Waterproofing Effect Research Articles

An antimicrobial film of silver/nanocellulose crystal/oxalic acid/polyvinyl alcohol with real-time bactericidal and prevention of biofilm formation properties

Silver nanoparticles (AgNPs) is an excellent antibacterial agent, which is widely used in medical, food, environmental and other fields, but AgNPs are easy to accumulate in aqueous solution, so their application in various fields is limited. Therefore, it is particularly important to propose a new application method or to prepare a new composite material. In this study, OA/PVA was obtained by cross-linking oxalic acid (OA) with polyvinyl alcohol (PVA). Then Ag/NCC was obtained by in situ reduction of AgNPs on nanocellulose crystals (NCC). Finally, Ag/NCC/OA/PVA composite antimicrobial films with good waterproofing effect were prepared by mixing Ag/NCC with OA/PVA. Subsequently, the films were characterized using SEM, UV–vis, FTIR and XRD, as well as physicochemical properties such as mechanical strength and hydrophilic properties were determined. The results indicated that the Ag/NCC/OA/PVA films possess good light transmittance, mechanical properties, water resistance, antibacterial activity, and biodegradability. The results of the mechanism study showed that Ag/NCC/OA/PVA films can destroy cell integrity, inhibit succinate dehydrogenase (SDH) activity, thereby reducing intracellular ATP levels. And induce a large number of reactive oxygen species (ROS) production, eventually leading to the death of C. sakazakii. In summary, Ag/NCC/OA/PVA film has good physical and chemical properties, antibacterial activity and biocompatibility, and has promising applications in food and medical antibacterial fields.

Preparation of cementitious osmotic crystalline waterproof material and its waterproofing mechanism analysis

Cementitious Capillary Crystalline Waterproofing materials (hereinafter: CCCW) with the advantages of good waterproof effect, green and low cost, it is widely used in the field of building waterproofing. Researchers and scholars have studied the proportioning of such materials. However, the experimental methods used in these studies are not perfect enough, therefore, this study uses a seven-factor, two-level orthogonal test method to conduct experiments and to study the waterproofing effect of CCCW coated on the substrate at different ages, and to discuss the existing waterproofing mechanism in conjunction with it. The results show that the group's homemade waterproofing agent has a good waterproofing effect, and the compressive strength is significantly increased at different ages, which suggests that CCCW can promote the hydration of cement and produce more penetrating crystals, thus blocking the capillary pores and microcracks, and making the matrix dense and waterproof.

Study on improvement of waterproofing performance of CCCW with silicone waterproof material and waterbased capillary inorganic waterproofer

The silicone waterproof material and waterbased capillary inorganic waterproofer possess the advantages of rapid film formation and significant hydrophobic effect. In this study, the material composition and mixing ratio of the silicone waterproofing material and waterbased capillary inorganic waterproofing were investigated by multiple performance tests. The results indicated that a white coating was formed on the surface when the mixing ratio of isobutyl-triethoxy-silane and isooctyl-triethoxy-silane was more than 69 %. When the content of sodium and potassium methyl silicate exceeded 0.5 %, respectively, there was an upward trend of contact angle while the reduction in water absorption gradually decreased. Meanwhile, the contact angle and water absorption height of silicone waterproof material were tested. The results showed that the coating performance and hydrophobicity were the best when the mixing ratio of isobutyl-triethoxy-silane, isooctyl-triethoxy-silane, sodium methyl silicate, and potassium methyl silicate was 1.5:0.2:1:0.5. When the matrix mortar specimen was made of Cementitious Capillary Crystalline Waterproofing Materials (CCCW), the lowest water absorption height and water absorption of the experimental group consisted of sodium silicate, sodium tetraborate, sodium phosphate, and sodium hydroxyethyl cellulose were 316.7 % and 39%, respectively. The lowest water absorption height and water absorption of the experimental group consisted of sodium silicate, sodium tetraborate, nano-silica, and sodium hydroxyethyl cellulose were 215.4 % and 28 %, respectively. The results showed that CCCW combined with the experimental group consisted of sodium silicate, sodium tetraborate, sodium phosphate, and sodium hydroxyethyl cellulose had better waterproofing effect.

