Caracterização e avaliação do índice de atividade Pozolânica do resído do beneficiamento do caulim para produção de cimentos de baixo impacto ambiental / Characterization and evaluation of the Pozzolanic activity index of kaolin processing waste for the production of low environmental impact cements

ABSTRACTRefuse-derived-fuel (RDF) consisting mainly of waste paper and plastics is a viable fuel source for the production of power. An experimental test burn partially substituting coal with RDF was undertaken by the Public Service of New Hampshire at the Merrimack Power Station.Five percent and ten percent RDF were substituted, on a BTU basis, for coal in the test bums. The chemical and physical properties of the resulting fly ash were determined. Twelve test burn days were run with 4 days of 5% RDF and 8 days of 10% RDF. Emphasis was placed on investigating the effect of the RDF fly ash on Portland cement concrete.Most of the chemical and physical properties of the coal-RDF fly ash were found to be comparable with ordinary coal fly ash except for the amount of cadmium and lead, the pozzolanic activity index and the compressive strength of fly ash concrete. Cadmium and lead were at average levels of 5.1 ppm and 102.6 ppm for the 5% RDF, and 7.8 ppm and 198.3 ppm for the 10% RDF, respectively. Although the pozzolanic activity index of coal-RDF fly ash increases over normal coal fly ash, preliminary results show that the 28-day compressive strength of concrete with direct replacement of cement and sand decreases by up to 30%. Leaching tests on crushed concrete were conducted to evaluate the environmental effect of acid rain.

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Evaluating the Effect of Calcination and Grinding of Corn Stalk Ash on Pozzolanic Potential for Sustainable Cement-Based Materials

Advances in Materials Science and Engineering ◽

10.1155/2020/1619480 ◽

2020 ◽

Vol 2020 ◽

pp. 1-13

Author(s):

Shazim Ali Memon ◽

Saba Khan ◽

Israr Wahid ◽

Yekaterina Shestakova ◽

Muhammad Ashraf

Keyword(s):

Activity Index ◽

Pozzolanic Activity ◽

Second Phase ◽

Corn Stalk ◽

Cement Concrete ◽

Carbon Particles ◽

Cement Based Materials ◽

Two Phases ◽

Pozzolanic Properties ◽

Ash Disposal

In developing countries, one of the usual practices is the uncontrolled, open burning of corn stalk (CS) or its utilization as a fuel. It is known that the ash obtained under uncontrolled burning conditions constitutes blackish and unburnt carbon particles as well as whitish and grayish particles (representing crystallization of silica) due to over burning. However, controlling the burning process can improve the quality of ash produced to effectively use it in cement-based materials. Hence, this research was aimed at exploring the pozzolanic properties of corn stalk ash upon calcination and grinding, for it to be used in the manufacturing of sustainable cement-based materials. In order to obtain a suitable corn stalk ash (CSA), which can be used in cement/concrete, a research investigation consisted of two phases. In the first phase, calcination was carried out at 400°C, 500°C, 600°C, 700°C, and 800°C for 2 hours. The tests applied on the resulting ashes were weight loss, XRD, pozzolanic activity index (PAI), Chapelle, Fratini, and consistency. From XRD spectra, it was found that, at lower temperatures, silica remained amorphous, while it crystallized at higher temperature. Ash combusted at a temperature of 500°C possessed largest pozzolanic activity of 96.8%, had a Fratini CaO reduction of 93.2%, and Chapelle activity of 856.3 mg/g. Thus, 500°C was chosen as an optimum calcination temperature. In the second phase, the ash produced at 500°C was grinded for durations of 30, 60, 120, and 240 minutes to ascertain the optimum grinding times. Resulting ashes were examined for hydrometer analysis, Blaine fineness, Chapelle activity, and pozzolanic activity. Experiment outcomes revealed a direct relationship between values of Blaine fineness, surface area, Chapelle activity, PAI, and grinding duration. It was concluded that CSA can be used as a pozzolan, and thus, its utilization in cement/concrete would solve ash disposal problems and aid in production of eco-friendly cement/concrete.

