Influence of different calcined clays to the water transport performance of concretes

2021 ◽  
pp. 1-38
Author(s):  
Alejandra Tironi ◽  
Ricarda Sposito ◽  
Gisela P. Cordoba ◽  
Silvina V. Zito ◽  
Viviana F. Rahhal ◽  
...  
Keyword(s):  
Water Absorption ◽  
Low Cost ◽  
Plain Concrete ◽  
Chloride Ions ◽  
Cement Matrix ◽  
Optical Analysis ◽  
Pozzolanic Reactivity ◽  
Water Transportation ◽  
Kaolinitic Clay ◽  
The Impact

This study compares the pozzolanic activity of kaolinitic and illite clays after calcination as they are the most abundant types of clays worldwide. The impact of calcined clays on microstructure development is tested by determining the porosity of cement paste as well as by phase and optical analysis of cement matrix and interfacial transition zone of concrete. As water transportation with damaging carbonate or chloride ions is the main reason for reduced durability of reinforced concrete, the results are complemented with water absorption tests on blended concretes. At 28 days, system with calcined kaolinitic clay reveal a higher densification of its microstructure with lower water absorption rate compared to plain concrete and concrete with calcined illite clay, which is related to its higher pozzolanic reactivity. Nonetheless calcined illite clays can be considered as low-cost clinker replacement as a significant pozzolanic contribution is detectable and after 90 days, the water absorption behaviour is comparable with those of the other systems investigated.

scholarly journals A REVIEW ON MECHANICAL PROPERTIES OF NATURAL FIBRE REINFORCED CONCRETE FOR RIGID PAVEMENTS

2021 ◽  
pp. 266-270
Author(s):  
M.Venkata Naga Prasad ◽  
Dr.J.Sridhar
Keyword(s):  
Low Cost ◽  
Natural Fibers ◽  
Natural Fibre ◽  
Cement Matrix ◽  
Rigid Pavements ◽  
Steel Bars ◽  
Coconut Coir ◽  
The Impact ◽  
Coconut Fibers

This study focuses on fiber reinforcement, specifically the use of jute and coir as a fiber reinforcing material in concrete. Natural fibers have been used to provide substantial toughness and strength in a very fragile cement matrix composite. It is necessary to make effective changes in this regard. Uses a very alkaline cement matrix to achieve durability. It is preferable to have a chemical composition that is clear. Reinforce the cement and change the surface of the fibers composite. The usage of jute fiber in this article is discussed. Concrete and the impact it has on the characteristics of the concrete it produces, for example this is an attempt to review the work that has just been completed. In the discipline, as well as to establish a foundation for future study in that case. It is critical to create low-cost building and reinforcing techniques that are suited for developing countries. If agricultural by-products like coconut coir can be used to replace steel bars as reinforcement, building costs can be reduced. Down significantly the purpose of this study is to evaluate the characteristics of coconut fibers. Species produced in India and their uses in many fields of engineering, notably civil engineering enhancing the long-term durability of concrete and mortar using engineering as a building material with the addition of coconut fibers the overall objective is to look into the possibility of utilizing domestic resources. Wastes for construction on a tiny scale a review of several researchers’ experiences utilizing is presented in this publication. The performance of coconut coir as a reinforcing component is explored in depth.

Experimental Study on Impact Resistance of Concrete Containing Steel Fibers

2021 ◽  
Vol 872 ◽  
pp. 1-6
Author(s):  
Khaleel H. Younis ◽  
Firas F. Jirjees ◽  
Hozan K. Yaba ◽  
Shelan M. Maruf
Keyword(s):  
Experimental Study ◽  
Steel Fiber ◽  
Low Cost ◽  
Impact Resistance ◽  
Plain Concrete ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Steel Fiber Reinforced Concrete ◽  
Maximum Increase ◽  
The Impact

This study is an experimental study aims to examine the effect of utilization of straight, and low cost steel fibers on the impact resistance of concrete. The impact resistance of steel fiber reinforced concrete (SFRC) was assessed using drop weight test as per ACI committee 544. The steel fibers were randomly dispersed in concrete during mixing. Five mixes made with steel fibers dosages of 0% (control mix), 0.5%, 1%, 1.25% and 1.5% by volume of concrete were examined in the study. The results show that mixes containing steel fibers show better impact resistance than plain concrete (control Mix). The results also indicate that increasing the dosage of fiber increases the impact resistance of concrete but up to a certain content of fibers. The maximum increase was recorded at steel fiber dosage of 1.25% by volume of concrete. Also the patterns of failure of the concrete specimens show that fibers are very effective in increasing the concrete toughness which enhance the ductility of concrete and delays the crack initiation.

