micro, macro and durability properties of self compacting...

Indian Journal of Geo Marine Sciences Vol. 47 (08), August 2018, pp. 1702-1712

Micro, macro and durability properties of self compacting concrete using various filler materials

R Manju* & J. Premalatha

Department of Civil Engineering, Kumaraguru College of Technology, Coimbatore, Tamilnadu, India *[E-mail: [email protected]]

Received 08 June 2016 ; revised 14 September 2016

Present study is an experimental programme to evaluate the micro level properties of SCC using the above materials. For the study a total of 5 SCC mixes was produced, namely Control mix, 10MP, 10SF, 10LP and 10MPSFLP. X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) with EDAX (Energy Dispersive X-ray analysis) were performed to study the micro characteristics of SCC. Under the macro study Compressive strength, Split tensile strength and Flexural strength tests were conducted to know the strength properties of the mixes at the age of 7 and 28 days respectively. Various durability tests were also performed to ensure quality and serviceability when exposed to the environment. From the results it is observed that the mix having combination of all materials (10MPSFLP) recorded the higher strength values than other mixes.

[Keywords: Self Compacting Concrete, Mechanical properties, Micro Analysis, SEM analysis, EDAX analysis, Durability Properties.]

Introduction Durability was the main concern in buildings and

the purpose was to develop a concrete mix that would reduce or eliminate the need for vibration to achieve compaction1. Self-Compacting Concrete (SCC) achieves this by its unique fresh properties. In the plastic state, it flows under its own weight and maintains homogeneity while completely filling any formwork and passing around congested reinforcement. It will replace manual compaction of fresh concrete with a modern semi-automatic placing technology and in that way improve health and safety in and around the construction site2.

In the hardened state, it equals standard concrete with respect to strength and durability3 Self Compacting Concrete (SCC) offers a rapid rate of concrete placement, with faster construction times and ease of flow, around congested reinforcement. The fluidity and segregation resistance of SCC ensures a high level of homogeneity, minimal concrete voids and uniform concrete strength, providing the potential for a superior level of finish and durability of the structure4. SCC is often produced with low water-cement ratio providing the potential for high early strength, earlier demoulding and faster use of elements and structures5. The improved construction practice and performance, combined with the health

and safety benefits, makes SCC a very attractive solution for precast concrete construction. Increase in cost of SCC production is due to the usage of higher powder content and chemical admixture1.This can be reduced by using mineral admixtures and filler materials. Mineral admixture has an advantage on SCC like to improve workability with reduced cement content2 additionally, these mineral admixtures may also improve particle packing and decrease the permeability of concrete. Apart from the economic benefits, use of byproducts or waste materials in concrete reduces environmental pollution. The use of SCC is considered to have a number of advantages as: Faster placement Better consolidation around reinforcement. Easily placed in the walled element. Improves the quality, durability and reliability of

the concrete structures. Reduces the total time of construction and the

cost. There are exhaustive researches pursued in

connection to application of fillers to achieve the Self Compacting characteristics with a perspective to make it economically viable. It was observed that the fly ash when used as an admixture of SCC increased

mailto:[email protected]

MANJU & PREMALATHA: PROPERTIES OF SELF COMPACTING CONCRETE

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the filling and passing ability of concrete. Fly ash is an industrial waste from thermal power stations. Utilization of these waste products as cement replacement will not only help to achieve an economical mix, but it is envisaged that it may improve the microstructure and consequently the durability of concrete. This provides solution to disposal problems and other environmental pollution6 Replacement of cement with limestone powder as a mineral admixture in SCC with 30% fly ash shows improved workability and mechanical properties up to 20%7. Another experiment was pursued on the mechanical properties of hardened SCC and it was identified how it got decreased by using marble dust (MD), especially just above 200 kg/m²² content. With reference to the test results, a conclusion was made stating that the workability of fresh SCC had not been affected up to 200 kg/m3 MD content8.

There are various researches that have been carried out in SCC with alternative materials like Limestone Powder (LP), Fly Ash (FA), Silica Fume (SF) and Granulated Blast Furnace Slag (GBFS). While there are many other alternatives or recycled material like Marble Powder (MP), Dolomite Powder (DP), Crump Rubber (CR), Recycled Aggregate (RA) and Rise Husk Ash (RHA) can also be used in producing SCC. Each material showed both positive and negative performances while using in SCC. Such negative effects can be reduced by using these materials in combinations.

