scholarly journals Carbonation of Water Repellent-Treated Concrete

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Peng Zhang ◽  
Peibing Li ◽  
Hong Fan ◽  
Huaishuai Shang ◽  
Siyao Guo ◽  
...  
Keyword(s):  
Concrete Structures ◽  
Hyperbolic Function ◽  
Water Repellent ◽  
Water Penetration ◽  
Carbonation Depth ◽  
Carbonation Reaction ◽  
Capillary Suction ◽  
Time Treatment ◽  
Surface Impregnation ◽  
Preventive Method

Water repellent treatment has been considered an effective preventive method against water and aggressive ions penetration into concrete and consequently can improve the durability of concrete structures. In reality, many concrete structures are exposed to conditions with high risk of carbonation. In this contribution, one type of ordinary concrete had been prepared and surface impregnated by 400 g/m2silane cream and 100 g/m2and 400 g/m2silane gel. In addition, integral water repellent concrete was produced by adding 2% silane emulsion. Then, the specimens were exposed to accelerated carbonation for 7, 28, and 72 days. The effect of water repellent treatment on carbonation of concrete has been investigated. The results indicate that surface impregnation reduced carbonation depth of concrete under RH 70%, but integral water repellent concrete increased carbonation. Carbonation reaction started behind the hydrophobic layer in the surface-impregnated concrete. The coefficient of carbonation can be described better by a hyperbolic function of time. Treatment by 400 g/m2silane gel and silane cream showed better efficiency on reducing carbonation than usage of 100 g/m2. Coefficient of water capillary suction was decreased significantly by both surface impregnation and integral water repellent treatment. It is an effective method to protect concrete from water penetration into the material.

scholarly journals The Effect of Water Repellent Surface Impregnation on Durability of Cement-Based Materials

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Peng Zhang ◽  
Huaishuai Shang ◽  
Dongshuai Hou ◽  
Siyao Guo ◽  
Tiejun Zhao
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Concrete Structures ◽  
Chloride Penetration ◽  
Water Repellent ◽  
Reinforced Concrete Structures ◽  
Capillary Suction ◽  
Surface Impregnation ◽  
Cement Based Materials ◽  
Ft Ir

In many cases, service life of reinforced concrete structures is severely limited by chloride penetration until the steel reinforcement or by carbonation of the covercrete. Water repellent treatment on the surfaces of cement-based materials has often been considered to protect concrete from these deteriorations. In this paper, three types of water repellent agents have been applied on the surface of concrete specimens. Penetration profiles of silicon resin in treated concrete have been determined by FT-IR spectroscopy. Water capillary suction, chloride penetration, carbonation, and reinforcement corrosion in both surface impregnated and untreated specimens have been measured. Results indicate that surface impregnation reduced the coefficient of capillary suction of concrete substantially. An efficient chloride barrier can be established by deep impregnation. Water repellent surface impregnation by silanes also can make the process of carbonation action slow. In addition, it also has been concluded that surface impregnation can provide effective corrosion protection to reinforcing steel in concrete with migrating chloride. The improvement of durability and extension of service life for reinforced concrete structures, therefore, can be expected through the applications of appropriate water repellent surface impregnation.

Water Repellent Treatment on Lime/Lime-Fly Ash/Lime-Cement Mortar with and without Carbonation

2008 ◽  
Vol 400-402 ◽  
pp. 145-150 ◽  
Author(s):  
Peng Zhang ◽  
T. Scherer ◽  
Tie Jun Zhao ◽  
F.H. Wittmann
Keyword(s):  
Compressive Strength ◽  
Porous Materials ◽  
Cement Mortar ◽  
Hyperbolic Function ◽  
Water Repellent ◽  
Capillary Absorption ◽  
Square Root ◽  
Water Penetration ◽  
Carbonation Reaction ◽  
Feasible Method

Water repellent treatment (WRT) has proved to be effective to prevent porous materials from water penetration and consequently can improve the durability of structures. In this contribution, three types of mortar, which are pre-carbonated and non-carbonated, had been water repellent treated by silane gel with usage of 400 g/m2, to investigate into the influence of WRT on carbonated and non-carbonated mortar. Results indicate that carbonation reaction increased the compressive strength of all three types of mortar. Silane gel penetrated to a comparatively higher depth for the carbonated mortar. WRT reduced the absorbed water and capillary absorption coefficient greatly, both for non-carbonated mortar to 2 % ~ 7 % and for carbonated mortar to 22 % ~ 66 %, compared with non-treated ones. WRT is still a feasible method for porous materials with some carbonation to prevent from water penetration. However, the efficiency of WRT on reducing capillary absorption became much lower compared with the non-carbonated mortar. Capillary absorption curves of non-WRT mortar, both carbonated and non-carbonated, could be well fitted by a hyperbolic function of square root of time. For the treated mortar, the absorption curves could be described as a linear equation before carbonation, but an exponential function when the mortar carbonated.

