Water Absorption Measurements Research Articles

Effect of bio-stabilizers on capillary absorption and water vapour transfer into raw earth

While raw earth can be used as a structural material, its water sensitivity limits its use in modern construction. Earth has a strong affinity with water. Both water imbibition and water vapour transfer have to be taken into consideration. This affinity can be a positive point to regulate indoor ambience, but it can also negatively affect earth’s mechanical properties. To avoid this possible detrimental effect, bio-based additions are used all around the world to stabilize, protect from water and enhance the mechanical properties of earth-based building materials. Bio-based stabilizers have to limit liquid water absorption and maintain mechanical properties without acting as a water vapour barrier that can lead to durability issues. In this article, capillary water absorption and water vapour permeability measurements are performed for combinations of various earths and bio-based additions (linseed oil, xanthan gum, casein, alginate and tannins). Linseed oil and xanthan gum help to protect the earth-based samples from absorbing liquid water without affecting the water vapour transfer in these materials.

Green adsorbents for copper (II) biosorption from waste aqueous solution based on hydrogel-beads of biomaterials

An innovative prototype machine was invented for hydrogel bead production, used for preparing novel hydrogel beads, based on biomaterials, fabricated from chitosan (CS), poly(vinyl alcohol) (PVA) and their blend for heavy metal removal from aqueous solution. The adsorption capacity of copper (II) ion onto the beads as adsorbents with their varying compositions and pH from aqueous solution was investigated. The properties of beads were determined using FTIR, SEM-EDX analysis and elemental mapping analysis, and water absorption measurement. The results showed that the CS, PVA and their blend were successfully crosslinked with glutaraldehyde solution. The swelling ratio, equilibrium water content and adsorption capacity depended on their compositions and pH. The spherical appearance of PVA hydrogel bead (PHB) exhibited the equilibrium swelling ratio higher than PVA/CS hydrogel bead (PCHB) and CS hydrogel bead (CHB), respectively. However, the adsorption capacity of copper (II) ion onto CHB was higher than PCHB and PHB, respectively. This behavior is due to their reactive sites being increased, resulting in the increase of interaction between copper (II) ion and CS molecules. Besides, the contact time directly affected the adsorption capacity in aqueous solution. Additionally, it was found that the pseudo-second-order exhibited the best fit for the kinetic studies, indicating the copper being limited by chemisorption process and the mechanism diffusion was controlled by intraparticle diffusion process. All the studied results indicated that hydrogel beads were an efficient and reusable adsorbent for the removal of copper (II) ion from aqueous solutions.

Production of Green Cement from Slag Enhanced by Egyptian Metakaolin Materials

New geopolymer-based materials offer excellent perspectives for the future; they should not be regarded as competitive materials for Portland cement, which has been the reference construction material for so long, but as alternative materials with a series of important advantages to be considered. Metakaolin (MK) produced from firing kaolin material up to 750 ºC for 2 h with a heating rate of 5ºC/min; leads to an enhancement in mechanical and microstructural properties of alkali activated geopolymer of water cooled slag material using (6:6, wt%) of sodium hydroxide and sodium silicate. In the present work the ratios of MK which will be added are less than 20% of the total mass, because of the used MK was very fine with average pore structure less than 30 mµ, which hinders the geopolymerization reaction if used as high ratio. Curing was performed under 100% relative humidity at a temperature of 38ºC and ages of 7, 14, 28 & 90 days. The properties of geopolymer specimens have been studied through measurement of XRD, SEM imaging, FTIR, compressive strength and water absorption. Results showed that the mixes of metakaolin up to 15% results in an enhancement in the mechanical properties as compared with slag control mix up to 90 days.

Assessment of Soil and Fungal Degradability of Thermoplastic Starch Reinforced Natural Fiber Composite

High water absorption capacity and low biodegradation of fiber reinforced composites are the major drawbacks, which limit their applications in different sectors. Development of composites with complete biodegradability is challenging as biodegradability may be incomplete by lowering of its water adsorption capacity. In this work, a series of thermoplastic starch (TPS) reinforced jute (10–40 wt%) composites were developed by compression molding and measured by their mechanical properties. The composite with 30% jute showed the maximum tensile strength (27.3 MPa). Contact angle, and water absorption measurements exposed that composites are moderately hydrophobic in nature. Both soil burial and fungal degradation testing showed biodegradability of composites. Characterizations of optimized composite before and after biodegradation test, were carried out by FTIR, SEM and optical microscope. The present study showed promise on feasible applications of jute-starch composites in packaging, automobile sector, cutlery, indoor furnishing, etc. as a substitute of plastic-based composites.

