scholarly journals Effect of type cement on the mechanical strength of copper slag mortars

2013 ◽  
Vol 66 (1) ◽  
pp. 85-90 ◽  
Author(s):  
Amin Nazer ◽  
Osvaldo Pavez ◽  
Ithamar Toledo
Keyword(s):  
Environmental Impact ◽  
Flexural Strength ◽  
Construction Industry ◽  
Mechanical Characteristics ◽  
Copper Slag ◽  
Cement Mortars ◽  
Alternative Material ◽  
Binder Type ◽  
Initial Resistance

Copper slag is a massive metallurgist waste. Annual production rises up to 24.6 million tons, approximately, and the main environmental impact derived from slag disposal is the usage of great soil extensions and the resulting visual contamination of the landscape. Along time, copper slag has been used in the manufacture of concrete and cement mortars. Thus, with the aim of verifying binder-type influence in the final hardness of mortars, two types of cement were used: regular cement and high initial resistance cement. Copper slag was characterized from the chemical, mineralogical and grading viewpoints. Official Chilean regulations were used in the applied methodology for the determination of some important slag parameters. Compression and flexural strength trials were carried out on cement mortars in specialized laboratories. The obtained results showed that mortars manufactured with copper slag presented a better resistance to compression and flexural strength than mortars manufactured with normal sand, and those made with high initial resistance cement were even better. It can be concluded from this work that copper slag offers optimal mechanical characteristics to be used in the manufacturing of cement mortars, becoming a sustainable and adequate alternative material for usage in the construction industry.

IMPACTOS AMBIENTAIS CAUSADOS POR ATIVIDADE DE MINERAÇÃO DE AREIA EM DUNAS FIXAS, CAUCAIA, CEARÁ

2019 ◽  
Vol 21 (2) ◽  
pp. 1060-1069
Author(s):  
Letícia De Freitas Vieira ◽  
Antonio Jeovah De Andrade Meireles ◽  
Henrique Sampaio De Castro
Keyword(s):  
Environmental Impact ◽  
Construction Industry ◽  
Interaction Matrix ◽  
Office Work ◽  
Check List ◽  
Landscape Characterization ◽  
High Magnitude ◽  
Negative Impacts

Este trabalho propõe-se em trazer uma discussão acerca da mineração, enfocando nos impactos ambientais causados pela extração de agregados para a construção civil. A área de estudo é uma poligonal de 44,8 hectares, licenciada para extrair areia até 2018. Localizada em uma duna fixa, foi possível constatar os impactos relacionados com o desmatamento, retirada do solo e do minério, mudança topográfica e o afloramento do lençol freático. A metodologia consistiu em trabalho de campo, gabinete e aplicações de métodos da Avaliação de Impactos Ambientais que foram a Metodologia de listagem (Check-list) e Matrizes de interações. Através dessas metodologias, alguns dos resultados obtidos foram a descaracterização da paisagem, a determinação dos processos evolutivos do campo de dunas com a extração mineral e o afloramento do lençol freático. Por meio do check-list, foram elencados os impactos positivos e negativos, e a matriz de interações relacionou os impactos do empreendimento com o meio ambiente. Baseado nos resultados, concluiu-se que os impactos da mineração são 44% negativos e apenas 6% positivos e que, na maioria dos casos, o impacto ambiental foi de elevada magnitude, representando atividade nitidamente insustentável no âmbito social e ambiental.Palavras-chave: Mineração; Descaracterização da paisagem; Impacto ambiental. ABSTRACTThe present work proposes a discussion about mining, with emphasis on the environmental impacts caused by the extraction of aggregates for the construction industry. The study area is a 44.8 hectare polygon that was auctioned for sand extraction until 2018. Located on a fixed dune, Related to: deforestation, removal of vegetation, soil and ore, topographic change and outcropping of groundwater . The methodology consisted of fieldwork, office work and the applications Environmental Impact Assessment Methods that were the List Methodology (Checklist) and Interaction Matrices. Through these methodologies, some of the results obtained were the de-characterization of the landscape,The determination of the evolutionary processes of the dune field with the mineral extraction and the outcrop of the water table Positive and negative impacts were listed throughout the checklist and the interaction matrix related to development impacts within the environment. Based on the results, it was concluded that the impacts of mining are 44% negative and only 6% positive and that in most cases, the environmental impact was of high magnitude, representing a clearly unsustainable social and environmental activity.Keywords: Mining; Landscape characterization; Environmental impact.

