scholarly journals Durability of Hydrophobic/Icephobic Coatings in Protection of Lightweight Concrete with Waste Aggregate

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 101
Author(s):  
Danuta Barnat-Hunek ◽  
Jacek Góra ◽  
Marcin K. Widomski
Keyword(s):  
Frost Resistance ◽  
Lightweight Concrete ◽  
Physical And Mechanical Properties ◽  
High Porosity ◽  
Freezing And Thawing ◽  
Adhesive Properties ◽  
Surface Protection ◽  
High Durability ◽  
Before And After ◽  
Freezing And Thawing Cycles

The aim of the research presented in this paper is to evaluate the feasibility of using hydrophobic agents based on organosilicon compounds for surface protection of lightweight concrete modified with waste polystyrene. The experimental part pertains to the physical and mechanical properties of polystyrene-modified lightweight concrete. The concrete samples were prepared with the following ingredients: CEM I 42.5 R cement, recycled polystyrene (0–2 mm), quartz sand (0–2 mm), coarse river aggregate (2–16 mm), and water. Silane and tetramethoxysilane were employed for surface hydrophobization. Concrete with 20% polystyrene exhibits high porosity (25.22%), which is related to an increase in absorptivity (14.75%) compared to the reference concrete. The hydrophobized concrete is characterized by the lowest surface free energy (SFE) value, which is 7 or 11 times lower than the value of reference concrete, depending on the agents. The test on the contact angle (CA) was performed before and after the frost-resistance test (F–T test). Lower SFE translates into lower adhesive properties, higher resistance of the material to the infiltration of water and corrosive compounds, e.g., salts, and higher resistance to freezing and thawing cycles. Silane and tetramethoxysilane coating raised frost resistance by 54–58% compared to the reference samples. This agent reduced absorptivity by 30%. Recycled polystyrene can be successfully used to produce lightweight concrete (LC) with high durability provided by hydrophobic/icephobic coatings.

scholarly journals Concrete based on sulfur binder being modified with inorganic additives

2018 ◽  
Vol 212 ◽  
pp. 01013
Author(s):  
Vadim Balabanov ◽  
Victor Baryshok ◽  
Nikita Epishkin
Keyword(s):  
Frost Resistance ◽  
Building Materials ◽  
Physical And Mechanical Properties ◽  
High Strength ◽  
Strength Properties ◽  
Climatic Conditions ◽  
Freezing And Thawing ◽  
Concrete Mixtures ◽  
Irkutsk Region ◽  
Water Saturated

The sharply continental climate of the Irkutsk region is characterized by wide temperature intervals throughout the year. The repeated cyclicity of freezing and thawing of building materials in the water-saturated state influences the change in technical characteristics and the durability of concrete products and structures. The concrete products’ features in such climatic conditions create the need for the production of concretes with improved indicators of physical and mechanical properties. The effect of modifying additives on the technological characteristics of sulfur concrete is established. The effect of all elements of sulfur concrete on its strength and frost resistance. The composition of sulfuric concrete is obtained, which meets all the requirements and also has high strength and increased frost resistance. Formulations with a certain ratio of structural sulfuric concrete mixtures were developed. As a result of the use of technical sulfur in the composition of concrete products, the problem of utilizing annually accumulating reserves of technical sulfur is partially solved. The strength properties of sulfuric concretes easily compete with high-quality brands of concrete, special types of concretes that have in their composition additives.

scholarly journals Experimental Study on Freezing and Thawing Cycles of Shrinkage-Compensating Concrete with Double Expansive Agents

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1850
Author(s):  
Jinjun Guo ◽  
Ting Guo ◽  
Shiwei Zhang ◽  
Yan Lu
Keyword(s):  
Frost Resistance ◽  
Large Scale ◽  
Mass Loss Rate ◽  
Test Results ◽  
Freezing And Thawing ◽  
Expansive Agent ◽  
Hydraulic Concrete ◽  
Mix Proportion ◽  
Three Stages ◽  
Freezing And Thawing Cycles

