Influence of Textile Effluent Waste Water on Compacted Lateritic Soil

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Laboratory test was conducted on lateritic soil treated with various concentration of ... bagasse ash and locust beans ash) with varying degree of success. ... load bearing capacity, most laterite require some sort of stabilization for use in road ...
Influence of Textile Effluent Waste Water on Compacted Lateritic Soil F.O.P. Oriola1 and A. Saminu2 1

Department of Civil Engrg., Nigerian Defense Academy, Kaduna, Nigeria. [email protected]

2

Department of Civil Engrg., Nigerian Defense Academy, Kaduna, Nigeria. [email protected]

ABSTRACT Laboratory test was conducted on lateritic soil treated with various concentration of textile effluent waste water (0, 25, 50 and 100%) by dry weight of soil to assess its influence on the engineering properties of road pavement material. Specimens were compacted using the energies of the British Standard Light (BSL) and West African Standard (WAS) or “intermediate”. The laterite soil classified as A-7-6 or CL using the America Association of Highway and Transportation Officials (AASHTO) and Unified Soil Classification System (USCS), respectively. Natural soil treated with textile effluent waste water (TEWW) gave a peak 7 day UCS value of 875kN/m2 and 1033kN/m2 at 100% TEWW concentration at BSL and WAS energy level respectively. This values fall short of 1710 kN/m2 specified for base materials stabilization using OPC. However, this value meets the requirement of 687–1373 kN/m2 specified for sub-base materials. The peak resistance to loss in strength recorded for BSL and WAS were 25.3 and 26.8% (i.e. loss in strength) was attained at 0% TEWW concentration at both energy levels. This resistance to loss in strength values falls short of the acceptable conventional minimum of 80%. Finally, the strength and durability test conducted failed to meet the minimum specified values for base, sub-base and sub-base material.

KEYWORDS: Textile Effluent Waste Water, Compaction, Durability, Unconfined Compressive Strength, California Bearing Ratio

INTRODUCTION Problematic lateritic soil abounds in many parts of the world such that their avoidance becomes inevitable especially in places where there deposits are extensive. On the other hand industrial waste disposal is constantly throwing up challenge in terms of the cost and safe disposal of these wastes that other unexplored waste are being researched upon to determine their suitability as road pavement material. Various researchers (Osinubi et al., 1997, 2008; Osinubi - 167 -

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and Stephen, 2005,2006a,b, 2007, 2008; Osinubi and Medubi, 1997;.Osinubi and Katte, 1997; Osinubi and Mohammed, 2005; Osinubi, 1995,1998a,b, 1999 2000, 2006) have attempted to stabilize Nigerian laterite soils with different types of stabilizers agents (lime, cement, bitumen, bagasse ash and locust beans ash) with varying degree of success. In the tropics and subtropics, the common material for road construction is laterite, which is residual in nature. The term Laterite is derived from the Latin word ―later, meaning brick. It was first used in 1807 by Buchanan to describe a red iron-rich material found in the southern parts of India. Laterites are widely distributed throughout the world in the regions with high rainfall, but especially in the inter-tropical regions of Africa, Australia, India, South-East Asia and South America, where they generally occur just below the surface of grasslands or forest clearings. Their extension indicates that conditions were favorable for their formation at some point in time in the history of the world, but not necessarily simultaneously in all regions. (Maignien, 1966). Laterites contribute to the general economy of the regions where they are found. Their scope is very wide and includes civil engineering, agronomic, mining research (iron, aluminium and manganese) deposits. There is no need to emphasize the importance of laterites for various building purposes. Laterite crusts were originally widely used for the construction of monuments and dwellings. Certain African megaliths like ―Tazunu, located in the northwest of the Central African Republic, are of lateritic origin, in addition to rock minerals (Maignien, 1966; Zangato, 1965). Studies on these materials are now in progress, with focus on their use in road and earth dam construction. Although there are some lateritic soils that do not require treatment to give them sufficient load bearing capacity, most laterite require some sort of stabilization for use in road construction. Textile effluent waste water (TEWW) is an industrial waste from textile production. The quantities and characteristics of TEWW generated depend upon a number of operational factors and characteristics of the inputs to the manufacturing process. Although the relative constituent’s concentrations in TEWW can vary significantly, TEWW has certain biological/chemical characteristics that are relatively consistent. In various attempts to accelerate the chemical reaction resulting in high strength gains of stabilized soils, many chemical additives have been used in conjunction with lime and OPC. Test results of Balogun (1991) indicated a significant increase in the geotechnical properties of lime treated black cotton clay when 2 % sodium chloride was added to the lime- clay mixture. Sambhandharaksa and Moh (1971) studied the effect of sodium chloride (NaCl) on the thixotropic characteristics of clay soil. They reported an increase in the dry unit weight as well as the thioxotropic strength of the treated clay with higher NaCl content. Water-soluble calcium chloride (CaCl2) has been used simultaneously with cement to stabilize clay soils containing appreciable amounts of organic matter (Maclean, 1953). It was also indicated that the salt generally satisfies the absorption capacity of the organic matter for calcium ions, thus permitting the calcium from OPC to complete its reaction with the other components in the normal way. In the past, it has been shown that CaCl2 and NaCl when used accordingly reduced the shrinkage, moisture loss as well as the strength and heaving resistance of montmorillonite soils (O’Glesby and Hicks, 1982; Rizkallah, 1982). So (1992) illustrated a marked increase on the strength of slag stabilized clay when sodium hydroxide (NaOH) was used in conjunction with slag. The presence of certain compound textile effluent waste water such as the chlorides which are known to posses stabilizing potentials can be exploited in the stabilization of poor engineering material.