Effect of APPT Treatment on Mechanical Properties and Durability of Green Composites with Woven Flax.

Through this study, two different natural fibres green composites were characterised from the point of view of mechanical properties and durability. These green polymers allow manufacturing with a respectful life cycle due to their biodegradable or recyclable character. Composite materials were prepared in a hot plates press with two biopolymeric matrices, green low density polyethylene (GPE) and polybutylene succinate (PBS). As reinforcement, Atmospheric Pressure Plasma Torch (APPT) treated and untreated unidirectional woven flax were used. Mechanical properties were evaluated by tensile tests and the adhesion between matrices and reinforcement by peeling tests. The durability of each composite was analysed by water absorption measurements, Fourier Transform Infrared Spectroscopy (FTIR) analysis and tensile tests, during several aging times, up to 60 days, under high temperature and humidity conditions. The influence of the Atmospheric Pressure Plasma Torch treatment (APPT) was evaluated in all studies. It was found that GPE composites present better durability against aging conditions than PBS materials, due to the tendency of polyester to hydrolyse compared to the good resistance to humidity of polyolefins. The adhesion between matrices and reinforcement improves with APPT treatment. This improvement is more evident by avoiding the absorption of water than in the mechanical properties results, where only a slightly improvement is shown.

High-added-value biomass-derived composites by chemically coupling post-consumer plastics with agricultural and forestry wastes

Currently, the ever-increasing post-consumer polypropylene (PP) plastics and agricultural and forestry wastes that are relatively difficult to be degraded have led to serious resource waste and environmental pollution. To achieve the rational utilization of resources and meanwhile reduce the potential influences on ecological environment, in this study, high-added-value biomass-derived composites were produced by chemically coupling post-consumer plastics with agricultural and forestry wastes (e.g. pine nutshell and corn straw) in the presence of interfacial compatibilizers. In terms of chemical composition, the as-proposed compatibilizer contains CC bonds and NCO group, which can be effectively enhance the interfacial compatibility and mechanical stability of hydroxyl-rich biomass wastes and plastics. Experimental results conclude that the highest tensile strength of forestry pine nutshell/PP composite is 25.44 MPa and the flexural strength is 47.84 MPa with the assistance of 5.0 wt% compatibilizer. If agricultural corn straw is used as the raw materials, the highest flexural strength of corn straw/PP composite is 42.94 MPa and the tensile strength is 22.60 MPa under the same experimental conditions. Besides the improved mechanical properties, the thermal stability and water retardation capacity of the produced biomass-waste/PP composites is enhanced with the addition of the chemical compatibilizer as confirmed by thermal gravimetric analysis and water absorption measurements. This conversion of the post-consumer plastics and the biomass wastes into the environmentally benign high-added-value composite materials is favorable to promote the recycling economy and achieve the recyclable utilization of these wastes that are harmful to environment.

Evaluating the effectiveness of DAP as a consolidant on Turkish building stones

DAP is a new, bio-inspired consolidant already proven to be useful for limestones. In this study, we investigate the effectiveness of DAP on four different types of Turkish stones; Ankara (andesite), Bitlis (andesite), Mardin (limestone) and Nevsehir (ignimbrite). The effectiveness was analysed by means of weight, water absorption, surface hardness, surface roughness, color change, UPV and DRMS measurements. The DAP treated samples were exposed to weathering and a control set treated with TEOS for comparison. The DAP treatment performed comparably to TEOS resulting in an overall improvement in mechanical properties, without significantly altering water absorption or colour properties.

Water absorption of recycled aggregates: Measurements, influence of temperature and practical consequences

Recycled Concrete Aggregates are highly porous and may therefore absorb more water than natural aggregates. Several methods allow for the measurement of water absorption requiring drying at temperature above ambient conditions. We show here that, for temperatures above the ambient temperature (>30 °C) and at low relative humidity, the drying of recycled aggregates removes some bounded water contained in hardened cement paste and increases both measured porosity and water absorption. Porosity and XRD suggest that porosity increases due to ettringite dehydration. Thus, the drying step required to characterize recycled aggregates leads to a systematic overestimation of the water absorption. Moreover, this overestimation induces an error in mix-design leading to a higher effective water/cement ratio. If absorption and water content are measured with the same preparation protocol, correction is not needed. We finally propose a correction method for the water absorption measured according to the standard protocol (drying at 105 °C).

