Hydrophobic Impregnation Research Articles

Integral and Surface Treatment Method of Waterproofing: A Review and Comparative Analysis

Water seepage into concrete can cause deterioration and other aesthetic issues that limit the life of concrete constructions. This paper examines and contrasts the various kinds of waterproofing techniques. There are essentially two types: surface treatment method and integral method. Water repellents, crystalline admixtures, and densifiers are examples of integral methods. Surface treatment methods encompass pore-blocking, hydrophobic impregnation, surface coating, and multifunctional surface treatment. The processes of various approaches are examined in this article, followed by a comparison of their durability and mechanical properties. We discuss several properties, such as sulfate attack, chloride penetration, carbonation, reinforcement corrosion, water absorption and permeability, compressive, flexural, and tensile strength. The findings indicate that each has merits and demerits of their own. The inclusion of an integral admixture to concrete offers a number of advantages over surface protection, including convenience of application, the removal of the need for ongoing maintenance, and minimal to no deterioration over time. While surface treatment methods significantly reduce water permeability and porosity. In conclusion, we give a succinct summary of certain issues regarding the present state of research and future directions for the hydrophobic modification of concrete.

Assessment of Surface Treatment Systems for Protecting Concrete Structure

The BS EN 1504-2:2004 groups surface treatments into three types: impregnations, hydrophobic impregnations, and surface applied corrosion inhibitors. Impregnations reduce surface porosity by filling concrete pores, while hydrophobic impregnations create a water-repellent surface without filling pores. Surface applied corrosion inhibitors form a protective film on the rebar surface. Impregnation strengthens the surface by blocking pores with reaction products that reduce ingress of aggressive agents. Hydrophobic impregnation produces a hydrophobic and water-repellent surface that inhibits water penetration while allowing concrete to breathe. Corrosion inhibitors migrate to the steel surface and form a mono-molecular film, preventing further corrosion. In this study accelerated corrosion test was used for determination of the effectiveness of each category in offering corrosion protection by subjecting concrete specimens coated with these surface treatments to accelerated corrosion conditions that is intended to induce corrosion in the embedded rebars. This paper presents test results for the performance of these three surface treatments on grade G30 and G40 concretes. Results show that hydrophobic agents are more effective than traditional impregnates in reducing water absorption and chloride penetration.

Sustainable preventive maintenance of MMC-based concrete building structures in a harsh environment

The construction industry plays a significant role in environmental strain, attributed mainly to its substantial resource consumption, primarily driven by the surge in residential construction. Modern Methods of Construction (MMC) presents an innovative paradigm for designing and constructing infrastructure and buildings more efficiently, using conventional materials with unconventional techniques. The article aims to apply this approach to an MMC-based building structure, minimizing its life cycle impact by optimizing the consumption of building materials, with particular attention to the effects of the maintenance phase from a preventive point of view. This study focuses on assessing the sustainability of reinforced concrete flat slabs employing a hollow structural body system, explicitly emphasizing environmental aggressiveness factors contributing to corrosion, such as carbonation and chlorides. The research explores ten design options for a waterfront public residential building, examining their impact on the economy, the environment, and even society regarding the maintenance cycles required over the structure's lifetime, depending on the preventive strategy employed for each design. In assessing the sustainability of these options, researchers employed a combination of the best-worst method (BWM) and the VIKOR technique, considering nine criteria related to sustainability. The study found that 5 % silica fume concrete is the most cost-effective and environmentally friendly option, with hydrophobic impregnation reducing social impacts. However, compared to one- and two-dimensional evaluations, the study demonstrates the importance of simultaneously considering a design's life cycle's economic, environmental, and social impacts to achieve sustainability in maintenance with a holistic view. This approach led to an 86 % higher sustainability rating for a design using sulforesistant cement in the concrete mix than the baseline.

Evaluation of the Effect of Impregnation Coatings on Concrete Protection

The paper deals with evaluation and comparison of the effect of two substances on reduction of concrete absorbability and increasing the durability. In four tests the effect of hydrophobic impregnation of investigated substances on various properties of test specimens was examined. The penetration depth, the rate of water absorption and alkali resistance, drying ratio and weight loss after freeze-and-thaw cycles in sodium chloride solution were the followed parameters. The positive effect of both substances on the final durability of concrete was confirmed.

