The document discusses the effect of high MgO content in cement and how it can lead to delayed expansion when hydrated. Some key points:
1) MgO content above 2% in the clinker appears as free MgO (periclase) which hydrates slowly to form brucite, causing delayed expansion over time.
2) Factors that influence the autoclave expansion caused by MgO include the particle size and distribution of periclase crystals, cement fineness, cooling rate of the clinker.
3) To control expansion, the document recommends limiting MgO in the raw mix to below 2-3%, increasing iron content which stabilizes MgO, and rapidly quenching the
The Indian cement industry today stands at
260 MTPA capacity, with greater growth prospects
and promising future ahead. Cement industry has
been an excellent example of a fast growing sector
showing consistent and steady reduction in its
energy consumption. This has largely been
possible by steady and continuous improvement
across all equipments in cement manufacturing
process.
The Indian cement industry today stands at
260 MTPA capacity, with greater growth prospects
and promising future ahead. Cement industry has
been an excellent example of a fast growing sector
showing consistent and steady reduction in its
energy consumption. This has largely been
possible by steady and continuous improvement
across all equipments in cement manufacturing
process.
ENERGY MODELING OF THE PYROPROCESSING OF CLINKER IN A ROTARY CEMENT KILNISA Interchange
This paper highlights the efforts taken by the author in developing an Energy Model for the pyro-processing of Clinker production in a dry-process rotary cement kiln. In this paper this Energy Model is applied to a state of the art cement plant in a Far East Asian country. However this Energy Model is also applicable to all the modern dry process cement kilns. This model is based on actual field input data and site observations.
STUDY THE CORRELATION OF CLINKER QUALITY, RESIDE, PSD ON THE PERFORMANCE OF P...IAEME Publication
This research establishes the correlation between clinker quality, residue, particle size distribution and performance behaviour of cement. Different qualities of clinker were identified to understand the influence of mineralogy on the performance of cement. Chemical and mineralogical evaluation of clinker and gypsum were carried out as per the Indian specified standards, XRD and Optical microscopy. Cement samples were prepared by inter mixing of clinker and gypsum with 95 and 5% respectively for different fineness zones such as 225, 250, 275, 300, 325 and 350 m2/kg. The resultant samples were studied for residue, particle size distribution and performance evaluation as per IS 4031. It was observed that clinker quality plays an important role to achieve the desired performance characteristics in addition to the residue and particle size distribution of the cements.
ENERGY MODELING OF THE PYROPROCESSING OF CLINKER IN A ROTARY CEMENT KILNISA Interchange
This paper highlights the efforts taken by the author in developing an Energy Model for the pyro-processing of Clinker production in a dry-process rotary cement kiln. In this paper this Energy Model is applied to a state of the art cement plant in a Far East Asian country. However this Energy Model is also applicable to all the modern dry process cement kilns. This model is based on actual field input data and site observations.
STUDY THE CORRELATION OF CLINKER QUALITY, RESIDE, PSD ON THE PERFORMANCE OF P...IAEME Publication
This research establishes the correlation between clinker quality, residue, particle size distribution and performance behaviour of cement. Different qualities of clinker were identified to understand the influence of mineralogy on the performance of cement. Chemical and mineralogical evaluation of clinker and gypsum were carried out as per the Indian specified standards, XRD and Optical microscopy. Cement samples were prepared by inter mixing of clinker and gypsum with 95 and 5% respectively for different fineness zones such as 225, 250, 275, 300, 325 and 350 m2/kg. The resultant samples were studied for residue, particle size distribution and performance evaluation as per IS 4031. It was observed that clinker quality plays an important role to achieve the desired performance characteristics in addition to the residue and particle size distribution of the cements.
This is an invitation for panel discussion on Durability of Concrete Structures. The event is organised by Ambuja Cement Knowledge Centre and ICI, Pune, on 28 May 2016.
This slideset was prepared as a student group assignment, for a class on-Introduction to Construction Materials. The facts shown and data used are most relevant to the Indian Context. Prepared by- K. Hari Chandana, Sukirti Sah, Tanya Talwar, Rana Sarkar, Akriti Srivastava, Jitendriya Meher, Anshuman Abhisek Mishra : 1st Sem B. Arch, School of Planning & Architecture, Bhopal, MP, India
This presentation covers the chemical constituents of Portland cement (PC) and the effects and properties of each of the main and minor compounds that make up the (PC). Their typical ranges in PC and in various types of PC. (edited)
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
Cement is the world's most used construction binder material. Cement production emits large amounts of CO2 and consumes significant amount of energy. As a result, it is necessary to find a new concrete material to replace traditional Portland cement concrete, which is environmentally stressful, yet provides an effective building material. Geopolymer is an emerging alternative binder to Portland cement for making concrete. Geopolymer concrete is principally produced by utilizing industrial by-product materials such as fly ash, blast furnace slag, and other aluminosilicate materials. RCC structures undergo serious durability problems like spalling, erosion, wear, cracking, corrosion etc. years after the construction. Repair to damaged concrete are important not only to ensure the planned useful life, but also to provide good performance and security. This paper review the literature related to the studies conducted on geopolymer and repair materials.