Surface Impregnation of Concrete Damaged by Elevated Temperature

2011 ◽  
Vol 675-677 ◽  
pp. 567-570
Author(s):  
Peng Gang Wang ◽  
Peng Zhang ◽  
Tie Jun Zhao ◽  
F.H. Wittmann ◽  
Ling Cui
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Service Life ◽  
Water Absorption ◽  
Concrete Structures ◽  
Salt Solutions ◽  
Water Penetration ◽  
Surface Impregnation ◽  
Different Levels

By now, it is well-known that concrete will lose strength after exposure to elevated temperature. In this case, the damaged concrete is extremely vulnerable with respect to ingress of water and aggressive compounds. Therefore the potential for the protection of concrete from excessive ingress of water after exposure to high temperature, as for instance in an accidental fire, has been investigated. So far, surface impregnation of concrete with silane has been proved to be beneficial to reduce water penetration. In this contribution, surface impregnation with silane was applied on concrete exposed to elevated temperature. The efficiency of surface impregnation with respect to absorption of water and salt solutions by concrete with different levels of damage induced by elevated temperature has been investigated in particular. Results indicate that the increased water absorption of damaged concrete can be reduced significantly by surface impregnation. A reduction of more than 90 % can be achieved. The effective chloride barrier established by surface impregnation can help to extend the service life of fire-exposed concrete structures.

scholarly journals Application of ground-penetrating radar technique to evaluate the waterfront location in hardened concrete

2016 ◽  
Author(s):  
Isabel Rodríguez-Abad ◽  
Gilles Klysz ◽  
Rosa Martínez-Sala ◽  
Jean Paul Balayssac ◽  
Jesús Mené-Aparicio
Keyword(s):  
Ground Penetrating Radar ◽  
Concrete Structures ◽  
Hardened Concrete ◽  
Concrete Durability ◽  
Water Penetration ◽  
Wave Parameters ◽  
Two Factors ◽  
Almost All ◽  
Ground Penetrating ◽  
Term Performance

Abstract. The long term performance of concrete structures is directly tied to two factors: concrete durability and strength. When assessing the durability of concrete structures, the study of the water penetration is paramount, because almost all reactions like corrosion, alkali-silica, sulfate, etc., which produce their deterioration, require the presence of water. Ground-penetrating radar (GPR) has shown to be very sensitive to water variations. On this basis, the objective of this experimental study is, firstly, to analyze the correlation between the water penetration depth in concrete samples and the GPR wave parameters. To do this, the samples were immersed into water for different time intervals and the wave parameters were obtained from signals registered when the antenna was placed on the immersed surface of the samples. Secondly, a procedure has been developed to be able to determine, from those signals, the reliability in the detection and location of waterfront depths. The results have revealed that GPR may have an enormous potential in this field, because excellent agreements were found between the correlated variables. In addition, when comparing the waterfront depths calculated from GPR measurements and those visually registered after breaking the samples, we observed that they totally agreed when the waterfront was more than 4 cm depth.

scholarly journals Effect of Graphene Nanoplatelet on the Carbonation Depth of Concrete under Changing Climate Conditions

2021 ◽  
Vol 11 (19) ◽  
pp. 9265
Author(s):  
Yingzi Zhang ◽  
Yanze Wang ◽  
Mingqian Yang ◽  
Huatao Wang ◽  
Guofang Chen ◽  
...  
Keyword(s):  
Control Sample ◽  
Co2 Concentration ◽  
Favorable Effect ◽  
Carbonation Depth ◽  
Graphene Nanoplatelet ◽  
Carbonation Reaction ◽  
Climate Conditions ◽  
Ordinary Concrete ◽  
Changing Climate ◽  
Carbon Dioxide Co2

Climate change has been unprecedented in the past decades or even thousands of years, which has had an adverse impact on the mechanical properties of concrete structures. Many researchers have begun to study new concrete materials. Graphene nanoplatelet (GNP) is an attractive nanomaterial that can change the crystal structure of concrete and improve durability. The aim of the present study was to investigate the effect of GNP (0.05%wt) on the carbonation depth of concrete under simulated changing climate conditions (varying temperature, relative humidity, and carbon dioxide (CO2) concentration), and compare it with ordinary concrete. When the concentration of CO2 is variable, the carbonation depth of graphene concrete is 10% to 20% lower than that of ordinary concrete. When the temperature is lower than 33 °C, the carbonation depth of graphene concrete is less than that of the control sample; however, above 33 °C, the thermal conductivity of GNP increases the carbonation reaction rate of concrete. When the humidity is a variable, the carbonation depth of graphene concrete is less than 15% to 30% of ordinary concrete, and when the humidity is higher than 78%, the difference in the carbonation depth between the ordinary concrete and the graphene concrete decreases gradually. The overall results indicated that GNP has a favorable effect on anti-carbonation performance under changing climate conditions.

