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Study of Self-Compacting Cementitious Systems Using

Different Secondary Raw Materials

(Session 2008)

Submitted by

Hafiz Farhan Iqbal (2008-NUST-BE-CE-48)

Jaleel-ur-Rehman (2008-NUST-BE-CE-58)

BACHELORS

IN

CIVIL ENGINEERING

YEAR

2012

PROJECT SUPERVISOR

Professor Dr.-Ing Syed Ali Rizwan

NUST Institute of Civil Engineering (NICE)

School of Civil & Environmental Engineering (SCEE) National University of Sciences & Technology (NUST)



This is to certify that

thesis entitled

A STUDY OF SELF COMPACTING CEMENTITIOUS SYSTEM

USING BAGASSE ASH AND BENTONITE

Submitted by

Hafiz Farhan Iqbal (2008-NUST-BE-CE-48)

Jaleel-ur-Rehman (2008-NUST-BE-CE-58)

Has been accepted towards the partial fulfillment

of

the requirements

for the award of degree of

Bachelor of Engineering in Civil Engineering

_____________________

(Prof. Dr. Syed Ali Rizwan, PhD)

Head of Structural Engineering Department

NUST Institute of Civil Engineering

School of Civil Engineering and Environment

National University of Sciences and Technology

Islamabad, Pakistan



Acknowledgements

We grateful to Almighty Allah, the most beneficent, the most merciful, whose

blessings gave me the strength and courage to complete this research work.

We express our gratitude and sincere thanks to Prof. Dr.-Ing. Syed Ali Rizwan for

graciously providing us his kind encouragement, untiring guidance and able supervision

throughout the research work reported in the thesis..

We must not forget the supporting role of laboratory staff at SCEE, NUST,

Islamabad as well as at SCME, NUST, who provided technical assistance and cooperation

during the execution of the research work.

We appreciate the support provided to us by our parents as this research work would

not have been completed without their prayers and whole hearted encouragement and

support.



Abstract

Self-Compacting Cementitious Systems (SCCS) fall in the realm of modern concrete

technology which has been used effectively all over the world. Such systems offer uniform

compaction as well as have uniform durability and are characterized by higher powder

content with lower w/p ratio compared with the conventional concrete.

Effect of Marble Powder, Fly Ash and Silica Fume on response of self-compacting

cement paste system was studied. This would encourage effective use of recycled industrial

byproducts like inert marble powder resulting in more economical and self-compacting

concrete placements. Cement industry contributes 7% of Cemission. So using SRMs as

cement replacement would reduce the clinker production and hence C

emission can be

reduced. In this way these SRMs are used as environmental friendly materials.

The results showed that the broken, edgy particles with rough surface morphology

offers high internal friction during flow so increasing the superplasticizer demand of self-

compacting paste system. Water demand, setting times, strength tests were also conducted.

Scanning electron microscopy (SEM) has been done at different ages to study the formation

of different hydration products.

can also be stated that the SRMs investigated, can be used in Pakistan as cement

replacement successfully as each contributes positively towards improvement of certain

properties of paste system.



Table of Contents

Acknowledgements II

Abstract III

Table of Contents IV

List of Notations and Abbreviations VI

Chapter 1- Introduction and Literature Review ...............................................................................1

1.1 General .............................................................................................................................................. 1

1.2 Pozzolans .......................................................................................................................................... 2

1.3 Secondary Raw Materials ................................................................................................................. 2

1.4 Superplasticizers ............................................................................................................................... 4

1.4.1 Action of Superplasticizers ............................................................................................................ 5

1.5 Research Objectives ......................................................................................................................... 5

Chapter 2-Secondary Raw Materials ..................................................................................................6

2.1Marble Powder ................................................................................................................................... 6

2.2Fly Ash ............................................................................................................................................... 7

2.3Silica Fume ........................................................................................................................................ 8

Chapter 3- Experimental Studies ......................................................................................................10

3.1 General ............................................................................................................................................ 10

3.2 Materials ......................................................................................................................................... 10

3.2.1 Cement ......................................................................................................................................... 10

3.2.2 SRM‘s .......................................................................................................................................... 10

3.2.3 Superplasticizer ............................................................................................................................ 10

3.3 Formulation ..................................................................................................................................... 11

3.4 Mixing Regime ............................................................................................................................... 11

3.5 Flow Tests ....................................................................................................................................... 12

3.6 Setting Times and Water Demand .................................................................................................. 12

3.7 Casting, Curing and Strength of Samples ....................................................................................... 13

3.8 Scanning Electron Microscopy (SEM) ........................................................................................... 14



3.9 Relative Water Absorption.............................................................................................................. 14

Chapter 4- Results ...............................................................................................................................15

4.1 Marble Powder Characterization .................................................................................................... 15

4.2 Particle Shape of SRMs .................................................................................................................. 15

4.3 Physical and Chemical Analysis ..................................................................................................... 16

4.4 Water Demand ................................................................................................................................ 17

4.5 Setting Times without using Superplastisizer ................................................................................. 18

4.6 Setting Times using Superplastisizer .............................................................................................. 19

4.7 Flow Tests ....................................................................................................................................... 19

4.8 Strength Of the SCP Systems ......................................................................................................... 20

4.8.1 Flexural Strength of the SCP Systems ......................................................................................... 20

4.8.2Compressive Strength of the SCP Systems ................................................................................... 21

4.9 Relative Water Absorption.............................................................................................................. 22

4.10 Microstructure of the SCP Systems .............................................................................................. 23

Chapter 5-Discussion ..........................................................................................................................28

5.1 Particle Characterization, water and Superplastisizer Demand and Setting Demand ..................... 28

5.2 Flow of Self-Compacting Paste Systems ........................................................................................ 29

5.3 Strength of Self-Compacting Paste Systems .................................................................................. 30

5.4 Micro-Structure of Self-Compacting Paste System ....................................................................... 30

Chapter 6-Conclusions .......................................................................................................................32

References ...........................................................................................................................................33

Annexure 1 .......................................................................................................................................... 36