The freezing and thawing of construction concrete is becoming an increasingly important structural challenge. In this study, a shrinkage-compensating concrete based on a double expansive admixture was developed and its frost resistance was assessed through rapid freezing and thawing cycling. The frost resistance of the concrete was derived through the measurement and calculation of the relative dynamic modulus of elasticity (RDME) and the mass loss rate (MLR), and the freezing- and thawing-cycle microstructures and products of concretes with different expansive agents were analyzed using scanning electron microscopy (SEM). It was shown that changes in the properties of the concrete under freezing and thawing could be divided into three stages: slow-damage stage, fast-damage stage, and stable stage. Compared to concrete without an expansive agent, a single-expansive-agent concrete demonstrated excellent frost resistance during the slow-damage stage, but the frost resistance rapidly decreased during the fast-damage age. After 150 cycles (the stable-damage stage), the concrete with a U-type expansive agent (UEA): MgO expansive agent (MEA) mix proportion of 2:1 had the best frost resistance, with RDME and MLR values 17.35% higher and 25.1% lower respectively, than that of an expansive-agent-free concrete. These test results provide a basis for the study of frost resistance in large-scale hydraulic concrete structures.

scholarly journals The analysis of influence of polymer admixtures on properties of lightweight concrete

2019 ◽  
Vol 252 ◽  
pp. 08007 ◽  
Author(s):  
Jacek Góra ◽  
Danuta Barnat-Hunek ◽  
Paweł Wlaź ◽  
Monika Garbacz
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Statistical Analysis ◽  
Lightweight Concrete ◽  
Strength Properties ◽  
Freezing And Thawing ◽  
Factors Of Influence ◽  
Freezing And Thawing Cycles ◽  
Acetate Copolymer

The article presents the results of testing physical and strength properties of concrete with the addition of lightweight perlite in the amount of 10 and 20%. The additive was introduced by volume substituting a part of the sand. In addition, the effect of using siloxane admixtures and a vinyl acetate copolymer with different degree of dosing, as well as applied simultaneously, were analysed. The tests were carried out in the field of bulk density and proper density, determination of tightness and porosity, compressive strength and tensile strength after 28 days of maturation. In terms of durability of concrete, absorption and resistance of concretes to the freeze-up effects after 100 freezing and thawing cycles were tested. The results of the study were subjected to statistical analysis using the analysis of variance. The analysed factors of influence were the amount of perlite addition, as well as the type and amount of the added admixture

Method for Computational Estimation of Frost Resistance in Aircraft Paint Coatings

2020 ◽  
pp. 4-17
Author(s):  
A.A. Aliyev ◽  
A.Yu. Аmpilogov
Keyword(s):  
Frost Resistance ◽  
Linear Thermal Expansion ◽  
Physical And Mechanical Properties ◽  
Temperature Cycling ◽  
Operating Conditions ◽  
Computational Method ◽  
Ice Accretion ◽  
Freezing And Thawing ◽  
Paint Coating ◽  
Paint Coatings

The paper considers the issues of temperature cycling and ice accretion on external paint coatings of aircraft as well as the negative effects of these processes expressed in periodic tension-compression strain and absorption of atmospheric moisture by surface microasperities with its subsequent freezing resulting in gradual cavity wedging. We note that laboratory testing methods recreating the temperature cycling that simulates actual operating conditions of aircraft paint coatings are increasingly labour-intensive. We substantiate the feasibility of developing a computational method for frost resistance estimation in specific operating conditions. The method takes into account the combination of contraction stresses, excessive cooling and wedging caused by ice build-up. We assume the main physical and mechanical properties of ice and paint to be homogeneous and equal to cumulative average values, and the linear thermal expansion coefficients of the substrate and coating to be constant and not dependent on temperature. We disregard ice friction over the microasperity cavities and in-flight loads on the paint coating caused by incident air flows and structural deformations of the aircraft. We present a method of computing frost resistance of aircraft paint coating subjected to cyclical ice accretion, which is based on the method of equivalent stresses. We tested frost resistance of a polyesterurethane coating over a duralumin plate in the range of --50 to 25 °C for F = 2000 freezing and thawing cycles. We performed a temperature cycling computation of the factor of safety for frost resistance in the case of periodic ice accretion. The results obtained are in good agreement with experimental data