Sandstone monuments still standing after storms: Waterproofing and durability protection

Using the Surface waterproofing to solve moisture expansion which leads to the acceleration of surface weathering of sandstone relics is a hot topic. This study focuses on surface coating protection because of the special status of cultural relics. The fluorinated ZnO/SiO2 nano-coating was applied on the sandstone matrix in this work. The loading of the fluorinated ZnO/SiO2 in the nano-coating, the penetration depth of the nano-coating in the sandstone matrix, and the waterproofing effect of the sandstone surface were investigated within the limitation of the color difference systematically. The freeze-thaw cycles, light exposure, water absorption, and aging tests were carried out to evaluate the environmental durability of the nano-coating in a simulated humid environment of southwestern of China. All the tests meet the criteria for the heritage protection color difference. When the loading of fluorinated ZnO/SiO2 nano-coating is 0.4%, the water contact angle (WCA) and oil contact angle (OCA) are significantly improved, which are larger than 160° and 140°, respectively. The WCA and OCA have little changed after freeze-thaw cycle for three weeks, and the WCA only decreases only 7% after 300 h UV aging treatment. This significantly enhanced stability is due to the good penetration depth of the fluorinated ZnO/SiO2 nano-coating on the sandstone matrix. Moreover, the excellent air permeability is achieved as well to ensure substrate breathing. This work would provide a new idea for the long-term protection of sandstone heritage in practical environment.

Study on the Improvement of Waterproof Performance of Historical Silt Sites with Silicone Waterproofing Agent

Silt has the characteristics of obvious capillary water effect and strong water sensitivity. The flooding of the Yellow River caused the water level in Kaifeng to be high, and the damage of capillary water to the silt site of Kaifeng Zhouqiao site is increasing day by day. In order to improve the waterproof performance of the site soil, three kinds of silicone waterproof materials were selected, and the site soil was improved by internal mixing. The improvement effects of different materials were compared through the capillary water rise test, and the contact angle of the modified soil with the optimal ratio was measured. Microscopic tests were conducted to evaluate its wetting properties and reveal the mechanism of action of the modified materials. The results show that the three kinds of silicone waterproofing agents can improve the waterproofing effect of soil, among which 0.5% sodium methylsilicate modified soil has the most significant waterproofing effect; its capillary water absorption inhibition effect can reach 98.34%, and the contact angle is 137.06. The surface of the modified soil is hydrophobic after the addition of sodium methylsilicate. An evenly distributed waterproof film is thus formed on the surface of the soil particles, which changes the contact mode between the soil particles and strengthens the connection between the soil particles, so that the proportion of large pores decreased. The proportion of mesopores and small pores increased, which made the soil sample more compact. These results explain the improvement of the waterproof performance of the soil sample.

The suitability of physical and chemical properties of rocks for land reclamation in different subzones of the Ukrainian Steppe


 
 
 The study of the properties of disturbed soils and rocks makes it possible to establish the parameters of the natural fertility of the studied substrates, to detect limiting factors, and to determine a set of restoration measures. The tested overburden rocks with the largest stratigraphic share of the open-pit quarries of the Nikopol manganese and Kerch iron ore deposits were loamy-like loess (Quaternary) and grey-green clay (Neogene). There is a certain parametric relationship between texture, density, porosity, the structural and physical state of different models of artificial reclaimed profiles. The composition and properties of rocks of edaphic structures of technosoils differ according to zonal natural and climatic conditions of the subzones of the Ukrainian Steppe. Loess-like loam and grey-green clay of the Kerch iron ore deposit are distinguished by a higher bulk density, lower porosity, and wilting moisture compared to samples from the Nikopol manganese ore basin. The use of the rotor complex leads to mechanical destruction and an increase in the content of small particles of rocks. Self-compacting processes occur to a large extent in multilayer structures. This pattern is observed at the boundary of the backfill differentiated in texture layers of technosoils. This indicates the existence of a barrier that prevents the relationship of edaphic properties between substrata stratums. Optimal ratio of clay minerals provides a rather high capacity of grey-green clay for water absorption. The model of technosoil composed of grey-green clay differs in a larger number of water-resistant micro-aggregates. The best conditions for land reclamation are connected with including grey-green clay in two- and three-layer constructions of technosoils, providing a waterproofing effect.
 
 

An impervious sand used as separation layer in collapsible loess embankment: A case study

In this study, a novel impervious sand is modified from the desert sand. It has a good waterproofing and thermal-isolating capacity. Hence. it was used as the separation layer in the collapsible losses embankment to prolong the service life. It has the advantages of lightweight, good waterproofing effect, and cycled usage. The application of impervious sand in collapsible losses embankment could constrain water immigration effectively. Hence, local collapsible losses could be used in highway construction, which means the construction cost could be saved to a large extent. In this study, an artificial fill and impervious sand of different thicknesses were both used in collapsible losses embankment. In-suit monitoring on soil temperature, water content, settlement, and strains of different directions were conducted for more than one year. Hence, the waterproofing effect between the artificial fill and impervious sand could be compared. Furthermore, the collapsible losses embankment side slope stability was calculated through a finite element model. The long-term performance of embankment stability, which took the filling loess’s water content into consideration, was also calculated and compared between the separation layer made of artificial fill or impervious sand.

