scholarly journals Creep and Shrinkage Behaviour of Disintegrated and Non-Disintegrated Cement Mortar

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7510
Author(s):  
Rihards Gailitis ◽  
Beata Figiela ◽  
Kalvis Abelkalns ◽  
Andina Sprince ◽  
Genadijs Sahmenko ◽  
...  
Keyword(s):  
Cement Mortar ◽  
Partial Replacement ◽  
Structural Application ◽  
The Past ◽  
Considerable Research ◽  
Shrinkage Behaviour ◽  
Cement Mortars ◽  
Creep And Shrinkage ◽  
Creep Strains

One way to prevent cement from ending up in landfills after its shelf life is to regain its activity and reuse it as a binder. As has been discovered, milling by planetary ball mill is not effective. Grinding by collision is considered a more efficient way to refine brittle material and, in the case of cement, to regain its activity. There has been considerable research regarding the partial replacement of cement using disintegrated cement in mortar or concrete in the past few decades. This article determines and compares the creep and shrinkage properties of cement mortar specimens made from old disintegrated, old non-disintegrated, and new non-disintegrated Portland cement. The tests show that the creep strains for old disintegrated and old non-disintegrated cement mortars are close, within a 2% margin of each other. However, the creep strains for new non-disintegrated cement mortar are 30% lower. Shrinkage for old disintegrated and non-disintegrated cement mortar is 20% lower than for new non-disintegrated cement mortar. The research shows that disintegration is a viable procedure to make old cement suitable for structural application from a long-term property standpoint. Additionally, it increases cement mortar compressive strength by 49% if the cement is disintegrated together with sand.

Unemployment, Underemployment, Occupational Stress and Psychological Well-Being

2002 ◽  
Vol 27 (1_suppl) ◽  
pp. 137-148 ◽  
Author(s):  
Anthony H. Winefield
Keyword(s):  
Occupational Stress ◽  
Social Issues ◽  
Well Being ◽  
Research Interest ◽  
Future Research ◽  
Research Directions ◽  
The Past ◽  
Considerable Research ◽  
Future Research Directions

Research on unemployment, underemployment and organisational stress have become major social issues over the past 20 years and have attracted considerable research interest on the part of organisational psychologists both in Australia and overseas. Globalisation has led to restructuring and downsizing in many industrialised societies and a shift, for many workers, from the prospect of secure, long-term employment, to unemployment or inadequate or insecure employment. This paper reviews the research on these topics, discusses their theoretical implications and suggests future research directions.

Use of Spongilites as Pozzolanic Additives in Cement Mortars

2021 ◽  
Vol 325 ◽  
pp. 65-70
Author(s):  
Martin Vyšvařil ◽  
Patrik Bayer ◽  
Tomáš Žižlavský
Keyword(s):  
Mechanical Properties ◽  
Bulk Density ◽  
Frost Resistance ◽  
Water Retention ◽  
Cement Mortar ◽  
Partial Replacement ◽  
Fine Grained ◽  
Natural Pozzolans ◽  
Cement Mortars ◽  
Pozzolanic Additives

In this study, the utilization of two types of spongilites in various addition in cement mortars has been investigated with the purpose of exploring a new application of this natural pozzolans as cement mortar additives. The influence of the addition of spongilites on the physico-mechanical properties, frost-resistance, and microstructure of cement mortars as a function of time was studied. The results revealed that the rising proportion of spongilites in cement mortars causes increase in water retention of mortars, reduction of their bulk density, increase in porosity of mortars due to the growing predominance of capillary pores maintaining sufficient mortars strengths, and slightly increase in the frost-resistance of mortars. After initial tests, partial replacement of cement in fine-grained cement mortars with hitherto unexploited spongilites seems to be very promising. Based on the achieved results, a 20% cement replacement can be recommended as optimal.

Influence of Pozzolana Admixture on Long-Term Chemical Characteristic of Cement Mortars

2013 ◽  
Vol 438-439 ◽  
pp. 50-53 ◽  
Author(s):  
Daniel Dobiáš ◽  
Radka Pernicová
Keyword(s):  
Cement Mortar ◽  
Chemical Properties ◽  
Mineralogical Composition ◽  
Chemical Characteristic ◽  
Time Intervals ◽  
Clay Bricks ◽  
Cement Mortars ◽  
Aggressive Liquid ◽  
Predetermined Time

nfluence of non-flowing model sulphate solution determined for cement mortar with pozzzolana admixture are presented in this paper. In the predetermined time intervals the influence of the aggressive liquid on chemical properties and mineralogical composition was tested. The changes caused by corrosive sulphate environment on the testing specimens were determined in dependence on the different type of cement and used ground clay brick as pozzolana admixture. From the results obtained follows that the additive of ground clay bricks has positively impact on the sulphate resistance.