List of Notations/Abbreviation

ACI American Concrete Institute

ASTM American Society of Testing of MaterialsCH Calcium Hydroxide

C2S Di-Calcium Silicate

C3S Tri-Calcium Silicate

C3A Tri-Calcium Aluminate

C4AF Tetra-Calcium Alumino Ferrite

FA Fly Ash

LOI Loss On Ignition

MP Marble Powder

SSC Self-Compacting Concrete

SCCS Self-Compacting Cementitious Systems

SCP Self-Compacting Paste

SRM Secondary Raw Material

SEM Scanning Electron Microscopy

SF Silica Fume

SP Superplasticizer

W/C Water to Cement Ratio

WD Water Demand



1

Chapter 1Introduction and Literature Review

1.1. General

Pouring concrete in sections which are heavily reinforced like in columns and beams of

moment resisting frames in seismic areas can be quite a difficult and challenging task and it

requires extensive efforts to provide internal or external vibration. Ensuring proper vibration for

critical sections is part and parcel. The use of standard vibration techniques and conventional

concrete that lacks fluidity results in some construction problems. So need of a concrete that is

easily compactable by its own weight, flow able and can provide high deformation without

segregation and bleeding is needed [1]. Concrete that is able to flow under its own weight andcompletely fill the formwork, even in the presence of dense reinforcement, without the need of

any vibration, whilst maintaining homogeneity [2].

ACI defines SCC as high performance concrete that meets special performance and

uniformity requirements that cannot be achieved otherwise using conventional materials and

practices [3].

SCC is normally characterized by the three properties named as passing ability, filling

ability and segregation resistance. SCC flows under its own weight [2] and it completely fills

the formwork in which it is being casted, this property is known as filling ability. SCC can be

poured in heavily reinforced section so it can pass thorough obstacles caused by the

reinforcement without blocking, this is called passing ability. From batching plant to placing on

site SCC remains homogenous, this is termed as segregation resistance property of SCC.

Ingredients used in SCC other than of normal concrete are powder and super plasticizers.

Addition of SP ensures high deformation without bleeding and segregation. Moreover, the

addition of super plasticizer has a slight beneficial effect on the packing density[4]. In modern

concrete due to low WC ratio all grains of cement may not fully hydrated so cement is replaced

partially by secondary raw materials typically in the range of 5µm-10µm for improving packing

density and for increased pozzolanic activity[5].



2

Use of fine powders and super plasticizers also improves the micro structure of the SCC

and hence the transportation of the fluids is restricted which leads to a greater level of

durability.

1.2. Pozzolan

Pozzolan is a material that has little or no binding characteristics but in presence of water

it reacts with calcium hydroxide and shows cementitious properties.

ACI 237 R defines pozzolan as

“A siliceous or siliceous and aluminous material, which in itself possesses little or no

cementitious value but will, in finely divided form and in the presence of moisture, chemically

react with calcium hydroxide at ordinary temperatures to form compounds possessing

cementitious properties.”

Since calcium hydroxide produced in cement hydration is water soluble so leaching can

occur and voids in the concrete micro structure are expected. In a pozzolanic reaction calcium

hydroxide is used in calcium silicate hydrate (CSH) gel so a better micro structure is attributed

to the use of pozzolan. A better micro structure means comparatively better mechanical

properties. On the other hand the most obvious disadvantage of using pozzolans in replacement

of OPC is that concrete with pozzolans has low early strength [6].

1.3Secondary Raw Materials (SRMs)

Secondary Raw Materials or Supplementary Cementitious Materials are waste or by-

products of industry that require no or less processing prior to their usage as cement

replacement There are basically two reasons involved in using SRMs. One is related to the cost

that is involved in production of cement in terms of detrimental environmental impacts and in

terms of use of energy in cement production [7]. Improvement in fresh and hardened properties

of SCC is the second reason to use SRMs in SCC. It has been reported that emission of total

carbon dioxide produced for production of one ton of cement is nearly 1.1 tones ton for the wet

process. Cement industry adds up nearly 7% of the total carbon dioxide emission [8].World is

facing a severe energy crisis now a days so efforts are in full swing to use energy efficiently.

Energy consumption is very high for cement industry so there is always a need to find some



3

substitute materials that are environment friendly and less processing is required for them.

Addition of SRMs like FA, SF, LSP, MP, Slag in OPC does not affect the properties and

characteristics of the cement but improves certain other properties e.g. workability, durability,

strength, resistance to external environment other than effect on setting times.[9] Different

types of SRM‘s have been in use and have been reported by many researchers. They enhance

the response of the system in fresh state as well as in hardened state. Two types of mechanisms

are involved in enhancing the response of SCC systems namely the ―filler effect‖ and

―pozzolanic activity‖. Two mechanisms are attributed to filler effect i.e. extra spaces for

hydration products of the clinker phase as fillers do not produce hydration products. Fillers due

to their very fine size provide a large surface area and this large area acts as nucleation sites for

the hydration products formed of the clinker phase [9]. Hydration is believed to be followed by

three mechanisms. A diffusion mechanism in which an hydration layer surrounds the anhydrous

grains, an interaction boundary phase between hydration layer and anhydrous grains and lastly

nucleation and growth mechanism. This nucleation and growth mechanism is a dominant factor

for rate of hydration and strength gain rate. Marble Powder, Silica Fume and Fly Ash were used

as SRM in this study. MP is an inert material and provides filler effect. Whereas, Fly ash due to

its comparatively large particle size enhances the response by pozzolanic activity. Silica Fume

shows an interesting behavior as it offers both, filler effect at early days and pozzolanic activity

at later days.

Different SRM‘s have showed different impact on the properties. SF particles had lowest

pore size whereas FA particles had the highest pore size [6] Studies have shown that SF

absorbs more water due to porous structure of its round particles and as a result less water is

available in the system. Due to its small particle size SF shows filler effect in early days and

this effect is responsible for the early strength gain. A 10% substitution of Portland Cement by

SF gave a higher cumulative heat of hydration and a higher strength level is achieved at all

stages as compared to control [10] As pozzolana SF reacts with (CH) present due to the

hydrolysis of C3S and C2S of Cement. Hydration products contain nearly 20%-25% CH. These

crystals grow in solution and week in nature. The percentage consumed by SF represents an



4

index of pozzolanic activity of SF. Nearly 25% of SF consumes most of the Calcium

Hydroxide at 28 days .The reaction process is given by the following equations:

2S + 6H +3CH (1)

Portland cement

2S +4H + CH (2)

Silica Fume

3CH +2S (3)

Whereas FA has a larger particle size of nearly 20 micron. FA improves the workability

due to the round particle shape but larger particle size does not improve workability. So

Pozzolanic Activity is prominent in case of FA. The strength gains for FA are slower at early

ages. However FA is added to provide later age strength gain and to reduce the heat of

hydration [11]. Researchers have reported that at different WC different SRM‘s showed

different response.at higher WC SF accelerates hydration of cement and reverse is true for

lower WC. FA has showed an opposite behavior [12].

