SPECIMEN ATTACK IN PARTIALY SUBMERGED CONCRETE

INVESTIGATION ON EXISTANCE OF DUAL SULPHATE ATTACK IN PARTIALY SUBMERGED CONCRETE

SPECIMEN

Swapna Channagoudar1, Dr. K.E Prakash2, Dr. D.S Viswanath3

Research Scholar, Department of Civil Engineering, STJ Institute of Technology, Ranebennur

Director, Shree Devi Institute of Technology, Mangalore

Dean Academic, STJ Institute of Technology, Ranebennur

Abstract

Site knowledge with concrete subjected to sulphate environment has often

indicates that concrete may affected by scaling in the top portion from the level of ground

due to physical sulphate attack. Physical sulphate attack has been neglected and in many

cases, unable to distinguish with chemical sulphate attack. In the prsent paper, the

behavior of concrete subjected to dual sulphate attack was studied. Results conclude that

concrete is suffered from dual sulphate attack i.e bottom soaked portion can affected by

chemical sulphate attack, whereas the top portion can be susceptible attack of physical

sulphate.

Keywords: Sulphate attack, Crystallization

1.1 INTRODUCTION

At present sulphate attack damage due to sulphate attack has taken considerable interest for

the researchers. Since from 1930 several researches conducted on deterioration mechanism of

concrete. However they have focused on only chemical sulphate attack and ignored physical

sulphate attack. According to Tian and Cohen, 2000, chemical sulphate attack was mainly due to

WAFFEN-UND KOSTUMKUNDE JOURNAL

Volume XI, Issue VI, June/2020

ISSN NO: 0042-9945

Page No:14

the formation of chemical compounds such as ettringite and gypsum. When cement compounds

such as calcium hydroxide and calcium aluminate hydrate chemically reacts with sulphate ions,

which results in expansion, volume change and cracking on the surface of concrete and finally

leads to strength loss (Roziere, et al., 2009).

However physical sulphate attack showed different results compared to chemical sulphate

attack. When concrete structure partially soaked with sulphate environment shows surface

scaling above the ground level. It was proved by the investigation carried by the Stark 1989;

Yoshida et al, 2010. Unfortunately this type of sulphate attack was mainly ignored this is

because deterioration on the concrete was studied when it was completely immersed. In

continuation current codes that estimates the behavior of concrete subjected to sulphate attack

such as ASTM C 1012 and CSA A3004-C8 only discuss with chemical aspects of sulphate attack

(Aye and Oguchi, 2011, Santhanam et al., 2001)

The process of physical sulphate attack involves two important mechanism i.e capillary rise

and evaporation (Irassar et al, 1995; Haynes et al., 1996). Capillary rise and evaporation from the

ground water containing sulphate ions at the above ground level, shows crystal growth in the

pores of concrete and subsequent damage. Similar results observed in the investigation of A. R.

Suleiman (2014). On the other hand another study by Liu et al., (2012) reported that the concrete

deterioration above the solution level is due to chemical sulphate attack. This is because high

concentration sulphate solution leads to surface damage in the upper portion. Their study was

based on chemical reaction theory ie high concentration sulphate solution results in extensive

chemical sulphate attack. This argument in the previous literartures leads to confusion in the

study of deterioration process of concrete subjected to sulphate attack.

1.2 CONSTITUENTS AND PREPARATION OF SPECIMEN

The different materials such as cement, fine aggregate, coarse aggregate and supplementary

cementitious materials (SCM) have used. The descriptions of the materials and related codes or

specifications are summarized below.

a) Cement

Ordinary Portland Cement (OPC) of 53 grade and specific gravity 3.15 was used. It

satisfies the requirements of IS: 12269 – 1987.



ISSN NO: 0042-9945

Page No:15

b) Sulphate resisting cement

It is one of the types of Ordinary Portland Cement in which the amount of tricalcium

aluminate (C3A) is restricted to lesser than 5% and 2C3A+C4AF are lesser than 25%. It satisfies

the requirements of 12330:1988.

c) Coarse aggregate

Naturally available angular shape coarse aggregate of size 20mm confirming to IS: 2386-

1963 was used. Coarse aggregate are the aggregates which are retained in 4.75mm sieve.

d) Fine aggregate

Fine aggregates are the aggregates which can pass through 4.75mm sieve. Locally available

river sand was used as fine aggregate. Fineness modulus of river sand was 3.79 and zone–II

grade confirming to IS: 383-1970.

e) Fly ash

Flyash forms a similar compound as Ordinary Portland Cement when mixed with water and

lime. It is obtained from thermal power plant. In the present research, Type – II class F fly ash

confirming to IS 3812-1981 was used.

f) Metakaolin

Metakaolin forms a similar compound as Ordinary Portland Cement when mixed with

water and lime. In the present paper metakaolin was purchased from the 20 MICRON LIMITED

company.

g) Silica fume

In the present paper silica fume of specific gravity 2.59 was used. Physical and chemical

properties of cement, flyash, silicafume, metakaolin and sulphate resisting cement were tabulated

in Table 1.