scholarly journals Time-Dependent Strength Behavior, Expansion, Microstructural Properties, and Environmental Impact of Basic Oxygen Furnace Slag-Treated Marine-Dredged Clay in South Korea

2021 ◽  
Vol 13 (9) ◽  
pp. 5026
Author(s):  
Gyeong-o Kang ◽  
Jung-goo Kang ◽  
Jin-young Kim ◽  
Young-sang Kim
Keyword(s):  
Particle Size ◽  
Environmental Impact ◽  
South Korea ◽  
Mechanical Characteristics ◽  
Basic Oxygen Furnace ◽  
Microstructural Properties ◽  
Compression Tests ◽  
Basic Oxygen ◽  
Strength Behavior ◽  
Bof Slag

The aim of this study was to investigate the mechanical characteristics, microstructural properties, and environmental impact of basic oxygen furnace (BOF) slag-treated clay in South Korea. Mechanical characteristics were determined via the expansion, vane shear, and unconfined compression tests according to various curing times. Scanning electron microscopy was conducted to analyze microstructural properties. Furthermore, environmental impacts were evaluated by the leaching test and pH measurements. According to the results, at the early curing stage (within 15 h), the free lime (F-CaO) content of the BOF slag is a significant factor for developing the strength of the adopted sample. However, the particle size of the BOF slag influences the increase in the strength at subsequent curing times. It was inferred that the strength behavior of the sample exhibits three phases depending on various incremental strength ratios. The expansion magnitude of the adopted samples is influenced by the F-CaO content and also the particle size of the BOF slag. Regarding the microstructural properties, the presence of reticulation structures in the amorphous gels with intergrowths of rod-like ettringite formation was verified inside the sample. Finally, the pH values and heavy metal leachates of the samples were determined within the compatible ranges of the threshold effect levels in the marine sediments of the marine environment standard of the Republic of Korea.

scholarly journals Properties of Calcium Sulfoaluminate Cement Mortar Modified by Hydroxyethyl Methyl Celluloses with Different Degrees of Substitution

Molecules ◽  
2021 ◽  
Vol 26 (8) ◽  
pp. 2136
Author(s):  
Shaokang Zhang ◽  
Ru Wang ◽  
Linglin Xu ◽  
Andreas Hecker ◽  
Horst-Michael Ludwig ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Bond Strength ◽  
Cement Mortar ◽  
Retention Rate ◽  
Methyl Cellulose ◽  
Tensile Bond Strength ◽  
Calcium Sulfoaluminate Cement ◽  
Calcium Sulfoaluminate ◽  
Cement Mortars

This paper studies the influence of hydroxyethyl methyl cellulose (HEMC) on the properties of calcium sulfoaluminate (CSA) cement mortar. In order to explore the applicability of different HEMCs in CSA cement mortars, HEMCs with higher and lower molar substitution (MS)/degree of substitution (DS) and polyacrylamide (PAAm) modification were used. At the same time, two kinds of CSA cements with different contents of ye’elimite were selected. Properties of cement mortar in fresh and hardened states were investigated, including the fluidity, consistency and water-retention rate of fresh mortar and the compressive strength, flexural strength, tensile bond strength and dry shrinkage rate of hardened mortar. The porosity and pore size distribution were also analyzed by mercury intrusion porosimetry (MIP). Results show that HEMCs improve the fresh state properties and tensile bond strength of both types of CSA cement mortars. However, the compressive strength of CSA cement mortars is greatly decreased by the addition of HEMCs, and the flexural strength is decreased slightly. The MIP measurement shows that HEMCs increase the amount of micron-level pores and the porosity. The HEMCs with different MS/DS have different effects on the improvement of tensile bond strength in different CSA cement mortars. PAAm modification can improve the tensile bond strength of HEMC-modified CSA cement mortar.

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