Performance of High Volume Fly Ash Concrete in Structural Applications

Application of high volume fly ash concrete is still not advocated by construction fraternity due to lack of standardisation. In India, fly ash as a pozzolanic material can be used in manufacturing of Portland Pozzolana cement and composite cement with a maximum limit of 35%. Present study had been carried out at various percentages of fly ash and a detailed mechanical and durability study was conducted. In this paper, concrete mixes were designed at two water binder ratio with 30%, 35%, 40% and 50% fly ash content. Mechanical behaviour of concrete was studied through tests like compressive strength (at age of 1, 3, 7, 28, 56 and 90 days) and flexure strength (at an age of 7, 28 and 90 days). Durability aspect of high volume fly ash concrete mixes were determined through various test like RCPT, non-steady state chloride migration, bulk conductivity, accelerated carbonation etc. and comparison is made with control mixes (i.e. concrete made with OPC). Alkali silica reactivity (ASR) study was also carried out at 30%, 35%, 40% and 50% fly ash content using reactive aggregates. It was quite evident from test results that strength characteristics of high volume flyash concrete mix made with 50% flyash content was remarkably lower than that of all other concrete mixtures. High volume flyash concrete mix designed at 40% flyash content had shown exemplarily performance in comparison to other high volume flyash concrete mixes as well as control mixes. Flyash content was found to most significant parameter influencing rate of carbonation

Enumeration of Family Fabaceae from Sechu Tuan Nalla Wildlife Sanctuary, Chamba District, Himachal Pradesh (India)

An account of 20 species under 11 genera of the family Fabaceae is presented based upon a thorough study of the collected specimens and field surveys in this paper from Sechu Tuan Nalla Wildlife Sanctuary, Chamba district, Himachal Pradesh. Of these, fourteen taxa are reported first time from the Chamba district of the state. The updated nomenclature of the species, local name if any, a brief description of the plant, flowering and fruiting period, distribution in the study area, habitat and ecology and specimen examined have been provided

Application of Vortex Methods to Coaxial Rotor Wake and Load Calculations

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143042/1/6.2017-0051.pd

MANAGEMENT AND CLASSIFICATION OF CONSTRUCTION AND DEMOLITION WASTE IN INDIA

Construction and Demolition (C&D) waste have a huge potential to replace virgin materials. However, due to lack of management, its utilization has not been optimized. Issues like sharing of responsibilities among various stakeholders and classification of C&D waste are some of bottleneck on part of effective implementation of C&D waste management in India. This paper illustrates quantity and quality of C&D waste generation in India, regulatory framework, policy interventions and R&D work carried out to classify C&D waste aggregate for production of concrete. Experimental studies were carried out using two different sources of recycled concrete aggregates; one batch of aggregates are obtained from Burari Plant located in New Delhi and another batch of aggregates were created in laboratory by crushing concrete cubes of 20- 30MPa. Thereafter, recycled concrete aggregates were classified on basis of their physical properties like specific gravity and water absorption and their performance in concrete have been evaluated in terms of fresh properties like workability, air content, bleed water percentage and mechanical properties like compressive and flexural strength. Study indicates that air content in concrete mixes prepared from recycled coarse aggregate (RCA) is 5-20 % higher than that of corresponding control mix whereas admixture requirement for concrete mixes prepared with RCA was found to be slightly higher in comparison to that of control. Experimental study indicates that compressive strength as well as flexural strength of concrete mixes prepared with recycled concrete aggregate has been reduced drastically in comparison to control mixes without recycled coarse aggregate

