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.

scholarly journals Hydrophobisation of mortars containing waste polyurethane foam

2018 ◽  
Vol 163 ◽  
pp. 04006 ◽  
Author(s):  
Danuta Barnat-Hunek ◽  
Sylwia Duda ◽  
Monika Garbacz ◽  
Grzegorz Łagód
Keyword(s):  
Contact Angle ◽  
Polyurethane Foam ◽  
Physical And Mechanical Properties ◽  
Lightweight Aggregate ◽  
Silicone Resin ◽  
Methyl Silicone ◽  
Freezing And Thawing ◽  
Thawing Processes ◽  
The One ◽  
Hydrophobic Material

This paper investigates the physical and mechanical properties of mortars modified with waste polyurethane foam (WPF) and the influence of hydrophobising agents on the physical characteristics. The sand was substituted with WPF (2-4 mm grain size) in the mortars which consisted of 5, 10 and 15% of foam, respectively. The contact angle of lightweight mortars was determined (θw) in the function of time, prior to and after the frost resistance test. The surface free energy characterizing the wettability and adhesion of mortars under normal conditions and following frost erosion was calculated with Neumann’s method based on the obtained data. The structure of mortars, adhesion of lightweight aggregate to cement paste and the structure of thin hydrophobic film were demonstrated by means of scanning electron microscopy. The mortars subjected to hydrophobisation process revealed a slight mass change caused by freezing and thawing processes: 0.1% for methyl silicone resin, 2.1% for alkyl-alkoxy-silane, and 9.2% for the samples which were not hydrophobized. On average, the contact angle of the standard mortars was 3 times lower than the one of hydrophobic material. The best results illustrating the efficiency of hydrophobisation were obtained for methyl silicone resin.

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.

Hexamethyldisiloxane-Plasma Coating of Wood Surfaces for Creating Water Repellent Characteristics

Holzforschung ◽  
1999 ◽  
Vol 53 (3) ◽  
pp. 318-326 ◽  
Author(s):  
A. R. Denes ◽  
M. A. Tshabalala ◽  
R. Rowell ◽  
F. Denes ◽  
R.A. Young
Keyword(s):  
Contact Angle ◽  
Treatment Time ◽  
Hydrophobic Surface ◽  
Plasma Coating ◽  
Building Blocks ◽  
High Water ◽  
Water Repellent ◽  
Macromolecular Structure ◽  
Water Contact ◽  
Wood Surfaces

Summary Southern yellow pine wood surfaces were modified under cold plasma conditions in order to create water repellent characteristics. The surface chemistry of the plasma “polymerized” hexamethyldisiloxane (PHMDSO) deposited onto wood surfaces was investigated using Electron Spectroscopy for Chemical Analysis (ESCA) and Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR). The presence of a crosslinked macromolecular structure, based on Si-O-Si and Si-O-C linkages was detected. Pyrolysis Mass Spectroscopy (MS) was carried out to investigate the nature of the building blocks of the plasma generated macromolecular structure. Plasma modified samples exhibited very high water contact angle values (contact angle = 130 degrees) in comparison to the unmodified samples (contact angle ≤ 15 degrees), indicating the presence of a hydrophobic surface. Atomic Force Microscopy (AFM) images, collected both from unmodified and HMDSO-plasma modified samples, indicate the progressive growth of the plasma “polymer”, resulting in the deposition of a smooth layer at 10 minutes treatment time. Differential Thermal Analysis (DTA) indicated high thermal stability of the PHMDSO.

scholarly journals Application of waste tyre rubber chips as coarse aggregate in concrete

2020 ◽  
Vol 30 (3) ◽  
pp. 328-334
Author(s):  
Z Muyen ◽  
F Mahmud ◽  
MN Hoque
Keyword(s):  
Coarse Aggregate ◽  
Lightweight Concrete ◽  
Physical And Mechanical Properties ◽  
Engineering Properties ◽  
Rubberized Concrete ◽  
Portland Cement Concrete ◽  
Lower Strength ◽  
Normal Concrete ◽  
Concrete Walls ◽  
Waste Tyre

