Effect of Metakaolin-Based Modifier on the Permeability of Concrete Structure in the Marine Environment

2013 ◽  
Vol 438-439 ◽  
pp. 117-120
Author(s):  
Jun Tao Ma ◽  
Liang Yan ◽  
Yu Ping Tong ◽  
Hui Xian Wang
Keyword(s):  
Fly Ash ◽  
Marine Environment ◽  
Concrete Structure ◽  
Chloride Ion ◽  
Penetration Resistance ◽  
Chloride Ion Penetration ◽  
Working Performance ◽  
Electric Flux ◽  
Penetration Behavior ◽  
Strength And Durability

Corrosion of the steel reinforcement in the concrete structure caused by chloride ion penetration becomes more serious in the marine environment. Metakaolin has been widely used in the concrete structure to improve the strength and durability. The combination of metakaolin (MK) and fine fly ash (FA) was studied in the article and the penetration behavior of concrete with various contents of metakaolin-based modifier is investigated. The penetration resistance of concrete was tested in combination of electric flux test. The improving mechanism was studied with mercury intrusion porosimetry analysis (MIP). The experiment results indicate that metakaolin-based modifier improved the penetration resistance of concrete obviously. The combination of fine fly ash weakened the water sucking action of metakaolin and preserved the working performance of concrete. The pore size distribution of concrete containing metakaolin-based modifier has been optimized to improve the microstructure and enhance the penetration resistance of concrete.

Research on the Durability of Reinforced Chemically Bonded Ceramics-Based Concrete Structural Members in Marine Environment

2014 ◽  
Vol 1044-1045 ◽  
pp. 189-194
Author(s):  
Zhong Xin Li ◽  
Qi Dong ◽  
Zhuo Bin Wei
Keyword(s):  
Marine Environment ◽  
Accumulation Rate ◽  
Chloride Ion ◽  
Structural Members ◽  
Ion Permeability ◽  
Chloride Ion Penetration ◽  
Corrosion Experiment ◽  
Electric Flux ◽  
Astm C1202 ◽  
Weight Loss Ratio

In order to study the durability of reinforced chemically bonded ceramics-based concrete structural members in marine environment, both the experiment of chloride ion permeability-resistance and rapid corrosion experiment of rebar in the CBC concrete were conducted. The methods of ASTM C1202,RCM and NEL were used to comprehensively assess the ability of chloride ion permeability-resistance of CBC concrete, electric flux and unsteady migration coefficients were taken as estimate indexes, while in the rapid corrosion experiment of rebar under the condition of immersing-drying circulating, rusty accumulation rate and weight loss ratio were taken as estimate indexes. The results of experiments indicate that CBC concrete has strong resistibility for chloride ion penetration, however, it cannot protect the internal rebar effectively, for the reason that the rebar in this test has been seriously corroded.

Permeability of Concrete Containing Air-Entraining and Mineral Admixtures

2011 ◽  
Vol 250-253 ◽  
pp. 425-429
Author(s):  
Wei Rong Huang ◽  
De Bin Yang ◽  
Jian Ting Zhou ◽  
Li Li ◽  
Wei Na Zhang
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Chloride Ion ◽  
Mineral Admixtures ◽  
Cement Ratio ◽  
Air Content ◽  
Chloride Ion Penetration ◽  
Saline Area ◽  
Electric Flux ◽  
Better Than

In this paper, the performance of concrete is studied through different water-cement ratio, different air-content, different mineral admixtures, different admixture contents, examined the mechanical properties of concrete, electric flux and chloride ion penetration depth of different mix concrete. The results show that, decreasing w/c ratio, proper air content, adding mineral admixtures can improve the resistance of chloride-permeation. Within some contents, the chloride-permeation resistance using silicides is better than that of fly-ash or slag. On this basis, the proper scheme of mix ratio used in saline area is recommended: the air-content is 3%～5%, the content of fly-ash or slag is 20%～30%, the content of silicides is 6%～8%, and double mixed with silicides.