MP is an inert filler material [13, 14] and does not show pozzolanic activity. It enhances

the response of the system due to its filler effect [15]. Its fine particles improve the packing

density of the system and hence stop the entrance and transportation of the fluids in the

structure. Due to its fine particle size it improves the cohesiveness and rheological properties of

the SCC systems [16]. MP if used alone then it reduce setting times and decrease the strength

when replaced in large amounts. Blends of MP and FA have been reported and it has been

shown that such blends improve the response of the system [17].

1.4 Superplasticizers

These are basically chemical admixtures which improve the workability of SCC systems

at lower WC ratios and indirectly improve the microstructure and the durability of the concrete

[18]. Normal water reducing agents can reduce the WD by only 10% but Superplasticizerz and



5

high range water reducers have made it possible to reduce the water requirements by 30%. SPs

not only reduce the water requirements but address the durability issues indirectly. The make it

possible to achieve a desired level of workability at lower WC ratio so less water is available in

the system and hence lesser empty spaces in the micro structure and capillary pores. This will

hamper the intrusion and transportation of the fluids like Carbon dioxide, sulphates into the

structures and hence durability is improved.

SPs have an impact on both the fresh properties as well as hardened properties. It has an

effect on the setting times of the system too. So in industries where setting times are of great

care like in Pre-cast industries, SPs should be used effectively and they should have no or

minimum effect on setting times.

1.4.1 Action of Superplasticizers

Cement particles act as a colloid in suspension and entraps the water particles. Each

colloid has a like electrical charge. C2S, C3S, C3A and C4AF are the basic clinker phases in

cement. In absence of SP, C2S and C3S have a negative zeta potential while C3A and C4AFhave

a positive zeta potential,. This accelerates the coagulation process of the cement grains. Some

types of plasticizers have a very high negative zeta potential and promote the dispersion of the

silicate phases which also have a negative zeta potential [19].Admixtures are adsorbed on the

cement grains and cause electrostatic or steric (in the case of polycarboxylate admixtures)

repellency that hinders flocculation [20]

1.5 Research Objectives

The objectives of this research conducted on SCP systems were the followings

1- To see the response of SCP systems using inert powder like marble powder and

pozzolanic powders like FA and SF on fresh properties of SCP systems.2- To study the effect of superplastisizer on the setting times.

3- To study the strength characteristics and water absorption of the system.

4- To study the microstructure of the SCP systems at early ages and its impact on the

properties of SCP systems.



6

Chapter 2

Details aboutSecondary Raw Materials (SRMs) Used

2.1 Marble Powder

Marble powder has been in used from the old days and it has been produced by the

marble industry. It is a waste product of the marble industry. During the cutting and sawing

process of the marble, MP is produced. Disposal of this very fine material is big problem as it

caused environmental related isses.It is estimated that millions of tons of MP is being produced

by the marble industry all over the world. It has been reported that USA, Belgium, Spain, France,

Egypt, Italy, Portugal, Sweden and Greece are countries which are blessed with amply sources of

marble [13].

In marble industry big blocks of marble are cut in quarries and these are brought to the

processing plants. In these processing plants the size of blocks is further reduced and different

types of decorative and tiles are manufactured from these blocks of marble. After this polishing

of these items is done. It is estimated that nearly 20-30% of the marble block becomes marble

powder. During the cutting process the marble powder and the water form slurry that is

environmentally harmful.

Marble Powder from different markets was bought and was analyzed physically by visualinspection for the color and fineness. Some samples were having some impurities and a blackish

color. Analyses showed that these samples had some impurities most probably remain of iron

oxides. Finally MP from Islamabad marble industry was selected as it fulfilled the requirements.

The color of this sample was white and free from impurities like iron oxide. Size of this sample

was found to be coarser by visual inspection then it was decided to subject his sample to some

process. Sample was then milled from Loss Angles Abrasion Machine in NIT (NUST), Pakistan.

It was milled in the machine for 4 hours. After this the size of MP particles was further by a

grinder and then sieved using sieve #325 having aperture of 45 micron. Particle size analysis was

performed and it was found out that the particle size of this sample was 8.9211 micron.

As stated earlier, MP is a non pozzolanic and inert filler material. In literature MP is also

termed as marble dust and it has been reported that MP has properties like limestone and it



7

participate in early hydration reaction. Due to its very fine size it acts as filler and provides a

better packing density.

2.2 Fly Ash

Fly ash is the most commonly used SRM. In thermal power plants, residue obtained from

the combustion of coal is known as fly ash. During the combustion process the mineral

impurities are separated and carried away with exhaust gases and the remaining melted coal

solidifies into glassy circular particles. These glassy particles are then collected via electrical

precipitators. The quality and size of FA particles are greatly dependent on the operation and

process of the thermal power plant and the coal quality that is used in combustion [19]. The

particle size of FA is typically less than micron and the specific surface area is 300 to 500 /kg.

The color of FA is generally gray and tan.

FA contains silica, alumina, iron oxide and calcium oxide as main constituents. ASTM C

618 classifies FA as class ―C‖ and ―F‖. If the sum of the above stated oxides is greater than 50 %

then it is called class ―C‖ FA and it is produced from lignite coal. Class ―F‖ FA has this sum as

more than 70%.

It has been reported that it is this class ‖F‖ FA that is mainly used in concrete and

produced from anthracite. This FA has little or no cementitious properties but only in presence of

moisture and in finely grounded form. The silica present in FA reacts with the calcium hydroxide

and from CSH gel. FA has a low heat of hydration so it finds its uses in mass concrete like in

Dam projects. In mass concrete heat of hydration is a major problem as this heat produces

thermal stress which results in cracks. One problem associated with FA is that it does not have an

effect on early age strength. One promising property linked with FA is later age strength.

