scholarly journals The effect of hydrophobic (silane) treatment on concrete durability characteristics

2018 ◽  
Vol 199 ◽  
pp. 07015
Author(s):  
Haris Sohawon ◽  
Hans Beushausen
Keyword(s):  
Bulk Diffusion ◽  
Cost Effective ◽  
Concrete Surface ◽  
Chloride Ions ◽  
Water Repellent ◽  
Capillary Absorption ◽  
Chloride Ingress ◽  
Concrete Durability ◽  
Product Lines ◽  
Hydrophobic Silane

Hydrophobic (silane) impregnation represents a cost-effective way to increase the durability of concrete structures in cases where insufficient design cover quality and depth have been achieved. The water repellent product lines the internal capillary pore structure and provides a water-repellent concrete surface. Thus, the risk of reinforcement corrosion initiation and subsequent deterioration can be reduced as the ingress of water-dissolved aggressive species (chlorides) is minimised or prevented. The purpose of this study was to investigate the effect of silane impregnation on durability indicators, including penetrability tests and chloride ingress (bulk diffusion). The results indicate that silane impregnation reduces capillary absorption and conductivity of chloride ions. Similarly, chloride ingress in the treated concrete mixes was suppressed.

The effect of hydrophobic impregnation on chloride ingress into cracked concrete

2019 ◽  
Author(s):  
Haris Sohawon ◽  
Hans Beushausen
Keyword(s):  
Service Life ◽  
Chloride Ions ◽  
Chloride Diffusion ◽  
Water Repellent ◽  
Chloride Ingress ◽  
Chloride Diffusion Coefficient ◽  
Product Lines ◽  
Cracked Concrete ◽  
Cover Depth ◽  
Hydrophobic Silane

<p>Premature concrete degradation due to rebar corrosion has many financial and social implications on a large scale. Direct costs relate to the repair and rehabilitation of existing structures to maintain serviceability while indirect costs include loss in productivity and reduced economic growth. Hydrophobic (silane) impregnation represents a cost-effective way to increase the durability of concrete structures in cases where insufficient design cover quality and depth have been achieved. The water repellent product lines the internal capillary pore structure and provides a water-repellent concrete surface. Thus, the risk of reinforcement corrosion initiation and subsequent deterioration can be reduced as the ingress of water-dissolved aggressive species (chlorides) is minimised or prevented. The purpose of this study was to investigate and quantify the influence of silane impregnation as a remedial measure for poor quality or insufficient cover depth in newly constructed structures and ultimately predict the service life extension possible for specific cover depths. The effectiveness of silane impregnation in cracked concrete was also studied. The results indicate that silane impregnation reduces capillary absorption and conductivity of chloride ions for all the mixes. Chloride ingress in the treated concrete mixes was suppressed and lower chloride surface concentration (C<sub>s</sub> and apparent chloride diffusion coefficient (D<sub>a</sub>) were recorded. A slight decrease in carbonation depth was observed in the w/b 0.60 concrete mixes. The results also suggest that silane impregnation reduces chloride ingress in cracked concrete (up to a crack width of 0.6 mm). A lower rate of chloride ingress was predicted in the silane treated concrete and consequently to achieve the same service life, smaller cover depths are required. The overall results indicate that the service life of concrete with inadequate cover depth and quality, regardless of the binder type, can be effectively extended using hydrophobic (silane) impregnation, assuming proper surface preparation and application methods.</p>

Concrete Surface Quality Improvement Technique Using Highly Water Repellent Sealing Method

2016 ◽  
Vol 54 (11) ◽  
pp. 1105-1110
Author(s):  
K. Watanabe ◽  
G. Sakai ◽  
N. Sakata ◽  
T. Ishida
Keyword(s):  
Quality Improvement ◽  
Surface Quality ◽  
Concrete Surface ◽  
Water Repellent

Capillary Absorption of Integral Water Repellent and Surface Impregnated Concrete

2014 ◽  
Vol 20 (4) ◽  
pp. 281-290
Author(s):  
F.H. Wittmann ◽  
A.D.A. Wittmann ◽  
P.G. Wang
Keyword(s):  
Water Repellent ◽  
Capillary Absorption

scholarly journals Effects of Anti-Graffiti Protection on Concrete Durability

2014 ◽  
Vol 634 ◽  
pp. 517-526 ◽  
Author(s):  
Elsa Neto ◽  
Ana Souto ◽  
Aires Camões ◽  
Arlindo Begonha ◽  
Paulo Cachim
Keyword(s):  
Water Absorption ◽  
Atmospheric Pressure ◽  
Surface Characteristics ◽  
Concrete Surface ◽  
Experimental Program ◽  
Concrete Durability ◽  
Protection Systems ◽  
Before And After ◽  
Paint Removal ◽  
Durability Of Concrete

