 79-82 ◽  
pp. 99-102 ◽  
Author(s):  
Zhu Ding ◽  
Feng Xing ◽  
Ming Zhang ◽  
Peng Liu
Keyword(s):  
Portland Cement ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Hydration Products ◽  
Portland Cement Concrete ◽  
Ion Diffusion ◽  
Cement Concrete ◽  
Dense Microstructure ◽  
Corrosion Of Steel ◽  
Chloride Ion Diffusion

Penetration and diffusion of chloride ions in concrete can lead to the corrosion of steel bar and shorten the service life of concrete structures. Phosphoaluminate cement (PAC) is a new cementitious material which has many special properties compared to Portland cement (PC). In the study, chloride ion diffusion in PAC concrete was tested with RCM method. The phase composition and morphology of hydration products, pore volume of hardened paste cured for 28d were analyzed with X-ray diffraction (XRD) and mercury intrusion porosimetry (MIP). The results show that chloride ion diffusion coefficient of PAC concrete is much lower than that of Portland cement concrete under the same test conditions. The hydration products of PAC are main micro-crystalline phase and gel of phosphate and/or phophoaluminate, which formed a dense microstructure. There is no calcium hydroxide produced in the PAC hydration system. In hardened PAC paste, chloride ions might replace the atom group [OH] - and [PO4]3- of hydrates and become stable compounds. The resistance to chloride ion diffusion of PAC concrete will increase with the hydration age, because its microstructure becomes denser with the hydration age increasing.

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