ISSN NO: 0042-9945

Page No:16

Table 1: Physical and Chemical constituents

Properties Cement Flyash Silicafume Metakaolin SRCColour Grey Dark grey Transperent/Black White GreyOdor Odorless Odorless Odorless Odorless Odorless

Specific gravity 3.15 2.51 2.59 2.21 3.12

Appearance Fine powder Fine powder Fine powder Fine powder Fine powderSpecific surface (cm2/g)

2900 _ _ _ _

Ignition loss (%) 1.80 1.73 1.98 1.2 0.71

Fineness (m2/kg) 372 _ _ _ 381

Initial setting time (min) 45 _ _ _ 80

Normal consistency 33 _ _ _ 32

Final setting time (min) 300 _ _ _ 240

SO3 3.60 1.73 0.25 0.05 2.3Fe203 3.4 7.8 0.2 1.9 4.4SiO2 19.7 42.30 95.6 52.3 23Al2O3 4.9 21.9 0.3 41.2 4.2MgO 3.1 _ 0.28 _ 1.2CaO 61.60 15.65 0.5 _ 65

i) Superplasticizer

To induce the additional desired properties, CONPLAST 430 superplasticizer was used.

Dosage of superplasticizer was taken 1 % by weight of cement.

j) Water

Natural potable water, which is free from salts, turbidity and oraganic content was used

for concrete mixing and curing.

k) Chemical



ISSN NO: 0042-9945

Page No:17

To conduct durability test sodium sulphate (Na2SO4), dosage of an 8% for litre of water was used.

1.3 EXPERIMENTAL WORK

a) Specimen preparation

Concrete cylinders of 100 mm diameter and 200 mm height were casted confirming to IS

10262 – 2009. Five mixes were used including Ordinary Portland Cement, OPC and 25% Flyash

(FA), OPC and 10% Metakaolin (MK), OPC and 10% silicafume (SF), and also sulphate

resisting cement (SRC). The replacement of SCMs with cement was done by weight of cement.

Table ‎13: Proportion of concrete constituents

S.NO Mix Cement Quantity (kg/m3)

Admixtures quantity(kg/m3)

Aggregate quantity (kg/m3)

Coarse Fine01 OPC 320 0 1186 75702 OPC+25% FA 240 80 1149 74903 OPC+10% SF 288 32 1152 75104 OPC+10% MK 288 32 1152 75105 SRC 320 0 1186 757

b) Curing conditions

All concrete cylinders were initially cured for 28 days under relative humidity (RH)

>95% and temperature (T) =200C. Then the specimens were exposed to sulphate environment.

According to ASTM C511, the curing of the concrete was done.

c) Environmental Exposure conditions

All cylinders after 28 days water curing, kept partially in an 8% sodium sulphate solution

with cyclic temperature and RH. Cycles used in the research were, T = 200C and RH =82% for

one week followed by T=400C and RH=31% for one week. Cycles were repeated (bi-weekly)

upto 180 days (6 months).

1.4 MERCURY INTRUSION POROSIMETRY (MIP)

It is a powerful technique utilized for the identification of the pore volume and the pore

volume distribution of concrete using the method i.e mercury intrusion porosimetry. The



ISSN NO: 0042-9945

Page No:18

identification of pore size distribution for every cylinder was evaluated by Micrometrics PM60-

GT-16 porosimeter with permitting a limit of pressures from 0 to 413.4 N/mm2. The assumed

surface tension of mercury was 0.484 N/m at 25°C according to ASTM D 4404. Figure 1

illustrates the MIP test results for tested concrete.

Figure 1: MIP values for various specimens before allowance to physical sulphate

attack.

1.5 CONCRETE MECHANICAL PROPERTIES

For cured concrete specimens partially soaked in sulphate environment.

Compressive strength was measured based on ASTM C39 and static modulus of

elasticity based on ASTM C469.

1.6 SEM, EDX, and XRD Analysis



ISSN NO: 0042-9945

Page No:19

XL 30 ESEM scanning electron microscopy having resolution 2 nm at 30

kV) with energy dispersive X-ray analysis (EDX) was carried to examine the character of

damage (At the top and bottom of the sodium sulphate solution). To conduct SEM

analysis, specimens were dried using desiccators and later coated using gold prior to

testing. Figure 2 shows SEM images for tested concrete.

(a)

(b)

Figure 2: SEM images a) Ettringite and Gypsum occurrence on the concrete surface immersed in solution. b) Thenardite formation above the solution level.

1.7 DISCUSSION OF RESULTS

The exposure of concrete cylinders was carried six months (24 cycles of wetting

and drying) and monitored to detect the degree of damage. Figure 3 shows scaling of

surface at the top of the solution level for the specimens. For all inspected concrete



ISSN NO: 0042-9945

Page No:20

cylinders, the part of concrete burried in the sulphate solution was occurred in

good condition. At the same time damage occurred on above the solution part. Concrete

specimens adding Pozzolanic minerals shows higher surface scaling on the top of the

solution level rather than that of the specimens casted with 100% OPC or 100% SRC.