Green composites based on Atriplex halimus fibers and PLA matrix

Abstract This work focuses on the potential use of cellulose fibers extracted from Mediterranean saltbush (Atriplex halimus) as a filler in the polymeric matrix. The fully biodegradable composites were prepared from polylactic acid (PLA) as matrix and microcellulose fibers ranging from 0 to 15 wt.%. The influence of the fiber content on the structure, mechanical, thermal, and water absorption properties was evaluated. Mechanical results indicated that fibers acted effectively as reinforcement, increasing the tensile strength and the Young’s modulus of PLA by 25 and 45%, respectively. This is due to the good stress transfer between fibers and matrix through the strong interactions that have been evidenced by Fourier Transform Infrared (FTIR) spectroscopy. The thermogravimetric analysis showed that PLA composites have a slightly lower degradation temperature than the pure PLA, but they still have favorable thermal stability. Water absorption measurements and biodegradability tests showed that the addition of fibers accelerates degradation kinetics and confirm that the prepared composites are an environmentally safe material suited for different applications.

Quantitative Measurement of Water Absorption of Coarse Lightweight Aggregates in Freshly-Mixed Concrete

The high water-absorption of lightweight aggregate causes a high slump loss and poor workability of concrete. A prewetting process is usually recommended to compensate for the workability problem, but its application needs more delicate consideration in field. A method is proposed to measure the additional water absorption of lightweight aggregate, and its application in cement paste and concrete mixes confirms the absorption amount remaining unaffected by the mix proportion. The additional water absorption in cement-based materials can be considered as a material property, and its value is smaller than the water absorption measured by a standard test method (water-soaking). Compensating the additional water absorption finally allows to use dry lightweight aggregates for concrete, which is more robust and stabler than taking a saturated surface-dry lightweight aggregates.

The Influence of Corn Straw Extrusion Pretreatment Parameters on Methane Fermentation Performance.

The aim of the study is to determine the energy consumption of the extrusion-cooking process of corn straw under various conditions (screw speed, moisture content), water absorption measurements and water solubility indices as well as biogas efficiency evaluation. The extrusion-cooking of corn straw was carried out using a single screw extruder with L/D = 16:1 at various rotational screw speeds (70, 90, and 110 rpm) and with various initial moisture content of raw material (25 and 40%). Prior to the process, the moisture content of the raw material was measured, and next, it was moistened to 25 and 40% of dry matter. For example, at 70 rpm extruder screw speed, the temperature range was 126–150 °C. Energy consumption of straw pretreatment through extrusion-cooking was assessed in order to evaluate the possibility of using the process in an agricultural biogas plant. Biogas and methane efficiency of substrates after extrusion was tested in a laboratory scale biogas plant and expressed as a volume of cumulative methane production for fresh matter, dry matter, and dry organic matter. Pretreated corn straw moistened to 25% and processed at 110 rpm during the extrusion-cooking processing produced the most advantageous effect for methane and biogas production (51.63%) efficiency as compared to corn straw without pretreatment (49.57%). Rotational speed of the extruder screw influenced biogas and methane production. With both dry matter and dry organic matter, the increase of rotational speed of the extruder screw improved the production of cumulated biogas and methane. Pretreatment of corn straw has a positive effect on the acquisition of cumulated methane (226.3 Nm3 Mg−1 for fresh matter, 243.99 Nm3 Mg−1 for dry matter, and 254.83 Nm3 Mg−1 for dry organic matter). Preliminary analysis of infrared spectra revealed changes in the samples also at the molecular level, thus opening up the possibility of identifying marker bands that account for specific degradation changes.

Synthesis and attributes of nano-SiO2 local metakaolin based-geopolymer

The present experimental study treats the synthesis of local meta-kaolin based geopolymer with and without incorporation of nano-silica. The physical behavior was examined by compressive strength, water absorption, density and ultra-pulse velocity measurements. The XRF, XRD and FTIR were used to investigate the chemical composition and structural properties of the synthesized geopolymers, while the microstructural characteristics were studied by SEM, optical transmittance and MIP analysis. The XRD and FTIR spectra showed that the addition of 5% nano-silica increased the amorphous structure and improved the nucleation site of geopolymer gel. Moreover, the addition of nano-silica densified the geopolymer matrix as shown by SEM and MIP analysis and confirmed by the trends of the optical transmission, water absorption and density values. Furthermore, the increase in the compressive strength was noticed with 5% addition of nano-silica at 20 °C and 80 °C. However, the increase in the compressive strength at 28 days for the nano-silica geopolymer was more significant at 20 °C as compared to the 80 °C. In addition, TG analysis revealed that the nano-silica geopolymers have shown greater weight loss compared to the control geopolymer. Finally, the experimental results have shown the possibility of using the local clay for the synthesis of alkali activated geopolymer; however, the detailed eco-environmental considerations are necessary for its industrial applicability.