Utilizing mineral admixtures and filler materials as substituting additions in concrete has a greater tendency to fulfill the expectations in providing greater sustainability in the construction industry. The issues regarding the cost, recycling the Industrial waste, rehabilitation in durability and mechanical performance of concrete will therefore put a pressure on the utilization of such materials. The current study aims at highlighting the fresh and hardened characteristics of SCCs produced with Portland cement, Fly Ash, Silica Fume, Lime Stone filler and marble powder. For this purpose, five series of concrete mixtures are designed with various proportions inclusive of Control Mix (CM) with 60% OPC and 40% fly Ash. A 10% Fly Ash (FA) is replaced by Silica Fume (SF) Limestone Powder (LP) and Marble Powder (MP). Mix incorporating all binder materials was produced with 60% OPC and 10% of various filler materials, respectively Fresh properties of SCCs were tested for flow and passing ability while compressive strength, split tensile

strength and flexural strength were measured for determination of the mechanical properties. Moreover, rapid chloride penetration test, water permeability test and saturated water absorption test were conducted, which are produced in the study. Materials and Methods

Ordinary Portland Cement (OPC) conforming to 53 Grade as per IS 12269:1993 with specific gravity of 3.15 was used in all SCC mixtures. Locally available crushed granite of 12.5 mm of maximum size aggregates were used as coarse aggregates with specific gravity of 2.65. Naturally available river sand was used as fine aggregate with 2.73 as specific gravity. Commercially available super plasticizer Glenium B233 with the specific Gravity of 1.09, manufactured by BASF Construction Chemicals (India) Pvt. Ltd., was used for producing SCC. Glenium B233 is an admixture of a new generation based on modified polycarboxylic ether. It Complies with IS: 9103 – 1999.

The FA and SF are used as a mineral admixture in this investigation. Actually, Fly ash is the waste that is obtained from coal. Fly ash should be highly fine & should contain lower carbon content. Fly ash conforming IS: 3812 – 2000 is used. LP and MP are used as filler materials in this investigation. The chemical properties of filler materials and properties of aggregates are listed in Tables 1 and 2. The binder materials are shown in Fig. 1.

A total of five concrete mixes were designed with various proportions inclusive of Control Mix (CM)

Table 1 — Chemical Properties of Filler Materials % by Weight of Sample

S.No. Constituents OPC Fly Ash Marble

Powder Lime Stone

Powder 1 SiO2 20.67 42.54 02.08 04.32 2 A12O3 06.21 23.59 - 01.47 3 Fe2O3 02.06 12.36 00.74 01.16 4 MgO 00.82 02.62 00.86 00.80 5 CaO 64.89 13.78 41.48 41.65 6 Na2O 00.06 01.44 - - 7 K2O 00.55 02.49 - - 8 SO3 02.71 00.55 - -

Table 2 — Properties of Aggregates Properties Fine Aggregate Coarse Aggregate

Specific Gravity 2.73 2.69 Water Absorption 1.2% 0.80% Moisture Content 0.8% NIL

INDIAN J. MAR. SCI., VOL. 47, NO. 08, AUGUST 2018

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with 60% OPC and 40% fly ash are summarized as shown in Table 3.

Silica Fume (SF), Limestone Powder (LP), and Marble Powder (MP) replaced 10% Fly ash individually. Mix incorporating all binder materials was also produced with 60% OPC and 10% of various filler materials respectively. Fine aggregate and coarse aggregate content were kept same for all the mixes. Water-Binder ratio (W/B) was taken as 0.35 for all mixes and Super-Plasticizer (SP) Glenium B233 was varied from 2.25% to 2.3% by weight of binder to produce Self Compacting Concrete.

The Fresh concrete properties like flow ability, filling ability and passing ability were tested by slump flow, V- funnel and L-box tests which were performed according to the procedure recommended by EFNARC (2005).

The macro level properties like compressive strength, split tensile strength and flexural strength were performed according to IS: 516-1959 and IS: 5816-1999. To determine compressive and split tensile strength for each mix three cubes of size 150 x 150 x 150 mm and cylinder of diameter 150 mm and height of 300 mm size specimens were cast and tested after 7 and 28 days of water curing. To determine flexural strength three prisms of size 100 x 100 x 500 mm were cast and tested after 28 days

of water curing. To determine the uniformity, the ultrasonic pulse velocity test was also performed. The experimental setup for strength tests is shown in Fig. 2.