scholarly journals Influence of Granite Powder on Physico-Mechanical and Durability Properties of Mortar

Materials ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 5406
Author(s):  
Christian Ramadji ◽  
Adamah Messan ◽  
Elodie Prud’Homme
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Water Demand ◽  
Setting Time ◽  
Chloride Ions ◽  
Heat Of Hydration ◽  
Pozzolanic Reactivity ◽  
Chloride Ions Diffusion ◽  
Granite Powder

This study explored the pozzolanic reactivity of granite powder (GP) and its influence on the microstructure of cement paste. An analysis of the physical properties (water demand, setting time, heat of hydration and total shrinkage), compressive strength and durability indicators (water absorption, porosity, acid attack and chloride ions diffusion) was carried out on mortar containing 10%, 15% and 20% of GP as partial substitution to cement (CEM I 42.5 R) in the short and long term. The results showed that the GP does not exhibit pozzolanic reactivity and that it reduces the heat of hydration. Water demand and setting time were not affected by the GP. The compressive strength decreases with increasing the content of GP; but in the long term, the compressive strength was not affected for 10% GP substitution. The presence of granite powder in mortar induces an increase in porosity, which led to an increase in the diffusion properties of fluids (capillary water absorption and chloride ions diffusion).

Computer simulation study about the dependence of amorphous silicon photonic waveguides efficiency on the material quality

2020 ◽  
Vol 90 (3) ◽  
pp. 30502
Author(s):  
Alessandro Fantoni ◽  
João Costa ◽  
Paulo Lourenço ◽  
Manuela Vieira
Keyword(s):  
Amorphous Silicon ◽  
High Throughput Screening ◽  
Simulation Analysis ◽  
Low Cost ◽  
Deposition Process ◽  
Large Area ◽  
Sidewall Roughness ◽  
Sensing Applications ◽  
Fabrication Defects ◽  
The Impact

Amorphous silicon PECVD photonic integrated devices are promising candidates for low cost sensing applications. This manuscript reports a simulation analysis about the impact on the overall efficiency caused by the lithography imperfections in the deposition process. The tolerance to the fabrication defects of a photonic sensor based on surface plasmonic resonance is analysed. The simulations are performed with FDTD and BPM algorithms. The device is a plasmonic interferometer composed by an a-Si:H waveguide covered by a thin gold layer. The sensing analysis is performed by equally splitting the input light into two arms, allowing the sensor to be calibrated by its reference arm. Two different 1 × 2 power splitter configurations are presented: a directional coupler and a multimode interference splitter. The waveguide sidewall roughness is considered as the major negative effect caused by deposition imperfections. The simulation results show that plasmonic effects can be excited in the interferometric waveguide structure, allowing a sensing device with enough sensitivity to support the functioning of a bio sensor for high throughput screening. In addition, the good tolerance to the waveguide wall roughness, points out the PECVD deposition technique as reliable method for the overall sensor system to be produced in a low-cost system. The large area deposition of photonics structures, allowed by the PECVD method, can be explored to design a multiplexed system for analysis of multiple biomarkers to further increase the tolerance to fabrication defects.

Advancing dairy farming profitability through research

2001 ◽  
pp. 17-22
Author(s):  
J.R. Caradus ◽  
D.A. Clark
Keyword(s):  
Research And Development ◽  
Dairy Cow ◽  
Low Cost ◽  
Pasture Management ◽  
Nitrogen Fertiliser ◽  
Grass Endophyte ◽  
Forage Species ◽  
Development Outcomes ◽  
Dairy Cow Nutrition ◽  
The Impact

The New Zealand dairy industry recognises that to remain competitive it must continue to invest in research and development. Outcomes from research have ensured year-round provision of low-cost feed from pasture while improving productivity. Some of these advances, discussed in this paper, include the use of white clover in pasture, understanding the impacts of grass endophyte, improved dairy cow nutrition, the use of alternative forage species and nitrogen fertiliser to improve productivity, demonstration of the impact of days-in-milk on profitability, and the use of feed budgeting and appropriate pasture management. Keywords: dairy, profitability, research and development

Motivating Compliance: Firm Response to Mandatory Disclosure Policies

2018 ◽  
Vol 32 (2) ◽  
pp. 103-119
Author(s):  
Colleen M. Boland ◽  
Chris E. Hogan ◽  
Marilyn F. Johnson
Keyword(s):  
Conflict Of Interest ◽  
Low Cost ◽  
Cost Effective ◽  
Data Availability ◽  
Policy Adoption ◽  
Future Research ◽  
Regulated Firms ◽  
Firm Response ◽  
Disclosure Rules ◽  
The Impact