Comparative Study of Different Types of Waterproofing Screeds with a Focus on Cohesion with Selected Building Materials after the Freeze-Thaw Exposure

The aim of the research was focused on the functionality of three types of waterproofing screeds from the perspective of their use in building structures. Bitumen, polymer, silicate (mineral) were studied in terms of their cohesion with the substrate and their sealing ability, used in combination with different building materials—ceramics, concrete, lime-sand bricks and marl stone, the permeability properties of which were taken into consideration, too. The cohesion was also studied after the freeze-thaw exposure to take into account the aspects of durability. During the experimental program, the basic waterproofing ability of all types of tested screeds applied on building materials was confirmed. Comparing the overall tested screeds, despite the best adhesion of the polymer-based screed, this material exhibited the lowest durability after the freeze-thaw exposure. The bitumen and silicate (mineral) screed attained similar values of adhesion to the studied base materials. However, they differ in their ability to withstand freeze-thaw cycles over time. The modified water permeability test on model masonry specimens was performed. No leakage of water during the test was monitored for the specimens with all types of applied screeds over time, and, in addition, water had not penetrated through the bricks, nor through the joints. The waterproofing effect of the screed is not affected by the joints in masonry.

The waterproofing effect and mechanism of graphene oxide/silane composite emulsion on cement-based materials under compressive stress

The influence of the water-to-binder ratio and compressive stress on the waterproofing effect of graphene oxide/isobutyltriethoxysilane (GS) composite emulsion on cement-based materials was investigated. The results show that GS combines with calcium silicate hydrate to form a hydrophobic film, which prevents the intrusion of external water and carbon dioxide. In addition, after undergoing self-condensation, silanol reacts with calcium hydroxide to generate calcium silicate hydrate gel, which improves the microstructure of cement-based materials. Furthermore, the increase in the water-to-binder ratio and stress ratio leads to the expansion and connection of the pore structure of cement-based materials, resulting in an increase in the capillary water absorption coefficient. Meanwhile, the higher porosity is conducive to the penetration of the emulsion in cement-based materials and the formation of a waterproof layer. Thus, the waterproofing effect of GS composite emulsion on the specimen was improved.

Printed Organic Light-Emitting Diodes on Fabric with Roll-to-Roll Sputtered ITO Anode and Poly(vinyl alcohol) Planarization Layer.

Electronic textiles, which are a combination of fabrics and electronics, can help realize wearable electronic devices by changing the rigidity of these textiles. We demonstrate organic light-emitting diodes (OLEDs) by directly printing the emitting material on fabric substrates using the nozzle-printing technique. Printing the emitting material directly on a fabric substrate with a rough surface is difficult. To address this, we introduce a planarization layer by using a synthesized 3.5 wt % poly(vinyl alcohol) (PVA) solution. The sputtered ITO anode with the thermally annealed PVA planarization layer on a fabric substrate achieves a low sheet resistance in the range of 60-80 Ω/sq, whereas the ITO electrode without a PVA layer exhibits high sheet resistance values of 10-25 kΩ/sq. This result is because the thermally annealed PVA layer on the fabric surface has a uniform surface morphology and a water contact angle as high as 96°, thus acting as a protective layer with a waterproofing effect; in contrast, the water is completely absorbed on the rough surface without a PVA layer. The fabric-based OLEDs with a thermally annealed PVA layer exhibit a lower turn-on voltage of 3 V and higher luminance values of 5346 cd/m2 at 8 V compared with the devices without a PVA layer (7 V and 3622 cd/m2) at 18 V. These fabric-based OLEDs with a PVA planarization layer can be produced by the nozzle-printing process and can achieve selective patterning as well as direct printing of the emitting material and ITO sputtering on a fabric substrate; furthermore, they emit well even when it bent into a circle with a radius of 1 cm.

