1,721,043 research outputs found
Resonant Frequency Ultrasonic P-Waves for Evaluating Uniaxial Compressive Strength of the Stabilized Slag–Cement Sediments
No full textAbstract Marine sediments can be stabilized by ultra high-strength binders: cement, Cement Kiln Dust (CKD) and slag. The properties of the stabilized soil indicate potential to their reuse. This study investigated the performance of the unconfined compressive strength (UCS) in the marine sediments stabilized by binder (cement, CKD, slag), tested by ultrasonic P-waves. Materials include 194 specimens collected from the port of Gothenborg. The experiment was performed in Swedish Geotechnical Institute (SGI). The UCS of specimens stabilized by different ratio of binders (cement, CKD, slag) was tested by resonance frequencies of the elastic P-waves. The significant increase in the UCS (>1500 kPa) was recorded for the highest values of CKD and cement, and low values of slag. The correlation profiles of low water/high binder (L W /H B ) cement/slag (40/60%) were controlled by curing time. The slag–cement–CKD simplex tests demonstrated UCS of samples with low/high water content and various binder ratio of cement (kg/m 3 ). The ratio of cement binder and curing time play a critical role in the increase of UCS followed by mechanical properties of specimens and intensity of stress. The highest values exceed 1000 m/s in P-waves. The results shown high accuracy (97%) and non-contacting approach for testing UCS of sediments. Seismic methods can be applied to test the UCS of the stabilized sediments, and also in-situ via seismic CPT, surface testing or cross hole seismic testing.info:eu-repo/semantics/publishe
Hardening Accelerators (X-Seed 100 BASF, PCC, LKD and SALT) as Strength-Enhancing Admixture Solutions for Soil Stabilization
No full textThis study is aimed at evaluating the strength of stabilised soil collected from the Port of Norvik, Stockholm, Sweden, where 350,000 m 3 of clay had to be stabilized. The tests were performed in the laboratory of the Swedish Geotechnical Institute (SGI). The soil was stabilised by binder mixtures using Portland cement clinker (PCC) and lime and lime kiln dust (LKD). Accelerators (X-seed 100 BASF, PCC, LKD and salt) were added to the soil samples for quicker stabilization. The strength of the stabilised soil was assessed using resonance frequency measurements of seismic P-waves by an ICP accelerometer in order to estimate the shear strength of the soil and to evaluate the effects from the accelerators, binder ratios, and the curing temperature on the gains in stabilization and strength. Various proportions of the binders were tested, i.e. 50/50 cement/lime and 50/50 PCC/lime. The temperature was measured using a calorimeter in double experiments. The results showed that the accelerators improve the strength in the stabilized specimens and enhance the soil performance for engineering construction work.info:eu-repo/semantics/publishe
Effects of GGBS and Fly Ash in Binders on Soil Stabilization for Road Construction
No full textIn this paper we propose a new technique of soil stabilization for road construction based on using new alternative binders. The project aims to evaluate the effects of alternative additive materials in soil stabilization contexts for road construction. The alternative binders (slag, energy ash and bio ash as new alternative road construction material) have been used to complement the traditional binders (cement and lime). The project used five binders and evaluated their effects on soil strength. The proposed method comprises advantages of using the alternative binders which are the residual products contributing to a lower environmental impact. The results have shown that only slag has significant effects on the strength of the stabilized soil, while bio ash and energy ash make a marginal contribution to the increase of strength. This is caused by the twofold reasons. First, the effects of the amount of ashes that should reach a certain threshold with respect to the total amount of binder that must be exceeded to have the effect of the soil mixture. Second, the bio fly ash was stored and it was not completely fresh which may have contributed to the carbonation during the storage period and results in a lower hardening ability. Based on the results of the study we recommend the use of bio fly ash as a supply material andfor its amount to be adjusted so the storage period is not too long. This study verified the effects of slag, cement and lime on stabilization of soil for road construction.