Bleeding is also referred as s problem with the use of FA. FA is generally known to retard the

setting times of concrete. The spherical glassy particles of FA offer the ball bearing effect in the

system and this enhances the slump flow and workability of the concrete systems.





9

Table 2.2Silicon Dioxide content of Silica Fume in different alloy making industries [23]

Alloy Type Silica content of SF

50% ferrosilicon 61-84%

75%ferrosilicon 84-91%

Silicon metal 87-98%

Because of amorphous nature of SF it absorbs most of the system water and hence

increases the water demand of the system. The small size and amorphous nature of SF make it

very reactive as well as very good filler material. It reacts with the cement hydration product CH

and produces the binder calcium silicate hydrate gel(C-S-H).It also increase the internal cohesion

and hence prevent bleeding [3]. At ITZ (interfacial transition zone) it reacts with CH to form

binder gel hence reducing the thickness of ITZ which ultimately reduce porosity and avoid

initiation of cracks. At ITZ filler effect is also significant.

The use of SF results in dense microstructure which ultimately provide many benefits

such as lower permeability and high durability, resistance to severe environment (sulfate

attacks), resistance to abrasion and impact, higher flexure and compressive strength,

environmental benefits due to low carbon dioxide emission, resistance to bleeding and high earlyage strength. The strength of system increases due to both pozzolanic and filler effect of SF.

Pozzolanic effect produces more binder gel while as filler it fills in the gaps which were to be

filled with water and after hydration would be there as pores. Low percentages of SF have

negligible effect on setting times while high percentages increase the setting times [24].



10

Chapter 3

Experimental Program

3.1 GENERAL:

Secondary raw materials which are used in the experimentation are first milled to

required size i.e minimum size is that SRM used should be passing from sieve # 325.consistency

of the system at 10% replacements, particle characterization and superplastisizer content is also

found .Standard molds are casted and tested at specified age of 1,3,7 and 28 days. Total flow and

required flow time for each system is found using Hagerman‘s mini-slump cone. SEM(scanning

electron microscopy) is done for morphology of cement, SRMs and analysis of hydration

products at early stages.

3.2 MATERIALS:

3.1.1 Cement:

Ordinary Portland cement (OPC), grade 43, type I of Pakistani company ‗Bestway‘

confronting to ASTM standard C150-04[25] is used for all formulations. Average particle size of

cement used was 15.41µm

3.1.2 Secondary Raw materials (SRMs):

Secondary Raw Materials used for experimentation consist of:

Silica Fume(SF) which are imported from RW-Fuller Silicium GmbH Germany.

Fly Ash(FA) imported from Germany.

Marble Powder from local marble industry of Islamabad.

3.1.3 Superplastisizer:

Third generation superplasticizer Melflux imported from Degussa Germany is used for

necessary flow tests and casting. The amount of superplasticizer is varied depending on the SRM

used and water content.



11

3.3 Formulation

Four formulations were proposed for this study as C-O, C-MP-10%, C-FA-10% and C-

SF-10%.The code of this formulation can be comprehends as the first alphabet refers to cement,

the second is for SRM. In first for mulation ―O‖ represents Ordinary Portland Cement or neat

cement paste. The number ―10%‖ indicates the amount of SRM that is being added.

Cement C-SRM-10% Percentage of SRM being added

SRM being used

3.3 Mixing Regime:

The material is first dry mixed by hand in a a plastic jar for 2 minutes and then poured

into the bowl of Hobart mixer already containing weighted mixing water. In Hobart mixer

mixing is done in two steps. First the formulation is slow mixed at 145 rpm for 30 seconds and

for the next 30 seconds the walls of bowl are cleaned with the help of spatula and in the second

step it is fast mixed at 285 rpm for 150 seconds in the Hobart mixer as shown in fig thus making

the full mixing time to be 3 minutes. Above mixing regime is kept same for all the formulations.

Both mixing time and mixing sequence is kept same for all the formulations as it is critical in

economy and durability of self-compacting cementitious system(SCCS)[19]

Fig. 3.1 Hobart mixer



12

3.4 Flow Tests:

Flow measurements were made using the Haggerman‘s mini slump cone (with bottom dia

of 10 cm, minimum dia of 7 cm and height of 6 cm) and the glass plate as shown in the fig. The

required total target flow is kept 30±1cm.At mixing water to cement ratio of WD, 40% and 50%

for all the formulation the dose of superplasticizer for target flow is obtained using hit and trial

procedure. Firstly the cone is placed on properly leveled glass plate having markings of

10cm,25cm and 30cm and then self-compacting paste from the Hobart mixer is poured into it.

Once the cone is lifted the self-compacting paste would move outward in a circular fashion.For

flow measurement two diagonal dia‘s are measured as shown in fig.3.2 and their average is

taken. While the paste move outwards two times to be noted T25 (time to reach 25cm Dia) and

for total flow i.e. once the paste stopped moving. It should be kept in mind that the total flow

should exceed the limit of 30±1cm.

Flow=D1+D2/2

Fig. 3.2 Slump Test Arrangements

Fig. 3.2Flow TestFig. 3.3Mini Slump Cone

3.4 Setting times and Water demand:

Setting times and water demand of neat cement paste and all other formulations water

demand of the system i.e. at 10% replacement with SRMs is calculated using standard Vicat

apparatus at temperature and humidity in accordance with EN 196-3[26].Setting time is

determined for all formulations for both with and without addition of superplasticizer.



13

3.5 Casting, Curing and Strength of Samples:

Casting, curing and testing of the formulations is done according to EN 196-1 of

1994.After mixing of material in Hobart mixer the materials are poured into prisms of standard

Sizes of 40x40x160mm size. After pouring prisms are covered with sheet in order to avoid

evaporation of moisture from the surface. Prisms are demolded after 24 hours and kept for moist

curing in water tub after weighing at room temperature. These prisms were then taken out of the

tub at specified ages of 1, 3, 7 and 28 days, weighted again to calculate relative absorption.