Exploration of Waterproofness of Concrete and Alkali-Aggregate Using Hydrophobic Impregnation and Coating

Part of the tunnel spoil can not be used for concrete due to alkali-aggregate reaction (AAR). Water is an indispensable condition for AAR, so separating the alkali-aggregate from water is of great benefit to controlling the AAR. This paper investigates the modification of concrete and aggregate by hydrophobic impregnation and organic coating and then evaluates their waterproof and mechanical properties by dynamic contact angle (DCA), ultrasonic wave velocity, scanning electron microscope (SEM), nuclear magnetic resonance (NMR), and so on. For waterproofness, hydrophobic impregnation and organic coating can both improve the waterproofness of concrete and aggregate. The organic coating is suitable for aggregate because it wrap aggregate well. And aggregate coated by PVA can improve the interfacial transition zone (ITZ). For mechanical properties, both materials will weaken the strength of the interface. Furthermore, concrete made by aggregate with organic coating shows plastic deformation and has a good correlation with the film thickness, a plastic estimation model based on film thickness is proposed. This paper evaluates the waterproof of concrete and aggregate and finds plastic concrete with good aggregate waterproofness which provides a new idea for the application of alkali-aggregate in seepage control facilities of water conservancy projects.

Simple and effective hydrophobic impregnation of concrete with functionalized polybutadienes

In order to extend the life of concrete, various impregnation methods are used to protect it from the damaging effects of external factors. This article proposes an easy and effective method of waterproofing concrete using functionalized polybutadienes. The effects of chemical structure of polymers as well as the type of solvent used, on the hydrophobicity of modified concrete were evaluated. The effectiveness of impregnation was assessed based on the water contact angle measurements and water sorption experiments. For the best hydrophobizing preparation, the water absorption was reduced by 94% compared to the absorption for the unmodified sample.

Полисилазаоксаны и клеевые композиции на их основе

The polymer formation proceeding with the participation of cardosilazaoxane organosilicon oligomers are considered. By the interaction of cardocyclic silazaoxanes with organosiloxane diols, new types of organosilicon oligomers are synthesized. They are capable to form elastic spatial-netted structures due to polymerization processes with the discovery of cyclic siloxane fragments without isolation of low molecular weight by-products. The influence of temperature and the silazaoxane: diol ratio on the nature of the products formed is studied. It was established that at 120-130 °C soluble oligomers of cyclolinear structure are formed, which are structured at 180-190 °C, with the most dense network structure being formed when the silazoxane: diol ratio is close to equimolar; a certain excess of hydroxyl groups at the final stage of polymerization leads to the association of the released ammonia with OH end groups and the formation of nucleophilic particles at the ends of the polymer chains – siloxanolate anions, possibly initiating structuring. The formation of regular three-dimensional structures – polysilazaoxanes, initiated by siloxanolate anions without the use of a special catalyst, is a new approach to the creation of adhesive compositions. In this case, in contrast to catalytically cured siloxane analogues, the resulting cross-linked polymer structures exhibit enhanced adhesion to the substrate material. Such polysilazaoxane oligomers can be used: a) as a basis for adhesives, only thermal effects and compounds containing siloxane films and coatings with various metals and characteristics can be used as a catalyst; b) for hydrophobic impregnation of textile materials and leather half-finished products, since this is clearly ammonia, which does not have a destructive effect on them.

A Simple, Long-Lasting Treatment for Concrete by Combining Hydrophobic Performance with a Photoinduced Superhydrophilic Surface for Easy Removal of Oil Pollutants.

Superhydrophobic surfaces present promising applications in the protection of building materials, such as the self-cleaning effect promoted by their high water-repellent properties. However, these surfaces easily lose their properties when exposed to oil contaminants. This is a critical weak point for their application in building facades, which are exposed to environmental pollutants such as hydrocarbons and vandalism (e.g., grafitti). A viable strategy to remove oils is to produce superhydrophilic surfaces, which present underwater superoleophobic behavior. In the case of buildings, the use of this strategy can be considered counterproductive because it promotes their interaction with water, the main vehicle of most decay agents. In this work, we have successfully combined the advantages of a superhydrophilic coating with a hydrophobic impregnation treatment, which prevents water ingress into the porous structure of the substrate. Specifically, a photoinduced superhydrophilic surface was produced on concrete by simple spraying of a starting sol containing TiO2NPs, which create a Cassie-Baxter state, a silica oligomer, producing a compatible matrix promoting good adhesion to the substrate and polydimethylsiloxane as a hydrophobic agent. After being exposed to sunlight, the treated surfaces switched from superhydrophobic (SCA 160°) to superhydrophilic (SCA < 10°). These surfaces presented underwater superoleophobicity (SCA 152° with CHCl3) and oil-contaminated dust was easily cleaned without employing detergents. The photoactivation does not alter the protection against water absorption (>85% reduction). The treatment showed suitable adhesion to the substrate and good resistance to rainfall and outdoor exposure due to the presence of the hydrophobic silica matrix in the concrete pore structure.