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Comparative life cycle assessment of ornamental stone processing waste recycling, sand, clay and limestone filler

Waste Management & Research ◽

10.1177/0734242x18819976 ◽

2019 ◽

Vol 37 (2) ◽

pp. 186-195 ◽

Cited By ~ 1

Author(s):

Thais Ayres Rebello ◽

Robson Zulcão ◽

João Luiz Calmon ◽

Ricardo Franci Gonçalves

Keyword(s):

Life Cycle Assessment ◽

Life Cycle ◽

Environmental Impact ◽

Waste Recycling ◽

Processing Waste ◽

Limestone Filler ◽

Ornamental Stone ◽

Rotary Dryer ◽

The Cost ◽

Comparative Life Cycle Assessment

Owing to the cost of destination and transportation of ornamental stone processing waste, many studies focused on the reuse and recycling of this product. However, there is a scarcity of articles addressing the environmental viability of the recycling of ornamental stone. In this context, this study comprehends a comparative life cycle assessment of ornamental stone processing waste and conventional materials: sand, clay and limestone filler. The modelling software used was SimaPro 8.3.0.0 with Ecoinvent 3.2 database, employing the ReCiPe H/H methodology for impact assessment. The results show that the recycling of ornamental stone processing waste is environmentally preferable, and the artificial drying alternatives, such as flash dryer and rotary dryer, have lower environmental impact than extracting and processing clay through atomisation methods and limestone filler production. The sensitivity analysis indicated that it is possible to transport the ornamental stone processing waste 37 km after processing, so it reaches the same environmental impact as sand extracted by dredging. On the other hand, an increase of 25% in the energy consumption incremented only 7% of the environmental impact owing to the Brazilian energy mix.

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Status of ASTM and Other National Standards for the Use of Fly Ash Pozzolans in Concrete

MRS Proceedings ◽

10.1557/proc-86-293 ◽

1986 ◽

Vol 86 ◽

Cited By ~ 1

Author(s):

Richard M. Majko

Keyword(s):

Fly Ash ◽

Activity Index ◽

Hydrated Lime ◽

Test Methods ◽

General Purpose ◽

Standard Test ◽

Heat Of Hydration ◽

Pozzolanic Activity ◽

National Standards ◽

Sulfate Resistance

ABSTRACTThe Subcommittee of ASTM that is responsible for pozzolan specifications, (C09.03.10) is currently revising C 618, the standard specification, and C 311, the standard test methods. It is no small task. It is generally considered that dividing fly ashes into two classifications (Class F and Class C) is no longer acceptable. The Subcommittee has reached the tentative conclusion that one class of fly ash pozzolan is more appropriate and less ambiguous, provided it is accompanied by an optional table outlining the appropriate limits for sulfate resistance, heat of hydration, hydraulic properties, etc. That is, the engineer need specify only a fly ash pozzolan. If the engineer needs more than a “general purpose” fly ash he calls for special characteristics from the optional requirement table. Any major revision in the C 618 specification challenges the Subcommittee to look for better and more useful test methods in C 311. The committee is looking at C 1012 for a sulfate resistance procedure, conduction calorimetry as a heat of hydration method, and better methods to evaluate pozzolanic activity. The committee is aware of the limited usefulness of hydrated lime or sodium hydroxide in evaluating pozzolanic activity. Perhaps a more suitable term, i.e. the activity index with cement, is more appropriate. Fly ash properties that need to be evaluated include water reduction, activation by lime and alkalies, hydraulic or self-cementing properties and pozzolanic activity. Any test that tends to compensate for a fly ash's lower reactivity (i.e., accelerated thermal curing at 35°C or 65°C) probably leads to misleading results. A critical look at the national standards of other countries might allow the committee to take a visionary yet practical approach toward a new fly ash specification.