X-ray diffraction (XRD) test, Scanning Electron Microscopy (SEM) analysis and Energy Dispersive X-ray analysis (EDAX) analysis were performed to evaluate the micro structural characters of the concrete. X-ray Diffraction (XRD) is used to identify the compounds and minerals present in powdered specimens. Chemical composition of mineral admixtures and filler materials was identified by performing EDAX analysis. Using SEM analysis, the surface morphology of each specimen with different filler materials were identified. By EDAX, any smaller size particles can be analyzed at larger magnification.

Water absorption tests were carried out on 150 mm cube specimens at the age of 28 days curing. The specimens were weighed before drying. The drying was carried out in a hot air oven at a temperature of 1050C (availability 1000C) as shown in Fig.3.

The drying process was continued, until the difference in mass between two successive measurements at 24 hours interval agreed closely. The dried specimens were cooled at room temperature and then immersed in water. The specimens were taken out and the surface dried using a clean cloth and weighed. The difference between the measured water saturated mass and oven dried mass expressed as a percentage of oven dry mass gives the saturated water absorption.

Fig. 1 — Binder Materials

Table 3 — Mix Proportions - Binder Content in %

Mix ID OPC FA SF LP MP W/B CM 60 40 - - - 0.35 10SF 60 30 10 - - 0.35 10LP 60 30 - 10 - 0.35 10MP 60 30 - - 10 0.35 10SFLPMP 60 10 10 10 10 0.35

Fig. 2 — Experimental Setup for Strength Tests

Fig. 3 — Specimens in oven for drying process


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Water absorption = 100.d

d

WWWs

Ws - Weight of specimen at fully saturated condition Wd - Weight of oven dried specimen

The RCPT method is the fastest method of those mentioned and often used for specification and quality control purposes. The test method involves obtaining a 100 mm (4 in.) diameter core or cylinder sample from the concrete being tested. A 50 mm (2 in.) specimen is cut from the sample. The side of the cylindrical specimen is coated with epoxy, and after the epoxy is dried, it is put in a vacuum chamber for 3 hours. The specimen is vacuum saturated for 1 hour and allowed to soak for 18 hours. It is then placed in the test device (see test method for schematic of device). The left-hand side (–) of the test cell is filled with a 3% NaCl solution. The right-hand side (+) of the test cell is filled with 0.3N NaOH solution. The system is then connected and a 60-volt potential is applied for 6 hours. Readings are taken every 30 minutes. The test setup for Rapid Chloride Penetration Test is shown in Fig.4.

At the end of 6 hours the sample is removed from the cell and the amount of coulombs passed through the specimen is calculated. The test results are compared to the values in the chart below.

Permeability of concrete is the most important aspect when dealing with durability. The test was conducted on 150 x 150 x 150 mm cube specimen at the age of 28 days of water curing. The standard test pressure head to be applied to the water in the reservoir should be 10 kg/cm2. The specimen shall be surface dried and the dimensions measured to the nearest 0.5 mm. It shall be centred in the cell with the lower end resting on the ledge. The experimental setup for water permeability test is shown if Fig.5.

Ensure that the permeability apparatus is completely filled with de-aired water and contains no air pockets or bubbles. Apply a constant pressure head of water to the inflow side of the permeability cell and continuously monitor the pressure throughout the duration of the test. The specimen is taken out at the end of 100 hours and tested under compression testing machine to determine the depth of penetration. More penetration of water refers that the concrete specimen is more permeable and has enormous voids which allows water to pass through it and making less durable. Results and Discussions

Chemical composition of filler materials is determined. Calcium content is found to be higher in both filler materials. Because of high calcium content in limestone powder, it required 0.05% additional super plasticizer quantity than other mixes. The test results of XRD analysis of LP and MP are shown in Fig.6 and Fig.7 respectively. Tested cube specimen is crushed and

Fig. 4 — Test set up for Rapid Chloride Penetration Test

Fig. 5 — Experimental setup for Water Permeability test

Fig. 6 — XRD Analysis Results for Limestone Powder


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given as sample for SEM analysis. Accelerating voltage is kept as 20 KeV for each sample during the scanning process. Images with magnification of 2000x were kept for the prediction of results.