(a) (b) (c)

(d) (e)

Figure 3: Specimens casted with w/c=0.60 after 180 days of immersion: (a)

Specimen having 100% OPC (b) OPC+25% FA (c) OPC+10% MK (d) OPC+10%

SF (e) Concrete made with SRC

MIP tests are conducted for cylinders of the different concrete mixes before

exposure to physical sulphate attack. Relatively large diameter pores occurs in the

mixture of concrete casted either with 100% OPC or 100% SRC cement. The

compressive strength and modulus of elasticity were evaluated for all the specimens

partially burried in an 8 % sulphate solution. In continuation, control specimens were



ISSN NO: 0042-9945

Page No:21

reserved in the laboratory condition at temperature = 23°C and RH = 70% for 6 months

(180) days. For all concrete cylinders regardless of their surface damage the compressive

strength and modulus of elasticity increased. This shows that the concrete core was in

good condition and the concrete surface scaling did not significantly affect the

mechanical properties of the concrete.

For all the specimens, not the major constituents responsible for chemical

sulphate attack, i.e gypsum and ettringite, were occurred in the detached parts at the

top of the solution level. This was confirmed by SEM analysis, which recognizes

thenardite in deteriorated parts at the top of the solution level.

On the other hand the concrete specimens casted with pure OPC, gypsum and

ettringite were generated in concrete at the bottom of the solution level. This shows that

concrete subjected to dual sulphate attack. The bottom part burried in the solution of

sodium sulphate was affected by chemical sulphate attack, where as the top part can be

affected by physical sulphate attack.

Conclusions

The following conclusions can be outlined based on the values in the present work.

Concrete can exhibit dual sulphate attack if it is partially burried in a sodium

sulphate solution. The below immersed part in the sodium sulphate solution is

affected by chemical sulphate attack, while the top part of the specimen can be

affected by physical sulphate attack. Physical sulphate attack only damages external surface of the concrete, hence compressive

strength and modulus of elasticity remains unchanged for 180 days of sulphate solution

exposure.

References

[1] ASTM C511., (2009), Standard Specification for Mixing Rooms, Moist Cabinets,

Moist Rooms, and Water Storage Tanks Used in the Testing of Hydraulic Cements



ISSN NO: 0042-9945

Page No:22

and Concretes, American Society for Testing and Materials ,West Conshohocken,

PA.

[2] ASTM D4404, (2010), Standard Test Method for Determination of Pore Volume and

Pore Volume Distribution of Soil and Rock by Mercury Intrusion Porosimetry,

American Society for Testing and Materials ,West Conshohocken, PA.

[3] Aye, T., Oguchi, C. T., (2011), “Resistance of plain and blended cement mortars

exposed to severe sulfate attacks”, Construction and Building Materials, Vol. 25,

No. 6, pp. 2988-2996.

[4] Boyd, A., Mindess, S., (2004), “The use of tension testing to investigate the effect of

W/C ratio and cement type on the resistance of concrete to sulfate attack”, Cement

and Concrete Research, Vol. 34, No. 6, pp. 373-377

[5] Haynes, H., O’Neill, R., and Mehta, P. K. (1996), “Concrete deterioration from

physical attack by salts”, Concrete International, Vol. 18, No. 1, pp. 63-68.

[6] Haynes, H., O’Neill, R., Neff, M. and Mehta, P. K. (2008), “Salt weathering distress

on concrete exposed to sodium sulfate environment”, ACI Materials Journal, Vol.

105, No. 1, pp. 35-43.

[7] Irassar, E. F., Di Maio, A., and Batic, O. R., (1995), “Sulfate attack on concrete with

mineral admixtures”, Cement and Concrete Research, Vol. 26, No. 1, pp. 113-123.

[8] Santhanam, M., Cohen, MD., Olek, J., (2001), “Sulfate attack research – whither

now?”, Cement and Concrete Research, Vol. 31, No. 6, pp. 845-51.

[9] Roziere, E., Loukili, A., Hachem R. EI, and Grondin, F., (2009) “Durability of

concrete exposed to leaching and external sulphate attacks”, Cement and Concrete

Research, Vol. 39, pp. 1188-1198.

[10] Tian, B., and Chen, M. (2000), “Expansion of Alite Paste Caused by Gypsum

Formation during Sulfate Attack”, Journal of Materials in Civil Engineering, Vol.

12, No. 1, pp. 24-25.



ISSN NO: 0042-9945

Page No:23

[11] Yoshida, N., Matsunami, Y., Nagayama, M., and Sakai, E., (2010), “Salt weathering

in residential concrete foundation exposed to sulfate-bearing ground”, Journal of

Advanced Concrete Technology, Vol. 8, No. 2, pp. 121-134.

[12] Liu, Z., Deng, D., Schutter, G. D., and Yu, Z., (2012), “Chemical sulfate attack

performance of partially exposed cement and cement + fly ash paste”, Construction

and Building Materials, Vol. 28, pp. 230-237.



ISSN NO: 0042-9945

Page No:24

Documents

SPECIMEN ATTACK IN PARTIALY SUBMERGED CONCRETE