scholarly journals Prediction of Occurrence of Cracks due to Autogeneous Shrinkage and Drying Shrinkage.

2000 ◽  
pp. 29-44 ◽  
Author(s):  
Toshio OHNO ◽  
Taketo UOMOTO
Keyword(s):  
Drying Shrinkage ◽  
Autogeneous Shrinkage

scholarly journals DRYING SHRINKAGE, AUTOGENEOUS SHRINKAGE, THERMAL STRAIN AND ELASTIC STRAIN OF STEEL-MAKING SLAG CONCRETE

2007 ◽  
Vol 63 (3) ◽  
pp. 468-484
Author(s):  
Takashi FUJII ◽  
Akihiro FUJIKI ◽  
Toshiki AYANO ◽  
Kenji SAKATA
Keyword(s):  
Elastic Strain ◽  
Thermal Strain ◽  
Drying Shrinkage ◽  
Steel Making ◽  
Autogeneous Shrinkage

Modified gach technique vs critical point drying: Shrinkage analysis for SEM

1987 ◽  
Vol 45 ◽  
pp. 954-955
Author(s):  
B. Thompson ◽  
N. Sculov ◽  
R.E. Crang
Keyword(s):  
Critical Point ◽  
Calf Serum ◽  
Drying Shrinkage ◽  
Specimen Preparation ◽  
Cell Shrinkage ◽  
Whole Cells ◽  
Critical Point Drying ◽  
Prepared Material ◽  
Inverted Microscope ◽  
Phosphate Buffered Saline

The use of co-polymerized glutaraldehyde-carbohydrazide (GACH) was proposed for specimen preparation in scanning electron microscopy (SEM) as a means of avoiding dehydration in organic solvents, and to provide dimensionally stable biological specimens through a process of air-drying. It has been assumed that shrinkage of specimens prepared by the GACH technique should be less than that of conventionally-prepared material by critical point drying (CPD). In a previous study, Bell has reported significant shrinkage of whole cells for SEM. This report compares cell shrinkage in GACH and CPD preparations.Fibroblasts from newborn rats were grown on collagen-coated glass cover-slips (with alpha numeric grids etched onto the surface of the coverslips) in Eagle's minimum essential medium + 10% fetal calf serum for 7 d. (3). Using an inverted microscope with phase-contrast optics, micrographs were taken of the cultures in their live state and 1 h. after fixation with 2.5% glutaraldehyde in Dulbecco's phosphate buffered saline (Figs. 1 and 3).

Environmental microscopy of capillary stress-induced strain behavior in ambient-pressure aerogels

1996 ◽  
Vol 54 ◽  
pp. 850-851
Author(s):  
Sudeep M. Rao ◽  
Joshua Samuel ◽  
Sai S. Prakash ◽  
C. Jeffrey Brinker
Keyword(s):  
Silica Aerogel ◽  
Ambient Pressure ◽  
Drying Shrinkage ◽  
Pore Filling ◽  
Silica Network ◽  
Strain Behavior ◽  
Partially Saturated ◽  
Capillary Stress ◽  
Wetting Liquid ◽  
Aerogel Films

Ambient pressure silica aerogel thin films have recently been prepared by exploiting reversible drying shrinkage caused by derivatization of the internal gel surface. Aerogels have porosities of upto 99.9% and due to the small size of the pores (few nanometers), large capillary stresses are produced in gels that are partially saturated with a wetting liquid. As a result of these capillary stresses, the flexible silica network undergoes strain which has been observed using environmental microscopy. This technique allows variation of the equilibrium vapor pressure and temperature, and a simultaneous monitoring of the deformation of the unconstrained film thickness. We have observed >600% deformation during the pore-filling and pore-emptying cycles. In this presentation, we discuss the unique stress-strain behavior of these films.Ref.: Sai S. Prakash, C. Jeffrey Brinker, Alan J. Hurd & Sudeep M. Rao, "Silica aerogel films prepared at ambient pressure by using surface derivatization to induce reversible drying shrinkage", Nature. Vol. 374, 30 March, 1995, 439-443.

Standardization and bacteria inhibitory test of purified extract of mahogany (Swietenia mahagoni (L.) Jacq) seeds and leaves

2019 ◽  
Vol 10 (3) ◽  
pp. 2132-2138
Author(s):  
Virsa Handayani ◽  
Rezki Amriati Syarif ◽  
Ahmad Najib ◽  
Aktsar Roskiana Ahmad ◽  
Abdullah Mahmud ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Heavy Metal ◽  
Bitter Taste ◽  
Drying Shrinkage ◽  
Ash Content ◽  
Water Soluble ◽  
Lead Contamination ◽  
Specific Parameter ◽  
Chemical Content ◽  
Swietenia Mahagoni