On visual observation from the images, the inferences are listed in Table 4. On further study with SEM images, mix with LP is characterized with increased number of pores, which may be the reason for reduction in strength when compared with other mixes. Mixes incorporated with all materials indicated the obtained strength values by showing uniform homogeneity.

The variation in the results is due to variation in permeability of concrete with respect to different constituent materials, since, Fly ash concrete reacting with lime and alkalis generate additional cementitious compounds act to block bleed channel, filling pore surface and reducing the permeability of the hardened concrete. The pozzolanic reaction consumes Ca (OH)2 which is leachable, replacing it with insoluble calcium silicate hydrates. The increased volume of fines and reduced water content play a major role. Hence, the variations in results arise, which is unavoidable.

The characterization of results of mixtures is presented in order to create a set of information rich enough to be able to link the composition of concretes with their performance. In this study, fresh and hardened properties of SCC were investigated using local available materials such as FA, SF, LP and MP.

Limestone powder can also physically improve the denseness of hardened Portland cement paste due to its filling effect. The optimum use of limestone

powder as a supplementary material to Portland cement has therefore technical benefits such as improved workability, bleeding control, lower sensibility to the lack of curing, and little bit increased early strengths. On the other hand, loss of strength at later ages due to incorporation of limestone has also been reported. During the last decade, LP as calcite, or crystalline CaCO, has proven to be an effective partial replacement for OPC. LP has two functions: it acts as relatively inert calcareous filler and a limited participant in the hydration process. During cement hydration, finely ground CaCO3 reacts with C3A and C4AF to form high and low forms of carboaluminates. Calcium hemicarboaluminate forms as an early hydration product in calcite-containing OPC, and then converts nearly completely to calcium monocarboaluminate, a stable AFm phase, after about 28 days. The particle size of LP must be considered in

Table 4 — SEM Images of All Mixes at 28 Days Mix ID SEM Image Inferences From Image

CM

Lesser voids were identified.

10MP

Proper bonding of filler material with aggregate resulted in better strength values when compared to control mix.

10SF

Because of higher surface area silica fume filled the voids and recorded strength values equivalent to all filler mix.

10LP

More number of voids was identified, which may be the reason for reduction in all strength values.

10MPSFLP

All binder materials ensured better packing and reduction in pores, which may be the reason for higher strength values when compared with othermixes.

Fig.7 — XRD Analysis Results for Marble Powder


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the mix design because the early strength of the concrete depends on blended cement composition and LP fineness, since interaction between gypsum and limestone during early C3A hydration interferes with setting time. An acceleration of C3S hydration may occur at early ages when LMSP, which produces nucleation, sites for cement hydration products such as calcium carbosilicate hydrate, thus reducing the size of C-S-H agglomerations. In blended cements with up to 5% calcite, for example, almost all the added calcite reacts with cement. The resulting concretes show compressive strength, flexural strength, and drying shrinkage similar to control concretes without LP. At 25% sand mass replacement with LP in mortar specimens, the fine CaCO3 particles produce denser packing of the cement paste and better dispersion of cement grains. When LP replacement of OPC exceeds 15% by mass, however, the less reactive calcite has a dilution effect on the more reactive cement; the amount of cement paste is considerably reduced, resulting in lower compressive strengths and physical modifications. Durability decreases as water

absorption and chloride diffusion coefficients increase9. It is observed that the incorporation of the Marble Power in cement enhance the compressive strength of the mortar compared to the mortar13. The increase in the strength of mortar can be attributed to the calcium carbonate content of Marble Powder. The additional surface area provided by the calcium carbonate in Marble Powder may provide sites for the nucleation and growth of hydration products that leads to further increase in strength. The flexural strength for the specimens with Marble Powder is explained.

The fresh concrete characterization was limited to tests recommended by the EFNARC namely slump flow test, V-Funnel Test and L Box Test. The results of each composition are shown in Table 5.

Comparing the results with SCC criteria, it can be seen that all the SCC mixtures exhibit satisfactory properties as fresh concrete. The slump flow values for CM, 10MP, 10SF, 10LP and 10 MPSFLP are presented in Table 5. The slump flow of Self Compacting Concrete cans rates from 600 mm to 800 mm (EFNARC). All mixtures are in this category. From Table 5, it can be seen that the improvements in the workability is achieved, in 10 MPSFLP with the slump flow of 690 mm.