scholarly journals Effect of Assembly Unit of Expansive Agents on the Mechanical Performance and Durability of Cement-Based Materials

Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 731
Author(s):  
Lin Wang ◽  
Chunxue Shu ◽  
Tiantian Jiao ◽  
Yong Han ◽  
Hui Wang
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Blast Furnace Slag ◽  
Chloride Ion ◽  
Penetration Resistance ◽  
Mineral Admixtures ◽  
Expansion Rate ◽  
Chloride Ion Penetration ◽  
Assembly Unit ◽  
Furnace Slag

This paper studies the influence of assembly unit of expansive agents (CaO and calcium sulphoaluminate) on the limited and free compressive strengths, the limited expansion rate, carbonation resistance, chloride ion penetration resistance and corrosion resistance of reinforcement concrete. The dosages of expansive agent were 0%, 3%, 6%, 9%, and 12% by the total amount of cementitious materials. Two kinds of mineral admixture (blast furnace slag and fly ash) were applied in this study. Results show that suitable dosage (lower than or equal to 9%) of double expansion agent with a large amount of mineral admixtures can improve the limited and free compressive strengths. However, when the dosage of the double expansion agent is higher than 9%, the addition of the double expansion agent leads to the reduction of limited and free compressive strengths. The variation of the limit expansion rate reaches the maximum value when the curing age is 14 days. The increasing addition of expansive agents and lower water-binder ratio demonstrate positive effect on the limited expansion rate. Concrete with 60% mineral admixtures (fly ash and ground granulated blast furnace slag) shows lower limited expansion rate and higher compressive strength than the concrete with 50% mineral admixtures. Finally, the incorporation of double expansion agent can improve the resistance to carbonation, chloride ion penetration resistance, anti-corrosion of steel bars and mechanical strengths (the limited and free compressive strengths).

scholarly journals Effect of High-Dispersible Graphene on the Strength and Durability of Cement Mortars

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 915
Author(s):  
Xiaoqiang Qi ◽  
Sulei Zhang ◽  
Tengteng Wang ◽  
Siyao Guo ◽  
Rui Ren
Keyword(s):  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Cement Mortar ◽  
Chloride Ion ◽  
Cementitious Materials ◽  
Chloride Ion Penetration ◽  
Cement Mortars ◽  
Strength And Durability ◽  
Durability Performance

Graphene’s outstanding properties make it a potential material for reinforced cementitious composites. However, its shortcomings, such as easy agglomeration and poor dispersion, severely restrict its application in cementitious materials. In this paper, a highly dispersible graphene (TiO2-RGO) with better dispersibility compared with graphene oxide (GO) is obtained through improvement of the graphene preparation method. In this study, both GO and TiO2-RGO can improve the pore size distribution of cement mortars. According to the results of the mercury intrusion porosity (MIP) test, the porosity of cement mortar mixed with GO and TiO2-RGO was reduced by 26% and 40%, respectively, relative to ordinary cement mortar specimens. However, the TiO2-RGO cement mortars showed better pore size distribution and porosity than GO cement mortars. Comparative tests on the strength and durability of ordinary cement mortars, GO cement mortars, and TiO2-RGO cement mortars were conducted, and it was found that with the same amount of TiO2-RGO and GO, the TiO2-RGO cement mortars have nearly twice the strength of GO cement mortars. In addition, it has far higher durability, such as impermeability and chloride ion penetration resistance, than GO cement mortars. These results indicate that TiO2-RGO prepared by titanium dioxide (TiO2) intercalation can better improve the strength and durability performance of cement mortars compared to GO.

