•Realizes the value-added reuse of waste sandstone resources.•Micron quartz grains <150 µm can improve compressive strength and ASR property.•Provides a convenient method in testing ASR.•S-sand ...produced from sandstone by-product can be used as high-quality fine aggregate.
The construction industry is facing a shortage issue of river sand, therefore broadening new sources of fine aggregate is imminent. This paper demonstrates the feasibility of a recycled sand from sandstone waste in mortar manufacturing by comprehensive assessment of workability, mechanical properties, water absorption, alkali silica reaction (ASR). The recycled sandstone sand (S-sand) has a smoother microscopic morphology and better particle size distribution than river sand (R-sand). Fine particles smaller than 150 µm in R-sand usually contain a large amount of impurities (such as clay) and are considered harmful. However, the S-sand containing ∼15.7% µm quartz grains <150 µm significantly improves the mortar performance in terms of compressive strength and ASR property. At the same water to binder ratio, the mortar using the S-sand shows worse workability than that using R-sand but a slight increase of water to binder ratio or adding water reducer improves not only the workability but also mechanical properties. For the ASR test, the S-sand shows potential uncertain risk as per ASTM C 1260. Using calcined clay or fly ash to replace 25% cement can effectively inhibit expansion risk. The compressive strength is reduced due to ASR, however, as the ASR progresses, it is somehow restored. This study also finds the good linear relationship between length change of mortar bar and mass change, which can be used to predict the sand ASR property. The results showed that S-sand produced by waste sandstone by-products can be used as high-quality fine aggregate.
Background; Bakery products such as cakes are widely consumed all over the world; so, their enrichment with nutrients is an effective way to prompt the people health. This goal can be achieved using ...the powder of dried fruit and vegetable in cake formulation.
Scope and approach; In this paper, the effects of dried fruits and vegetable powder (apple, quince, orange, various berries, grape pomace, mango, peach, melon, carrot, pumpkin and mushroom) on the batter rheology, physicochemical properties, organoleptic aspects and microbial attributes of the cakes were reviewed. It was determined that these kinds of powder raised the fibers content and nutritional values of the cakes (antioxidants, vitamins and minerals). The high water absorption capacity of the fiber affects batter rheology, the texture, volume, density and microbial attributes of the cake.
Key finding and conclusion; In conclusion, powder of fruit and vegetable exhibited benefits of attracting the consumers by improving appearance, texture, nutritional values, sensorial properties and shelf life of the cake.
•Bakery products such as cakes are widely consumed all over the world.•Powder of dried fruits and vegetables are good source of nutrients.•Cake formulation with this is an effective to prompt the people health.•The powder affects color, texture, nutritional and sensorial aspects of the cake.
Around 1000 million waste tyres are generated annually and over 5000 million more are estimated to be discarded by 2030. It is estimated that one waste tyre is discarded per person in developed ...areas, hence 1 billion waste tyres are disposed worldwide. Waste tyre is difficult to manage as it takes up space, is difficult to compress and combustion of tyre releases highly toxic substance into the air. Hence, most of them end up in the landfill, as past research data estimated that currently 4 billion waste tyres can be found in landfills. In this study, up to 30% tyre rubber with a fine grind size of 300nm to 500nm was used as partial sand replacement in type N cement mortar. The rubber was treated with 1M NaOH solution to enhance its ability to bond with the other constituent materials. Tests were conducted to determine the properties of rubberised mortar, including consistency, compressive strength, flexural strength, water absorption and acid attack. From the test result, tyre rubber reduced the consistency and strength of mortar. Mathematical regression model showed that reduction of strength occurred in a second-order polynomial function with percentage of rubber. It was concluded that at up to 20% replacement rubberised mortar has the best resistance against water absorption and acid attack while still achieving the target strength.
A study on the cross-linking of fluorinated acrylate and siloxane waterborne polyurethanes was carried out in order to produce a material with improved waterproof property. ...Trimethylolpropane-tris-(β-
N
-aziridinyl) propionate was employed as a simple, fast curing and low cost crosslinking agent. It follows that the acquired polyurethane film had the lowest water absorption and highest water contact angles so far among this series of compounds, and has better mechanical/thermal properties once the fluoride acrylic monomer content reaches 8 wt% and polyether modified polydimethylsiloxane content is 10 wt%. Once the crosslinked structure is acquired, the overall performance of the polyurethane films are enhanced,
i.e.
the water absorption decreases to 3.48% and
n
-heptane swelling decreases to 1.02%, the hardness reaches 6H and the tensile strength also rises to 33.2 MPa. Such eco-friendly crosslinked polyurethane films with outstanding waterproof property can find various applications in corrosion protection and optoelectronic devices.
Fluorinated acrylate and siloxane waterborne polyurethanes with crosslinked structure exhibit low water absorption, high water contact angles, and high mechanical/thermal properties.