The practicality and the engineering properties of portland cement concrete (PCC) and three types of rubberized PCC mixes prepared by partially replacing the conventional coarse aggregate with rubber were examined. The rubberized PCC mixes contained 5%, 10% and 15% waste tyre rubber chips as replacement of conventional coarse aggregate. Different physical and mechanical properties of the control (0% rubber chips) and the rubberized concrete samples were determined. A 5% replacement of conventional aggregates resulted in a 5% reduction of compressive strength, a 10% replacement resulted in a 26% reduction and a 15% replacement resulted in a reduction of 47%. A 5% replacement of conventional aggregates resulted in a 6% reduction of tensile strength, a 10% replacement resulted in a 33% reduction and a 15% replacement resulted in a reduction of 53%. A 5% replacement of conventional aggregates resulted in a 13% reduction of flexural strength, a 10% replacement resulted in a 33% reduction and a 15% replacement resulted in a reduction of 42%. Although concrete made from tyres had lower strength than the normal concrete, rubberized concrete can find its use in landscaping, sports field ground, architectural finishing, lightweight concrete walls etc. Progressive Agriculture 30 (3): 328-334, 2019

scholarly journals Evaluation of the Contact Angle of Hydrophobised Lightweight-Aggregate Concrete with Sewage Sludge

2015 ◽  
Vol 22 (4) ◽  
pp. 625-635 ◽  
Author(s):  
Danuta Barnat-Hunek ◽  
Piotr Smarzewski ◽  
Grzegorz Łagód ◽  
Zbigniew Suchorab
Keyword(s):  
Contact Angle ◽  
Sewage Sludge ◽  
Lightweight Concrete ◽  
Lightweight Aggregate ◽  
Contact Angles ◽  
Municipal Sewage ◽  
Municipal Sewage Sludge ◽  
Lightweight Aggregate Concrete ◽  
Aggregate Concrete ◽  
Surface Protection

Abstract 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 of lightweight aggregates modified with municipal sewage sludge. Issues related to the wettability of the surface layer of hydrophobised lightweight-aggregate concrete supplemented with sewage sludge are discussed in the paper. The experimental part of the study is focused on the physical and mechanical characteristics of lightweight-aggregate concrete and the effect of two hydrophobic preparations on the contact angle of the material. The contact angle for lightweight concrete (θw) was determined as a function of time using one measurement liquid. The hydrophobic coatings in the structure of lightweight concrete modified with sewage sludge were shown using electron microscopy. The investigations demonstrated the effectiveness of hydrophobisation of porous lightweight concretes. On the hydrophobic surfaces, the contact angles decreased with time and depended on the preparations used. The results of the research confirm the possibility to produce lightweight aggregate-concretes modified with sewage sludge with appropriate surface protection against external moisture.

Osteoconductivity of Superhydrophilic Ti- and Zr-Alloy for Biomedical Application

2016 ◽  
Vol 879 ◽  
pp. 2524-2527
Author(s):  
Masazumi Okido ◽  
Kensuke Kuroda
Keyword(s):  
Contact Angle ◽  
Water Contact Angle ◽  
Strong Influence ◽  
Biomedical Application ◽  
Hydrophobic Surface ◽  
Hydrophilic Surface ◽  
Water Contact ◽  
Zr Alloy ◽  
Zr Alloys

Surface hydrophilicity is considered to have a strong influence on the biological reactions of bone-substituting materials. However, the influence of a hydrophilic or hydrophobic surface on the osteoconductivity is not completely clear. In this study, we produced super-hydrophilic and hydrophobic surface on Ti-and Zr-alloys. Hydrothermal treatment at 180 oC for 180 min. in the distilled water and immersion in x5 PBS(-) brought the super-hydrophilic surface (water contact angle < 10 (deg.)) and heat treatment of as-hydrothermaled the hydrophobic surface. The osteoconductivity of the surface treated samples with several water contact angle was evaluated by in vivo testing. The surface properties, especially water contact angle, strongly affected the osteoconductivity and protein adsorbability, and not the surface substance.

