Susceptibility to Compaction of Lime and GGBS Treated Bauxite Residue K. Sateesh Babu Master’s student & N. Gangadhara Reddy Research Scholar Dr. B. Hanumantha Rao & Dr. Partha Patim Dey Assistant Professors’ IIT Bhubaneswar Bhubaneswar, India

Introduction: Problems and Need of the Study Red mud is a solid insoluble waste generated by aluminium industry Utilization: 5%, and 95% of it is stored in impoundments Problems: Land acquisition Construction and maintenance Leachate generation Ground, soil and water pollution High alkalinity: pH above 11 Need: Alkali (sodium ion) regeneration Impact on environment Utilization in civil engineering applications is least explored

Characteristics of Red Mud Low strength due to presence of caustic content Sodium cations are predominant due to the high NaOH It is completely free from sand or clayey type mineral constituents In spite of absence of clay type mineral constituents, shows plastic behavior similar to that of clayey tailings and shows significantly low volumetric deformation alike sands

Objectives of the Study To evaluate the compaction characteristics of red mud by adapting chemical analysis methods To study the influence of Lime and GGBS stabilization on compaction characteristics of red mud

Materials & Testing Methodology Red Mud: collected from Vedanta limited at Lanjigarh, Odisha Stabilizers lime of a commercial grade quality is procured from the local market, GBS & GGBS are procured from M/s. Counto Microfine Products Pvt. Ltd., Panaji, Goa, India. GBS GGBS Lime Red Mud 5

Characterization of Red Mud and Stabilizers Red Mud: Physical Properties Property Value Gs 3.09 Consistency limit (%) wL 40 wP 29 wPI 11 % fractions Sand 18.3 Silt 55.35 Clay 26.35 Classification MI pH 10.5-12.5 Chemical Composition: XRF analysis Oxide % (by dry weight) Na2O 6.48 Al2O3 22.72 SiO2 13.43 CaO 4.06 TiO2 10.17 Fe2O3 39.89 MgO 0.64 P2O5 0.47 SO3 0.75 K2O 0.44 others 2 Elemental Composition: EDS analysis Element % (by dry weight) Red Mud GGBS GBS Lime Iron 34.81 2.77 -   Aluminum 23.38 16.67 15.65 2.03 Silicon 13.42 30.63 34.12 9.77 Titanium 8.68 0.79 Calcium 4.96 42.27 38.61 82.44 Sodium 14.75 Magnesium 6.61 9.96 5.76 Total 100.00 100 Observation: Iron oxides dominant in Red mud Strength giving elements dominant in stabilizers

Mineralogical Characteristics: XRD Morphological Characteristics: XRD Red mud: non uniform particle size GGBS and GBS: No similarity in shape Untreated red mud Lime Hematite is dominant mineral type Minerals belongs to Fe family GGBS GBS

Experimental Program: Stabilization Additive % replacement (by dry weight) Sample designation Experimentation Lime 0.0 RM+0L Consistency limits: IS:2720 (Part 5) Compaction Test (Mini compaction by Sridharan) UCS Test : IS: 2720(Part 10) CBR Test: IS:2720 (Part 16) Morphological Characteristics (SEM) Mineralogical Characterization (XRD) Elemental characterization (EDS) Neutralization study 0.5 RM+0.5L 1.0 RM+1L 2.0 RM+2L 5.0 RM+5L 8.0 RM+8L GBS 10 RM+10%GBS 20 RM+20%GBS GGBS 90RM+10GGBS 15 85RM+15GGBS 80RM+20GGBS 25 75RM+25GGBS RM – RED MUD; L-LIME; GBS- GRANULATED BLAST FURNACE SLAG; GGBS- GROUND GRANULATED BLAST FURNACE SLAG

Compaction Characteristic A range of factors affect the compaction of soil: water content compaction effort type of soil method of compaction, etc. In natural soils, the oxide compositions variations are insignificant. Industrial waste materials are increasingly being utilized in geotechnical engineering applications. Contrary to natural soils, waste materials constitute oxide compositions in disproportionate contents, making them susceptible to compaction. Influence of certain properties like oxide compositions not received adequate attention. Variability in dmax & wopt Sensitive to waste content

Results & Discussion: Compaction properties Red mud : dmax 16.44 to 17.8 kN/m3, wopt from 27 to 28% Lime stabilized: decreased dmax increased for 2-5%. wopt increased up to 1% ,constant beyond this value GGBS: marginal variations in the values of dmax & wopt GBS stabilized: no change in wopt, marginal improvement in dmax

Values of dmax and wopt of treated red mud waste samples s.no Combination of sample Experimental Results As per IRC: SP: 20:2002 (Rural roads) OMC(%) MDD(gm/cc) Embankment Subgrade & Earthen shoulders 1 Raw RM 27- 28 16.44-17.8 a) Up to 3m, not subjected to Extensive flooding, MDD shall not less than 1.44 gm/cc. b) Height exceeding 3m, MDD shall not less than 1.52gm/cc Recommendation: Acceptable MDD shall not less than 1.65 gm/cc   Except 5% Lime treated samples, all other combinations are Acceptable 2 90RM+10GGBBS 29.70 1.65 3 85RM+15GGBBS 27.314 1.655 4 80RM+20GGBBS 27.5 1.69 5 75RM+25GGBBS 28.29 6 RM+0.5L 26.8 1.696 7 RM+1L 27.6 1.682 8 RM+2L 28.35 1.676 9 RM+5L 29.36 1.606 10 RM+10%GBS 27.66246 1.68 11 RM+20%GBS 26.67706 1.71