Further, it is observed that, V-funnel flow times are in good agreement to that of the values give by European guidelines6 (EFNARC). Therefore, the Mix ID 10MPSFLP guaranteed a level of suitable viscosity to decrease the risk of segregation and improve the workability.

Table 6 — Compressive Strength Test Re

Mix ID Specimen No. Density (Kg/m3)

7th day Strength (N/mm2)

Avg. 7th day Strength (N/mm2)

28th day Strength (N/mm2)

Avg. 28th day Strength (N/mm2)

Standard Deviation

% increase in strength

CM 1

2385.48 26.67

27.14 29.78

29.72 0.60 - 2 27.64 30.27 3 27.11 29.11

10MP 1

2424.69 30.80

29.47 31.73

31.78 0.65 6.93 2 27.24 31.16 3 30.36 32.44

10SF 1

2474.07 32.53

32.92 34.09

33.96 1.14 14.26 2 33.42 32.76 3 32.78 35.02

10 LP 1

2431.60 29.60

29.23 29.51

30.24 0.73 1.74 2 28.18 30.98 3 29.91 30.22

10MPSFLP 1

2518.52 31.07

30.21 34.58

34.33 0.94 15.51 2 29.82 35.11 3 29.73 33.29

Table 5 — Fresh Properties of SCC (Workability Test Results of SCC Mixtures)

Mix ID Slump Flow (mm)

V-Funnel (Sec)

L-Box (h2 /h1)

EFNARC Limits

600-800 6-12 0.8-1

CM 650 11.8 0.85 10MP 670 10.4 0.89 10SF 692 9.3 0.92 10LP 660 10.9 0.88 10MPSELP 690 9.4 0.90


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The L-Box ratio characterizes the filling and passing ability of SCC. All the mixtures of SCC are within this target range which should be between 0.8 and 1.00. The Mix ID 10 MPSFLP has not negatively affected the blocking ratio which is 0.90.

The compressive strength of concrete with different mixture proportions was determined at the age of 7 and 28 days as shown in table 6. The compressive strength of 10MPSFLP on 28th day works out to 34.33 N/mm2. This may be due to the physical nature of all the filler which gives the compressive strength, due to denser matrix and the better dispersion of cement. While the marble powder, which is not pozzolanic or completely inert, reacts with the aluminium phases of cement. Hence it is justified that the cement used has a low tricalcium aluminate (C3A), which results in increase in strength of 6.48% which is lower than the strength of 10MPSFLP having an increase in strength of 13.43%.

The compressive strength of 10SF, on the 7th day is 32.92 MPA, & on 28th day is 33.96 N/mm2. The compressive strength of 10MPSFLP on 28th day is 34.33 N/mm2, which is due to all filler materials10. Further, It is interesting to note that the compressive strength of 10LP, on 28th day works out to only 30.24 N/mm2, whereas, the compressive strength of 10MP on 28th day arrives at 31.78 N/mm2. The reason for the increase in strength in 10MP is due to the calcium carbonate content of marble powder. The additional surface area provided by the calcium carbonate in marble powder may provide sites for nucleation and growth of hydration products that leads to increase in

strength, than the strength of 10LP. 10MP is the finest material in all the mixtures. The effect of nucleation on the strength is dependent on the mineral admixtures affinity to cement hydrates and it increases with the fineness and specific surface area of the mineral admixture. MP is not pozzolanic, but nor fully inert as it reacts with the aluminum phases of the cement. If the cement has a significant amount of tricalcium aluminate (C3A), Calcium carboaluminate will be produced from the reaction between Calcium carbonate (CaCO3) from the MP and C3A. This reaction has accelerating hydration and increasing the compressive strength, increases with the C3A content of the cement and the fineness and specific surface area of the mineral admixture. Thus, MP produced as increase in early age performance of SCC11. The compression strength of 10 SF at 28th day is 33.96 N/mm2. This is due to Silica Fume being a reactive pozzolan and a compressive strength up to 15000 psi, can readily be obtained, as per the Silica Fume association.