The Chloride Ion Penetration Model Coupled with Temperature and Moisture Transfer in Marine Environment

2012 ◽  
Vol 591-593 ◽  
pp. 2422-2427
Author(s):  
Juan Zhao
Keyword(s):  
Marine Environment ◽  
Moisture Transfer ◽  
Regional Climate ◽  
Chloride Ion ◽  
Chloride Penetration ◽  
Chloride Diffusion ◽  
Tidal Zone ◽  
Analog Simulation ◽  
Chloride Ion Penetration ◽  
Ion Penetration

Considering the complexity of the chloride ion penetration in concrete exposed to marine environment, an integrated chloride penetration model coupled with temperature and moisture transfer is proposed. The governing equations and parameters embody fully the cross-impacts among thermal conduction, moisture transfer and chloride ion penetration. Furthermore, the four exposure conditions are classified based on the different contact with the aggressive marine environment, and then the micro-climate condition on the concrete surface is investigated according to the regional climate characteristics, therefore, a comprehensive analog simulation to the chloride penetration process is proposed. To demonstrate that the proposed numerical model can correctly simulate the chloride diffusion in concrete, the integrated chloride diffusion model is applied in reproducing a real experiment, finally the model gives good agreement with the experimental profiles, and it is proved the tidal zone exposure results in a more severe attack on the reinforcement

Ultra-Low Cement Dosage Hill Sand Concrete’s Electric Flux and Carbonization Performance Study

2014 ◽  
Vol 584-586 ◽  
pp. 1332-1336
Author(s):  
Wei Wei Hu ◽  
Li Bin Xu ◽  
Yi Dong ◽  
Xiao Peng Nie
Keyword(s):  
Materials Science ◽  
Chloride Ion ◽  
Social Stability ◽  
Concrete Durability ◽  
Test Results ◽  
Performance Study ◽  
Chloride Ion Penetration ◽  
Concrete Materials ◽  
Electric Flux ◽  
Low Dosage

Concrete durability is closely related to the national economy and social stability, environmental protection, sustainable development is a major research topic concrete materials science, engineering and technological problems are a major concern. This paper studies resistance to chloride Ion penetration performance and anti-carbonation of low cement concrete sand hill. And combined with the test results analysis and discussion the low dosage of cement to sand concrete electric flux and the influence of carbonization resistance.

scholarly journals Recycled Plastic and Cork Waste for Structural Lightweight Concrete Production

2019 ◽  
Vol 11 (7) ◽  
pp. 1876 ◽  
Author(s):  
Carlos Parra ◽  
Eva M. Sánchez ◽  
Isabel Miñano ◽  
Francisco Benito ◽  
Pilar Hidalgo
Keyword(s):  
Compression Strength ◽  
High Performance ◽  
Lightweight Concrete ◽  
Chloride Ion ◽  
Total Porosity ◽  
Lightweight Aggregates ◽  
Chloride Ion Penetration ◽  
Concrete Production ◽  
Risk Areas ◽  
Strength And Durability

The use of waste materials as lightweight aggregates in concrete is highly recommended in seismic risk areas and environmentally recommended. However, reaching the strength needed for the concrete to be used structurally may be challenging. In this study four dosages were assayed: the first two-specimen had high cement content (550 and 700 kg/m3 respectively), Nanosilica, fly ash and superplasticizer. These samples were high performance, reaching a strength of 100MPa at 90 days. The other two mixtures were identical but replaced 48% of the aggregates with recycled lightweight aggregates (30% polypropylene, 18.5% cork). To estimate its strength and durability the mixtures were subjected to several tests. Compression strength, elasticity modulus, mercury intrusion porosimetry, carbonation, attack by chlorides, and penetration of water under pressure were analyzed. The compression strength and density of the lightweight mixtures were reduced 68% and 19% respectively; nonetheless, both retained valid levels for structural use (over 30MPa at 90 days). Results, such as the total porosity between 9.83% and 17.75% or the chloride ion penetration between 8.6 and 5.9mm, suggest that the durability of these concretes, including the lightweight ones, is bound to be very high thanks to a very low porosity and high resistance to chemical attacks.

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