The upper part of the prosthesis is called a socket, which contacts the amputated part. While wearing the prosthesis, there are several problems that the patient may suffer from, such as shear force ...between the socket and amputated part, pressure on the bony prominences, sweating, and bacteria generation, all leading to skin problems and a bad smell. It makes the patient refuse to wear the prosthesis because it is uncomfortable. Therefore, the aim of this study was comfortable lining from silicone rubber which cross-links at room temperature, with properties corresponding to the needs of this application, such as stress distribution, moisture absorption, and antibacterial.In the current work, silicone rubber was selected with the addition of nano-fillers (ZnO, Mg(OH)2, and Chitosan). Mechanical and physical properties were studied (tensile strength, tear strength, hardness, water absorption, porosity, and antibacterial).Chitosan showed the highest effect on the mechanical properties of silicon, as it achieved the highest value of tensile strength of 2.2 MPa elongation of 572%, tear strength 13.9 kN/m, and shore A hardness of 33.3. While the highest value of the modulus, 0.636 MPa was achieved by adding ZnO. The results also showed an increase in the water absorption and the porosity, which were the highest values at 1.6 % and 0.24%, respectively with the addition of Mg(OH)2. The samples showed a clear resistance to preventing the microorganisms growth.Manufactured linings require additional improvement in mechanical properties by mixing more than one type of additives mentioned in the research. Thus, physical and biological properties can be obtained simultaneously with mechanical properties.The above results qualify the silicone rubber composites for use as a socket liner due to their flexibility and ability to absorb water in addition to their resistance and prevent the growth of fungi and bacteria.The method of preparation and properties of the lining material and additives qualify it for such applications as physical and biological properties.
The study examines the impact of WGP on the resistance of mortar to sulfuric acid solution attack, with specimens containing 0%, 5%, 10%, 15%, 20%, 25%, and 30% WGP produced as cement substitutes. ...Some fundamental properties of mortar mixtures were evaluated, such as the pozzolanic activity index assessment, fresh density, water absorption, and compressive strengths during water curing times. Subsequently, the behavior characteristics of mortars when subjected to sulfuric acid solutions were assessed, including mass loss, residual compressive strength, visual inspection, and microstructure features during eight weeks of immersion in sulfuric acid. The results of the study indicated that the incorporation of WGP led to improved sulfuric acid resistance in the mortar. Furthermore, an increase in WGP content resulted in a reduced reduction in compressive strength against sulfuric acid attacks as the ages progressed. The study revealed that the mortar containing 5% WGP as a cement substitute had the highest compressive strength compared to other specimens, and using 10% WGP as a supplementary cementitious material was comparable to the control mixture. Finally, the microstructure tests indicated that the sample containing 5% WGP had a lower intensity of CH peaks than the reference sample. The study suggests that the optimum amount of GWP for strength and economic parameters is 5%, and 10% substitution, respectively. However, when considering acid solution resistance, 25% GWP cement replacement is the ideal content.
•Effects of high temperature on the properties of HSSC-LWAC were explored.•Water absorption by high temperature-damaged HSSC-LWAC was studied.•Microstructural evolution of HSSC-LWAC after 200 and ...800 °C was observed.•The high temperature resistance increases as the LWA content increases.•The damage evolution of HSSC-LWAC after high temperature was well exhibited.
An experimental investigation on the influence of elevated temperatures on the thermal resistance, water absorption and microstructure of high-strength self-compacting lightweight aggregate concrete (HSSC-LWAC) is presented. In total, 315 concrete specimens from 7 different mixtures with different replacement ratios (0, 30 %, 50 % and 100 % by weight) of two kinds of LWAs, namely cloud concrete stone (CCS) and fly ash ceramsite (FAC), were prepared. The workability of fresh concrete mixtures including slump, J-Ring and T500 tests was first conducted aiming at meeting the requirements of self-compacting performance. Hardened concrete specimens were then exposed to different elevated temperatures (i.e. 200 °C, 400 °C, 600 °C and 800 °C) increased with a heating rate of 10 °C/min. A series of tests including the apparent morphology, ultrasound pulse velocity (UPV), residual compressive strength and capillary water absorption were carried out on unheated control concrete and after air-cooling period of heated concrete. Finally, the thermal analysis and microstructural observation were further conducted through the thermogravimetry (TG), differential scanning calorimetry (DSC), mercury intrusion porosimetry (MIP), laser scanning microscopy (LSM) and scanning electron microscope (SEM) to characterize the evolution of high temperature damage. Generally, the high temperature resistance of HSSC-LWAC shows an increasing trend as the LWAs content increases, while the residual mechanical strength increases and then decreases with an increase of the temperature gradient. The microstructural observation indicates that the evolution behavior of thermal damage promotes the continuous development of micropores in the interfacial transition zones (ITZ) to form wider microcracks, resulting in the degradation of residual mechanical properties.