The heritage of fair-faced concrete, largely built in the twentieth century and nowadays recognized as heritage to be protected, is susceptible to attacks by graffiti, a form of vandalism that causes a major social and economic impact on society. Concrete is a porous material sometimes deteriorated over the years, and the interactions between the inks and the substrate and removal methods sometimes deteriorate or alter the concrete surface, especially if it is necessary to repeat the removal process. The anti-graffiti products are applied on the surface of the concrete, hindering the adhesion of paints or preventing its penetration into the pores of concrete, which in turn facilitates their removal. However, it appears that many of the existing protective products on the market may also alter the surface characteristics of the concrete irreversibly. Considering that the durability of concrete depends on the composition and characteristics of the surface, it is essential to know the effects of anti-graffiti protection systems on the durability of concrete and adopt the appropriate methodology to preserve this heritage. Thus, an experimental program was developed for analyzing changes in durability indicators and surface properties that protect concrete from deterioration (i) concrete without protection before and after application of spray paint, (ii) concrete with protection before and after application of spray paint and (iii) after paint removal were studied. Two anti-graffiti products were evaluated: a permanent and a sacrificial one. Effects of the anti-graffiti systems on the concrete durability are investigated and the tests performed include: water absorption by capillary and immersion at atmospheric pressure. The results of the water absorption tests show that the graffiti protection reduces the water absorption into the concrete and facilitates the removal of the graffiti without affecting negatively the characteristics of the surface and thus contributing to improve its durability.

Preventing chloride ingress in concrete with water repellent treatments

2010 ◽  
pp. 1189-1194 ◽  
Author(s):  
A Johansson-Selander ◽  
J Trägårdh ◽  
J Silfwerbrand ◽  
M Janz
Keyword(s):  
Water Repellent ◽  
Chloride Ingress

Application of electrical fields to reduce chloride ingress into concrete structures

2021 ◽  
pp. 1-27
Author(s):  
Carla Driessen-Ohlenforst ◽  
Michael Raupach
Keyword(s):  
Chloride Ions ◽  
Chloride Ingress ◽  
Textile Reinforced Concrete ◽  
Electrical Field ◽  
Joint Research ◽  
Electrical Fields ◽  
Joint Research Project ◽  
Anodic Polarisation ◽  
Current Densities ◽  
Field Strengths

In the context of a joint research project, a system for monitoring, protection and strengthening of bridges by using a textile reinforced concrete interlayer has been developed which consists of two carbon layers with a spacing of 15 mm and a special mortar. This setup led to the idea to build up an electrical field between the carbon meshes, which suppresses the ingress of chlorides into the concrete. This paper focuses on the question which voltages and electrical field strengths are necessary to prevent critical chloride contents at the reinforcing steel. For this purpose, extensive laboratory tests have been performed, followed by a numerical simulation study. By applying an electrical field, the negatively charged chloride ions are forced to move to the upper carbon mesh that is polarized as an anode. It has been investigated whether the voltages to implement an electrochemical chloride barrier are smaller than they have to be for the common preventive cathodic protection. One advantage of this chloride barrier is that because of the lower current densities the anodic polarisation of the carbon meshes can be reduced. Therefore, different voltages, electrical field strengths, anode materials and anode arrangements were investigated.

Influence of TiO2 on Selfclean Bio Coating

2013 ◽  
Vol 315 ◽  
pp. 399-403 ◽  
Author(s):  
Nurulsaidatulsyida Sulong ◽  
Anika Zafiah Mohd Rus
Keyword(s):  
Contact Angle ◽  
Organic Contaminants ◽  
Concrete Surface ◽  
Waste Cooking Oil ◽  
Water Repellent ◽  
Angle Measurements ◽  
Contact Angle Measurements ◽  
The Difference ◽  
Micro Features ◽  
Coated Surfaces

Treatment on the exposed surface to the environmental attack was studied based on biopolymer coating from waste cooking oil doped with a superhydrophilic filler of Titanium Dioxide (TiO2), known as TOP. TOP was found to affect the physical properties of the coated concrete surface in a systematic way. Contact angle measurements are interpreted with respect to nanoand micro-features existing on the surface of the water repellent superhydrophilic filler filled bio-polymer composite coating. The smooth coated surfaces of polymer filled or doped with superhydrophobic filler shows the systematic increasing static Waste Contact Angle, WCA (θst) and revealed that polymer filled superhydrophobic fillers by only 2.0 % shows the ability to form superhydrophobicity property. Scanning Electron Microscope (SEM) pictures revealed the difference between the concrete surface roughness of concrete biopolymer with and without TOP coating is to provide self-cleaning concrete biopolymer coating based on two principal ways: (1) the development of surface coating of semiconducting photocatalytic superhydrophilic. (2) If such a superhydrophilic is illuminated by light, then grease, dirt and organic contaminants will be decomposed and can easily be swept away by rain.

