scholarly journals Study on the Deterioration of Concrete under Dry–Wet Cycle and Sulfate Attack

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4095
Author(s):  
Fang Liu ◽  
Tonghuan Zhang ◽  
Tao Luo ◽  
Mengzhen Zhou ◽  
Kunkun Zhang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Sodium Sulfate ◽  
Distribution Curve ◽  
Early Stage ◽  
Sulfate Attack ◽  
Industrial Computed Tomography ◽  
Spectrum Distribution ◽  
Compressive Strength Of Concrete ◽  
Internal Pore Structure ◽  
Internal Pore

In order to study the deterioration and mechanism of dry–wet cycles and sulfate attack on the performance of concrete in seaside and saline areas, the deterioration of compressive strength of concrete with different water cement ratios under different erosion environments (sodium sulfate soaking at room temperature and coupling of dry–wet cycling and sodium sulfate) was studied here. At the same time, ICT (industrial computed tomography) and NMR (nuclear magnetic resonance) techniques were used to analyze the internal pore structure of concrete under different erosion environments. The results show that the compressive strength under different erosion environments increases first and then decreases, and the dry–wet cycle accelerates the sulfate erosion. With the increase of dry and wet cycles, larger pores are filled with erosion products and developed into small pores in the early stage of erosion; in the later stage of erosion, the proportion of larger pores increases, and cracks occur inside the sample. In the process of sulfate soaking and erosion, the smaller pores in the concrete account for the majority. As the sulfate erosion continues, the T2 spectrum distribution curve gradually moves right, and the signal intensity of the larger pores increases.

Experimental Study on Accelerated Speed of Concrete Sulfate Attack

2012 ◽  
Vol 204-208 ◽  
pp. 3754-3759
Author(s):  
Hong Fei Liu ◽  
Fa Jun Huang
Keyword(s):  
Experimental Study ◽  
Compressive Strength ◽  
Sodium Sulfate ◽  
Sulfate Solution ◽  
Solution Concentration ◽  
Sulfate Attack ◽  
Sodium Sulfate Solution ◽  
Insignificant Difference ◽  
Compressive Strength Of Concrete

Through test on compressive strength of concrete and mass changes, the effects of solution concentration and temperature on speed of concrete sulfate attack were investigated. The results show that, the speed of attack is accelerated with increasing concentration and temperature, as well as the decreasing of the size of the specimen, sulfate attack speed at 45 °C sodium sulfate solution soak with wet and dry cycle is insignificant difference with at 20 °C.It is suitable to adopt compressive strength as the assessing criterion of the sodium sulfate attack.

Study about Characteristics of Cement Paste on Fractal Theory

2013 ◽  
Vol 423-426 ◽  
pp. 1051-1054
Author(s):  
Tian Yang Zhai
Keyword(s):  
Compressive Strength ◽  
Fractal Dimension ◽  
Cement Paste ◽  
Permeability Coefficient ◽  
Fractal Theory ◽  
Fractal Model ◽  
Concrete Compressive Strength ◽  
Internal Pore Structure ◽  
The Relationship ◽  
Internal Pore

A fractal model to simulate cement paste internal pore structure, and on this basis deduce that fractal dimension is D and the corresponding pore is r, the relationship between porosity is P. MIP was measured test. Then calculated the different ages of the fractal dimension of cement and concrete compressive strength, tensile strength and permeability coefficient. The results showed that: compressive strength, permeability and fractal dimension has a good correlation. Whey in cement in the process of hydration of cement products continue to fill the pores, making the compressive strength increased 70%, permeability is declining.

scholarly journals Acción externa acelerada de sulfatos y cloruros en el estudio de la corrosión del acero en tracción en el hormigón armado

2017 ◽  
Vol 67 (328) ◽  
pp. 141
Author(s):  
M. A. G. Silva ◽  
M. P. Cunha ◽  
A. Pinho-Ramos ◽  
B. Sena da Fonseca ◽  
F. F. S. Pinho
Keyword(s):  
Compressive Strength ◽  
Sodium Sulfate ◽  
Concrete Beams ◽  
Significant Loss ◽  
Lower Porosity ◽  
Compressive Strength Of Concrete ◽  
Flexural Tests ◽  
Different Diameters ◽  
Steel Rebars ◽  
Loss Of Strength

Corrosion of the reinforcing steel may cause significant loss of strength of reinforced concrete structures. The study focuses on accelerating such corrosion and examining the degradation of (i) the compressive strength of concrete due to sodium sulfate in a wet atmosphere; and (ii) the flexural strength by a solution of sodium sulfate and sodium chloride. Three types of concrete were used and different beam specimens were reinforced by steel rebars of different diameters (6, 8 and 10mm), part of the beams being pre-cracked. The concrete with least strength allowed higher sulfate penetration along the entire process and the compressive strength increased slightly, possibly due to lower porosity of concrete after contamination. The results of the flexural tests showed decrease of strength in all cases. Pre-cracked beams exhibited smaller influence of porosity of concrete. Beams with 6mm rebars showed the largest loss of strength due to the contamination and corrosion process

scholarly journals Influence of boulder machine-made sand powder on compressive strength of concrete