Tensile strength is one of the most important fundamental properties of concretes. All concrete typically show low tensile strength (10% of compressive strength) and a low strain capacity12. However tensile strength is important in highways design and airfield slabs when shear strength and crack resistance are a priority. The addition of MP, SF and LP exacerbates these short comings. The split tensile strength results are furnished in Table 7.

It can be seen from Table 7, that the 28th day tensile strengths of MP mixtures are slightly higher than that

Table 7 — Split Tensile Strength Test Results

Mix ID Specimen No.

Load (KN) Split Tensile Strength at 28th day (N/mm2)

Avg. Split Tensile Strength at 28th day (N/mm2)

Standard Deviation

% increase in Strength

CM 1 194 2.75

2.45 0.31 - 2 150 2.12 3 175 2.48

10MP 1 201 2.85

2.63 0.19 7.35 2 177 2.51 3 179 2.53

10SF 1 191 2.70

2.72 0.02 11.02 2 194 2.75 3 192 2.72

10LP 1 180 2.55

2.55 0.04 4.08 2 178 2.52 3 183 2.59

10MPSFLP 1 195 2.76

2.66 0.10 8.57 2 188 2.66 3 181 2.56


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of LP mixture. But tensile strength is higher for 10MPSFLP than both MP and LP mixtures, as seen in compressive strength results. This may occur because of the denser microstructure in SCC mixes leads to increased brittleness and thus decreases the tensile strength. In SCC mixer, high powder contents can increase shrinkage resulting in Micro-cracking within the allowable limits, which affects tensile strength.

The flexural strength of different concrete mixes is shown in Table 8. It is seen from the below table, that the 28th day tensile strength of MP mixture is 5.34 N/mm2, which is slightly higher than that of LP mixture. However, 10MPSFLP tensile strengths are higher than MP and LP mixture. This is due to the denser microstructure in SCC leads to increased brittleness and thus decreases the Flexural tensile strength. It is seen that tensile strength is more sensitive to the type of curing compared to compression strength. It may be concluded that the moisture content of the preservation medium has a significant influence on the strength of concrete.

This is based on the principle that the velocity of an ultrasonic pulse through any material depends upon the density, modulus of elasticity and poisson’s ratio. Comparatively higher velocity is obtained when concrete quality is good in terms of density, uniformity, homogeneity, etc. Pulse Velocity measurements may be used to assess the homogeneity of concrete presence of cracks, voids etc., quality of concrete relative to standards requirements, quality of one element of concrete relative to another and elastic

modules values of concrete. Ultrasonic pulse velocity measurements are influenced by surface condition, moisture content, temperature of concrete, path length, shape and size of member and presence of reinforcing bars. The method is complex and requires skill to obtain usable results, which can often provide excellent information regarding condition of concrete.

Using the special equipment, ultrasonic pulse is produced by a transducer held in contact with one surface of concrete member under test. After traversing a known path length (L) in the concrete, the pulse of the vibration is converted into an electrical signal by the second transducer held in contact with another surface of the concrete member at the pre-determined place and an electric timing circuit enables the transit time (T) of the pulse to be measured. The pulse velocity is given by V=L/T in unit km/sec.

The guidelines for assessing the condition of concrete based on pulse velocity are listed in Table 9.

All produced concretes are classified as excellent as all measured UPV values are greater than 4.5 km/sec.

The trend in UPV values is to increase with the increasing compressive strength for all the mixtures.

Table 8 — Flexural Strength Test Results

Mix ID Specimen No. Flexural Strength at 28th day (N/mm2)

Avg. Flexural Strength at 28th day

(N/mm2)

Standard Deviation % increase in Strength

CM 1 5.10

5.05 0.08 - 2 4.97 3 5.09

10MP 1 5.95

5.34 0.61 5.74 2 4.73 3 5.35

10SF 1 5.19

5.51 0.32 9.11 2 5.83 3 5.51

10LP 1 4.37

5.19 0.82 2.77 2 6.05 3 5.17

10MPSFLP 1 6.08

5.67 0.41 12.28 2 5.25 3 5.67

Table 9 — Pulse Velocity S.No. Pulse Velocity in (Km/s) Condition of Concrete

1 Above 4.5 Excellent 2 3.5 to 4.5 Good 3 3.0 to 3.5 Medium 4 Below 3.0 Poor


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The concrete strain gauges measured strains, and the strains and stresses were accumulated. The following equation is used to represent the dynamic young’s modulus of concrete.