The specimens of size 40x40x160mm are then tested both in flexure and compression.

For flexure three samples are tested average is taken as the flexure strength at specified age.

Broken samples from flexure are then used for test in compression average of six samples is

taken as compressive strength. Cross-sectional area of samples tested in compression was

40x40mm and these are tested between two steel plates of size 40x40mm one at the bottom and

other at the top as shown in fig.

Fig. 3.4 Machine used for Flexural and Compressive Strength



14

3.6 Scanning Electron Microscopy (SEM):

Scanning Electron Microscopy is very beneficial in study of microstructure and to

analyze the hydration progress at different ages. For SEM studies after the compression testing

of sample it is broken into small piece and a small piece of about 1-2mm is preserved in

Isopropanol in order to stop hydration at particular age. SEM analysis is then done on machine

jed-2300 Scanning Electron Microscope.

3.7 Relative Absorption:

For relative absorption samples are weighted at the time of molding and prior to testing,

the difference of the two weights is calculated which ultimately give the weight of water

absorbed between casting and testing of samples. This weight of water is percentage over the

initial weight (weight at demolding) and regarded as relative absorption. This relative water

absorption was calculated at 1, 3, 7 and 28 days.



15

Chapter 4

Results

In this chapter, results from the experimental program on SCP system have been presented.

First of all particle size tests and chemical composition tests were conducted and the obtained

results are provided in table no.

4.1. Marble Powder Characterization

MP was collected from the market so after the inspection it seemed coarser and it was decided

to subject it to milling process. For that Los Angles Abrasion machine was used and after that for

further reducing the size grinder was used and required size of ranging from 8-9 microns was

achieved.

4.2. Particle Shape of SRM’s

Size and shape of SRM‘s used in the study are important to find out as these parameters are

instrumental in determining the properties of the SCC systems.

(a) Fly Ash (Rizwan 2006) (b) Silica Fume (Rizwan 2006)

Fig. 4.1SEM Images of SRM particles used in study



16

Irregular shapes and flaky particles cause problems in transportation and placing as

compared to regular and circular ones.

4.3 Physical and Chemical Analysis

Tests were conducted to find out the physical and chemical properties of cement and

SRMs that were used. The results are shown in table 4.1.

Table 4.1 Physical and Chemical Composition of Cement and SRMs

Parameters CEM 1 MP FA SF

Particle Size (micron)

Chemical Analysis

(Per cent)

Silicon dioxide

Aluminum Oxide

Ferric Oxide

Calcium Oxide

Magnesium Oxide

Sulfur trioxide

Sodium Oxide

Potassium Oxide

15.41

18.23

4.36

3.53

66.67

3.15

2.42

-

1.64

8.922

2.93

-

-

94.34

2.73

-

-

-

26.56

51.44

26.13

5.55

4.03

2.51

1.89

1.23

2.63

8.66

95

0.2

0.05

0.25

0.4

-

0.1

1.2

It is important to note that SF has a very high BET surface Area which is instrumental in

many of its properties. Content of Silicon dioxide in SF is 95%. This very high BET area and

higher content of amorphous silicon dioxide make SF very reactive [22].



17

According to ASTM C618 if the sum of silicon dioxide, aluminum oxide and iron oxide is

greater than 70 then it is classified as class ‖F‖ FA. If the sum is Greater than 50 the FA is Class

―C‖ FA. From the above table it is clear that the FA used in our research is class ―F‖ FA.

4.4 Water Demand

The WD of all the formulations was find out according to ASTM C187 -11e1.The results

graph of WD show that different formulations have different WD.WD is a very important

parameter which is ignored by many researchers.

Fig. 4.2 WD of Different Formulations

It is obvious from the fig. 4.2 that all the formulations other than the one with neat cement

paste have WD above than that of C-0. Maximum WD is shown by C-SF-10%. A very sticky

paste was observed for C-SF-10%. Very fine particle size and hence greater surface area is

instrumental for a higher WD of concrete containing SF [11]. Amorphous nature of SF is also

responsible for increased water demand.

Excessive addition of fine particles results in increase in Specific surface area of the binding

component which ultimately increases the water requirements of the system to achieve the givenconsistency. FA showed a comparatively lower WD which can be attributed to its larger particle

size, circular particle shape and glassy surface so it has a less affinity for water.

27%31% 29.50%

36%

0%

10%

20%

30%

40%

C-0 C-MP-10% C-FA-10% C-SF-10%

W / C %

Water Demand (WD)%

C-0 C-MP-10% C-FA-10% C-SF-10%



18

4.5 Setting Times without Using Super Plasticizers

The effect of SP on setting times was also studied and reported. For this purpose setting

times with super plasticizer and without super plasticizer at WD were determined. The results of

this study are shown in Fig. 4.3 and Fig 4.4.

Formulation having 10% MP accelerated the setting time of the SCP system [27]. FA has

been known to retard to hydration of the system and hence the setting times are delayed. It has

been reported in the literature that FA acts as Ca sink in that it removes C , this reduces the

concentration of Ca in the early hours and delays the crystallization of CH and CSH hence

retarding the hydration [12]. SF on the other hand has shown acceleration in setting times. The

reason associated with this acceleration may be that during first few minutes release of C and

alkali ions from cement particles is rapid, the reduction in C in the solution increases the rate

of release and amount of heat evolution i.e. hydration at this stage is accelerated [12,10]

Fig. 4.3 Setting Times Without SP at WD

160 155

185

168

190 185

216

187

0

50

100

150

200

250

C-0 C-MP-10% C-FA-10% C-SF-10%

T i m e ( M i n u t e s )

Formulations

Setting Times Without SP at WD

Initial Setting Time Final Setting Time



19

4.6 Setting Times with Super Plasticizers

Usually SPs are known to retard the setting times. The level of retardation depends upon

type of cement, temperature and the type of SP itself. It is reported that SP generally retard

the conversion of ettringite to monosulfate. The retardation effect of ettringite- may be

caused by the adsorption of the SP on the hydrating surface [28].

Fig. 4.4 Setting Times SP at WD

4.7 Flow Tests:

Flow tests were conducted to find out the required dose of SP for targeted flow of

1 cm. These tests were performed at WD of the SCP system and at W/C of 40% and 50%.