Rock Wool and Printed Circuit Boards (PCBs) as Partial Fine Aggregate Replacements in Cement Mortar

2018 ◽  
Vol 775 ◽  
pp. 567-575
Author(s):  
Panisara Namchan ◽  
T. Denpetkul ◽  
P. Pheinsusom ◽  
Sutha Khaodhiar
Keyword(s):  
Thermal Conductivity ◽  
Printed Circuit Boards ◽  
Cement Mortar ◽  
Industrial Wastes ◽  
Partial Replacement ◽  
Fine Aggregate ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Cement Mortars ◽  
Rock Wool

The utilization of industrial wastes such as, fly ash, silica fumes, and slag in construction materials, has been receiving increased attention due to its environmental friendliness and reduction of natural resources consumptions. This study investigates and compares the utilization of spent rock wool from industrial insulation and printed circuit boards (PCBs) (the non-metallic part) as a partial replacement for conventional fine aggregates in cement mortar. Each of the waste materials was used as a partial fine aggregate ranging from 0% to 20%, by weight. The cement mortar samples were cured at 7 days, 14 days and 28 days. To investigate the properties of the cement mortars with different amounts of industrial wastes, the density, compressive strength, transverse strength and thermal conductivity of each mortar variation were measured. The results indicate that the compressive and transverse strengths of the cement mortars decreased as more industrial wastes was present in the mixtures. However, the fine aggregate substitutes improved thermal resistance, as indicated by the decreasing thermal conductivity values of the cement mortars. Thus, the use of these two industrial wastes in cement mortar could be a viable option for non-structural and non-load bearing construction applications because these substitutes have the ability to produce mortar with suitable mechanical and insulating properties.

scholarly journals Effect of nano silica on the properties of concrete and mortar – A state of art

2021 ◽  
Author(s):  
Pandiaraj Karthigai Priya ◽  
Sankararajan Vanitha
Keyword(s):  
Construction Industry ◽  
Building Materials ◽  
Fresh Concrete ◽  
Partial Substitution ◽  
Partial Replacement ◽  
Nano Silica ◽  
Normal Concrete ◽  
The Past ◽  
Cement Mortars ◽  
Strength And Durability

Abstract Construction industry is one of the biggest sectors globally and a wide variety of materials are used to carry out various works. Particularly, cement is a material that is used in the construction of various structures and it is also the major source of emission of CO2 gas into the atmosphere which results in global warming. Many researchers have identified various replacement materials for cement as a partial substitution and carried out experiments successfully. Nano silica is widely utilized as a partial replacement for cement and a lot of research is carried out. This paper reviews the past studies in which nano silica is utilized in various building materials such as cement mortars, normal concrete and special concretes. The fresh concrete properties, strength and durability of the material are the parameters reviewed and it is apparent that by incorporating nano silica in cement it absorbs more water, which makes the mix less workable and it imparts additional strength to the concrete and also provides better durability when compared with the control specimen. Hence it has been revealed that nano silica will be a good replacement for cement as it is pozzolanic in nature and also possessing good microstructure.

Enabling Community Well-being Self-Monitoring in the Context of Mining: The Naskapi Nation of Kawawachikamach

2016 ◽  
Vol 1 (2) ◽  
Author(s):  
Robert Klinck ◽  
Ben Bradshaw ◽  
Ruby Sandy ◽  
Silas Nabinacaboo ◽  
Mannie Mameanskum ◽  
...  
Keyword(s):  
Indigenous Peoples ◽  
Well Being ◽  
Aboriginal Community ◽  
Self Monitoring ◽  
Community Engaged Research ◽  
The Past ◽  
Mineral Development ◽  
Iron Deposits ◽  
Term Monitoring