Mahogany (Swietenia mahagoni (L.) Jacq) is one of the plants that is often used by the community as traditional medicine. One of them is antifungal, antibacterial, antidiabetic, and eczema. This study aims to obtain standardized extracts from mahogany seeds and leaves. Standardization of purified extract of mahogany has been carried out according to the monographs of extract standardization guidelines, which include testing of specific and non-specific parameters. The results of the specific parameter testing showed that the purified extract of mahogany seeds is a thick extract, brown to reddish, smells distinctive and has a bitter taste. While the purified extract of mahogany leaves is a thick extract, greenish-brown in color, distinctive smell and has a bitter taste. The chemical content of purified extract of mahogany seeds and leaves showed the presence of flavonoids, alkaloids, terpenoids and saponins. Water-soluble essence levels in mahogany seeds and leaves was 14.84% and 10.28%. While the ethanol-soluble essence levels in mahogany seeds and leaves were 15.38% and 12.43%. Testing of non-specific parameters on mahogany seeds and leaves showed the results of drying shrinkage levels of 0.22% and 8.84%, moisture content of 2.60% and 4.04%, total ash content of 1.71% and 1.93%, levels acidic insoluble ash 0.38% and 0.32%, Total Plate Number (ALT) of mahogany seed bacteria 1x102 colonies/g, Number of mahogany mold seeds 4x10 colonies/g, heavy metal lead contamination and cadmium in mahogany seeds 0.0607µg/g and<0.003µg/g. The inhibitory diameter of each concentration of seeds against Escherichia coli, 3%, 5%, 7%, and 9%, is 12,67; 13,67; 17,67; and 19,67 mm, respectively. The inhibitory diameter of each concentration of leaves against Escherichia coli, 3%, 5%, 7%, and 9%, is 10,27; 10,90; 13,46; and 15,68 mm, respectively.

Drying Shrinkage on Payday

2018 ◽  
Vol 56 (4) ◽  
pp. 354-354
Author(s):  
T. Hasegawa
Keyword(s):  
Drying Shrinkage

scholarly journals Incorporation of Natural Fibres in Rendering Mortars for the Durability of Walls

2021 ◽  
Vol 6 (6) ◽  
pp. 82
Author(s):  
Cinthia Maia Pederneiras ◽  
Rosário Veiga ◽  
Jorge de Brito
Keyword(s):  
Modulus Of Elasticity ◽  
Drying Shrinkage ◽  
High Water ◽  
Natural Fibre ◽  
Accelerated Ageing ◽  
Flax Fibres ◽  
Aesthetic Appearance ◽  
Cement Binder ◽  
Drying Rates ◽  
Adherence Strength

One of the main functions of renders, together with the overall aesthetic appearance of the building, is the protection of the walls against external aggressive actions, such as water, salts solutions, erosion, and mechanical impacts. However, some anomalies of renders may drastically hinder their protection ability. In fact, cracking, high water permeability, and loss of adherence to the substrate of renders limit their barrier effect and favour the exposure of the substrate to external actions. The incorporation of fibres in mortars is commonly pointed out to reduce their cracking susceptibility, due to the probable enhancement in tensile strength and ductility of the composite. The use of lime in substitution of the part of the cement binder is seen as a method to reduce the modulus of elasticity and therefore enhance the resistance to cracking due to drying shrinkage. Therefore, this study investigates the wall protection-related properties of natural fibre-reinforced renders with cement-lime as a binary binder at 1:1:6 volumetric ratio. With this purpose, wool, coir, and flax fibres are used at 20% by total mortar volume and the water behaviour, cracking susceptibility, and adherence to the substrate of the mortars are assessed. Specifically, the water absorption by capillarity, drying rates, permeability to water under pressure, adherence strength, and shrinkage are evaluated. In order to evaluate the renders’ durability and therefore the durability of the protection to the walls, an artificial accelerated ageing test is performed based on heating-freezing and humidification-freezing cycles. The results indicate that the fibres’ addition reduced the shrinkage and modulus of elasticity of the mortars, which suggests lower susceptibility to cracking. The addition of fibres in mortars seemed to slightly affect their water performance and only at early ages. From the results, it was concluded that the adherence strength is not affected by the fibres’ incorporation. The fibres seem also to reduce the impacts of the ageing cycles on the mortar and the improvements provided by the fibres’ addition to the mortars’ performance remained after ageing when compared to the mortars without fibres, thus being a potential alternative to increase their durability. These aspects are particularly important for buildings, since they can extend their service life and promote their sustainability.

scholarly journals The performance of ultra-lightweight foamed concrete incorporating nanosilica

2021 ◽  
Vol 21 (2) ◽  
Author(s):  
Mohamed Abd Elrahman ◽  
Pawel Sikora ◽  
Sang-Yeop Chung ◽  
Dietmar Stephan
Keyword(s):  
Wall Thickness ◽  
Probabilistic Approach ◽  
Drying Shrinkage ◽  
Dry Density ◽  
Optimal Dosage ◽  
X Ray ◽  
Mechanical And Physical Properties ◽  
Fresh State ◽  
Foamed Concrete ◽  
The Stability

