scholarly journals Compressive strength of green concrete with low cement and high filler content

2021 ◽  
Vol 64 (2) ◽  
pp. 93-108
Author(s):  
Andrija Radović ◽  
Snežana Marinković ◽  
Aleksandar Savić
Keyword(s):  
Compressive Strength ◽  
Filler Content ◽  
Negative Impact ◽  
Economic Benefits ◽  
Limestone Filler ◽  
Suitable Alternative ◽  
Green Concrete ◽  
Cement Replacement ◽  
Alternative Materials ◽  
Wide Availability

It is estimated that by the end of the current decade, about 26% of clinker will be replaced by suitable alternative materials, among which limestone filler probably has the greatest potential due to its wide availability and relatively low price. Although codes allow as much as 35% of clinker to be replaced by limestone filler, the amounts used in practice are far lower and average only 6-7% globally. In order to use the great potential of fillers, it is necessary to know the key parameters that affect the properties of green concrete with low cement and high filler content in fresh and hardened states. Therefore, thorough literature review was conducted, followed by design of 18 concrete mixtures, in order to analyze the effects of the percentage of cement replacement, water-cement ratio, but also the particle size of the applied filler. The results of experimental research show that at the same w/c ratio there is an increase in compressive strength with increasing percentage of cement replacement and that it is possible to make medium-strength concrete with significantly reduced amount of cement 180 kg/m3 compared to traditional concrete. Thus, economic benefits can be achieved, but also the negative impact of the concrete industry on the environment can be reduced. Unfortunately, the workability of such mixtures can be impaired to the extent that their practical application is prevented, so it is necessary to take further steps to solve this problem.

scholarly journals Influence of cement replacement with limestone filler on the properties of concrete

2021 ◽  
Vol 64 (3) ◽  
pp. 165-170
Author(s):  
Ksenija Tešić ◽  
Snežana Marinković ◽  
Aleksandar Savić
Keyword(s):  
Particle Size ◽  
Compressive Strength ◽  
Mineralogical Composition ◽  
Limestone Filler ◽  
Green Concrete ◽  
Cement Ratio ◽  
Cement Replacement ◽  
Concrete Mixtures ◽  
Water To Cement Ratio ◽  
Compressive Strength Of Concrete

This paper presents an experimental research of one type of green concrete in which Portland cement was replaced with two types of limestone filler of the same origin and mineralogical composition, but with a different fineness of particles. Ten concrete mixtures were designed in which 0%, 15%, 30% and 45% (by mass) of cement were replaced with filler. The water to cement ratio for each mixture was constant (w/c=0.54), and the water to powder ratio was decreasing with increasing cement replacement. Particle size distribution was selected using Funk and Dinger, as well as using Fuller's model. The results showed that it is possible to increase the compressive strength of concrete by reducing 45% of cement, but further research should be focused on improving the workability.

Flexural and Compressive Strength of the Cement Paste with Recycled Concrete Powder

2017 ◽  
Vol 1144 ◽  
pp. 65-69
Author(s):  
Jaroslav Topič ◽  
Josef Fládr ◽  
Zdeněk Prošek
Keyword(s):  
Compressive Strength ◽  
Cement Paste ◽  
Cost Reduction ◽  
Negative Impact ◽  
Reference Sample ◽  
Strength Properties ◽  
Recycled Concrete ◽  
Cement Composites ◽  
Cement Production ◽  
Cement Replacement

In previous work focused on using recycled concrete powder as cement replacement the basic dependency of the mechanical properties on the amount of recycled concrete powder was defined. Influence of the amount of recycled concrete powder on the flexural and compressive strength was shown on 0, 33, 67 and 100 wt. % cement replacement. Based on the previous data the strength properties of the cement paste with recycled concrete powder below 33 wt. % was almost constant and strength properties were comparable with reference sample made of cement only. After the recycled concrete powder in cement paste exceeded amount of 33 wt. % the flexural and compressive strength decrease rapidly. In case of 67 wt. % amount of recycled concrete powder the compressive strength decrease about 65 %. The aim of this article is define critical amount of recycled concrete powder in cement paste when strength properties start decrease rapidly and cement replacement is no longer beneficial. This critical amount will be located somewhere between 30 and 50 wt. % of recycled concrete powder. Replacement below critical amount could lead to cost reduction of cement composites and also the negative impact of the cement production and concrete disposal on environmental could be reduced.