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Research work has been carried out on the improvement of geotechnical characteristics of laterite soil with varying degree of success. However, no work has been done on the use of TEWW treated laterite soil as a road pavement material. The study was aimed at the evaluation of the suitability of compacted laterite soil treated with TEWW for use as a road pavement material.

MATERIALS AND METHODS Materials Laterite Soil: The soil used in this study is red in colour lateritic soil, it was obtained in Kano Local Government Area of Kano State using the method of disturbed sampling. The location lies along (latitude 10° 18’N and longitude 12° 24’E). Specimens were varied with 0, 25, 50 and 100% of textile effluent waste water concentration by dry weight of soil. Textile Effluent Waste Water: The textile effluent waste water used was obtained from a textile company as freshly discharged waste water from the production plant located in Kano Local Government Area of Kano State using the method of disturbed sampling. The location lies along (latitude 10° 18’N and longitude 12° 24’E). Methods Index Properties: Laboratory tests were conducted to determine the index properties of the natural soil and soil – textile effluent waste water mixtures in accordance with British Standards BS 1377 (1990) and BS 1924 (1990) respectively. A summary of the soil index properties is presented in Table 2. Table 2: Engineering Properties of TEWW Treated Lateritic Soil Engineering Properties Liquid Limit, % Plastic Limit, % Plasticity Index, % Linear Shrinkage, % Percentage Passing BS No. 200 Sieve. AASHTO Classification USCS Classification Specific Gravity MDD Mg/m3 Standard Proctor West African Standard OMC% Standard Proctor West African Standard pH Value Color Dominant Clay mineral

Textile effluent waste water (%) 0 40.0 26.9 13.1 13.2

25 44.1 32.5 11.6 12.3

50 48.0 37.0 11.0 11.4

100 52.0 41.2 10.8 8.3

85.0

83.0

85.0

81.0

A-7-6 CL 2.60

A-7-6 CL 2.55

A-7-6 CL 2.50

A-7-6 CL 2.40

1.800 1.880

1.780 1.900

1.770 1.800

1.770 1.800

19.2 18.0 7.2

18.8 18.3 -

18.4 16.3 -

18.0 15.0 -

Red Kaolinite

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Table 3: Engineering Properties of TEWW Treated Lateritic Soil Parameter Sodium Boron Sulphate Chloride Alkalinity Total hardness BOD COD SAR pH

Concentration (mg/l) 48 11.4 18.1 199.5 93.0 91.7 2000 670 3.04 10.0

Compaction All the compactions involving moisture-density relationships, CBR and UCS were carried out using energies derived from the Standard Light (BSL) and West African Standard (WAS). The BSL compactions was carried out using energy derived from a rammer of 2.5 kg mass falling through a height of 30 cm in a 1000 cm3 mould. The soil was compacted in three layers, each receiving 27 blows. The WAS compaction, was carried out using energy derived from a rammer of 4.5 kg mass falling through a height of 45 cm in a 1000 cm3 mould. The soil was compacted in five layers, each layer receiving 10 blows. The UCS test specimen was compacted at BSL and WAS energy levels. Specimens were cured for 7, 14 and 28 days before testing.

RESULTS AND DISCUSSIONS Index Properties: Results of tests carried out on the natural soil are summarized in Table.1. The soil is classified under the A – 7 – 6 subgroup of the AASHTO classification system. Liquid limit and plasticity index values of 40.0 % and 13.1 %, respectively, suggest that the soil is plastic. Thus, from the results obtained, the soil falls below the standard recommended for most geotechnical works (Butcher and Sailie, 1984).

Maximum Dry Density The MDD for the BSL and WAS compactive effort was not in conformity with the trend of decreasing OMC with increasing MDD. This could possibly be as a result of TEWW forming newer compounds as a result of reactions due to the exchange of ions present in the textile water waste of the clay particle (Osinubi, 2000 a; Moses, 2008; Oriola and Moses, 2010,). While the final decrease in MDD for BSL compactive effort can be attributed to TEWW, a low specific gravity material replacing the soil material which has a high specific gravity (Osinubi and Stephen 2007).