AbstractThis paper aims to investigate the feasibility of the incorporation of nanosilica (NS) in ultra-lightweight foamed concrete (ULFC), with an oven-dry density of 350 kg/m3, in regard to its fresh and hardened characteristics. The performance of various dosages of NS, up to 10 wt.-%, were examined. In addition, fly ash and silica fume were used as cement replacing materials, to compare their influence on the properties of foamed concrete. Mechanical and physical properties, drying shrinkage and the sorption of concrete were measured. Scanning electron microscopy (SEM) and X-ray microcomputed tomography (µ-CT) and a probabilistic approach were implemented to evaluate the microstructural changes associated with the incorporation of different additives, such as wall thickness and pore anisotropy of produced ULFCs. The experimental results confirmed that the use of NS in optimal dosage is an effective way to improve the stability of foam bubbles in the fresh state. Incorporation of NS decrease the pore anisotropy and allows to produce a foamed concrete with increased wall thickness. As a result more robust and homogenous microstructure is produced which translate to improved mechanical and transport related properties. It was found that replacement of cement with 5 wt.-% and 10 wt.-% NS increase the compressive strength of ULFC by 20% and 25%, respectively, when compared to control concrete. The drying shrinkage of the NS-incorporated mixes was higher than in the control mix at early ages, while decreasing at 28 d. In overall, it was found that NS is more effective than other conventional fine materials in improving the stability of fresh mixture as well as enhancing the strength of foamed concrete and reducing its porosity and sorption.

scholarly journals A Textile Waste Fiber-Reinforced Cement Composite: Comparison between Short Random Fiber and Textile Reinforcement

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3742
Author(s):  
Payam Sadrolodabaee ◽  
Josep Claramunt ◽  
Mònica Ardanuy ◽  
Albert de la Fuente
Keyword(s):  
Construction Material ◽  
Drying Shrinkage ◽  
Cement Composite ◽  
Nonwoven Fabric ◽  
Textile Waste ◽  
Nonwoven Fabrics ◽  
Potential Applications ◽  
Reinforced Cement ◽  
The One ◽  
Garment And Textile

Currently, millions of tons of textile waste from the garment and textile industries are generated worldwide each year. As a promising option in terms of sustainability, textile waste fibers could be used as internal reinforcement of cement-based composites by enhancing ductility and decreasing crack propagation. To this end, two extensive experimental programs were carried out, involving the use of either fractions of short random fibers at 6–10% by weight or nonwoven fabrics in 3–7 laminate layers in the textile waste-reinforcement of cement, and the mechanical and durability properties of the resulting composites were characterized. Flexural resistance in pre- and post-crack, toughness, and stiffness of the resulting composites were assessed in addition to unrestrained drying shrinkage testing. The results obtained from those programs were analyzed and compared to identify the optimal composite and potential applications. Based on the results of experimental analysis, the feasibility of using this textile waste composite as a potential construction material in nonstructural concrete structures such as facade cladding, raised floors, and pavements was confirmed. The optimal composite was proven to be the one reinforced with six layers of nonwoven fabric, with a flexural strength of 15.5 MPa and a toughness of 9.7 kJ/m2.

scholarly journals Cement-Based Renders Manufactured with Phase-Change Materials: Applications and Feasibility

2016 ◽  
Vol 2016 ◽  
pp. 1-6 ◽  
Author(s):  
Luigi Coppola ◽  
Denny Coffetti ◽  
Sergio Lorenzi
Keyword(s):  
Compressive Strength ◽  
Phase Change ◽  
Phase Change Materials ◽  
Residential Buildings ◽  
Setting Time ◽  
Drying Shrinkage ◽  
Hydration Kinetics ◽  
Mechanical Performances ◽  
Entrapped Air ◽  
Kinetics Of

The paper focuses on the evaluation of the rheological and mechanical performances of cement-based renders manufactured with phase-change materials (PCM) in form of microencapsulated paraffin for innovative and ecofriendly residential buildings. Specifically, cement-based renders were manufactured by incorporating different amount of paraffin microcapsules—ranging from 5% to 20% by weight with respect to binder. Specific mass, entrained or entrapped air, and setting time were evaluated on fresh mortars. Compressive strength was measured over time to evaluate the effect of the PCM addition on the hydration kinetics of cement. Drying shrinkage was also evaluated. Experimental results confirmed that the compressive strength decreases as the amount of PCM increases. Furthermore, the higher the PCM content, the higher the drying shrinkage. The results confirm the possibility of manufacturing cement-based renders containing up to 20% by weight of PCM microcapsules with respect to binder.

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