scholarly journals Pengaruh Silica Fume sebagai Subtitusi Semen terhadap Nilai Resapan dan Kuat Tekan Mortar (Hal. 12-21)

2018 ◽  
Vol 4 (4) ◽  
pp. 12
Author(s):  
Bantot Sutriono ◽  
Retno Trimurtiningrum ◽  
Aditya Rizkiardi
Keyword(s):  
Compressive Strength ◽  
Silica Fume ◽  
Negative Impact ◽  
Cement Industry ◽  
Partial Replacement ◽  
Fume Silica ◽  
Pozzolanic Material ◽  
Alternative Materials ◽  
Increasing Demand ◽  
Test Result

ABSTRAKBeton dan mortar banyak digunakan sebagai bahan konstruksi di seluruh dunia. Meningkatnya permintaan beton dan mortar juga meningkatkan permintaan semen di pasar yang berdampak negatif bagi lingkungan. Industri semen  menghasilkan sekitar 6 hingga 7 persen dari seluruh CO2 di seluruh dunia. Oleh karena itu, para peneliti mencoba mengembangkan gagasan tentangbeton ramah lingkungan, dengan mengurangi penggunaan semen dengan menggunakan bahan alternatif seperti silica fume. Silica fume adalah bahan pozzolan yang kaya akan silika dan dapat bereaksi kimia dengan kalsium hidroksida, membentuk gel kalsium silikat (CSH) pada beton. Tujuan dari penelitian ini adalah untuk menyelidiki pengaruh silica fume sebagai pengganti parsial semen terhadap nilai resapan dan kekuatan tekan mortar. Persentase silica fume bervariasi 0%, 5%, 10%, 12% dan 15%. Hasil pengujian menunjukkan nilai resapan minimum adalah 3,276% diperoleh campuran dengan 15% silica fume dan kuat tekan maksimum 312,574 kg/cm2 diperoleh campuran dengan 8% silica fume.Kata kunci: silica fume, nilai resapan, kuat tekan, mortar ABSTRACTConcrete and mortar are widely used as contruction materials. The increasing demand of concrete and mortar also increase the demand of cement in the market which has negative impact for environment. The cement industry produced for approximately 6 to 7 percent of all CO2 worldwide. Therefore, the researches try to develop the idea of green concrete with reducing the utilize of cement with using the alternative materials such as silica fume. Silica fume is a pozzolanic material that contain rich of silica and has chemical reaction with calcium hydroxide forming calcium silicate hydrate (C-S-H) gel in concrete.The aimed of this research is to investigate the influence of silica fume as partial replacement of cement on absoption and compressive strength of mortar.The percentage of silica fume were varied from 0%, 5%, 10%, 12% and 15%. The test result showed that the minimum absorption value is 3.276% obtain from the mixture with 15% of silica fume and the maximum compressive strength is 312.574 kg/cm2 obtain from the mixture with 8% of silica fume.Keywords: Silica fume, absorption, compressive strength, mortar

Global challenges to functioning of precious gemstones market

2019 ◽  
pp. 15-19
Author(s):  
Maryna Khmara
Keyword(s):  
Social Impact ◽  
Negative Impact ◽  
Economic Benefits ◽  
Small Enterprises ◽  
Ecological Responsibility ◽  
Global Challenges ◽  
Production And Consumption ◽  
Managerial Strategies ◽  
The Impact ◽  
Complicated Nature