scholarly journals Effect of Soorh Metakaolin on Concrete Compressive Strength and Durability

2017 ◽  
Vol 7 (6) ◽  
pp. 2210-2214 ◽  
Author(s):  
A. Saand ◽  
M. A. Keerio ◽  
D. K. Bangwar
Keyword(s):  
Compressive Strength ◽  
Corrosion Resistance ◽  
Life Time ◽  
Natural Material ◽  
Concrete Durability ◽  
Concrete Compressive Strength ◽  
Water Penetration ◽  
Carbonation Depth ◽  
Ordinary Concrete ◽  
Strength And Durability

Concrete durability is a key aspect for forecasting the expected life time of concrete structures. In this paper, the effect of compressive strength and durability of concrete containing metakaolin developed from a local natural material (Soorh of Thatta Distict of Sindh, Pakistan) is investigated. Soorh is calcined by an electric furnace at 8000C for 2 hours to produce metakaolin. One mix of ordinary concrete and five mixes of metakaolin concrete were prepared, where cement is replaced by developed metakaolin from 5% to 25% by weight, with 5% increment step. The concrete durability was tested for water penetration, carbonation depth and corrosion resistance. The obtained outcomes demonstrated that, 15% replacement level of local developed metakaolin presents considerable improvements in concrete properties. Moreover, a considerable linear relationship was established between compressive strength and concrete durability indicators like water penetration, carbonation depth and corrosion resistance.

Influence of Silane Treatment on the Freeze-Thaw Resistance of Concrete

2011 ◽  
Vol 250-253 ◽  
pp. 565-568 ◽  
Author(s):  
Xiao Jian Gao ◽  
Hong Wei Deng ◽  
Ying Zi Yang
Keyword(s):  
Surface Treatment ◽  
Water Adsorption ◽  
Concrete Structures ◽  
Air Entrainment ◽  
Concrete Surface ◽  
Silane Treatment ◽  
Cold Regions ◽  
Bonding Force ◽  
Freeze Thaw ◽  
Surface Impregnation

The influences of silane impregnation on water adsorption, bonding force between ice and concrete surface and resistance to freeze-thaw of concretes were studied. Two strength grades (C30 and C50) and the air entrainment were considered for concrete preparation. The results show that surface impregnation with silane reduces the final water adsorption of concrete by more than 90% when compared with the untreated specimen. The silane treatment significantly decreases the bonding force between ice and concrete surface. The resistance to freeze-thaw of both new and old concretes can be improved by the silane treatment. Therefore, the surface treatment with silane is suggested as an effective method to improve the durability of concrete structures in cold regions.

Microbial Carbonate Mineralization as an Improvement Method for Durability of Concrete Structures

2011 ◽  
Vol 365 ◽  
pp. 280-286 ◽  
Author(s):  
Pei Hao Li ◽  
Wen Jun Qu
Keyword(s):  
Laboratory Experiments ◽  
Concrete Structures ◽  
Capillary Water ◽  
Water Penetration ◽  
Mineral Crystal ◽  
Microbial Carbonate ◽  
Improvement Method ◽  
Alternative Techniques ◽  
Capillary Water Uptake ◽  
Durability Of Concrete

Biodeposition treatment had been proposed as alternative techniques for improvement in the durability of concrete structures. Laboratory experiments were conducted by bacterially mediated carbonate precipitation on the surface and subsurface of specimens of concrete. Some properties of specimens and crystal, such as the crystal phase, morphology and growth of the crystal deposited on specimens, water penetration, the resistance towards carbonation of concrete and so on, were analyzed by XRD, SEM, water absorptivity test and concrete accelerated carbonation test. Some efficiencies of biodeposition treatment for were investigated by experiment. Results show that the mineral crystal deposits uniformly on the surface and subsurface of specimens, phases of crystal are calcite and vaterite. Biodeposition effectively reduces capillary water uptake and leading to carbonation rate constant decreased by 25~40%. Bacterially mediated carbonate mineralization can be an ecological and novel alternative for improvement in the durability of concrete structures.

Sign in / Sign up

Export Citation Format

Share Document