Research on Waterproof Performance of Prefabricated Utility Tunnel with Different Types of Joints

In the waterproof system of prefabricated utility tunnel, rubber gasket is usually used at the joint of adjacent pipes. The waterproofing effect of prefabricated utility tunnel joint is mostly judged by the field water injection test and the practical effect of former project. In this paper, the finite element software ANSYS is used to carry out the finite element simulation for three types of joint waterproofing of prefabricated utility tunnel. Considering the uneven settlement of utility tunnel foundation, the influence of different staggered joint installation spacing on the waterproofing of the joints is analyzed. Thus, suggestions are provided for the selection of utility tunnel joint. For the prefabricated utility tunnel with side+end face and double-side joint waterproof type, the longitudinal distance between socket joints should be constrained within 3mm after the joint is installed. It is suggested that the end face+side joint waterproof type should be used for the collapsible foundation, and the longitudinal displacement of the control socket and socket should be less than 3mm. For non-collapsible and settled foundation, double-end joint waterproof type or side+end joint waterproof type can be selected.

The application of high-pressure rotary jet grouting curtain on the ocean engineering structure

The high-pressure rotary jet grouting curtain is a common water-proof structure in civil engineering. This paper analysed the application of high-pressure rotary jet grouting curtain in ocean engineering based on construction of the western man-made island of the Shenzhen-Zhongshan Channel project, modelling the pile forming, shearing strength, and water proofing effect, and emphasizes the key points in the construction.

Research on the Ecological Protection of Coal Gangue Slope Based on a Polymer Curing Agent

To improve the ecological protection of coal gangue slopes, this work developed a polymer curing agent using a pure acrylic emulsion and cement as the main raw materials. By testing the workability, waterproofing, durability, and adhesion of the curing agent with different polymer‐to‐cement ratios, the optimum mixing ratio of the polymer curing agent was obtained, and the protection mechanism was analysed based on the test results and by scanning electron microscopy (SEM). Then, simulated slope and practical engineering applications were carried out. The results show that pure acrylic emulsion curing agent with a polymer‐to‐cement ratio of 6 : 5 is most suitable for the ecological protection of coal gangue slopes. The polymer curing agent can form a network structure film layer with a good waterproofing effect on the coal gangue surface. Simultaneously, the network structure film layer can reduce the influence of weathering and leaching on the coal gangue, prevent the heavy metal elements in coal gangue from entering the surrounding soil, improve the growth environment of plants, and improve the effect of ecological restoration. This research can be applied to the ecological protection of coal gangue slopes.

Recent Advances and New Discussions on Superhydrophobic Coatings and Admixtures Applied to Cementitious Materials

Increasing the durability of buildings is one of the biggest challenges of the construction industry of the 21st century. The problems concerning durability are usually related to the presence of humidity or to water infiltration in the porous cementitious materials used in buildings. Advances in biomimetics have allowed the development of superhydrophobic surfaces and materials, with contact angles greater than 150°, which are able to repel water and aqueous products. In this context, this work summarizes the recent advances on superhydrophobic coatings and admixtures applied to cementitious materials. Recommendations for the future improvement of such products are made. The synthesis of superhydrophobic coatings generally includes the deposition of a low surface energy material (LSEM), especially fluoroalkylsilanes, on a microroughened surface, which, in cementitious materials, is usually achieved with the help of nanoparticles or micrometric molds. In this sense, variables as the spraying time duration, and the nanoparticles concentration, surface area and average particle size were identified as directly influencing the surface superhydrophobicity. Functionalized nanoparticles can also be introduced in cement matrix during the paste mixing in order to obtain a longer lasting waterproofing effect. In this case, hybrid nanosilica may react with Ca(OH)2 through pozzolanic reaction. The C-S-H formed may incorporate the organic group of hybrid nanosilica, and might present superhydrophobicity as well, modifying the composite’s microstructure. Besides, the cost of fabricating hydrophobic materials is decisive for their market entry. Hence, the partial or total replacement of fluoroalkylsilanes with less expensive LSEMs seems promising and needs to be further explored.

Improvement in the water resistance of MAPC coatings as a function of NaCl concentration

This study focused on the waterproofing effectiveness of magnesium ammonium phosphate cement (MAPC) coatings at different sodium chloride (NaCl) concentrations (0, 3, 5 and 7%). It included qualitative analyses and quantitative tests of the effect of sodium chloride on three characteristics: tensile strength, water absorption rate and thickness of coatings. The influence of the changes in the structure and composition of MAPC coatings on their water resistance performance was also analyzed. It was found that 3% sodium chloride concentration could remarkably improve the waterproofing effect of MAPC coatings. Another finding showed that tensile strength, water absorption rate and coating thickness increased at the very beginning but these decreased as the sodium chloride content increased. Moreover, compared with other concentrations, the structure and composition of MAPC coatings containing 3% sodium chloride were found to be stable in water. The coatings were bonded to the concrete more tightly, which resulted in a more compact structure and thus a higher water resistance effect.