Concrete, Cement, Raw Material of Cement, Types, Water, Aggregates, Sand, Mix...Naqeeb Khan Niazi
Concrete is an engineering material that simulates the properties of rock and is a combination of particles closely bound together. It is simply a blend of aggregates, normally natural sand and gravel or crushed rock.
Cement is a dry powdery substance made by calcining lime and clay, mixed with water to form mortar or mixed with sand, gravel and water to make concrete. It is a binder material. Once hardened, cement delivers sufficient strength to erect large industrial structures
Cement is manufactured through a closely controlled chemical combination of calcium, silicon, aluminum, iron and other ingredients. Common materials used to manufacture cement include limestone, shells, and chalk or marl combined with shale, clay, slate, blast furnace slag, silica sand, and iron ore.
Sand a loose granular material that results from the disintegration of rocks, consists of particles smaller than gravel but coarser than silt, and is used in mortar, glass, abrasives, and foundry molds. : soil containing 85 percent or more of sand and a maximum of 10 percent of clay.
Concrete, Cement
Raw Material of Cement, Types
Water, Aggregates, Sand
Mixing of concrete
Transportation, Rate Analysis
Effect of Steel Fiber on Alkali activated Fly Ash ConcreteIJERA Editor
Concrete is the world’s most important Construction material so the demand of cement is increases. The
production of cement is highly energy intensive & the production on one ton of cement liberates about one ton
of CO2 to atmosphere. The contribution of cement industry to the greenhouse gas emission is estimated to be
about 70% of the total green gas emission. Also it consumes large amount of natural resources. Hence it is
essential to find alternative to cement. Geopolymer concrete is an innovative material in which the binder is
produced but the reaction of an alkaline liquid with a source material that is rich in silica alumina.
The present work deals with the result of the experimental investigation carried out on geopolymer concrete
using steel fiber. The study analyses the effect of steel on compressive strength. Geopolymer concrete mixes
were prepared using low calcium fly ash & activated by alkaline solution. (NaOH & Na2SiO3) with alkaline
liquid to fly ash ratio of 0.35 Alkaline solution. Used for present study combination of sodium hydroxide &
sodium silicate with ratio 2.5. The mix was designed for molarity of 16M & grade chosen for investigation was
M30. Hooked end steel fiber . All tests were conducted according to IS-code procedure. The result for each
variation are tabulated & discussed in details & some important conclusions are made.
It consists of required concrete ingredients such as Cement, Fine Aggregate, coarse aggregate and water. Steps to reduce carbon footprint,Hydration of cement and M-sand introduction.
Similar to Effect of high mg o on cement expansion (20)
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
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Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
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II Subalternation and Theology
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VI Theology as a Natural Science
VII Theology’s Certitude
VIII Conclusion
Notes
Bibliography
All the contents are fully attributable to the author, Doctor Victor Salas. Should you wish to get this text republished, get in touch with the author or the editorial committee of the Studia Poinsotiana. Insofar as possible, we will be happy to broker your contact.
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1. Effect of High MgO on Cement expansion
(Autoclave Expansion)
Introduction
The Autoclave expansion test is used to provide an index of potential
delayed expansion caused by the hydration of CaO and MgO in hydraulic
cements.
Cement soundness may be monitored by cement paste expansion in boiling
water with the Le-chatlier test apparatus.
Lechatlier procedure determines unsoundness from the hydration of the free
CaO only
Autoclave procedure measures the expansion from either free Cao, free
MgO, or both.
However it should be noted that a High C3A and low C4AF content in
cement, in addition to the known additive effects of CaO and MgO may also
contribute to the total autoclave expansion.
Dreizer(1981) has investigated the causes of the cement expansion due to
periclase ( Crystalline MgO), and identified the following factors as
influencing cement soundness:
MgO content of the raw materials
Mineralogical composition of the raw materials.
Chemical composition of the raw materials.