SF demanded a highest dose of SP because of its extremely high surface area. It is also

reported that because of very fine nature of SF it reduces the size of the flow channels by

occupying the empty spaces and hence increase the contact points between solid particles

resulting in more cohesive paste [22]. From the following graph it can also be deduced that aswe increase the W/C ratio the doze of SP reduces as more water is available for the system to

achieve the target flow. But overall the demand of SP mainly depends on the shape, size, surface

morphology and internal porosity of the SRMs being used. Because of circular nature of the FA

the amount of SP is low to achieve target flow.

370380

400

375

410415

435

405

320

340

360

380

400

420

440

C-0 C-MP-10% C-FA-10% C-SF-10%

T i m e ( M i n u t e s )

Formulations

Setting Times With SP At WD

Initial Setting Time Final Setting Time



20

Fig. 4.5

4.8 Strengths of the SCP Systems

4.8.1 Flexural Strength of the SCP Systems

Prism samples of size 40x40x160mm were tested at 1, 3, 7 and 28 days for flexural

strengths. The results are given in table 5 of annexure 1. Flexural strengths of different

formulations are presented in fig. 4.6.

Fig. 4.6Flexural Strength at WD

0

0.05

0.1

0.15

0.2

0.25

0.3

W/D 40% 50%

S P D o s e ( % )

W/C

Required SP Dose for Different W/C

C-O

C-MP10%

C-FA-10%

C-SF-10%

0

1

2

3

4

5

6

7

8

Formulation

: C-O

Formulation

: C-MP-10%

Formulation

: C-FA-10%

Formulation

: C-SF-10%

F l e x u

r a l S t r e n g t h ( M P a )

Flexural Strength at WD

1 day strength

3 days strength

7 days strength

28 days strength



21

4.8.2 Compressive Strength of the SCP Systems

Compressive strength tests were performed on the samples that were broken from the

flexural test samples. Formulation with Marble powder showed overall decrease in strength gain

rate as compared to cement control formulation but early age strength was significant when

compared with fly ash. It is well conversant with the results reported in past. MP shows filler

behavior and acts as nucleation site and accelerates the hydration of clinkers phases mainly of

and improvement in early strength was reported [29]. Silica fume showed an overall increase

in strength as compared to all others formulations both at early and later ages. It has been

reported that replacement of 10% SF gave a greater compressive strengths at all ages [30]. SF

has very fine particles, at early ages it provides filler effect and due to its very fine size and

amorphous nature it is very reactive so it has pozzolanic activity as well which contributes in

later age strength development. In case of Fly Ash rate of strength gain is low at early age but

long term compressive strength is significant and appreciated Due to its bigger particle size than

that of SF its reactivity is slower but it promises later age strength comparable to formulation

having SF.

Fig. 4.7 Compressive Strength (MPa) at WD

0

10

20

30

40

50

60

70

80

90

Formulation

: C-O

Formulation

: C-MP-10%

Formulation

: C-FA-10%

Formulation

: C-SF-10%

C o m p r e s s i v e S t r e n g t h ( M P a )

Compressive Strength (MPa) at WD

1 day strength

3days strength

7 days strength

28 days strength

56 days Strength



22

Fig. 4.8Trend of Compressive Strength at WD

4.9 Relative Water Absorption

The relative water absorption tests results are presented and shown in fig.4.8.

Fig. 4.9 Relative Water Absorption (%) of Formulations At WD

0

10

20

30

40

5060

70

80

90

0 10 20 30 40 50 60

S t r n g h t ( M p a )

Days

Trend of Compressive Strength at WD

C-0

C-MP-10%

C-FA-10%

C-SF-10%

0

0.5

1

1.5

2

2.5

3

0 5 10 15 20 25 30

R e l a t i v e W a t e r A b s o r p a t i o n %

Age(Days)

Relative Water Absorption(%) of Formulations At WD

C-0

C-MP-10%

C-FA-10%

C-SF-10%







25

EDAX

Elements

Weight (%)

MgO 3.37

Al2O3 4.39

SiO2 20.58

SO3 3.11

K 2O 2.60

CaO 56.47

Fe3O4 2.69

Fig. 4.13: Self compacting paste system sample containing 10% Fly Ash in addition mode

at the age of 3 day along with EDAX.

EDAX

Elements Weight (%)

MgO 3.01

Al2O3 4.25

SiO2 17.18

SO3 2.20

K 2O 1.95

CaO 62.99

Fe3O4 2.45

Fig. 4.14: Self compacting paste system sample containing 10% Marble Powder in addition

mode at the age of 1 day along with EDAX.



26

EDAX

Elements

Weight (%)

MgO 3.40

Al2O3 4.45

SiO2 19.81

SO3 2.43

K 2O 1.93

CaO 60.25

Fe3O4 2.72

Fig. 4.15: Self compacting paste system sample containing 10% Marble Powder in addition


EDAX

Elements

Weight (%)

MgO 1.94

Al2O3 3.67

SiO2 30.02

SO3 0.48

K 2O 4.39

CaO 51.52

Fe3O4 2.75

Fig. 4.16: Self compacting paste system sample containing 10% Silica Fume in addition


CSH gel

Ettringite



27

EDAX

Elements

Weight (%)

MgO 2.13

Al2O3 4.21

SiO2 29.08

SO3 2.00

K 2O 5.76

CaO 45.95

Fe3O4 2.24

Fig. 4.17: Self compacting paste system sample containing 10% Silica Fume in addition


Calcium hydroxide

CSH gel

Ettringite



28

Chapter 5

Discussion

5.1 Particles Characterization, Water and Super Plasticizer Demand and Setting Times

Particle shape, size and morphology of secondary raw materials are very instrumental for

understanding their role in terms of water and super plasticizer demands, flow, strength and

microstructure of self-compacting paste (SCP) systems. The SEM images of secondary raw

material particles used in the study are shown in Fig 4.1.