The peculiarities of gemstone market functioning under the impact of globalization are examined. Modern condition of financial stabilization in world is defined and main features of gemstones are outlined. Negative impact of illegal market on socio-economic development of countries, namely on revenues to the country’s budget from the business, is revealed. The importance of the problem of transferring most of gemstones processing operations beyond the countries of production is emphasized. Poor public control over the circulation of precious stones is proven. The challenges are substantiated to be aggravating under the impact of globalization. The diamonds market, which has peculiar high demand, is analyzed: diamonds and derivatives account for 85% of global turnover. Application of managerial strategies for gemstones market to efficiently use resources is defined to be complicated by the fact that managerial strategies impact the high cost of product items and its variability; unique features; intangible qualities; complicated processing. More environmentally friendly production and social responsibility are confirmed to have impact on forming of demand on gemstones. Investment attractiveness of gemstones, except for diamonds, is proven to be low. Condition of production and consumption of diamonds is analyzed. Development condition of the market segment – non-diamonds gemstones – is shown. The activity of small enterprises and households engaged in gemstones production is confirmed to be characterized by chaotic and complicated nature of broker networks, leading to aggravated global challenges. The paper defines that expansion of spectrum and emergence of new opportunities for illegal activity, reduced income and loss of other types of economic benefits, growing negative ecological and social impact, growing exploitation of workers at illegal enterprises remain to be the global challenges of gemstones market functioning. The author suggests increasing of social and ecological responsibility of business, strengthening of the state regulating functions and promotion of gemstones market legalization in order to reduce the challenges.

scholarly journals Microstructural characterization of catalysis product of nanocement based materials: A review

2018 ◽  
Vol 34 ◽  
pp. 01039
Author(s):  
Norsuzailina Mohamed Sutan ◽  
Nur Izaitul Akma Ideris ◽  
Siti Noor Linda Taib ◽  
Delsye Teo Ching Lee ◽  
Alsidqi Hassan ◽  
...  
Keyword(s):  
Carbon Dioxide Emission ◽  
Essential Element ◽  
Microstructural Characterization ◽  
High Energy ◽  
Green Technology ◽  
Microstructural Development ◽  
Cement Replacement ◽  
Alternative Materials ◽  
Partial Cement Replacement

Cement as an essential element for cement-based products contributed to negative environmental issues due to its high energy consumption and carbon dioxide emission during its production. These issues create the need to find alternative materials as partial cement replacement where studies on the potential of utilizing silica based materials as partial cement replacement come into picture. This review highlights the effectiveness of microstructural characterization techniques that have been used in the studies that focus on characterization of calcium hydroxide (CH) and calcium silicate hydrate (C-S-H) formation during hydration process of cement-based product incorporating nano reactive silica based materials as partial cement replacement. Understanding the effect of these materials as cement replacement in cement based product focusing on the microstructural development will lead to a higher confidence in the use of industrial waste as a new non-conventional material in construction industry that can catalyse rapid and innovative advances in green technology.

scholarly journals The use of groundwater crustacean communities as indicators for aquifers quality in the semi-arid region of north-central Chile

2018 ◽  
Vol 1 ◽  
Author(s):  
Sanda Iepure ◽  
Nicolas Gouin ◽  
Angeline Bertin ◽  
Ana Camacho ◽  
Antonio González-Ramón ◽  
...  
Keyword(s):  
Negative Impact ◽  
Groundwater Resources ◽  
Economic Benefits ◽  
Nutrient Loads ◽  
Groundwater Temperature ◽  
Groundwater Levels ◽  
Water Abstraction ◽  
Over Exploitation ◽  
The Impact ◽  
Semi Arid