Raw meal fineness
Clinker burning
Clinker cooling
Periclase size and size distribution in the clinker
Cement fineness
Cement storage
Cement additives
2. Technical Literature
The MgO in cement is a dangerous ingredient, if present in large
quantities due to its slower hydration.
MgO in excess of 6 % deteriorated with the age and exhibited both
reduced tensile strength and expansion after five years of storage.
Autoclave Expansion Test
The failure of Autoclave test is due to either free CaO( Lime )or free
MgO ( magnesia) but rather to the amount of Coarse( greater than 200-
mesh sized) particles in the cement.
On Le-Chatlier test for cement unsoundness demonstrated that free lime
(CaO) alone was responsible any abnormal expansion, cracking, or
distortion of the cement paste.
If the materials was fine enough, the cement in every case became
sound.
In 1963, the autoclave expansion limit was increased to 0.8 %.
It is mainly hard-burned lime (CaO) rather than hard-burned magnesia
(MgO) that cause expansion under autoclave conditions.
Correlation with concrete
It is found that MgO recrystallized as dense, compact periclase crystals
at rotary kiln.
Its harmful expansion seemed to be inhibited by chilling the clinker so
that MgO was retained in the solution in the glass form.
If Clinker was cooled slowly, more periclase crystallized out of the melt
and larger crystals were formed.
Blended Portland cements produced with a clinker containing 7.5 % MgO
showed satisfactory properties in a 4- year old concrete, with no
evidence of deterioration.
Conclusion: Rapid Chilling clinker causes the MgO in the
solution in the glass form and reduce the autoclave
expansion.
Cement fineness effects
Coarser ground cements have always exhibited a greater amount
autoclave expansion, all other parameters remains same.
The effects of cement fineness on autoclave expansion as follows.
High MgO- content cement ground to a fineness of
225m2/Kg showed an autoclave expansion of 7.06 %.
When the cement was ground to a higher fineness of 350
M2/Kg, the autoclave expansion dropped to 1.39 %
3. When the fineness increased to a value of 400 M2/Kg, the
resulting autoclave expansion was only 0.24 %.
Conclusion: when the cement ground more finer
then the autoclave expansion will reduce.
Periclase size and Distribution
No autoclave expansion were found for smaller periclase crystals
which were predominately located in the interstitial phases.
The clinker cooled by more rapid cooling process results in smaller
periclase crystals.
At constant 5 % MgO content, as the lime saturation factor of
clinker increased, the free MgO (periclase) content increase and
resulting cement autoclave expansion increased.
Hard burning mixes with only 1.5% to 3 % MgO often failed the
autoclave test due to excessive amounts of free lime.
Addition of fluorspar to high raw mix has aided in the formation of
smaller periclase crystals (1 to 7 µm) and more uniform distribution
in the clinker.
Portland cement ground from Clinker containing 6% MgO can pass
the autoclave test by the use of 0.8 % CaF2 in the raw mix.
A high MgO Clinker ground with 2.0 % SO3 containing and the
cement was having 6.5 % MgO (5.4 % free periclase) and free CaO
content 0.47 %. The particle size distribution showed 80 % of
periclase is of size less than 5 µm and remaining 20 % periclase is in
the size 5 to 15 µm range. The autoclave expansion of the same
cement found to be 0.47 %
Conclusion :
1. Rapid cooling clinker decreases the size of periclase
crystals and ultimately decreases the autoclave
expansion.
2. At constant MgO %, lowering the LSF reduce the free
MgO content resulting the less autoclave expansion.
3. Hard burning mixes failed autoclave expansion.
4. CaF2 (fluorspar) reduce the Periclase size and hence
reduce the effect of MgO expansion. Addition of
0.8 % CaF2 in raw mix can pass the autoclave
expansion.
4. Long-term Storage and hydration
Cement (containing 5.0 % MgO and 0.22 % free CaO) paste bar were
autoclave at three different periods and other bar cured in water
for a longer period (1 years). A paste bar that was autoclave after
24 hours disintegrated from excessive expansion. A Paste bar
autoclave after 3 days of water curing was 0.48 % and that of 7 days
water curing was 0.22 %. A paste bar after 1 year curing shows an
expansion of 0.03
Conclusion – Long curing of cement decreases the
autoclave expansion.
Hard –burned Periclase additions
Hard burn MgO more than 2.5 % added to cement failed the
autoclave expansion.
However no expansion was found for cement mixture containing up
to 5 % of light-burned magnesia, as this materials hydrated before
set had taken place
Conclusion: - light –burned MgO hydrate rapidly before the
cement set.
