Research Proposal Enhancementof the Pozzolanic reaction in Peat clays for stabilization by Calcium CarbideResidues with fly ash K.D.Elpitiya140145KSupervisor(s): Dr. A.S. Ranathunga 12thJanuary, 2018 Departmentof Civil EngineeringFacultyof EngineeringUNIVERSITYOF MORATUWA – SRI LANK Contents 1.
Introduction. 1 2. Statement of the problem.. 2 3. Significance of the research. 2 4. Scope and Limitations of the study.
3 5. Objectives of the research. 4 6. Proposed Methodology. 4 7. Time Schedule.
6 8. Estimated cost built up. 7 9. References. 8 1. Introduction In the presentmost of geotechnical engineers and highway engineers who work underconstruction of expressways through areas underlain by soft peaty clays facemajor challenge which is the improvement of strength and stiffnesscharacteristics of such soil in-situ within relative short period of time.Peaty clay has characteristics of high compressibility andlow stability. So this soil should be stabilized prior to the constructions.
InSri Lanka several remedies are taken such as: ground improvement techniques andremoval existing soil and filling back with granular soil etc. As groundimprovement techniques based on consolidation, pre-loading with vertical drainshas been used successfully in the present. But the problem is the long timeduration for these processes. Lots of researches are being implemented and someof them have been already done under this scenario. Soft peaty clay is commonlyencountered in recent construction projects in Sri Lanka. It had been improvedmainly by different techniques of Pre-Consolidation.
If peat clay is mixedin-situ with an appropriate binder material, significant rise in strength andstiffness may be achieved within short time period. Cement was a suggested as abinder material which was mixed in-situ with peaty clay. In laboratoryexperiment studies, required cement content was high to be treated with peatyclay. The percentage of cement added should be greater than 15% to achieve areasonable improvement. (W G S Munasinghe, 2001) When weregard the weight of cement needed, it was about 150 – 250 kg per cubic meterof treated soil.
Thuscost of this treatment would be very high. Therefore any alternative materialsare to be needed as binder material or any material is used to reduce therequired cement content. (S A S Kulathilaka)Currently, severalstudies are focused on using industrial byproducts to replace the cement usage.Further, use of these byproducts reduces the higher costs associated with theprocess and also are environmental friendly. Calcium Carbide Residues (CCR) isone such byproduct from manufacturing of Acetylene gas.
It is also used toenhance stabilization process of peat clay by mixing. Fly ash (FA) is also abyproduct of coal power plants and it is also used for such purpose. In thisresearch we mainly focus on adoption of CCR and FA from various proportions.There several factories manufacturing acetylene gas in Sri Lanka such as CeylonOxygen Limited in Colombo 15, Industrial Gases (Pvt) Ltd at Supugaskanda andOvin Gases (Pvt) Ltd at Nugegoda etc.
We will get CCR from these factoriesfreely. Fly ash will be available from Norochcholi power plant. As bothmaterials are freely available in Sri Lanka, we have selected these materialsfor this research. 2. Statement of the problem In Sri Lanka, soft peat clay is most probably encountered duringConstruction of highway embankment.
When that soil is used for constructionswithout doing any soil improvement techniques, life time of the road will beless, can cause for construction failures and much time is taken for thestabilization process. Therefore,Engineers have to find solutions to overcome this problem. Up to now severalprecautions have been taken by doing researches. When we take remedies for this issue, we should think that it would becost effective, that process can be continued with less amount of drawbacks andrequired materials are easily available.
Mixing cement with peat clay is used as a remedy today. It will enhancethe strength as well as the permeability characteristics of peat. But thismethod is costly. That is the drawback of it. Generally in Sri Lanka, FA are mainly generated from the Norochcholaipower plant and it is categorized under Class F.
Calcium content issignificantly low in Class F fly ash. Hence when we use that type FA for theimprovement of peat clay, it could not provide required enhancement. BecauseCaO content is 12.
15% in FA and 70.78% in CCR. (Suksun Horpibulsuk, 2012) 3. Significanceof the research The outcome of this research is very significant for Geotechnicalengineers and Highway engineers.
This research is based on experimental study.Although several researches were carried out under this statement of theproblem, more effective and useful remedy could not be achieved yet. That iswhy this research is going to be done while supervising previous results offormer researches. Improvement of soft soil characteristics is vital in road embankment.Peat clay is the most common soil type which is encountered in the siteunderlying with thick layers. In the extension of Southern expressway project,the heaviest soil type is the peat clay. So this soil must be stabilized priorto construction.