Ed = 10 ∗ V ∗∆g

where Ed is the dynamic elastic modulus, V is UPV in m/s , ∆ is unit weight of the specimen (kg/dm3) and g is acceleration due to gravity (9.81 m/s2). According to the test results in table 10, if the strength of SCC mixtures increased, dynamic elastic modulus will also be increased.

When concrete is exposed to the marine environment, it leads to deterioration of concrete as a result of the combined effect of the chemical action of sea water constituents on cement hydration products.

The deterioration of concrete can be measured in terms of loss of weight and compressive strength.

A Salt water resistance test was carried out on 150 x 150 x 150 mm cube specimens at 28 days of curing. The cube specimens were weighed and immersed in water diluted with 3% NaOH by weight of water for 28 days continuously. Then the specimens were taken out from the salt water and the surfaces of the cube were cleaned. Then the weight and compressive strength of specimens were found out and the average percentage loss of weight and compressive strength were calculated.

The experimental test results of the salt resistance test were given in Table 11.

The compressive strength of concrete subjected to salt water curing with different mixture proportions was determined at the age of 28 days. The compressive strength loss was observed in all specimens. The comparison of compressive strength before and after salt bath was shown in Fig.8.

It can be concluded that the reference concrete for compressive strength with fly ash, strength attainment was 28.78Mpa at 28 days of additional salt water curing. However, for mix incorporating all filler materials, the strength value was found to be 33.92 N/mm2. Also weight loss percentage was found to be lesser in 10MPSFLP mix. The significant improvement in the strength was noticed at when all filler materials were added to the concrete. Hence it is evident that 10MPSFLP mix is more durable than control mix.

The Rapid Chloride Penetration Test (RCPT) method is the fastest method of those mentioned and is often used for specification and quality control purposes. The digital LED display indicates the voltage available across the concrete specimen under test as shown in Fig.4.

The test method involves obtaining a 100 mm (4 in.) diameter core or cylinder sample of the concrete being tested. A 50 mm (2 in.) specimen is cut from the sample. The side of the cylindrical specimen is coated with epoxy, and after the epoxy is dried, it is put into a vacuum chamber for 3 hours. The specimen is vacuum saturated for 1 hour and allowed to soak for 18 hours. It is then placed in the test device (see test method for schematic of device).

Table 10 — Ultrasonic Pulse Velocity for Different Mixes

Mix ID Time taken (µs)

Velocity (Km/s)

Dynamic Young’s Modulus of Elasticity

106 N/mm2 CM 37.63 5.34 10.83

10MP 36.5 5.48 11.26 10SF 35.17 5.69 11.96 10LP 37.33 5.39 11.14

10MPSFLP 34.70 5.75 12.31

Table 11 — Salt Water Resistance Test Results Mix ID

Weight of cube (Kg)

Weight loss in

%

Compressive strength (N/mm2)

Strength loss in % Before

salt bath After salt

bath Before

salt bath After salt

bath CM 8.40 8.25 1.78 29.72 28.78 3.16

10MP 8.45 8.30 1.81 31.78 30.68 3.46 10SF 8.30 8.20 1.22 33.96 32.91 3.09 10LP 8.40 8.25 1.81 30.24 28.94 4.30

10MPSFLP 8.20 8.15 0.61 34.33 33.92 1.19

Fig. 8 — Comparison of Compressive Strength before and after salt bath


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The left-hand side (–) of the test cell is filled with a 3% NaCl solution. The right-hand side (+) of the test cell is filled with 0.3N NaOH solution. The system is then connected and a 60-volt potential is applied for 6 hours. Readings are taken every 30 minutes. At the end of 6 hours the sample is removed from the cell and the amount of coulombs passed through the specimen is calculated. The test results are compared to the values in the table 12 and table 13.

All the mixes exhibited low permeability. Out of all five mixes tested, 10MPSELP mix recorded the lease charge passed value which signifies that it is less permeable. One of the most important factors, affecting the permeability of concrete is the internal pore structure, which in turn is dependent on the extent of hydration of the cementations materials. The curing conditions and the age of the concrete, thus largely determine the ease with which chloride ions can move into a concrete.

The decrease in depth of penetration in 10MPSFLP may be attributed due to the filler-effect of addition of marble powder. The particle size of marble powder is smaller. As such when marble powder is added to the SCC, it fills the voids between the particles. The physical phenomenon is known as the filler effect. It reduces the porosity, which in turn reduces the permeability of the normal concrete.