Raw Mix Composition factors
As a thumb rule “approximately 2 % of the total MgO content in a
cement clinker will remain in solid in the other clinker phases, and
the remainder of the MgO is expected to be present in the form of
periclase crystals.
The amount of periclase in clinker , particle size and particle size
distribution will varying based upon such factors as
(a) Chemical composition of the raw feed ,
(b) raw feed fineness,
(c) raw feed mineralogy,
(d) Clinkering temperature.
(e) Clinkering cooling history. This may have direct influence on
the amount of autoclave expansion.
An elevated –SO3 clinker (from CaSO4 additions to the raw mix or
by the use of high sulfur fuel) also prevented the excessive
autoclave expansion of high MgO cement.
With 5 % MgO-containing clinker with
(a) 2.17 % SO3 the autoclave expansion was 0.44 %
(b) 1.01% SO3 the expansion was 4.0 %
(c) 0.37 % SO3 the specimen was disintegrated.
5. With lower LSF (0.94 to .97) increasing MgO has no influence on
the free CaO. With a higher LSF (0.97 to 1.00), any increase MgO
content result in free CaO and the risk of unsoundness.
Conclusion :
1. High sulfur fuel (pet coke) or CaSO4 in raw mix prevent the
excessive expansion of high MgO cement.
2. With lower LSF (0.94 to 0.97) increasing MgO has no
influence on the free CaO. With a higher LSF (0.97 to 1.00), any
increase MgO content result in more free CaO and the risk of
unsoundness.
Iron addition effects
The free MgO will decrease as Fe2O3 increases in the raw mixture.
A cement containing 5.0 % MgO and2.3 % Fe2O3 had autoclave
expansion of 1.28 % whereas another cement containing 4.9 5 MgO
and 3.6 % Fe2O3 expanded 0.15 %.
C4AF is an excellent stabilizer for MgO and capable of
transformation of considerable amount of MgO into a non-
expanding compound.
It is suggested that lowering the alumina modulus and thereby
lowering the C3A and increasing the C4AF contents, could readily
counteract the autoclave expansion influence of MgO , but it was
conceded that rapid cooling of clinker also has very beneficial
effect on the stabilization of MgO.
Conclusion :
1. Free MgO will decreases as Fe2O3 increases in the raw
mixture.
2. Lowering the alumina modulus and thereby lowering the C3A
and increasing the C4AF contents, could readily counteract the
autoclave expansion influence of MgO.
Mixed Design Guidelines
Different plant have different design mix control criteria and
limit. The ratio between (alumina+ magnesia) and Iron oxide
should be maximum 2.7
The ratio of MgO to Fe2O3 is to be considered for raw mix
design
MgO: Fe2O3 > 1.53 – plant in trouble , autoclave expansion
prevalent danger zone
MgO: Fe2O3 > 1.40 – High probability of expansion, any
appreciable free CaO gives excessive expansion.
6. MgO: Fe2O3 < 1.40- Probability of expansion failure decreases
rapidly.
MgO: Fe2O3 < 1.20- Standard control target (maximum value)
failure due to MgO very unlikely.
Conclusion : Raw Mix guidelines
1. Ratio: (Al2O3+MgO)/Fe2O3 ≤ 2.7 % (maximum).
2. Ratio : MgO: Fe2O3 < 1.20
The effect of MgO on the composition and properties of alite-
sulphoaluminate cement clinker with commercial-grade raw materials such
as limestone, clay, gypsum and fly ash as starting materials has been
investigated in order to confirm results obtained with pure raw materials.
What will happen if MgO >2% in raw mix? How it will affect
the clinker formation process in kiln?
(i) The addition of MgO retards the initial hydration of cement and
increases the setting time of cement.
Two causes for the retardation of hydration are proposed:
(a) As the solubility product constant of Mg (OH)2 is far smaller
than Ca(OH)2, Mg(OH)2 precipitates earlier than Ca(OH)2. The
formation of Mg (OH) 2 reduces the Ca (OH)2 saturation ratio, thus
delaying the initiation of the maximum of Ca(OH)2 saturation ratio.
(b) When MgO hydrates in high-alkali medium such as the liquid
phase of hydrating cement, Mg (OH)2 with tiny crystals precipitates
around the cement grains to form a protective layer, hence retarding
further hydration of the cement grains.)
(ii) MgO is good for nothing in raw mix. it gives some darker colour to
the clinker. More MgO consumes extra thermal energy, if the
particle size also more the clinker will get disintegrate quickly
because of expansion.