Results & Discussion: Unconfined Compressive Strength Observation UCS (Mpa) Lime Doubled at 90 days GBS Doubled at 90 days, max at GBS 10% GGBS Four times at 90 days, max at 15% GGBS

Values of UCS for treated samples at different curing periods Combination of sample Experimental Results (UCS: MPa) IRC 37:2012 IRC: SP: 72-2015 Curing period(days) 7 28 45 90 For chemically stabilized material: 0.75 to 1.5 MPa at 7 days curing period For subbase: 1.7 MPa   For base course: 3 MPa RM 0.34 0.39 0.44  0.65 0.70  90RM+10GGBBS 0.33 0.38 0.47 1.20 1.46 85RM+15GGBBS 0.35 0.386 0.49 1.32 1.84 80RM+20GGBBS 0.36 0.41 0.51 1.22 1.75 75RM+25GGBBS 0.365 0.43 0.48 1.08 1.67 RM+0.5L 0.32 0.45  0.64 0.68  RM+1L  0.66 0.72  RM+2L 0.42 0.53  0.67  0.78 RM+5L 0.52 0.55 0.77  RM+10%GBS 0.37 0.40 0.46  0.7 0.74  RM+20%GBS 0.50  0.70

California Bearing Ratio Variations of CBR value with Stabilizers at different curing periods Observation: Maximum at Lime 5% Maximum at GBS 20% Maximum at GGBS 15%

Results of California Bearing Ratio tests of stabilized red mud samples Combination of sample Experimental Results IRC 37:2012 IRC:SP:72:2015 Curing Periods(Days) 7 Un soaked Soaked soaked RM 18.2 5.4 22.0 6.32 Soaked CBR value: 8% for roads with traffic ≥ 450 CVPD Recommendation: Only GBS Stabilized samples are acceptable Soaked CBR value: 4-6% Recommendation: Acceptable 90RM+10GGBBS 15.7 5.7 21.7 6.92 85RM+15GGBBS 14.9 6.1 21.1 7.4 80RM+20GGBBS 15.12 6.41 21.0 7.9 75RM+25GGBBS 14.80 6.5 22   7.58 RM+0.5L 18.5 6.2  21.4  6.3 RM+1L 19.6 6.4  22.4  6.9 RM+2L 19.8 6.9  23  7.4 RM+5L 22.21 7.5  24  7.9 RM+8L 21.09 7.1 22.5 RM+10%GBS 20.2 23.4 8.2 RM+20%GBS 23 6.8 26 8.9 RM+25%GBS 22.9 6.78 25.8 8.8

Mineralogical characteristics of Lime Stabilized Red Mud Observation: Increasing the lime content, peak intensity decreasing calcite phase prominently increasing.

Mineralogical characteristics of GGBS Stabilized Red Mud Observation: Increasing the GGBS content, decrease in peak intensity of hematite No major change in the various mineral phase

Untreated red mud 1% lime 5% lime Morphological characteristics Observation: increase in lime content, Gel formation is increasing Untreated red mud 1% lime 5% lime

Morphological characteristics of Stabilized Samples RM 90+ GGBS 10 Untreated red mud RM 90+ GBS 10 RM 85+ GGBS 15 11/27/2018

Elemental characteristics of Stabilized samples Lime GGBS & GBS Element % (by dry weight) % change RM RM +05L RM +1L RM +2L RM +5L Fe 34.81 31.78 30.74 28.69 26.24 -24 Al 23.38 22.86 20.76 15.12 15.62 -33 Si 13.42 13.78 12.98 9.10 11.25 -15 Ti 8.68 7.89 7.38 6.06 6.34 -27 Ca 4.96 8.42 13.68 28.79 28.98 +485 Na 14.75 11.87 11.30 10.19 9.66 -34 Mg - 3.4 2.96 2.04 1.92 Sample designation % (by dry weight) Fe Al Si Ti Ca Na RM+ GBS 0 34.81 23.38 13.42 8.68 4.96 14.75 RM 90+GBS 10 29.66 23.47 17.55 7.92 7.77 13.62 RM 80+GBS 20 38.44 23.58 13.44 8.49 3.11 12.94 RM 90+GGBS 10 25.78 21.68 20.58 6.40 12.57 10.64 RM 85+GGBS 15 20.54 23.43 23.16 6.36 12.98 10.97 RM 80+GGBS 20 19.04 20.85 23.25 5.26 18.24 9.03 RM 75+GGBS 25 19.80 19.43 24.13 5.08 18.85 7.83 %ge change for GBS -10.4 -0.855 -0.15 2.18 37.29 12.27 %ge change for GGBS 43.12 16.9 -79.8 41.47 280 46.91

Summary Studies reveal that the red mud susceptible to applied compaction energy, as it is noticed a contrast in the values of dry unit weight and optimum water content The study finds that addition of 5% lime or 15% of GGBS is advantageous for obtaining reliable and consistent values of maximum dry unit weight and optimum water content. Comparison with compaction characteristics of the red mud with fly ash and foundry sand shows, the red mud has a potential to be a resource material in the construction of an embankment or a subgrade

Thanks for your kind attention Waste is a waste if you waste it… Otherwise it is a RESOURCE.