Permeability of concrete is the most important aspect when dealing with durability. The test was

conducted on 150 x 150 x 150 mm cube specimen at the age of 28 days of water curing. The standard test pressure head to be applied to the water in the reservoir should be 10 kg/cm2. The specimen shall be surface dried and the dimensions measured to the nearest 0.5 mm. It shall be centered in the cell with the lower end resting on the ledge. Ensure that the permeability apparatus is completely filled with de-aired water and contains no air pockets or bubbles. Apply a constant pressure head of water to the inflow side of the permeability cell and continuously monitor the pressure throughout the duration of the test. The specimen is taken out at the end of 100 hours and tested under compression testing machine to determine the depth of penetration. More penetration of water refers that the concrete specimen is more permeable and has enormous voids which allows water to pass through it and making less durable. As per IS 3085 water permeability test is conducted on all specimens and test results are shown above in Table 14. Results indicated that the depth of penetration of water was found to be higher in 10LP mix which signifies that presence of more pores is identified.

10MPSFLP recorded the least penetration value which indicated that better packing and lesser voids are observed.

The decrease in depth of penetration in 10MPFLP may be attributed due to the filler effect of addition of marble powder. The particle size of marble powder is smaller. As such when marble powder is added to the SCC, it fills the voids between the particles. The physical phenomenon is known as the filler effect. It reduces the porosity, which in turn reduces the permeability of the normal concrete. Conclusions

This paper is aimed to compare several properties of Self Compacting Concrete, containing different filler materials. Lab-Tests were conducted to determine some fresh and hardened properties of SCC mixtures. As a result of this experimental study the following conclusions were drawn.

Table 12 — Chloride Permeability Based on Charge Passed

Charge Passed (Coulombs)

Chloride Permeability Typical of

>4,000 High High W/C ratio (>0.60) Conventional PCC

2,000-4,000 Moderate Moderate W/C ratio (0.40-0.50) Conventional PCC

1,000-2,000 Low Low W/C ratio (<0.40) Conventional PCC

100-1,000 Very Low Latex-modified concrete or internally-sealed concrete

<100 Negligible Polymer-impregnated concrete, Polymer concrete

Table 13 — Rapid Chloride Penetration Test Results for all SCC Mixes

Mix ID Charge passed (Coulombs)

Chloride permeability

CM 611 very low 10MP 646 very low 10LP 626 very low 10SF 570 very low

10MPSFLP 504 very low

Table 14 — Water Permeability Test Results Mix ID Depth of Penetration in mm

CM 110 10MP 85 10SF 55 10LP 135

10MPSFLP 35


1712

The workability is controlled by particle shape, particle packing, effect, particle size distribution and the smoothness of surface texture. So 10MPSFLP has provided more slump flow, because the characteristics of the filler materials allow better flow. Other mixtures containing 10LP & 10MP have a reduction in workability when comparing to 10MPSFLP. The modular and angular shape of 10LP & 10MP hinder the workability of SCC. Among all, 10MPSFLP provides the best fresh state performance when added to concrete. Limestone Powder, Marble Powder and Silica Fume offer a number of advantages for its use as cement compensating by enhancing flow properties and increases compressive strength. The addition of LP, MP SF has positive effects on the workability.

Splitting tensile strengths of the 10MPSFLP concrete show relatively the same trend with compressive strength.

There is a reasonable correlation between the compressive strength and ultrasonic pulse velocity of the five SCC mixtures. When the strength of SCC mixtures is increased, the dynamic elastic modulus is also increased. Ultrasonic pulse velocity and the value of dynamic modulus of elasticity is found to be higher for 10MPSFLP mix.

The combination of filler materials has decreased the water absorption in SCC.

All the SCC mixes exhibit low permeability in rapid chloride penetration Test.

In general, these results are of great importance, because this kind of innovative concrete requires larger amounts of fine particles. Recycling and using waste to produce SCC may be the best option to sustain the future economy. The abundance of fly ash found in India and the Limestone Powder, Marble Powder and Silica fume are remarkable, which is a boon to the nation, which can be used for Self Compacting Concrete, easily and economically.

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micro, macro and durability properties of self compacting...

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