Experiment and molecular dynamics study on the mechanism for hydrophobic impregnation in cement-based materials: A case of octadecane carboxylic acid

A novel method that specimen is impregnated with octadecane carboxylic acid (OCA) solution is proposed to prevent water and ions from penetrating into concrete/mortar. Molecular dynamics is utilized to model capillary absorption in calcium silicate hydrate (C-S-H) channel to reveal related mechanism. The simplified model of decane carboxylic acid (DCA), coating on C-S-H channel and DCA mixed in solution, is used in the simulation. While the hydrophilic functional terminal of DCA chain is bridged to surface calcium in C-S-H, the other hydrophobic end diffuses free in the solution. The reduction of capillary transport rate induced by DCA is mainly due to two reasons. (1) DCA coating decreases the hydrophilicity of the channel; (2) Aqueous ions accumulate around DCA, forming huge DCA-based clusters and blocking the transport channel. This study can contribute to development of water repellent materials in durability design of cement-based materials.

Hygric properties of hydrophobized building materials

Moisture loads due to wind-driven rain can lead to accelerated decay of exposed building facades. Hydrophobic impregnation reduces water absorption of facade materials and is thus presumed to decrease moisture related damages. Hydrophobic impregnation however also lowers the drying speed of the exposed facade, leaving mainly water vapour transfer to take place. This study examines the open porosity and capillary absorption coefficient of impregnated brick samples as well as the effect of hydrophobic impregnation on the vapour permeability of brick and mortar samples. The open porosity was measured with vacuum saturation test, the absorption coefficient was determined by water uptake tests, both done after one month of curing of the impregnated brick samples. The vapour permeability was `derived from cup tests and from drying tests. The resulting open porosity from brick samples indicates that the changes in the overall pore structure are minimal after impregnation. In addition, the absorption coefficient of brick was found to be fairly close to zero, even with low concentrations of active ingredient, and regardless the percentage of silane/siloxane. Our findings support the claim that the hydrophobic impregnation does not influence significantly the water vapour permeability of brick and mortar.

Reinforced concrete corrosion prevention/reduction by hydrophobic impregnation

The prevention of corrosion in reinforced concrete structures can be achieved by different means. The aim of this paper is to present the efficiency of corrosion prevention using silane hydrophobic impregnation, through laboratory investigations as well from long term field studies. The laboratory investigation was carried out in Zürich, is based on modified ASTM C109, where the product was applied on cracked concrete beams (before cracking and before corrosion initiation; after cracking and before corrosion initiation and finally after cracking and after corrosion initiation). The long term field studies were carried out over 12-years exposure to de-icing salts in a Swiss tunnel, and after 10 years exposure to a marine zone simulation in Japan. This paper will show that the use of a silane hydrophobic impregnation can be an effective way to reduce the risk of corrosion for concrete structures, including structures exposed to chlorides in a marine environment, or from the use of de-icing salts in winter time.

Hygrothermal simulation assessment of internal insulation systems for retrofitting a historic Danish building

The built environment is accountable for 1/3 of the European energy consumption. Thermal insulation is a key factor affecting the energy performance of buildings. Historic buildings typically were made with solid external walls of brick masonry or natural stone, rarely insulated afterwards. Often the buildings have worth-preserving façades making internal insulation the only feasible technique, however significantly modifying the hygrothermal performance of the façade. The research objective of this paper is to simulate the hygrothermal performance of solid masonry walls in an old Danish hospital that will be internally insulated following the Danish requirement (U-value) for external walls (change of use of buildings) and transformed into dwellings, involving different insulation systems. Heat loss and masonry moisture content level after adding internal insulation and the possible effects of hydrophobization on the moisture content is simulated. Simulations show an increased moisture content in the original wall when adding internal insulation implying an increased risk for moisture-related damage (mould growth, frost damage and interstitial condensation). The results also show that hydrophobic impregnation of the internally insulated facades may be vital in avoiding moisture problems and securing a moisture-safe energy renovation of buildings like the one studied.

MOISTURE EFFECTS ON THE BUILDINGS ENCLOSING STRUCTURES

Analysis of the most common damages due to moisture effects on brick, reinforced-concrete and wooden buildings enclosing structures has been carried out. Causes of their occurrence and prevention ways have been analyzed. The most dangerous moisture types such as constructional, soil, atmospheric, operational, hygroscopic and condensed have been outlined. Measures to ensure protection against water-saturation of building elements such as eaves size, walls waterproofing, available airways, protective painting, hydrophobic impregnation, sufficient ventilation, heating, water supply systems and draining timely repairs have been recommended.

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

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.