•A spraying method, which could save material and time, was proposed to strengthen recycled coarse aggregate.•The solution/slurry absorption was proposed and taken as the spraying control ...criterion.•Influences of the spraying method on the properties of RCA and compressive strength of RAC were studied.•The strengthening effects of the soaking method and the spraying method were basically the same.
Strengthening recycled coarse aggregate (RCA) by soaking it in a variety of solutions/slurries is being explored by many researchers. However, several problems have appeared, for example, (i) plenty of solution/slurry is needed; (ii) the soaking process is time-consuming; (iii) it is difficult to integrate the soaking process into the recycled aggregate (RA) production line. To effectively enhance RCA and save material and time, a spraying treatment method, using sodium silicate based solution/slurry, was proposed based on the solution/slurry absorption property of RCA. The influences of the spraying method on RCA and recycled aggregate concrete (RAC) were tested, including the apparent density, crushing value, 24 h water absorption, dynamic water absorption, and compressive strength. A comparative study was also conducted between the spraying method and the soaking method. To reveal the influence mechanism, scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) were adopted. The scheme of the integration of the spraying process was also discussed. Results showed that RCA was basically saturated during 3 spraying cycles when the flow rate was 4 g/s per kilogram RCA, and only about 1 min was needed to treat RCA using the spraying method. The crushing value and 24 h water absorption were decreased. When silica fume was incorporated, the crushing value was further decreased, but the 24 h water absorption was increased. The apparent density was increased slightly when the single sodium silicate solution was used, however, the apparent density was decreased slightly when silica fume was incorporated. Based on the dynamic water absorption, a three-stage model was proposed which could be used to evaluate the evolution of workability of recycled aggregate concrete (RAC) and make a proper water supply scheme. The compressive strength of RAC was enhanced when the treated RCA was used regardless the treatment method. It is worth noting that the strengthening effects of the spraying method and soaking method were basically equivalent, however, less material and time were required when the spraying method was used.
This work deals with characterizing concrete based on baobab trunk fibers for thermal in- sulation in buildings. The aim is to study the effect of the fiber content and the type of fiber treatment on ...the hygroscopic and thermo-physical properties of the concrete. Therefore, two types of treatment were carried out: an alkaline treatment and a thermo-alkaline treatment. Hygroscopic test results (34.25% to 54.92% for fiber content ranging from 14% to 28%) show that adding fibers to concrete makes them more sensitive to water. However, thermochemical treatment of the fibers reduces this water sensitivity. The thermal conductivities of concrete range from 0.202 to 0.086 W/m.K for the same fiber content. These results show that these biomaterials can be used in construction to improve building insulation.
In order to contribute to the reduction of energy consumption in building exploitation, we proposed to study the properties of a bio-based building material. This work deals with the characterization of a concrete based on baobab trunk fibers for thermal insulation in buildings. The aim is to study the effect of the fibers content and the type of fibers treatment on the hygroscopic and thermo-physical properties of the concrete. Therefore, two types of treatment were carried out : an alkaline treatment and a thermo-alkaline treatment.
The hygroscopic results show that these concretes are more sensitive to water than the control concrete. This high water absorption of these bio-based materials restricts their application in the construction field. However, we noted that the thermochemical treatment of the fibers better contributed to the reduction of this water sensitivity of the concretes. The thermal conductivity varies between 0.202 W.m-1.K-1 and 0.086 W.m-1.K-1. These results show that these biomaterials can be used in construction to improve insulation in buildings. The experimental thermal conductivities are close to those of the self-consistent model applied to the concrete.
Baobab fibers – Cement -Thermal conductivity -Density -Water absorption -Self-consistent.
The combination of biomimetic scaffolds and nano drug delivery has been proposed to be an effective solution to the inherent limitations of the former in regulating cell behavior and bone tissue ...regeneration. Herein, a series of three-dimensional (3D) aspirin-loaded polylactic acid/graphene oxide (PLA/GO) porous biomimetic nanofibrous composite scaffolds (PBNCSs) was successfully prepared by phase separation. Results showed that the PLA/GO scaffolds have a biomimetic nanofibrous porous structure and a thin GO film covering the PLA nanofibers, which endows the latter with significantly improved hydrophilicity. Close interactions were noted in the GO–PLA interface. GO reduced the mechanical properties of the composite scaffolds but increased their thermal stability. The water absorption rate increased from 12.5% to 206.81% as the GO content increased from 0 to 5%. Addition of GO improved the deposition rate and amount of hydroxyapatite on the scaffolds. Overall, the PLA/GO PBNCSs demonstrated good cytocompatibility and sustained-release performance.
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•The prepared PLA/GO scaffold can mimic the structure of the natural extracellular matrix.•The water absorption of PLA/GO scaffold can reach 206.81%.•The prepared scaffold has good bioactivity and cytocompatibility.•The prepared nanofibrous scaffold has a good sustained release for aspirin because of nano-size effect.