DESIGN OF LOW CARBON HIGH PERFORMANCE CONCRETE INCORPORATING ULTRAFINE MATERIALS

In general, high performance concrete (HPC) is associated with high strength and improved durability in comparison to normal strength concrete. However, HPC invariably involves high binder content at low water/binder ratio and its application has been limited to specialised concrete works. In this study, an attempt was made to design high performance concrete, at high water/binder ratio made with OPC content varying from 40%-80% in concrete mixes with low binder content of 280 kg/m3. Binary and quaternary, low carbon mixes were prepared by incorporating  Supplementary Cementitious Materials (SCM) and Ultrafine (UF) materials (silica fume, ultrafine GGBS, ultrafine fly ash and metakaolin) and were characterised for strength and durability parameters such as charge passed using RCPT, electrical resistivity and carbonation depth. Findings of the study shows that with appropriate choice and combination of SCM and ultrafine materials, low carbon high performance concrete mixes can be designed for strength up to 50 MPa with improved durability performance even at 45% OPC content. Overall, performance of low carbon high performance concrete mixes depends on the type and extent of SCM as well ultrafine materials such as metakaolin, ultrafine GGBS, ultrafine fly ash and silica fume use along with their compatibility

Analysis of intraoperative frozen section consultations and audit of accuracy: a two year experience in a tertiary care multispeciality hospital in India

Background: Diagnostic accuracy of intra-operative frozen section (FS) depends largely on quality of tissue sections backed by good clinical communication and experience of reporting pathologist. Periodic audit of this consultation in surgical pathology help in assessing the efficiency of procedure and addressing the pitfalls. In this study authors have analysed the spectrum, indications and assessed the accuracy of FS consultation in their institution.Methods: A retrospective study of 212 consequent tissue specimens submitted for FS over two years in study centre was conducted. The FS and corresponding formalin fixed paraffin embedded (FFPE) tissue section with their final histopathological examination (HPE) reports were studied and analyzed. The results were classified in concordant, discordant and deferred categories. Accuracy rates and discordant frequencies were calculated and comparison with other similar studies was done. Reasons for inaccuracies were deduced.Results: A total of 212 tissue specimens for FS were reported over two years in this study institute, six of which showed discordant results. Most common site of FS in this study centre was from central nervous system (CNS) lesions (28.77%). Indications for intra-operative consultation were mainly for establishment of tumor diagnosis (66.51%) and status of margins (29.25%). The accuracy rate was found to be 97.17% with error rate of 2.83%. On analysis of discordant cases; the reason for inaccuracy was mainly due to interpretation error (83.33%).Conclusions: The audit of FS consultation established that accuracy rates of this study institution are comparable with most international quality control statistics for FS. The discordant cases were mostly false positive hence emphasising that a variable degree of reservation is required while interpreting and communicating the FS results. The closest possible diagnosis should be communicated on FS and definitive diagnosis should be deferred to HPE in case of doubt

A Comprehensive Characterization of Simple Sequence Repeats in the Sequenced Trichoderma Genomes Provides Valuable Resources for Marker Development

Members of genus Trichoderma are known worldwide for mycoparasitism. To gain a better insight into the organization and evolution of their genomes, we used an in-silico approach to compare the occurrence, relative abundance and density of SSRs in T.atroviride, T. harzianum, T. reesei, and T. virens. Our analysis revealed that in all the four genome sequences studied, the occurrence, relative abundance, and density of microsatellites varied and was not influenced by genome sizes. The relative abundance and density of SSRs positively correlated with the G+C content of their genomes. The maximum frequency of SSRs was observed in the smallest genome of T. reesei whereas it was least in second smallest genome of T. atroviride. Among different classes of repeats, the tri-nucleotide repeats were abundant in all the genomes and accounts for ~38%, whereas hexa-nuceotide repeats were the least (~10.2%). Further evaluation of the conservation of motifs in the transcript sequences shows a 49.5% conservation among all the motifs. In order to study polymorphism in Trichoderma isolates, 12 polymorphic SSR markers were developed. Of the 12 markers, 6 markers are from T. atroviride and remaining 6 belong to T. harzianum. SSR markers were found to be more polymorphic from T. atroviride with an average polymorphism information content value of 0.745 in comparison with T. harzianum (0.615). Twelve polymorphic markers obtained in this study clearly demonstrate the utility of newly developed SSR markers in establishing genetic relationships among different isolates of Trichoderma