Biocomposites of Bio-Polyethylene Reinforced with a Hydrothermal-Alkaline Sugarcane Bagasse Pulp and Coupled with a Bio-Based Compatibilizer

Bio-polyethylene (BioPE, derived from sugarcane), sugarcane bagasse pulp, and two compatibilizers (fossil and bio-based), were used to manufacture biocomposite filaments for 3D printing. Biocomposite filaments were manufactured and characterized in detail, including measurement of water absorption, mechanical properties, thermal stability and decomposition temperature (thermo-gravimetric analysis (TGA)). Differential scanning calorimetry (DSC) was performed to measure the glass transition temperature (Tg). Scanning electron microscopy (SEM) was applied to assess the fracture area of the filaments after mechanical testing. Increases of up to 10% in water absorption were measured for the samples with 40 wt% fibers and the fossil compatibilizer. The mechanical properties were improved by increasing the fraction of bagasse fibers from 0% to 20% and 40%. The suitability of the biocomposite filaments was tested for 3D printing, and some shapes were printed as demonstrators. Importantly, in a cradle-to-gate life cycle analysis of the biocomposites, we demonstrated that replacing fossil compatibilizer with a bio-based compatibilizer contributes to a reduction in CO2-eq emissions, and an increase in CO2 capture, achieving a CO2-eq storage of 2.12 kg CO2 eq/kg for the biocomposite containing 40% bagasse fibers and 6% bio-based compatibilizer.

The Use of Contact Sponge Method to Measure Water Absorption in Earthen Heritage Treated with Water Repellents

ABSTRACT Earthen heritage represents an important legacy regarding construction history and technological development, with a significant cultural value that must be preserved. According to UNESCO, around 10% of the World Heritage is built using earth, and 57% of these heritage structures are in danger. Although the interest regarding earthen heritage has grown in the last few years, there is still a significant lack of knowledge in terms of material characterization, especially from conservation science point-of-view. In particular, tests regarding water absorption are always difficult to perform with a material that changes completely when in contact with water. Indeed, due to the presence of clay particles, a normal capillarity test is almost impossible to perform. Moreover, water is responsible for a significant number of degradation phenomena often found in earthen heritage. As a result, there is an urgent need to develop suitable water repellent treatments and to evaluate their efficiency. For this reason, this study focuses on the contact sponge method to assess water absorption rates for adobe and for rammed earth specimens treated with three different water repellents — siloxane, linseed oil, and beeswax. Two sets of specimens were prepared and tested, showing that this method can represent an effective way to measure initial water absorption in earthen materials, and promising results from the tested water repellent treatments were found.

Engineering Properties of Basalt Fiber-Reinforced Bottom Ash Cement Paste Composites.

Extinction of natural resources builds up pressure on governments to invest in research to find more sustainable resources within the construction sector. Earlier studies on mortar and concrete show that bottom ash and basalt fiber are independently alternative binders in the concrete sector. This study aims to use bottom ash and basalt fiber blends as alternative novel-based composites in pure cement paste. The strength and durability properties of two different percentages of bottom ash (40% and 50%) and three volume fractions of basalt fiber (0.3%, 0.75%, and 1.5%) were used at three curing periods (7, 28, and 56 days). In order to measure the physical properties of the basalt-reinforced bottom ash cement paste composites flowability, dry unit weight, porosity, and water absorption measurements at 7, 28, and 56 days of curing were performed. Furthermore, the mechanical properties of composites were determined by unconfined compressive strength and flexural strength tests. Finally, to assess the durability, sulfate-resistance and seawater-resistance tests have been performed on composites at 28 and 56 days of curing. Results showed that the addition of basalt fiber improves the physical, mechanical, and chemical stability properties of paste up to a limiting basalt fiber addition (0.3% volume fraction) where, above, an adverse effect has been monitored. It is clear that observed results can lead to the development of sustainability strategies in the concrete industry by utilizing bottom ash and basalt fiber as an alternative binder.

Water loss during dynamic recrystallization of Moine thrust quartzites, northwest Scotland

AbstractInfrared absorption measurements of molecular water in sheared Cambrian quartzites in the footwall to the Moine thrust reveal a decrease in water content from 4080 to 1570 ppm with increasing recrystallization traced toward the overlying thrust at the Stack of Glencoul in northwest Scotland. These results are contrary to the expected correlation between shear strain and water content for quartz deformed by dislocation creep and water-weakening processes. The observed inverse correlation indicates that fluid inclusions and hydrous defects within grains were lost by mobile grain boundary sweeping and grain boundary diffusion. Although reduced water contents might lead to hardening as chemical weakening is diminished, quartz mylonites in the immediate footwall (5 mm) to the thrust are characterized by intense strain localization and contain the least water, and there is little evidence of shear zone widening. Water weakening appears to have been important throughout the quartz mylonites, controlled by the presence of water, not by water concentration. Fluids present within relict inclusions and at grain boundaries may have governed the high water fugacities critical for water weakening.