If cement is used for stabilization process, high amountcement will be needed then it will be more expensive. Both FA and CCR are easily available in Sri Lankan industry. Thus both ofthem are useful for the improvement of soft clay characteristics. Since theyare available with high amount, adoption of them is very useful for theextension of Southern Expressway project. 4.
Scopeand Limitations of the study. This research is not focused on a single parameter. When soil isstabilized by using any method, we want to know how strength behavior, flowbehavior, what consolidation characteristics there and what microstructuralcharacteristics in that soil. This research will be going under consolidationcharacteristics of peat clay which directly represented field behavior of thetreated soil.
Here calcium carbide is the key component to be used to enhancethe pozzolanic reaction in peat clay. Combination of FA and CCR are going to beadded and then we can select best percentage and proportion of them by carryingout the experiments. We should regard specially for secondary consolidation settlements inpeat clay. It typically shows large amount of secondary consolidationsettlements. So here the effect on the parameters corresponding to primary andsecondary consolidation are going to be analyzed.
Considering time durations for the current project, several combinationswill be adopted. The samples for the research are collected from SouthernExpressway extension project and will be used as remoulded specimens to avoidthe higher heterogeneity of the samples. 5. Objectivesof the research Many Geotechnical researchers have used various materialsand techniques in an attempt to improve engineering characteristics of peatyclay underlying in road embankment constructions. Early study for improvementof peaty clay presented various methods of stabilization in practice at thetime. In the present, required time for stabilization process of peaty clay canhave been minimized in road embankment construction. The main aim of thisresearch is:To determinethe suitability of using CCR as a high calcium additive to improve thepozzolanic reactions of FAThis will be achieved using the following sub-objectives: i. Evaluation ofoptimum mix proportion of CCR and FA to obtain the best consolidationcharacteristics suitable for the filed application.
ii. Investigation ofthe micro-structural variation of the soil due to the addition of CCR and FA.6. Proposed Methodology Peat will be brought from theExtension of Southern Expressway project. At the very first, all debris andother incidental particles should be removed. When the peat sample keep in thelaboratory, buckets of sample should be filled with water as the top surface ofpeat must be fully submerged.
Materials for mixing especially flay ash andcalcium carbide will be brought from places mentioned above. Then preparationof sample for selected mixing proportions will be commenced as next stage. Then all samples should be cured well. Curingshould be done separately to the sample for 28 days and 90 days. First of allbasic properties of peat will be determined by doing tests as follows: i.
Atterberg limits ii. Specific gravity iii. Orgnic Content iv. Moisture content v. PH value.After 28 daysall tests will be started to carry out for different mix proportions. In thisresearch, laboratory consolidation test (Oedometer test) will be carried to theprepared peat samples as following mix proportions. Mixing FA/Cem Pro(%) CCR Pro(%) No of tests for Consolidation S+Cem 20 2 10 2 S+CCR 15 2 20 2 10 10 2 20 2 S+CCR+FA 10 15 2 20 2 10 20 2 20 2 One test by onewill have to be done and take results.
If the results are more deviated thanwhat we are expecting, that particular samples must be tested again. Finallyall results are going to be analyzed. When the curing time for 90 day willaccomplish, tests of them will be carried out. Those results also should beanalyzed then we can come to a conclusion about this research. 7. Time Schedule 2017 2018 DEC JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV Literature Review Preparation of material and equipment Submission of the research proposal Submission of the literature review Preparation of the different mixes in selected proportions Curing time Basic property testings for peat Carrying out tests for 28 days cured samples Analyzing Results Curing time for 90 day Testing Carrying out tests for 90 days cured samples Analyzing Results Finalizing 8.
Estimated cost built up Items No of Units Price/ unit (Rs) Table Amount Buckets 20 200 4000 Tied Rings 20 100 2000 Plywood Sheets 2 3000 6000 10mm Steel Bar 2 600 1200 Cement Bag 1 960 960 Transport 1200 Miscellaneous 5000 Total 20360 9. References · S A S Kulathilaka, D. R. (n.d.
). Enhancement of Engineering Characteristics of Peaty Clay due to Mixing With Cement. Moratuwa. · Suksun Horpibulsuk, C. P.
(2012). Strength development in silty clay stabilized with calcium carbide residue. Nakhon Ratchasima. · W G S Munasinghe. (2001).
Methods for Improvement of Engineering properties of Peat. Moratuwa.