2021 ◽  
Vol 293 ◽  
pp. 02023
Author(s):  
Pengtao Wang
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Early Stage ◽  
Cementitious Materials ◽  
Mineral Admixtures ◽  
Rock Powder ◽  
Manufactured Sand ◽  
Slag Powder ◽  
Compressive Strength Of Concrete ◽  
Curing Age

In order to recycle the boulder powder produced in the process of manufactured sand production and reduce the cost of engineering concrete, this article studied the influence of boulders powder on the compressive strength of concrete. The results show that in the early stage of concrete test, the compressive strength of rock powder concrete is slightly lower than of fly ash and mineral powder concrete. With the development of curing age, the strength of boulders powder concrete developed slower. As the increase of boulders powder content, the compressive strength of different curing age gradually decreased, and it was suggested that the content of boulders powder should be controlled within 20% of cementitious materials mass. The positive effect of boulders powder fineness on the strength of concrete is limited, so it is suggested to use unprocessed collected boulders powder in the project, which is economical and environmentally friendly. With the adjustment of water-to-binder ratio, boulders powder can be prepared with different strength grades of concrete to meet the needs of engineering; the composite of boulders powder with traditional mineral admixtures, such as fly ash, and especially granulated blast furnace slag powder, can significantly improve the strength of concrete.

scholarly journals PROPERTIES OF CEMENT-FLY ASH MIXTURES WITH SUBSTANDARD FLY ASH AS A PARTIAL CEMENT AND FINE AGGREGATE REPLACEMENT

2021 ◽  
Vol 11 (3) ◽  
pp. 71-88
Author(s):  
Piseth Pok ◽  
Parnthep Julnipitawong ◽  
Somnuk Tangtermsirikul
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Sulfate ◽  
Chloride Penetration ◽  
The Other ◽  
Fine Aggregate ◽  
Carbonation Depth ◽  
Cement Replacement ◽  
Durability Properties ◽  
Compressive Strength Of Concrete

This research investigated the effects of using a substandard fly ash as a partial cement and/or fine aggregate replacement on the basic and durability properties of cement-fly mixtures. Experimental results showed that utilizing the substandard fly ash led to increase in water requirement and autoclave expansion of pastes. The strength activity indexes of the substandard fly ash passed the requirements of TIS 2135 and ASTM C618. Utilization of the substandard fly ash as cement replacement led to higher expansion of mortar bars stored in water and sodium sulfate expansion as compared to that of the OPC mixture. However, sodium sulfate resistance of mortar mixtures improved when utilizing the substandard fly ash as sand replacement material. The compressive strength of concrete at all ages was higher with the increase of the content of the substandard fly ash as sand replacement material. When the substandard fly ash was used as cement replacement material in concrete, the carbonation depth increased. On the other hand, the use of the substandard fly ash as sand replacement material decreased the carbonation depth of the concrete. Utilization of the substandard fly ash, both to replace cement and/or fine aggregate, reduced the rapid chloride penetration of the concrete.

scholarly journals Anti-acid Corrosion Property of Concrete Improved by Microstructure Optimizing

2018 ◽  
Vol 238 ◽  
pp. 02008
Author(s):  
L Yu ◽  
S X Zhang ◽  
L Chen
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Distribution Curve ◽  
Acid Corrosion ◽  
Acid Soil ◽  
Corrosion Property ◽  
Pore Distribution ◽  
Silicone Emulsion ◽  
The Common ◽  
Compressive Strength Of Concrete

To enhance the performance of anti-acid erosion, silica fume, silicon nitride, organic silicone emulsion agent and fly ash ceramsite are all mixed into concrete as admixture. The acid corrosion environment is simulated by laboratory test. Compressive strength of concrete with different curing ages are tested. Compressive strength and pore distribution of concrete dipping in sulphate and in hydrochloride for 90d are tested. The result shows that concrete with additional materials has better anti-acid corrode performance than the common one. The compressive strength of concrete with additional materials is higher than the common concrete. The pore distribution curve of the concrete with additional materials can keep steady no matter in sulphate or in hydrochloride. This kind of concrete with high anti-acid corrosion durability has been used in the piles construction of the bridges which is surrounded by acid soil and play an important role in enhancing the durability of the bridge.