Enhancement of mechanical, thermal and water uptake performance of TPU/jute fiber green composites via chemical treatments on fiber surface

Abstract Chopped jute fiber (JF) surfaces were modified using alkaline, silane and eco-grade epoxy resin. Surface characteristics of jute fibers were confirmed by FTIR and EDX analyses. JF filled polyurethane elastomer (TPU) composites were prepared via extrusion process. The effect of surface modifications of JF on mechanical, thermo-mechanical, melt-flow, water uptake and morphological properties of TPU-based eco-composites were investigated by tensile and hardness tests, dynamic mechanical analysis (DMA), melt flow index (MFI) test, water absorption measurements and scanning electron microscopy (SEM) techniques, respectively. Mechanical test results showed that silane and epoxy treated JF additions led to increase in tensile strength, modulus and hardness of TPU. Glass transition temperature (Tg) of TPU rose up to higher values after JF inclusions regardless of treatment type. Si-JF filled TPU exhibited the lowest water absorption among composites. Surface treated JFs displayed homogeneous dispersion into TPU and their surface were covered by TPU according to SEM micro-photographs.

Multifunctional hybrid structures made of open-cell aluminum foam impregnated with cellulose/graphene nanocomposites

This work focuses on exploring combinations of disintegrated bacterial cellulose nanofibres (BC) with graphene oxide (GO) (reduced and non-reduced) and phase change materials (PCMs) prepared in the form of foam-like structures. The presence of GO remarkable improves the fire-retardancy and provides dimensional stability to the foams while PCMs gives thermal energy storage capacity. The foams were exposed to methyltrimethoxysilane (MTMS) vapour to become hydrophobic which was confirmed by measuring water absorption capacity and water contact angle. To extend the multifunctionality of these nanocomposite foams, a selected composition was impregnated into an open-cell aluminium foam creating a hybrid structure (Al-BC/GO) with higher mechanical properties (increase in stress of 100 times) and high sound absorption coefficient (near 1 between 1000-4000 Hz). The low thermal conductivity confirms that this hybrid structure is a thermal insulator. These advantages highlight the potential applications of the proposed materials e.g. construction, automotive and aeronautical sectors.

Paraffin as a Phase Change Material in Concrete for Enhancing Thermal Energy Storage

Phase change material (PCM) for thermal energy storage (TES) is the material that can absorb energy during heating process as phase change takes place and release energy to environment during cooling process. Nowadays, energy consumption trends in construction building show a significant increase. It is important for reducing energy consumption in building by decreasing the energy demand and providing thermal human comfort inside the building. The objectives of this research are to determine the optimum percentage of PCM in concrete affected by time to achieve high thermal storage performance and evaluate the mechanical properties in different percentage of PCM concrete. Various percentage of 0%, 5%, 10% 15% and 20% of PCM concrete added with Ground Granular Blast Slag (GGBS) as filler were prepared and tested after 7 and 28 days of curing process. The result shows the thermal storage energy effective when integration with PCM in concrete. Besides, the compressive strength, water absorption and density measurement decrease with increasing amount of PCM. In conclusion, 5% of PCM with 30% GGBS added in concrete resulted in better thermal energy storage and compressive strength compared to other percentages of PCM concrete samples.

The Influence of 30 Years Outdoor Weathering on the Durability of Hydrophobic Agents Applied on Obernkirchener Sandstones

The durability of eleven different water repellents applied on one sandstone type was studied after a long-term weathering at seven different locations in Germany. By measuring colour changes, it could be shown that the formation of black crusts, the deposition of particles and biogenic growth caused a gradual darkening as well as significant changes in total colour over time. Additionally, the water absorption behaviour was investigated with two different methods: applying a low pressure using the pipe method and capillary water absorption measurements from a wet underlay. Afterwards, the test results were analysed with four different evaluation methods: calculation of the protection degree from pipe method and capillary water absorption, determination of the velocity of water uptake during capillary water absorption and calculation of the damaged depth of the stone surface using single-sided NMR technique. The growing damaged depth leads to an increase of the water uptake velocity and to a decrease of the protection degree of the applied hydrophobing agents. Three protective agents based on isobutyltrimethoxysilane showed already after two years of outdoor weathering a clear loss of performance, which significantly increased after 30 years of exposure.