SYNOPSIS Mandatory existence disclosure rules require an organization to disclose a policy's existence, but not its content. We examine policy adoption frequencies in the year immediately after the IRS required mandatory existence disclosure by nonprofits of various governance policies. We also examine adoption frequencies in the year of the subsequent change from mandatory existence disclosure to a disclose-and-explain regime that required supplemental disclosures about the content and implementation of conflict of interest policies. Our results suggest that in areas where there is unclear regulatory authority, mandatory existence disclosure is an effective and low cost regulatory device for encouraging the adoption of policies desired by regulators, provided those policies are cost-effective for regulated firms to implement. In addition, we find that disclose-and-explain regulatory regimes provide stronger incentives for policy adoption than do mandatory existence disclosure regimes and also discourage “check the box” behavior. Future research should examine the impact of mandatory existence disclosure rules in the year that the regulation is implemented. Data Availability: Data are available from sources cited in the text.

scholarly journals X-ray Shielding, Mechanical, Physical, and Water Absorption Properties of Wood/PVC Composites Containing Bismuth Oxide

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2212
Author(s):  
Worawat Poltabtim ◽  
Ekachai Wimolmala ◽  
Teerasak Markpin ◽  
Narongrit Sombatsompop ◽  
Vichai Rosarpitak ◽  
...  
Keyword(s):  
Impact Strength ◽  
Water Absorption ◽  
Attenuation Coefficient ◽  
Bismuth Oxide ◽  
Morphological Properties ◽  
Linear Attenuation Coefficient ◽  
X Rays ◽  
Equivalent Thickness ◽  
X Ray ◽  
The Impact

The potential utilization of wood/polyvinyl chloride (WPVC) composites containing an X-ray protective filler, namely bismuth oxide (Bi2O3) particles, was investigated as novel, safe, and environmentally friendly X-ray shielding materials. The wood and Bi2O3 contents used in this work varied from 20 to 40 parts per hundred parts of PVC by weight (pph) and from 0 to 25, 50, 75, and 100 pph, respectively. The study considered X-ray shielding, mechanical, density, water absorption, and morphological properties. The results showed that the overall X-ray shielding parameters, namely the linear attenuation coefficient (µ), mass attenuation coefficient (µm), and lead equivalent thickness (Pbeq), of the WPVC composites increased with increasing Bi2O3 contents but slightly decreased at higher wood contents (40 pph). Furthermore, comparative Pbeq values between the wood/PVC composites and similar commercial X-ray shielding boards indicated that the recommended Bi2O3 contents for the 20 pph (40 ph) wood/PVC composites were 35, 85, and 40 pph (40, 100, and 45 pph) for the attenuation of 60, 100, and 150-kV X-rays, respectively. In addition, the increased Bi2O3 contents in the WPVC composites enhanced the Izod impact strength, hardness (Shore D), and density, but reduced water absorption. On the other hand, the increased wood contents increased the impact strength, hardness (Shore D), and water absorption but lowered the density of the composites. The overall results suggested that the developed WPVC composites had great potential to be used as effective X-ray shielding materials with Bi2O3 acting as a suitable X-ray protective filler.

scholarly journals Microstructure and Durability Performance of Mortars with Volcanic Powder from Calbuco Volcano (Chile) after 4 Hardening Years

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1751
Author(s):  
Rosa María Tremiño ◽  
Teresa Real-Herraiz ◽  
Viviana Letelier ◽  
José Marcos Ortega
Keyword(s):  
Water Absorption ◽  
Thermal Analyses ◽  
Length Change ◽  
Cement Industry ◽  
Chloride Diffusion ◽  
Beneficial Effects ◽  
State Diffusion ◽  
Calbuco Volcano ◽  
Reference Specimens ◽  
The Impact

One of the most popular ways to lessen the impact of the cement industry on the environment consists of substituting clinker by additions. The service life required for real construction elements is generally long, so it would be interesting to obtain information about the effects of new additions after a hardening period of several years. Analyzed here are the effects of the incorporation of volcanic ashes, coming from Calbuco volcano’s last eruption (Chile), as clinker replacement, in the durability and pore structure of mortars, after approximately 4 hardening years (1500 days), in comparison with reference specimens without additions. The substitution percentages of clinker by volcanic powder studied were 10% and 20%. The microstructure was characterized with mercury intrusion porosimetry and impedance spectroscopy. In order to evaluate the pozzolanic activity of the volcanic powder after 1500 days, differential thermal analyses were performed. Water absorption after immersion, steady-state diffusion coefficient and length change were also studied. In accordance with the results obtained, the 10% and 20% substitution of clinker by volcanic powder from the Calbuco volcano showed beneficial effects in the mortars after 4 years, especially regarding the microstructure and chloride diffusion, without noticeable influence in their water absorption.

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