The Naskapi Nation of Kawawachikamach is an Aboriginal community located in northern Quebec near the Labrador Border. Given the region’s rich iron deposits, the Naskapi Nation has considerable experience with major mineral development, first in the 1950s to the 1980s, and again in the past decade as companies implement plans for further extraction. This has raised concerns regarding a range of environmental and socio-economic impacts that may be caused by renewed development. These concerns have led to an interest among the Naskapi to develop a means to track community well-being over time using indicators of their own design. Exemplifying community-engaged research, this paper describes the beginning development of such a tool in fall 2012—the creation of a baseline of community well-being against which mining-induced change can be identified. Its development owes much to the remarkable and sustained contribution of many key members of the Naskapi Nation. If on-going surveying is completed based on the chosen indicators, the Nation will be better positioned to recognize shifts in its well-being and to communicate these shifts to its partners. In addition, long-term monitoring will allow the Naskapi Nation to contribute to more universal understanding of the impacts of mining for Indigenous peoples.

Courting the Youth Vote in 2008: The Obama Effect

2009 ◽  
Vol 5 ◽  
Author(s):  
Lindsey C Bohl
Keyword(s):  
Presidential Elections ◽  
Voter Registration ◽  
The Internet ◽  
The Past ◽  
Several Variables ◽  
High Turnout ◽  
Short And Long Term ◽  
Use Of The Internet ◽  
Youth Vote

This paper examines a few of the numerous factors that may have led to increased youth turnout in 2008 Election. First, theories of voter behavior and turnout are related to courting the youth vote. Several variables that are perceived to affect youth turnout such as party polarization, perceived candidate difference, voter registration, effective campaigning and mobilization, and use of the Internet, are examined. Over the past 40 years, presidential elections have failed to engage the majority of young citizens (ages 18-29) to the point that they became inclined to participate. This trend began to reverse starting in 2000 Election and the youth turnout reached its peak in 2008. While both short and long-term factors played a significant role in recent elections, high turnout among youth voters in 2008 can be largely attributed to the Obama candidacy and campaign, which mobilized young citizens in unprecedented ways.

Incorporation of Iraqi Rocks in the Production of Eco-Friendly Cement Mortar

2020 ◽  
Vol 38 (10A) ◽  
pp. 1522-1530
Author(s):  
Rawnaq S. Mahdi ◽  
Aseel B. AL-Zubidi ◽  
Hassan N. Hashim
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Compressive Strength ◽  
Water Absorption ◽  
Structural Properties ◽  
Mechanical Milling ◽  
Cement Mortar ◽  
Cement Mortars

This work reports on the incorporation of Flint and Kaolin rocks powders in the cement mortar in an attempt to improve its mechanical properties and produce an eco-friendly mortar. Flint and Kaolin powders are prepared by dry mechanical milling. The two powders are added separately to the mortars substituting cement partially. The two powders are found to improve the mechanical properties of the mortars. Hardness and compressive strength are found to increase with the increase of powders constituents in the cement mortars. In addition, the two powders affect water absorption and thermal conductivity of the mortar specimens which are desirable for construction applications. Kaolin is found to have a greater effect on the mechanical properties, water absorption, and thermal conductivity of the mortars than Flint. This behavior is discussed and analyzed based on the compositional and structural properties of the rocks powders.

The Influence of the Ash Addition from Thermal Power Plant on the Mechanical, Thermal and Dielectric Characteristics of Mortars

2018 ◽  
Vol 69 (8) ◽  
pp. 2040-2044
Author(s):  
Georgeta Velciu ◽  
Virgil Marinescu ◽  
Adriana Moanta ◽  
Ladislau Radermacher ◽  
Adriana Mariana Bors
Keyword(s):  
Thermal Conductivity ◽  
Fly Ash ◽  
Power Plant ◽  
Cement Mortar ◽  
Thermal Power ◽  
Total Content ◽  
Ash Content ◽  
Dielectric Losses ◽  
Dielectric Characteristics ◽  
Cement Mortars

The influence of fly ash adittion (90 % fraction [ 100 mm) on the cement mortar characteristics was studied. The XRD, XRF, SEM and FTIR determinations indicated that fly ash used has a hollow microstructure of microsphere and cenosphere whose total content in SiO2, Al2O3 and Fe2O3 is 88.63 % and that of CaO and MgO of 8.55 %. The mechanical, thermal and dielectric determinations made on mortar samples with content of fly ash in the 0-40 % range have highlighted fact that the mechanical strength of cement mortars is maximal at 20 %, the increase in fly ash content leads to a decrease in relative density and thermal conductivity as well as and to increased dielectric losses tgd.

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