În această lucrare propunem o nouă tehnică de stabilizare a solului pentru construcția drumurilor bazată pe folosirea de noi lianți alternativi. Proiectul își propune să evalueze efectele materialelor aditive alternative în contexte de stabilizare a solului pentru construcția drumurilor. Lianții alternativi (zgură Merit 5000, cenușă energetică și cenușă bio ca nou material alternativ de construcție a drumurilor) au fost folosiți pentru a completa lianții tradiționali (ciment și var). Proiectul a folosit cinci lianți și a evaluat efectele acestora asupra rezistenței solului. Metoda propusă cuprinde avantajele utilizării lianților alternativi care sunt produsele reziduale care contribuie la un impact mai mic asupra mediului. Rezultatele au arătat că numai Merit 5000 are efecte semnificative asupra rezistenței solului stabilizat, în timp ce cenușa bio și cenușa energetică au o contribuție marginală la creșterea rezistenței. Acest lucru este justificat de două motive. În primul rând, efectele cantității de cenușă care ar trebui să atingă un anumit prag în raport cu cantitatea totală de liant care trebuie depășită pentru a avea efectul amestecului de sol. În al doilea rând, biocenușa a fost depozitată și nu complet proaspătă, ceea ce ar fi putut contribui la carbonatare în timpul perioadei de depozitare și are ca rezultat o capacitate de întărire mai mică. Pe baza rezultatelor studiului, vă recomandăm să folosiți biocenușa ca material de alimentare și să ajustați cantitatea acestuia fără o perioadă prea lungă de depozitare. Acest studiu a verificat efectele zgurii, cimentului și varului asupra stabilizării solului pentru construcția drumurilor.info:eu-repo/semantics/publishe
Geotechnical Properties of Soil Stabilized with Blended Binders for Sustainable Road Base Applications
No full textThis study aimed at evaluating the effect of blended binders on the stabilization of clayey soils intended for use as road and pavement materials in selected regions of Sweden. The stabilization potential of blended binders containing five stabilizers (cement, bio fly ash, energy fly ash, slag and lime) was investigated using laboratory tests and statistical analysis. Soil samples were compacted using Swedish Standards on UCS. The specimens were stabilized with blended mixtures containing various ratios of five binders. The effects of changed ratio of binders on soil strength was analyzed using velocities of seismic P-waves penetrating the tested soil samples on the day 14 of the experiment. The difference in the soil surface response indicated variations in strength in the evaluated specimens. We tested combination of blended binders to improve the stabilization of clayey soil. The mix of slag/lime or slag/cement accelerated soil hardening process and gave durable soil product. We noted that pure lime (burnt or quenched) is best suited for the fine-grained soils containing clay minerals. Slag used in this study had a very finely ground structure and had hydraulic properties (hardens under water) without activation. Therefore, slag has a too slow curing process for it to be practical to use in real projects on stabilization of roads. The best performance on soil stabilization was demonstrated by blended binders consisted of lime/fly ash/cement which considerably improved the geotechnical properties and workability of soil and increased its strength. We conclude that bearing capacities of soil intended for road construction can be significantly improved by stabilization using mixed binders, compared to pure binders (cement)
Dynamics of Strength Gain in Sandy Soil Stabilised with Mixed Binders Evaluated by Elastic P-Waves during Compressive Loading
No full textThis paper addresses the problem of stabilisation of poor subgrade soil for improving its engineering properties and stiffness. The study aim is to evaluate the effects from single and mixed binders on the gain of strength in sandy soil over the period of curing. We propose an effective non-destructive approach of using P-waves for identifying soil strength upon stabilisation. The growth of strength and stiffness is strongly dependent on time of curing and type of the stabilising agents which can include both single binders and their blended mixtures. The diverse effects from mixed binders on the properties of soil were evaluated, compared and analysed. We performed the experimental trials of five different binders for stabilisation of sandy soil using cement, lime, Ground Granulated Blast Furnace Slag (GGBFS), energy fly ash and bio fly ash. The methodology included soil stabilisation by binders during a total period of 90 days, strength test for the Unconfined Compressive Strength (UCS) and seismic tests on the stabilised samples. The dynamics of soil behaviour stabilised by different binders for days 7, 14, 28 and 90 was statistically analysed and compared. The optimisation of binder blending has been performed using mixture simplex lattice design with three binders in each case as independent variables. Using P-waves naturally exploited strength characteristics of soil samples and allowed us to compare the effects from the individual and blended binders over the complete period of curing with dominating mixes. The results indicate that strength growth in stabilised soil samples is nonlinear in both time and content of binders with dominating effects from slag which contributed the most to the compressive strength development, followed by cement.SCOPUS: ar.jSCOPUS: ar.jinfo:eu-repo/semantics/publishe
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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