The Reinforced Concrete Durability and Rebar Erosion Monitoring

2012 ◽  
Vol 446-449 ◽  
pp. 3252-3258
Author(s):  
Jin Yang Zhang ◽  
De Mi Cui ◽  
Lie Min Lv ◽  
Zhi Yang
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Protective Layer ◽  
Concrete Surface ◽  
Monitor System ◽  
Concrete Durability ◽  
Information Feedback ◽  
Starting Time ◽  
Cast Concrete

On the basis of the advantages of low construction cost, remarkable dynamics property, easy cast moulding and more controllable construction, the reinforced concrete construct are widely applied in buildings and main structures of constructions in China. However, the reinforced concrete is found more or less aging after many years’ utilization and erosion from the environment, which will lead to a hidden risk to affect its functions. After technical development for decades, the concrete can assure its durability under normal situation, yet the function would be deteriorated due to the erosion from the complex and harsh environment to make it hardly reach its designed service life. With the assist of CorroWatch erosion monitor system, the concrete structures’ erosion can kept watched on to obtain the depassivation development and information feedback of some key data dynamically and in long term so as to foresee precisely the erosion starting time. The newly cast concrete depassivation frontline is located on concrete surface and will tend to go through the protective layer and penetrate towards rebar as time goes on. Its structure service life can be enhanced with the re-designed durability in terms of the mentioned characters and do well the erosion proof measures.

Bio-Inspired Advanced Materials for Reducing Friction & Wear in MEMS Devices

2012 ◽  
Vol 545 ◽  
pp. 359-363 ◽  
Author(s):  
Ramachandra Arvind Singh ◽  
Nalam Satyanarayana ◽  
Sujeet Kumar Sinha
Keyword(s):  
Friction Force ◽  
Thick Films ◽  
Cost Effective ◽  
Small Scale ◽  
Water Repellent ◽  
Oxygen Plasma Treatment ◽  
Mems Devices ◽  
Textured Surfaces ◽  
Lotus Effect ◽  
Lotus Leaf

Micro-Electro-Mechanical-Systems (MEMS) are miniaturized devices built at micro/nano-scales. At these scales, friction force is extremely strong as it resists the smooth operation and reduces the useful operating lifetimes of MEMS actuator devices. In order to reduce friction and wear in MEMS devices, we have undertaken a bio-inspired approach by applying the underlying principle of the “Lotus Effect”. Lotus leaf surfaces have small-scale protuberances and wax covered on them, which make the surfaces water-repellent in nature. By creating textured surfaces that mimic these bio-surfaces, surface energy and contact area can be reduced. This in turn reduces friction force and eventually increases the wear durability of surfaces. In our work, we have fabricated bio-inspired surfaces that resemble the texture on lotus leaf. The method includes oxygen plasma treatment of polymeric thin/thick films and application of a nanolubricant namely, perfluoropolyether (PFPE). When this method was applied to SU8 polymer thin/thick films spin coated on silicon wafers, friction reduced considerably, and simultaneously the wear durability increased by >1000 times. The method is time and cost effective, and is commercially viable.

scholarly journals Investigation on Durability Performance in Early Aged High-Performance Concrete Containing GGBFS and FA

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Seung-Yup Jang ◽  
Subbiah Karthick ◽  
Seung-Jun Kwon
Keyword(s):  
Diffusion Coefficient ◽  
High Performance ◽  
High Performance Concrete ◽  
Steel Corrosion ◽  
Chloride Ions ◽  
Chloride Diffusion ◽  
Structural Safety ◽  
Concrete Durability ◽  
Chloride Diffusion Coefficient ◽  
Rc Structures

The significance of concrete durability increases since RC (Reinforced Concrete) structures undergo degradation due to aggressive environmental conditions, which affects structural safety and serviceability. Steel corrosion is the major cause for the unexpected failure of RC structures. The main cause for the corrosion initiation is the ingress of chloride ions prevailing in the environment. Hence quantitative evaluation of chloride diffusion becomes very important to obtain a chloride diffusion coefficient and resistance to chloride ion intrusion. In the present investigation, 15 mix proportions with 3 water-to-binder ratios (0.37, 0.42, and 0.47) and 3 replacement ratios (0, 30, and 50%) were prepared for HPC (high-performance concrete) with fly-ash and ground granulated blast furnace slag. Chloride diffusion coefficient was measured under nonstationary condition. In order to evaluate the microstructure characteristics, porosity through MIP was also measured. The results of compressive strength, chloride diffusion, and porosity are compared with electrical charges. This paper deals with the results of the concrete samples exposed for only 2 months, but it is a part of the total test plan for 100 years. From the work, time-dependent diffusion coefficients in HPC and the key parameters for durability design are proposed.

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