scholarly journals Effect of Eco-Friendly Cellulose Nanocrystals on Physical Properties of Cement Mortars

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2088 ◽  
Author(s):  
Danuta Barnat-Hunek ◽  
Małgorzata Grzegorczyk-Frańczak ◽  
Monika Szymańska-Chargot ◽  
Grzegorz Łagód
Keyword(s):  
Weight Loss ◽  
Frost Resistance ◽  
Detrimental Effect ◽  
Physical And Mechanical Properties ◽  
Salt Crystallization ◽  
High Modulus ◽  
Freezing And Thawing ◽  
Low Thermal Expansion ◽  
Cement Mortars ◽  
Microstructure Examination

Nanocellulose, being a material with nanodimensions, is characterized by high tensile strength, high modulus of elasticity, low thermal expansion, and relatively low density, as well as exhibiting very good electrical conductivity properties. The paper presents the results of research on cement mortars with the addition of nanocrystals cellulose, applied in three different amounts (0.5%, 1.0%, and 1.5%) by weight of cement, including: physical and mechanical properties, frost resistance and resistance against the detrimental effect of salt, and microstructure examination (SEM). Along with an increase in amount of admixture, the weight loss following frost resistance and salt crystallization tests is reduced. Studies have shown that the addition of nanocrystalline cellulose improves the compressive and flexural strength by 27.6% and 10.9%, respectively. After 50 freezing and thawing (F–T) cycles for the mortars with 1.5% nanocellulose admixture, an improvement in frost resistance by 98% was observed. In turn, the sulfate crystallization tests indicated a 35-fold decrease in weight loss following 1.5% nanopolymer addition to the mortar.

Experimental Study of Remoulded Soil Properties Based on Freezing and Thawing Cycle

2015 ◽  
Vol 744-746 ◽  
pp. 490-494
Author(s):  
Jing Li ◽  
Zhi Nan Jiang ◽  
Jun Wei Li
Keyword(s):  
Mechanical Properties ◽  
Soil Properties ◽  
Physical And Mechanical Properties ◽  
Freezing And Thawing ◽  
Thaw Cycle ◽  
Remoulded Soil ◽  
Freeze Thaw Cycle ◽  
Change Trend ◽  
Mechanical Performances ◽  
Freezing And Thawing Cycles

The experiments were carried out on the remolded soil to study the change law of the soil properties with the numbers of freezing and thawing cycles. It aims at simulating the effect of natural environmental factors on the mechanical performances artificial filling roadbed in Songbei region. After the soil sample was compacted in the optimum moisture content, and undergone limited numbers of freezing and thawing cycles, physical and mechanical properties were measured respectively. The experimental results indicated distinct change trend on physical and mechanical properties of soil after limited numbers of freeze-thaw cycle to confirm that the fillings was susceptible of temperature and moisture in this region.