Microscopy Measurement of Open Porosity as a Function of Hydrophobic Impregnation

In this paper open porosity as a function of hydrophobic properties was examined. It was measured three kinds of porous building materials which differ in their structure and properties. Especially, concrete samples such as: aerated concrete (denote as AC), normal strength concrete (denote as NSC) and ultra high performance concrete (denote as UHPC). We were focused on measurement of open porosity and distribution of pores in structure by microscopic method. The result clearly shows that concrete samples differ in among of pores, its geometric shape and deep and mainly in its distributions.

Improvement of the Adhesion between Epoxy-Based Surface Coating and Hydrophobic Impregnated Concrete

Surface protection by hydrophobic impregnation and surface coating are widely used for concrete bridges located at coastal area in Japan. This paper deals with the improvement of adhesion between surface coating and hydrophobic impregnated concrete by different types of silanes and by invastigating surface treatment methods. As a result, adhesion between hydrophobic impregnated concrete and epoxy-based surface coating were improved by applying abrasive paper, portable electric grinder, solvent or diluted hydrochloric acid treatment. Especially, using portable electric grinder gave a remarkable improvement to the adhesive property. Also, hybrid-surface protection system consisting of surface coating and hydrophobic impregnation was discussed to prevent blistering.

Prolonged rainy conditions in the efficacy of concrete protection

Hydrophobic impregnation is the most widely employed method to combat chloride attack for concrete structures. According to the UK Design Manual for Roads and Bridges, it is required to apply impregnates onto dry surfaces, after natural drying for 24 h following wet conditions. Achieving a dry surface in this manner results only in superficially dry concrete in a structure that has been exposed for a prolonged period of wet conditions. In this study, a silane-based material and a water-based material were evaluated, each applied on concrete cubes subjected to moisture pre-conditioning for up to 48 h. The test cubes were all surface dried prior to the application of the impregnate, and then submerged in sodium chloride solution for 60 d, before collecting dust samples at various depths, by dry drilling. When applied in dry conditions, the silane-based impregnate was more effective than the water-based one. The performance of both impregnates was significantly reduced when the concrete was subject to wet conditions for long periods. Internal moisture thus has a significant effect on the performance of the impregnates. A practical interpretation is that the specified 24 h drying period may not be sufficient to secure the benefit from hydrophobic impregnation.

シラン系浸透性吸水防止剤の性能評価─欧州規格（EN 1504-2）との比較─

シラン系浸透性表面含浸材を対象に，国内外それぞれの規格に基づく性能評価試験を実施し，得られた測定値ならびに測定値に基づくグレーディングを比較した。その結果，含浸材塗布により止水性能は著しく向上し，塩化物イオン浸透抵抗性も著しく向上するものの，中性化抑制にはほとんど効果がないこと，および標準的な塗布量を超えて施工しても止水性能には影響しないことがわかった。欧州規格と国内規格の要求事項を比べた場合，共通の評価項目が少なく，かつ試験条件も大きく異なるため，評価結果の直接比較は困難であることが確認された。

Optimizing the Mechanical Strength of Adobe Bricks

AbstractEcologic building materials such as adobe bricks have become of greater economic importance in recent years. In the present work, the addition of selected materials to improve the compressive and bending strengths of adobe bricks was tested. The raw material (loam UD) was analyzed for its mineralogical and chemical composition. The loam studied consisted of quartz, feldspar, and the clay minerals chlorite, vermiculite, illite, and kaolinite. Prerequisites for using this loam for brick making were its grain-size distribution and the absence of expandable clay minerals.To optimize the compressive and bending strengths of the adobe bricks, seven natural and ‘eco-friendly’ synthetic additives were admixed with the raw material and homogenized.From this material, small adobe bricks and bars were made. One series of bricks and bars was made without additives but instead was coated with a hydrophobic impregnation cream. The bricks were stored for up to 20 days at 100 and 75% relative humidity (RH). After 1, 5, and 20 days, the compressive and bending strengths were measured to identify the critical humidity level for brick strength. The compressive and bending strengths of loam UD at dry conditions without additives showed values of 9 N/mm2 and 4.8 N/mm2, respectively. With some of the additives, the strength improved by up to 30%. The greatest increases in strength were achieved by mixing the loam with Acronal S650. Finely ground trass and diatomite also increased the dry strength. After storage at high levels of RH, these mixtures lost &gt;50% strength. In contrast, the loam mixed with blast-furnace slag has a small initial strength but showed the smallest decreases in strength after exposure to high levels of RH.

Silicon-Microemulsions-Konzentrate / Silicone Microemulsion Concentrates

The technology of silicone microemulsion concentrates eliminates for the first time the use of organic solvents in the hydrophobic impregnation of mineral building materials and coatings, in coating-priming and in wall-drying by drill hole injection. Water-based silicone microemulsions meet the requirements such as effectiveness, durability, aplication, toxicity and ecology. The use of water instead of organic solvents and the modern concentrate technique make an effective contribution to environmental protection.