MP though has a smaller particles size but it has irregular particles with a rough surface

texture unlike FA particles. Due to this irregular and rough surface texture MP has higher water

demand as compared to FA and a higher SP dose is also attributed to the reason stated above. Fig

4.1(a) shows the circular but relatively coarser particles of FA The circular nature of the FA

particles results in less internal resistance and is a reason for its improved workability. Besides

this FA has glassy surface which is instrumental for its low water demand (Fig. 4.2).SF has a

smaller particle size than MP and FA particles and its surface seems to have numerous minor

pores. Due to such characteristics SF particles show higher water demand and super plasticizer

demand for the target flow (Fig 4.2 and Fig 4.5).

Specific surface area may also indicate porosity. Greater specific surface area with

smaller particle size would mean that the particles have more internal porosity. This can be seen

in the SEM images of SF particles as shown in Fig.4.2 (b). Adding to this, it has already been

reported that certain amount of super plasticizer is also adsorbed by SRMs depending upon the

morphology and surface texture of the particles. Again same can be confirmed by higher super

plasticizer demand of SF (Fig 4.5). [31-33].

It is also observed that increasing water to cement ratio would lower the SP dose for

target flow. Fig.4.5 shows that at WD the dose of SP was highest. This dose was reduced for

higher water to cement ratios e.g. at W/C=0.40 and W/C=0.50. The reason for the decrease in

W/C is obvious that more unbound water is available in the system to react with the binder and

make hydration products. However at this point durability issue should be incorporated. Higher

water to cement ratios results in more unbound water and then this water initiates capillary effect



29

and pores are generated, packing is not very dense and ultimate result is compromise on the

structure durability. So water to cement ratio equals to water demand of the system is best to

address the durability problems of the structure.

Retardation in setting time is observed for the formulation containing 10% FA.FA has

been known to retard to hydration of the system and hence the setting times are delayed. It has

been reported in the literature that FA acts as Ca sink in that it removes C this reduces the

concentration of Ca in the early hours and delays the crystallization of CH and CSH hence

retarding the hydration [12]. In addition to this, coarser particles of FA are also a reason.

SF on the other hand has shown acceleration in setting times. The reason associated with

this acceleration may be that during first few minutes release of C and alkali ions from cement

particles is rapid, the reduction in C in the solution increases the rate of release and amount of

heat evolution i.e. hydration at this stage is accelerated [12,10].

MP also showed acceleration in setting times there is an overall acceleration in the setting time

for the self-compacting formulation with MP which can be attributed to the smaller particle size

of MP with more specific surface area. With the smaller particles of MP and these particles acts

as the center of nucleation for deposition of products of hydration, hence accelerates the setting.

Usually SPs are known to retard the setting times. The level of retardation depends upon

type of cement, temperature and the type of SP itself. It is reported that SP generally retard the

conversion of ettringite to monosulfate. The retardation effect of ettringite- may be caused

by the adsorption of the SP on the hydrating surface [28].

5.2 Flow of Self Compacting Paste Systems

After establishing the water demand, super plasticizer demand and the setting times, the

next parameter to be investigated for self-compacting cementitious system is the flowability of

the cementitious system; for which slump flow is usually prescribed. The slump flow test usingmini slump cone aims at investigating yield stress, deformability and the unrestricted filling

ability of self-compacting cementitious systems. It basically measures two parameters; the total

flow spread and a suggested flow time T25 cms. The former indicates the free unrestricted

deformability or the yield stress and the later indicates the rate of deformation within a defined



30

flow distance. The smaller value of flow time T25 cms indicates lesser internal friction offered,

during the flow, by the powder particles and translates into higher deformation.

Table 3 in annexure 1 shows that formulation with 10% FA has a lower value for T25

cms.This is attributed to the circular particle shape of FA. This resulted in a lesser internal

friction. Whereas MP showed a higher T25 cms. This is attributed to the irregular particle shape

and rough surface texture.

5.3 Strength of Self Compacting Paste Systems

Formulation with Marble powder showed overall decrease in compressive strength gain

rate as compared to cement control formulation (Fig.4.7) but early age strength was significant

when compared with fly ash. It is well conversant with the results reported in past. MP shows

filler behavior and acts as nucleation site and accelerates the hydration of clinkers phases mainly

of and improvement in early strength.

Silica fume showed an overall increase in strength as compared to all others formulations

both at early and later ages. It has been reported that replacement of 10% SF gave a greater

compressive strengths at all ages [30]. SF has very fine particles, at early ages it provides filler

effect and due to its very fine size and amorphous nature it is very reactive so it has pozzolanic

activity as well which contributes in later age strength development.

In case of Fly Ash rate of strength gain is low at early age but long term compressive

strength is significant and appreciated Due to its bigger particle size than that of SF its reactivity

is slower but it promises later age strength comparable to formulation having SF (Fig. 4.8)

5.4 Micro-structure of Self Compacting Paste Systems

For scanning electron microscopy a very small space of a specially prepared

representative sample is viewed at high magnifications with the help of special instruments to seethe hydration products, presence of different phases and their interconnectivity. An expert study

of images obtained can give very useful and accurate information about microstructure of cement

based composites.



31

The SEM images of various self-compacting formulations at the age of 1 and 3 days are

shown in Fig 4.10 to Fig. 4.17 to study the products of hydration. All formulations exhibit the

growth of ettringite in the form of needle like cubic crystals, calcium hydroxide‘s large

hexagonal crystals and the calcium silicate hydrate gel which does not possesses a well-defined

crystalline structure. The growth of crystals corresponds to the specified ages in the images. It is

clear from the figures that at day 3 the crystals of ettringite are more clear and strong. From the

figures it is clear that formulation of SF does not have calcium hydroxide crystals. It only has

CSH gel and ettringite crystals. A more dense structure is formed when SF is incorporated.



32

Chapter 6

Conclusions

Based on the research conducted, the following conclusions can be deduced.

1. Different SRMs show a different response in SCP systems.

2.

The Response of the SCP systems is greatly dependent on the particle shape, size

and morphology of SRMs used.

3.

SP retards the setting times of the systems

4.

FA has a coarser particle size so its reaction starts at later ages

5.

MP acts only as filler and contributes very little in later age strengths.



33

References:

[1]. Patrick Paultre, Kamal Khayat, Daniel Cusson, and Stephan Tremblay, ―Structural performance of self-consolidating concrete used in confined concrete columns‖ ,ACI

Structural Journal, v.102, no.4, July 2005, pp. 560-568.