(iii) Below about 2% in the clinker, MgO is incorporated into the crystal
structure of the clinker minerals. MgO in excess of about 2% appears in
the clinker as free MgO (the mineral periclase).
(iv) MgO present 1 - 1.5 % in clinker is a very good mineralizer and improve
nodulisation. If it is quenched it does not give expansion
problems .Good nodules are always preferred in burning and it helps in
improving cooling efficiency and there by recovering thermal energy
from clinker.
7. (v) If the clusters of MgO crystals are numerous and large enough this
can cause excessive expansion in the cement resulting in
unsoundness. Finer grinding of the cement can offset this problem
up to a point.
(vi) Withinthe kiln MgO increases the liquid phase and may therefore
promote the formation of clinker minerals. However, too much MgO
can increase the liquid phase to problematic amounts and cause
excessive coating and even balling of the clinker.
(vii) Most plants therefore try to keep MgO levels in the raw mix to
below 2 or 3%.
(viii) MgO at about 2–5% can
(a).Improve the burnability of raw meal, promote the absorption of free
lime and the formation of C3S and C4A3S¯.
(b)Increase the strength development of the cement
(c) Shorten the setting time.
(ix) When the content of MgO reaches about 8%, the strength of the
cement decreases slightly and the setting time is extended.
(x) Clinkers with 2% MgO it helps in better distribution of C3S and C2S in
clinker as per clinker microscopy studied. The C3S and C2S contents
were linearly related to the SO3/MgO ratio. Adding SO3 hindered the
formation of C3S, the formation temperature of which increased by
approximately 100 °C.
MgO enhanced the formation of C3S by both accelerating the
clinkerization reactions and lowering the formation temperature of C3S.
The C4AF content increased when MgO was added. Microscopically, MgO
led to the formation of small C3S crystals, whereas SO3 enlarged the size
of C3S crystals and promoted the formation of C2S rims. M3 alite was the
primary component of the MgO-doped clinkers, whereas the M1 type was
stabilized by SO3;
(xi) Cement clinker when it is stored outside as we see clinker cracks and
rate of cracking depends on the % of free lime. Periclase hydrates
slowly forming Brucite, which has more expansion (delayed) than free
CaO. So after many days the concrete structures expand. The size of
periclase and % is the most influential parameters for delayed
expansion and can be reduce by
(a) Grinding the raw meal finer,
(b) Increase Rate of burning,
(c) Rapid Annealing or quenching of clinker
8. (xii) By screening in crusher, small amount of MgO will be separated.
(xiii) If corrective (Iron ore) use also reduce the MgO % to some extent.
(xiv) MgO periclase crystalline would not reacted while on hydration.
(xv) Clinker cooling have to be done properly (clinker outlet temperature
-100 0C to convert MgO should convert glassy content form.
(xvi) MgO should be freezed as glassy content on cooling
(xvii) MgO should be bring to form smaller size periclase.
(xviii) Ash Content should be maintain above 32 % (if limestone TCO3 is
above 83 %), If maintain low ash, MgO % will increase due to low ash
absorption.
(xix) Low MgO Limestone grade to be consumed (either Kukurdih or
Sweetener).
(xx) Cement fineness to be increased.
(xxi) Ash abortion should be maintained 4-5 %
(xxii) C3A is to be maintained :6-8 %
(xxiii) MgO reacts with water to form Mg(OH)2 that cause volume expansion
of about 118 %(2-4)
(xxiv) The hard burnt MgO in cement reacts with water very slowly and the
expansion caused by MgO hydration takes place after the concrete
has hardened, so that the shrinkage of cement could be compensated
effectively.
(xxv) MgO content in the ordinary cement is restricted to less than 5 % and
can be 6 %.
(xxvi) Free lime should be maintained 1-1.5 %, if MgO is more in cement
then PPC, Slag cement is to be ground.
(xxvii)Up to around 2% the MgO will dissolve in the clinker minerals,
predominantly in the C4AF and therefore contribute to the liquid
phase in the kiln. That is why changes in MgO content of kiln feed
can sometimes cause clinker ball or coating ring formation. Above 2%
the MgO will be present as periclase, MgO, as a solid phase. It is this
solid MgO that can lead to long-term unsoundness in hydrated
cement due to slow hydration of the periclase. When MgO is higher
than 2% then rapid heating and cooling is beneficial to ensure the
MgO is present in small, reactive crystals of periclase, which will
hydrate while the cement is hardening and therefore not cause
unsoundness by later expansion of periclase.