Efficacy of iron-based bioproducts as surface biotreatment for earth-based plastering mortars

Abstract The use of bacteria for the enhancement of construction materials has been a focus of study in the past few years. Microbial cells have been applied to consolidate the surface of different materials. Earthen plasters are eco-efficient building products that can be applied on new buildings but also used to protect cultural heritage structures, with several advantages. They are based on abundant, affordable and easy to obtain materials, but are vulnerable to water. New eco-efficient bioproducts were developed based on E. coli cultures supplemented with iron, that can be obtained as an industrial by-product. They were applied in laboratory on an earth plaster surface and the biotreatment efficacy was assessed. The main objective was to improve the durability of the plastering mortar when exposed to water. An optimized E. coli-iron based surface biotreatment strongly increased the plaster resistance to water with the application of only 0.0625 mL/cm2 of E. coli++Fe leading to a significant increase of water absorption time in comparison with similar plasters where the same amount of water was applied. Moreover, all biotreatments produced an increase of resistance to water absorption creating a slight waterproofing effect, ensuring compatibility. Their loss of efficacy with time guarantees reversibility of the intervention. The results show the interest to perform an in-depth study on the microstructure of biotreated earth mortars to understand the biotreatment effect.

Efficiency of Crystalline Coating Measured by Contact Angle Method

The paper deals with two problems in the field of cement-based crystalline coating: The uncertainties about the depth effect of crystalline coating and the influence of curing on resulting waterproofing effect. For coating depth effect investigation the authors used a method based on the analysis of surface hydrophobicity (contact angle method). The depth effect of crystalline coating can be detected on the basis of the different surface hydrophobicity in various distances from the coated surface. The results of measurement showed that the tested crystalline coatings affect concrete microstructure to depth of approximately 50 - 60 mm (measured 4 months after the coating application). But it turned out that used method is not appropriate for this purpose because the results can be affected by a lot of influences and it is necessary be cautious about the conclusions. Another part of experimental program showed that the curing of crystalline coating during its ageing is absolutely necessary for the consequent waterproofing effect. This fact is also the risk factor for the using of crystalline coatings because the waterproofing effect is dependent on a consistent technological discipline.

The Speed of the Crystalline Admixture’s Waterproofing Effect in Concrete

There have been many experimental measurements of the waterproofing ability and durability of concrete with a crystalline admixture but there are uncertainties about the speed of the waterproofing effect caused by the crystalline admixture. The paper describes water pressure test carried out in different time intervals during the initial phase of cement hydration. The test results have shown that the full waterproofing effect of concrete with a crystalline admixture was available approximately on the 12th day after the concrete creation.

CRYSTALLINE ADMIXTURES AND THEIR EFFECT ON SELECTED PROPERTIES OF CONCRETE

There have been many experimental measurements of the waterproofing ability and durability of concrete with a crystalline admixture, but some other important properties have not been reliably tested yet. The results of the tests, carried out by the authors, showed that crystalline admixtures reduce the water vapor permeability of concrete by 16-20 %. The authors also carried out the water pressure test in different time intervals, during the initial phase of cement hydration. The test results have shown that the full waterproofing effect of concrete with a crystalline admixture is available approximately on the 12th day after the concrete creation. The crystalline admixture effect on the compressive strength of concrete was also the subject of the testing. The results have shown that the compressive strength of the concrete with a crystalline admixture (added in an amount of 2 %) and the compressive strength of the specimens from concrete without admixture were almost identical after 28 days.

Effect of fatty acid soap on microstructure of lime-cement mortar

Different additives based on Na oleate, Na oleate – Ca stearate and Al stearate were used in two different quantities (0.15 %w/w and 0.30 %w/w of the solid amount) to enhance the waterproofing effect of mortars. From capillary water absorption test, Na oleate showed the better performance with a reduction of water absorbed of 86% in comparison with the reference mortar. The microstructure showed the presence of microcavities ranging between 0.01mm and 0.2mm, due to air bubbles trapped during the mortar preparation for the surfactant effect of Na oleate. The presence of a higher amount of pores (210mm3/g vs. 175mm3/g) was confirmed by the Hg porosimetry. Moreover a reduction of the carbonation rate for the presence of additive was verified.