Chile has large extensions of arid and semi-arid regions throughout the whole country, where the intensive demands and use of water resources, especially groundwater for irrigations and mining activities, increased dramatically over the last decades. The aquifer depletions due to water abstraction for irrigation and nutrient loads, exert major alterations of water quality, groundwater recharge and the natural renewal rate. All these factors diminish the aquifer value for the users and contribute to the degradation of groundwater as environment and habitat for fauna. This intensive use of groundwater resources in Chile brought to significant social and economic benefits, but their inadequate management resulted in negative environmental, legal and socioeconomic consequences. In this study, we aimed at providing a first assessment of environmental alterations of groundwater ecosystems from agricultural watersheds in northern Chile by specifically evaluating the effects of nitrogen and pesticide loads on groundwater communities and identifing the ecosystem service alterations due to agricultural activities. The study has been performed in a glacial aquifer from Coquimbo region; 250 km north of Santiago de Chile, the floodplain of which is dominated by agriculture (fruits tress, vineyards). Due to low regional precipitations (100-240 mm/year) the aquifer is primarily recharged by snowmelt from the Andean chain and surface runoff. The relative groundwater levels, groundwater temperature, chemical analysis of nitrogen and total phosphorus and pesticide concentrations were examined, along with the evaluation of crustacean biodiversity and spatial distribution pattern. Stygofauna taxonomic richness and the presence of stygobites have been related more to groundwater level stability than to chemical water parameters indicating that over-exploitation has a negative impact on habitat suitability for groundwater invertebrates. Groundwater biota assessment is essential in understanding the impact produced by agriculture activities on groundwater as a resource and as ecosystem, a nexus that becomes more and more widely recognized. The rationale and the preliminary results of this study are summarized in the Suppl. material 1.

scholarly journals Effect of Fly Ash on the Compressive Strength of Green Concrete

2020 ◽  
Vol 10 (3) ◽  
pp. 5728-5731 ◽  
Author(s):  
S. A. Chandio ◽  
B. A. Memon ◽  
M. Oad ◽  
F. A. Chandio ◽  
M. U. Memon
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Recycled Aggregates ◽  
Waste Materials ◽  
Partial Replacement ◽  
Equal Proportion ◽  
Standard Size ◽  
Green Concrete ◽  
Coarse Aggregates ◽  
Management Issues

This research paper aims at investigating the effects of fly ash as cement replacement in green concrete made with partial replacement of conventional coarse aggregates with coarse aggregates from demolishing waste. Green concrete developed with waste materials is an active area of research as it helps in reducing the waste management issues and protecting the environment. Six concrete mixes were prepared using 1:2:4 ratio and demolishing waste was used in equal proportion with conventional aggregates, whereas fly ash was used from 0%-10% with an increment of 2.5%. The water-cement ratio used was equal to 0.5. Out of these mixes, one mix was prepared with all conventional aggregates and was used as the control, and one mix with 0% fly ash had only conventional and recycled aggregates. The slump test of all mixes was determined. A total of 18 cylinders of standard size were prepared and cured for 28 days. After curing the compressive strength of the specimens was evaluated under gradually increasing load until failure. It is observed that 5% replacement of cement with fly ash and 50% recycled aggregates gives better results. With this level of dosage of two waste materials, the reduction in compressive strength is about 11%.

scholarly journals Aid, Governance and Public Finance Fraud: Evidence from Angola

Politeja ◽  
2020 ◽  
Vol 17 (6(69)) ◽  
pp. 19-50
Author(s):  
Weronika J. Krawczyk
Keyword(s):  
Public Finance ◽  
Natural Resources ◽  
Negative Impact ◽  
Political Corruption ◽  
Economic Benefits ◽  
Academic Community ◽  
Development Aid ◽  
Financial Flows ◽  
Ruling Elites ◽  
The Impact

This article examines the process of public finance fraud leading to unjust enrichment of ruling elites in Angola, a resource-rich, yet ironically povertytrapped country, owing to decades of rule of José Eduardo dos Santos. It analyses the phenomenon of political corruption in the Angolan context, translating into mismanagement of public revenues coming from natural resources as a means of attaining private economic benefits and consolidating power. Moreover, by examining cross-border inter-company networks aimed at concealing public assets behind front companies, the author attempts to establish a connection between corruption and illicit financial flows. Ultimately, since political corruption is intrinsically linked to governance, the article looks at the impact of the latter on social development as well as on the effectiveness of development aid granted to Angola. It was written based on secondary resources including existing literature and material evidence. Its findings and conclusions correspond with the overall theory postulated by the academic community, maintaining that natural resources and aid have negative impact on governance, institutional accountability, and in consequence on human development, especially in countries characterised by despotic rule.

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