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Multivariate Statistical Analysis of the Wfarddc North American Fly Ash Database

MRS Proceedings ◽

10.1557/proc-245-3 ◽

1991 ◽

Vol 245 ◽

Author(s):

Hans S. Pietersen ◽

Simon P. Vriend ◽

Gregory J. Mccarthy

Keyword(s):

Compressive Strength ◽

Statistical Analysis ◽

Specific Gravity ◽

North American ◽

Activity Index ◽

Pozzolanic Activity ◽

Mineral Admixtures ◽

Fly Ashes ◽

Glass Chemistry ◽

Bulk Chemistry

ABSTRACTThe database of chemical, mineralogical and physical characteristics of North American Fly ashes, assembled by the WFARDDC in North Dakota, was analyzed using multivariate statistics. Prior to the multivariate analysis, the data were rearranged in subgroups containing information on bulk-chemistry, glass chemistry, mineralogy and ASTM physical test results. These groups were analyzed individually. The multivariate technique used was Fuzzy C-Means Cluster Analysis, combined with Non-Linear Mapping. Analysis of the data-set indicates a relation between glass network former and network modifier content. The database shows that a subdivision on the basis of bulk CaO (< 11%; 11–20%; >20%) correlates well with the ASTM C618 Σ(SiO2 +Al2O3 +Fe2O3) and/or specific gravity. Mineralogical data indicate a subdivision into clusters containing varying amounts of mullite, quartz and/or ferrite spinel and a variety of Ca-containing minerals; high CaO ashes usually have high Ca-mineral contents. Of the CaO containing minerals, only portlandite contributed slightly to the compressive strength as defined by ASTM C618. Analysis of glass chemistry reveals smaller differences in absolute amounts of major oxides than would be expected on the basis of bulk chemistry alone. Surprisingly, the total glass content does not contribute significantly to 28 day compressive strength; multiple regression analysis only indicates a significant relation of particle size and specific gravity with the ASTM Pozzolanic Activity Index (portland cement). The Pozzolanic Activity Index with lime seems to be of limited importance in evaluating the performance of fly ashes as mineral admixtures in concrete. On the basis of the statistical analysis, suggestions for selection of important classifying variables are made.

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Measurement of Pozzolanic Activity Index of Scoria, Pumice, and Rice Husk Ash as Potential Supplementary Cementitious Materials for Portland Cement

Advances in Civil Engineering ◽

10.1155/2017/6952645 ◽

2017 ◽

Vol 2017 ◽

pp. 1-13 ◽

Cited By ~ 9

Author(s):

Hieronimi A. Mboya ◽

Cecil K. King’ondu ◽

Karoli N. Njau ◽

Alex L. Mrema

Keyword(s):

Portland Cement ◽

Rice Husk ◽

Rice Husk Ash ◽

Activity Index ◽

Cementitious Materials ◽

Pozzolanic Activity ◽

Supplementary Cementitious Materials ◽

X Ray Diffraction ◽

X Ray ◽

Setting Times

This work investigated the properties of scoria and pumice as supplementary cementitious materials (SCMs) for Portland cement and compared to those of rice husk ash (RHA). X-ray fluorescence, X-ray diffraction, and pozzolanic activity index (PAI) tests confirmed the suitability of these two materials as potential SCMs. Scoria and RHA samples achieved over 75% PAI at 7 days whereas pumice did this after 28 days. Initial and final mean setting times observed for the composite cement blended with these materials were 166 and 285 min, respectively. These setting times are longer than that of ordinary Portland cement but shorter compared to that of common Portland pozzolana cement. The ultimate mean compressive strengths achieved at 28 days of curing were 42.5, 44.8, and 43.0 MPa for scoria, pumice, and RHA, respectively, signifying that these materials are good SCMs. Higher fineness yielded higher ultimate mean strength. For instance, a scoria sample with a fineness of 575 m2/kg achieved the strength of 52.2 MPa after 28 days.

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