Study on Performance of Recycled Aggregate Concrete

2011 ◽  
Vol 477 ◽  
pp. 280-289 ◽  
Author(s):  
Shao Wei Yao ◽  
Zhen Guo Gao ◽  
Chang Rui Wang
Keyword(s):  
Mechanical Properties ◽  
Coarse Aggregate ◽  
Physical And Mechanical Properties ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Chemical Solution ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate ◽  
Natural Aggregate ◽  
Strength And Durability

The properties of recycled coarse aggregate and the slump, the physical and mechanical properties and durability of recycled aggregate concrete were studied through tests. The results indicate that the slump, compressive strength and durability of concrete with recycled aggregate are lower than that of concrete with natural aggregate when recycled coarse aggregate fully absorbs water. However, the slump can be similar to that of concrete with natural aggregate. The properties of recycled aggregate concrete can be improved by strengthening the recycled coarse aggregate, and it is also found that the recycled coarse aggregate strengthened by grinding is superior to that soaked by chemical solution.

Effects of Loading Percentage of Polyurethane in Lightweight Concrete

2013 ◽  
Vol 357-360 ◽  
pp. 1082-1085 ◽  
Author(s):  
Kamarul Aini Mohd Sari ◽  
Sohif Mat ◽  
Khairiah Haji Badri ◽  
Muhammad Fauzi Mohd Zain
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Lightweight Concrete ◽  
Palm Kernel ◽  
Physical And Mechanical Properties ◽  
Concrete Mixture ◽  
Experimental Program ◽  
Polymer Concrete ◽  
Optimum Level ◽  
Methylene Diphenyl Diisocyanate

An experimental program was performed to obtain the density, compressive strength, and thermal conductivity of palm-based lightweight concrete. Palm-based polyurethane (PU) particles were used as lightweight aggregates in creating concrete systems. Concrete systems contain palm kernel oil-based polyol (PKO-p) reacted with 2,4-methylene diphenyl diisocyanate (MDI). In this study, polymer concrete was improved to achieve the optimum level of PU with the lowest possible density. The PU particles in the concrete mixture comprised of 1% to 5% w/w with density of less than 1800 kg/m3. The PU particles were 5 mm in size. The ratio of PKO-p to MDI was set at 1:1 and the loading of the concrete mixture was set at 3% w/w to produce lightweight concrete. The resulting concrete has excellent compressive strength (17.5 MPa) and thermal conductivity (0.24 W/mK). Results show that the PU particle dosage has the most significant effect on the physical and mechanical properties of concrete.

scholarly journals The Effect of the Morphology of Coarse Aggregate on the Properties of Self-Compacting High-Performance Fibre-Reinforced Concrete

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1372 ◽  
Author(s):  
Krzysztof Ostrowski ◽  
Łukasz Sadowski ◽  
Damian Stefaniuk ◽  
Daniel Wałach ◽  
Tomasz Gawenda ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
Coarse Aggregate ◽  
Fresh Concrete ◽  
Physical And Mechanical Properties ◽  
Concrete Mixture ◽  
Rheological Parameters ◽  
Transverse Strain ◽  
Fibre Reinforced Concrete ◽  
High Performance Fibre

When understanding the effect of the morphology of coarse aggregate on the properties of a fresh concrete mixture, the strength and deformability of self-compacting high-performance fibre-reinforced concrete (SCHPFRC) can be seen to be critical for its performance. In this research, regular and irregular grains were separated from granite coarse aggregate. The morphology of these grains was described while using digital image analysis. As a result, the aspect ratio, roundness and area ratio were determined in order to better understand this phenomenon. Then, the principal rheological, physical, and mechanical properties of SCHPFRC were determined. The obtained results indicated that the morphology of the grains of coarse aggregate has an impact on the strength and stiffness properties of SCHPFRC. Moreover, significant differences in the transverse strain of concretes were observed. The morphology of the coarse aggregate also has an impact on the rheological parameters of a fresh concrete mixture. To better understand this phenomenon, the hypothesized mechanism of the formation of SCHPFRC caused by different morphology of coarse aggregate was proposed at the end of the article.

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