Papers by Keyword: Water Resistance

Abstract: The article provides some information about gypsum concrete, its applications, and the advantage of using organic fillers compared to mineral ones. The optimal technology for the production of gypsum concrete mix was determined, and an economically attractive type of organic filler in the form of chopped corn stalks was established. The compressive strength of the resulting material was studied depending on the fraction of crushed stone used. Effective methods for combating shrinkage cracks at the stage of manufacturing prototypes have been identified, which allows increasing the bearing capacity of the samples by 2.5 times. The water resistance and water absorption of the material, as well as their effect on strength, were investigated. As a result of experimental studies, it was found that the optimal concrete compositions with filler fractions of 3-5 and 5-10 mm should be considered 1:1 and 1:1.5 by volume (binder: filler), which can provide sufficient compressive strength (13-23 MPa) for blocks and slabs of internal partitions and good water resistance (0.91-1.0), while having good sound-absorbing properties.

Abstract: Weak water resistance is a big obstacle for clay materials to overcome in modern construction industry. Compared to the hydraulic stabilized additives, bio-additives have a lower carbon footprint and have been used in many vernacular construction techniques to immobilize clay. In this work, the traditional recipes of tannin and iron have been revisited, in particular, the question of pH and iron solubility has been explored. Oak tannin and FeCl₃ were chosen and their influence on the properties of clay materials in terms of rheological properties, compressive strength, and water resistance were characterized in the lab. Based on the results, tannin can reduce the yield stress of paste while with the addition of FeCl₃, the yield stress of tannin dispersed pastes increased to a value similar to the reference sample but lower than the value contain only FeCl₃. The increase was attributed to the complex reaction between tannin and Fe³⁺. The iron-tannin complexes can also increase the samples’ strength and water resistance. Although the complexes did not change the hydrophilic properties of the samples’ surface, they prevent the ingression of water. These results are very promising as they allow the production of a fluid earth material that is water-resistant. This opens a wide range of application potentials and can help to mainstream earth materials in construction.

Abstract: In the current context, the development of new bio-based and local building materials is becoming mandatory. Among them, earthen materials have a strong potential to be used as sustainable structural materials but their variability and their water sensitivity impact their mechanical properties that are difficult to guaranty. Recent developments have emphasised the ability of some bio-based additions to help to ensure these properties: linseed oil and xanthan gum are part of them. In this paper three different Breton earths, representative of a certain local variability, are studied. The impact of the selected bio-based additions on earths’ rheological behaviour is followed in order to adapt it to different forming processes. Then, the mechanical properties of different earth-addition combinations at the dry state, exposed to hygric variations and immersion are investigated for different forming processes. The findings highlight the fact that xanthan gum and linseed oil have a relevant ability to stabilise earthen blocks, that can be processed using different promising forming methods.

Abstract: Today, glued timber products occupy a significant place in the volume of finished products of modern construction and woodworking enterprises. Plywood is one such product. The durability and structural characteristics of plywood depend on the quality of binder, the type of wood and the quality of veneer. The paper explores the technology of ultraviolet treatment of thermally modified birch veneer with subsequent production of waterproof plywood. The results of a study on the influence of the operating parameters of veneer modification on the complex of sorption and strength characteristics of plywood materials are presented. It is established that the combination of thermal modification of wood throughout the entire volume with surface treatment with ultraviolet radiation allows creating glued wood material with increased water resistance and high-quality adhesive interaction.

Abstract: Magnesia binders provide strength to the stone, but have one drawback-low resistance and salt resistance. Increasing water and salinity tolerance, mechanical strength of the hardening magnesia binders can be achieved by introducing the system of micro-aggregates. The quality criteria that determine the activity of the micro filler are: high chemical resistance to water, aggressive media, high mechanical strength. Among the effective microfillers composite magnesia binders include diopside, wollastonite. It is shown that the introduction of 60-80 wt%. wollastonite or diopside with a specific surface of 2000-3500 cm²/g provides significant improvement in strength and water resistance that allows you to lengthen the lifespan and maintain the required quality of products based on composite of magnesia binders.

Abstract: Energy saving is one of today’s biggest challenges. Since the construction industry is very energy intensive, there is a question of drastic reduction of energy consumption in all types of buildings. There are different approaches to this issue, but ultimately there is a need to create materials that have high thermal resistance.

Abstract: Straw fiber (SF)/polylactic acid (PLA) composites were prepared from SF and PLA. The effects of the composite SF/PLA mass ratio investigated in terms of mechanical properties, water resistance, crystal structure, and thermal properties were investigated. These composites were characterized by scanning electron microscopic (SEM), X-ray diffractometric (XRD), differential scanning calorimetric (DSC), and thermogravimetric analyses (TGA). The results showed that, when the SF/PLA mass ratio was 3/7, the mechanical properties and water resistance of these composites were the best. When the mass ratio exceeded 3/7, the interface compatibility in the composites decreased. As the SF/PLA mass ratio increased, the crystallinity and the heat resistance of the composites were decreased.

Abstract: A molded pulp is increasingly used as eco-packaging, but it has poor water resistance. Therefore, surface coating is common to perform on pulp or paper packaging to overcome this shortcoming. In this study, the bagasse (BG) molded pulp sheets were mono-and bilayer coated with nanofibrillated cellulose (NFC), modified NFC (mNFC), and shellac (S) by using a spin coating technique. Surface morphology, surface wettability, water absorption, and mechanical properties of the coated sheet samples were evaluated and compared to the uncoated sample. It was found that mNFC could effectively provide an even and complete coverage coating layer on the BG-based sheet (BG/mNFC), thanks to the partially substituted ester groups. On the contrary, NFC could not be coated evenly on the BG-based sheet surface (BG/NFC) due to its tendency towards agglomeration. The homogeneity of surface obtained from the first layer coating by NFC or mNFC affected the surface quality of the second layer coating by shellac. As a result, the BG/mNFC/S bilayer coated sample showed the smoothest surface and also the highest water resistance confirmed by SEM, contact angle measurement, and water absorption results. Furthermore, the tensile properties of both bilayer coated samples (BG/NFC/S and BG/mNFC/S) were significantly improved (p<0.05) as compared to the uncoated BG sample. This results suggested that the current bilayer coating system is very promising for advancing the performance of molded pulps in novel packaging uses.

Abstract: One of the main components of urban design and landscape architecture that shapes and emphasizes the urban environment are small architectural forms. These elements of landscape architecture are used outdoors, so the material is influenced by a variety of atmospheric phenomena (temperature fluctuations, insolation, etc.). The results of the experiments showed that increased water resistance rates reduce the degree of exposure of the aggressive liquid medium, in particular sulfate and magnesium surface and groundwater, and frost resistance create conditions for the operation of these samples outdoors. The whiteness of the obtained results indicates that the obtained composition of concrete can be used as decorative with the addition of colored pigments.

Abstract: Modified graphene (MG) incorporated into a matrix of polyvinyl alcohol (PVA) were prepared by a hydrothermal method and ultrasonic dispersion. The effect of high MG content on the properties of composite films was studied. Due to the chemical reaction between MG and PVA, the water resistance and electrical conductivity were improved. The properties of new film and the possibility of its application as conductivity materials were discussed.