[2]. EFNARC,“Specification and Guidelines for Self-Compacting Concrete‖ Febraury 2005,

ISBN 0-9539733-4-4

[3]. ACI 363R-92, reapproved 1997, ―State of the Art Report on High Strength Concrete‖, ACI

Detroit, USA.

[4]. Kwan A.K.H., Fung W.W.S.,‖Packing density measurement and Modeling of FineAggregate and Mortar‖, Cement & Concrete Composites 31 (2009) 349– 357.

[5]. Rizwan, S.A and Bier, T.A,‖ Self-Consolidating Mortars Using Various Secondary Raw

Materials”, ACI Materials Journal, USA, Vol. 106, No. 1, January-February 2009, pp 25-32

[6]. G. Habert,N. Choupay, J.M. Montel, D. Guillaume, G. Escadeillas,‖ Effects of the

Secondary Minerals of the Natural Pozzolanas on their Pozzolanicactivity‖, ‖Cement and

Concrete Research,Volume 38, Issue 7, July 2008, Pages 963 – 975

[7]. Juenger M.C.G., Winnefeld, Provis J.L., Ideker J.H., ―Advances in Alternatives

Cementitious Binders‖, Cement and Concrete Research 41 (2011) 1232-1243

[8]. Malhotra V.M.,‖Role of Fly Ash in reducing Greenhouse Gas emission during the

Manufacturing of Portland Clinker‖.

[9]. Lothenbach B., Scrivener, Hooton R.D.,‖ Supplementary Cementitious Materials‖, Cement

and Concrete Research 41 (2011) 1244-1256

[10]. Kadri EI.H., Duval R.,‖ Hydration Heat Kinetics of Concrete with Silica Fume‖,

Construction and building materials 23(2009) 3388-3392

[11].

Malhotra V.M.,‖ Fly Ash, Slag, Silica Fume, and Rice Husk Ash in Concrete: A

Review‖, April 1993

[12]. Langan B.W., Weng K., Ward M.A,‖ Effect of Silica Fume and Fly Ash on heat of

hydration of Portland Cement‖, Cement and Concrete Research 32(2002) 1045-1051

http://www.sciencedirect.com/science/journal/00088846/38/7

http://www.sciencedirect.com/science/journal/00088846/38/7





35

[24]. Zhang W.,Zhang Y, et al., ― Investigation of the Influence of Curing Temperature and

Silica Fume Content on Setting and Hardenign Process of the Blended Cement Paste by an

Improved Ultrasonic Apparatus‖, Construction and Building Materials 33 (2012) 32– 40

[25].

ASTM C150-04 Standard Specification for Portland Cement.

[26]. EN 196-3, Methods of testing cement — Part 3: Determination of setting time and

soundness

[27]. J.Neeraj,‖ Effect of NonPozzolanic and Pozzolanic Mineral Admixture on the Hydration

Behavior of Ordinay Portland Cement‖, Construction and Building Materials 27 (2012) 39-

44

[28]. Ramachandran V.S., ―Concrete Admixtures Handbook‖, 2nd Ed.: Properties, Science and

Technology

[29]. Husson S. P.J, B. Guilhot,‖ Influence of Finely Ground Lime stone on Cement

Hydration‖, Cem Concrete Compos 1999;21(2):99-105

[30]. Papadakis V.G., ―Experimental Investigation and Theoretical Modeling of Silica Fume

Activity in Concrete‖, Cement and Concrete Research 29(1999) 79-86

[31]. Rizwan, S.A and Bier, T. A.; ―Early Volume Changes of High-Performance Self-

Compacting Cementitious Systems Containing Pozzolanic Powders‖, Proceedings of Intl

RIELM Conference on Volume Changes of Hardening Concrete: Testing and Mitigation,

20 – 23 Aug 2006, Technical University of Denmark, Lyngby, Denmark, pp. 283-292.

[32]. Rizwan, S.A. and Bier, T. A.; ―Role of Mineral Admixtures in High Performance

Cementitious Systems‖, 2nd

All Russian International Conference on ―Concrete and

Reinforced Concrete-Development Trends‖, Vol. 3, Concrete Technology, 5-9 September

2005, Moscow, Russia. pp. 727-732.

[33]. Magarotto, R., Moratti, F., and Zeminian, N., ―Characterization of Limestone and Fly ash

for a Rational use in Concrete‖, Proceedings of International Conference, Dundee,Scotland, UK, 5-7 July 2005, pp71-80.





37

C-SF-10 40 0.231.76

12.3 950 86.4 863.63 345.45

C-SF-10 50 0.1651.5

6.0 950 86.4 863.63 431.82

Table 4Relative Water Absorption (RWA) at 1,3,7 and 28 days.

Formulation RWA at Day1 RWA at Day3 RWA at Day7 RWA at Day28

C-O 0.614 1.283 1.436 1.812

C-MP-10 0.735 1.89 1.943 2.308

C-FA-10 0.806 1.36 1.436 1.969

C-SF-10 0.855 1.77 2.007 2.48

Relative Water Absorptions are given in percentages.

Table5 Flexural Strengths of the SCP systems at 200& Flow

Formulation Day1 Day3 Day7 Day28

C-O 3 5.22 5.667 6.9

C-MP-10 2.86 5.46 6.6 6.5

C-FA-10 1.43 4.36 5.4 5.83

C-SF-10 3.2 5.63 6 7.4

Table5Compressive Strengths (MPa) of the SCP systems at 200& Flow

Formulation Day1 Day3 Day7 Day28 Days 56

C-O 42.68 50.86 59.44 71.8 75.4

C-MP-10 39.3 49.86 53.6 64.24 69.4

C-FA-10 35.38 41.93 55.1 65.16 81.45

C-SF-10 45.25 54 62.34 79 85.1



Fig. 1 Cement SEM Image

Fig. 2 EDAX of Cement Sample

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00

keV

0

100

200

300

400

500

600

700

800

900

1000

C

o u n

t s

O K a

M g

K a

A l K

a

S i K

a

S K a

S K

b

K K a

K K

b

C a

K a

C a

K b

F e

L l

F e

L a

F e

K e s c

F e

K a

F e

K b

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