Study of Frost Resistance of 50 Years Concrete Exposed to Saline Areas

2013 ◽  
Vol 275-277 ◽  
pp. 1341-1346
Author(s):  
De Cheng Zhang ◽  
Yan Ping Lv ◽  
Zheng Mao Ye
Keyword(s):  
Frost Resistance ◽  
High Performance ◽  
Large Temperature ◽  
Freezing And Thawing ◽  
The North ◽  
Single Side ◽  
Concrete Mechanical Properties ◽  
Saline Area ◽  
Design Requirements ◽  
Freezing And Thawing Cycles

The Hong Run petrochemical oil depot is located in a saline area in the north of Weifang.This area is severe cold in winter and has large temperature span throughout a year. Due to the area's rigorous environmental conditions, concrete with 50 years durability and strength grade of C40 was fabricated with the ordinary Portland cement, high performance superfine mineral powder and high performance pumping agent. Tests using the onsite concrete samples show that concrete mechanical properties meet the design requirements. After 300 freezing and thawing cycles including accelerated freezing thawing method and single-side freezing thawing method, the quality loss rate and relative dynamic modulus both comply with the design requirements. This suggests that the sample concrete has excellent frost resistance ability.

Dependence of Relative Decreasing in Strength by Rate of Strain for the New Rapid Method for Determination of Concrete Frost Resistance

2015 ◽  
Vol 725-726 ◽  
pp. 505-510
Author(s):  
Olga Pertseva ◽  
Sergey Nikolskiy
Keyword(s):  
Tensile Strength ◽  
Rapid Method ◽  
Frost Resistance ◽  
New Method ◽  
Basic Method ◽  
Freezing And Thawing ◽  
Freeze Thaw ◽  
Freezing And Thawing Cycles ◽  
Non Destructive

The task of the project is obtaining the dependence between the relative decreasing of strength and rate of strain and substantiation of the new method for determination of concrete frost resistance. It has been analytically proved that using concrete’s rate of strain ε as a measure of damage, instead of decreasing of tensile strength R, increases freeze-thaw resistance’s accuracy of estimation a lot under otherwise equal conditions by the time of freeze-thaw cycling. Also it has been experimentally shown that ratio of relative decreasing R to ε in direction, perpendicular to compression, is assumed to be independent on values R and ε for a given concrete and on the ways of achieving them during mechanical or freeze-thaw cycling. To determine the dependence δR/R by ε (z) 8 specimens were tested by non-destructive method (RU 2 490 631) and two baths of 50 specimens by basic method (thermo cycling). Results of the non-destructive method are different from results by basic method for 6,3%. Dependence of relative decreasing in strength by rate of strain is near to linear and, therefore, value of z is constant. Taking this into account patented methods for estimation of concrete’s freeze-thaw resistance as per values R and ε received after freezing and thawing cycles of some specimens and their postlimenary failure by linear compression was substantiated.

scholarly journals Evaluation of the contact angle and wettability of hydrophobised lightweight concrete with sawdust

2020 ◽  
Vol 19 (2) ◽  
pp. 019-032
Author(s):  
Małgorzata Szafraniec ◽  
Danuta Barnat-Hunek
Keyword(s):  
Contact Angle ◽  
Coarse Aggregate ◽  
Lightweight Concrete ◽  
Physical And Mechanical Properties ◽  
Hydrophobic Surface ◽  
Water Repellent ◽  
Silicone Resin ◽  
Methyl Silicone ◽  
Organosilicon Compounds ◽  
Surface Protection

The aim of the research presented in the paper was to evaluate the feasibility of using hydrophobic preparations based on organosilicon compounds for protection treatment on the lightweight concrete modified with sawdust. The experimental part of the work concerns the physical and mechanical properties of lightweight concrete and the influence of two hydrophobic agents on the contact angle of the material. Lightweight concrete contact angle (θw) was determined as a time function using one measuring liquid. Water repellent coatings in lightweight concrete structure with the coarse aggregate sawdust (CASD) using electron microscopy were presented. The effectiveness of hydrophobisation of porous lightweight concretes was determined on the basis of the research. For the hydrophobic surface, the contact angle decreased and it depended on the used agents. The lowest contact angle of 40.2° (t=0) was obtained for reference concrete before hydrophobisation and 112.2° after hydrophobisation with a methyl-silicone resin based on organic solvent. The results of scientific research confirm the possibility to produce lightweight concretes modified with CASD with adequate surface protection against external moisture.

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