A Properties of Concrete using LCD Waste Glass Subjected to Sulfate Attack

2018 ◽  
Vol 773 ◽  
pp. 233-237
Author(s):  
Gyeom Boo Kim ◽  
Il Young Jang ◽  
Seong Kyum Kim ◽  
Kwang Woon Lee
Keyword(s):  
Particle Size ◽  
Compressive Strength ◽  
Magnesium Sulfate ◽  
Sodium Sulfate ◽  
Glass Powder ◽  
Sulfate Attack ◽  
Waste Glass ◽  
Replacement Ratio ◽  
Waste Glass Powder ◽  
Better Than

In this study, it investigated the micropore changes by aging of LCD waste glass powder and investigated the effects of particle size and replacement ratio on sulfate erosion. Also, the comparison of the compressive strength with that of OPC concrete was carried out to evaluate the sulfate resistance of the LCD waste glass mixed concrete. As a result, resistance to sodium sulfate is better than magnesium sulfate.

scholarly journals Experimental Study on the Strength and Deformation Characteristics of Concrete under True Triaxial Compression after Sulfate Attack

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Wei Xia ◽  
Erlei Bai ◽  
Jinyu Xu ◽  
Gaojie Liu
Keyword(s):  
Compressive Strength ◽  
Uniaxial Compressive Strength ◽  
Compression Test ◽  
Triaxial Compression ◽  
Sulfate Attack ◽  
Static Compression ◽  
True Triaxial ◽  
Triaxial Compressive Strength ◽  
Strength And Deformation ◽  
Compressive Strength Of Concrete

To explore the mechanical properties of concrete under true triaxial static compressive load after sulfate attack, uniaxial static compression test and true triaxial static compression test at four stress ratios were carried out on concrete specimens immersed in 15% sulfate solution for 0–120 days by the integrated true triaxial static and dynamic load testing system, and the variation of performance indicators such as the strength and deformation of concrete under the coupling action of sulfate attack and complex stress state was analyzed. The results show that the uniaxial compressive strength of concrete increases at the beginning and then decreases with the increase of sulfate attack time and reaches the peak on the 30th day, with an increase rate of 16.57%; the strength of concrete under triaxial compression increases significantly, and the maximum triaxial compressive strength is 3.18 times of uniaxial compressive strength under the combination of 0-day sulfate attack and 0.2 : 0.8 stress ratio; and the deterioration of concrete under sulfate attack is more prominent at high confining pressure, and as the sulfate attack worsens, the sensitivity of triaxial compressive strength of concrete to lateral compressive stress is reduced. In conclusion, triaxial compression can significantly enhance the ductility of concrete by playing a role in restraining the deformation and cracking of concrete after sulfate attack.

scholarly journals Experimental Study on the Vegetation Growing Recycled Concrete and Synergistic Effect with Plant Roots

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1855 ◽  
Author(s):  
Fengchi Wang ◽  
Chang Sun ◽  
Xiangqun Ding ◽  
Tianbei Kang ◽  
Xiaomei Nie
Keyword(s):  
Compressive Strength ◽  
Aggregate Size ◽  
Recycled Concrete ◽  
Plant Roots ◽  
X Ray Diffraction ◽  
Quick Freezing ◽  
Industrial Computed Tomography ◽  
Concrete Blocks ◽  
Cementing Material ◽  
Internal Pore

Vegetation growing recycled concrete (VGRC) is a relatively new building material that has both biocompatibility and engineering function. The basic performance of VGRC was investigated by experimental analysis, and the hydration products and pore structure of different VGRC mix proportions were studied by X-ray diffraction (XRD), scanning electron microscope (SEM), and industrial computed tomography (CT). The results show that ultrafine slag can reduce Ca(OH)2 content in cementing material and has a filling effect on micropores. VGRC has the best performance; the internal pore distribution is uniform when porosity is 20–25%, and the ultrafine slag content is 40%. The compressive strength of VGRC is greatly damaged by the quick-freezing method, while the degree of damage from natural freeze–thaw cycles is relatively small. Soaking in acid solution can effectively reduce the internal pore alkalinity of VGRC. Most plants can grow normally in vegetation concrete, and plant roots can penetrate 6-cm thick concrete blocks after being planted for 60 days. The compressive strength of VGRC decreased after turf planting of 30 days and then increased slowly. The permeability coefficient of VGRC increases with the increase in porosity and aggregate size and decreases after planting and covering. The frost resistance of VGRC is enhanced, and the influence of aggregate size and porosity is small after turf planting.

scholarly journals Assessment of the early-age compressive strength of concrete

2021 ◽  
Vol 20 (2) ◽  
pp. 005-014
Author(s):  
Dorota Michałowska-Maziejuk ◽  
Barbara Goszczyńska
Keyword(s):  
Compressive Strength ◽  
Early Stage ◽  
Concrete Strength ◽  
Early Age ◽  
Concrete Compressive Strength ◽  
Strength Parameters ◽  
Eurocode 2 ◽  
Strength Tests ◽  
Compressive Strength Of Concrete

This paper analyses the results of concrete compressive strength tests on cubic samples with different w/c ratios during the early stage of hardening (at 7, 14, and 28 days). Statistical and strength parameters were assessed and the quality of the concrete was estimated. The expected concrete grade, C25/30, was confirmed against the formulation provided by the prefabrication plant. Then, the amount of individual constituents was adjusted to obtain the target grade of concrete, i.e., C20/25. The concrete grade was estimated based on concrete strength parameters measured at three time points and compared with the expected 28-day strength values determined as per Eurocode 2 and with the concrete grade defined by these values. The paper also provides an overview of the most widely used methods of testing concrete compressive strength.

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