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Maximum dry density (Mg/m3)

2 1.95

BSL

1.9 WAS

1.85 1.8 1.75 1.7 0

20

40

60

80

100

Bagasse Ash Content (%)

Figure 1: Variation of Maximum Dry Density With soiltextile effluent waste water

Optimum Moisture Content For specimens compacted at the British standard light and West African Standard energy levels, a decrease in OMC was recorded this is probably due to self – desiccation in which all the water was used, resulting in low hydration. When no water movement to or from TEWW – paste is permitted, the water is used up in the hydration reaction, until too little is left to saturate the solid surfaces and hence the relative humidity within the paste decreases. The process described above might have affected the reaction mechanism of TEWW treated laterite soil (Osinubi and Stephen 2007, Moses 2008). 20 California Bearing Ratio (%)

19 BSL

18 17

WAS

16 15 14 13 12 0

20

40

60

80

100

Efflluent Waste (%)

Figure 2: Variation of Optimum Moisture Content With soiltextile effluent waste water

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Strength Characteristics Unconfined compressive strength

7days unconfined compressive strength (kN/m2)

The variation of unconfined compressive strength (UCS) with concentration for soil –TEWW mixtures at 7, 14 and 28 days curing periods are shown in Figs. 3 - 5. Generally, the UCS of the soil – TEWW – mixtures increased up to 12% TEWW treatment and thereafter decreased. The 7 days UCS of the untreated laterite soil improved from a value of 200kN/m2 and 260kN/m2 to a peak value of 875kN/m2 and 1033kN/m2 at 100% TEWW treatment level for both BSL and WAS energy levels. The peak blend of TEWW treated soil was attained at 100% TEWW concentration at BSL compactive effort produced a peak 7 day UCS value of 875kN/m2. This value falls short of 1710 kN/m2 specified by TRRL (1977) for base materials stabilization using OPC. However, this value meets the requirement of 687–1373 kN/m2 for sub-base as specified by Ingles and Metcalf (1972). 1200 1000

BSL

800 WAS

600 400 200 0 0

2

4

6

8

Efflluent Waste (%)

14 days unconfined compressive strength (kN/m2)

Figure 3: Variation of of unconfined compressive strength (7 days curing) with soil-textile effluent waste wate 1600 1400 1200 1000

BSL

800 WAS

600 400 200 0 0

20

40

60

80

100

Efflluent Waste (%)

Figure 4: Variation of of unconfined compressive strength (14 days curing) with soil-textile effluent waste wate

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28 days unconfined compressive strength (kN/m2)

The increase in UCS values could be attributed to ion exchange at the surface of clay particles. The chlorides in the additives reacted with the lower valence metallic ions in the clay microstructure which resulted in agglomeration and flocculation of the clay particles. The UCS of soil - TEWW mixture containing 100 % TEWW concentration as expected increased with curing period as shown in Fig. 4-5. The gain in strength of specimens with age was due primarily to the long-term hydration reaction that resulted in the formation of newer compounds due to the presence of chlorides which are known to be stabilizing agents. 700 600 500

BSL

400

WAS

300 200 100 0 0

4

8

12

16

CKD Content (%)

Figure 5: Variation of of unconfined compressive strength (28 days curing) with CKD content for soil-CKD mixtures

Durability In order to simulate some of the worst conditions that can be experienced in the field for any soil to be used for engineering purposes, cured specimen were immersed in water before testing (7days cured+7days immersion in water). Compressive strength is employed as an evaluation criterion to ensure that the stabilized material does not fail under adverse field conditions. The value obtained under this laboratory simulated field condition are analysis with the 14 days cured specimen to obtain the percentage resistance to loss in strength of the stabilized material as recommend for tropical countries (Ola, 1974). The peak resistance to loss in strength recorded for BSL and WAS were 26.7 and 25.3% (i.e. loss in strength) were attained at 0% TEWW concentration. This resistance to loss in strength falls short of the acceptable conventional minimum of 80% (Ola, 1974).

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Resistance to loss in strength (%)

30 25 BSL

20 15

WAS

10 5 0 0

20

40

60

80

100

Efflluent Waste (%)

Figure 7: Variation of of resistance to loss in strengthwith soiltextile effluent waste water

CONCLUSIONS The natural laterite soil was classified as A – 7 – 6 or CL in the AASHTO and Unified Soil Classification System (USCS), respectively. Soils under these groups are of poor engineering benefit. Natural soil treated with TEWW gave a peak 7 day UCS value of 381kN/m2 and 410kN/m2 at 12% and 8% TEWW concentration at BSL and WAS energy level respectively. This values fall short of 1710 kN/m2 specified by TRRL (1977) for base materials stabilization using OPC. And this value also fails to meet the requirement of 687–1373 kN/m2 for sub-base as specified by Ingles and Metcalf (1972). The durability assessment of the specimen failed to produce an acceptable result based on the resistance to loss in strength test carried out, with only a maximum peak value of 25.3 and 26.8% attained at enegy levels of BSL and WAS respectively. Finally, textile effluent waste water treated laterite soil failed to record desired result, therefore, it is not recommended for use as a single stabilizing agent for road pavements.

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