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A STUDY ON SOLIDIFICATION OF DREDGED MARINE SOLS USING CEMENT
AND BOTTOM ASH
AMIRA BINTI AZHAR
A thesis submitted in
Fulfillment of the requirements for the award of the
Degree of Master in Civil Engineering
Faculty of Civil and Environmental Engineering
UniversitiTun Hussein Om Malaysia
SEPTEMBER 20 15
A C T
Dredged marine soils (DMS) are the sediments and debris removed during the
dredging process. In Malaysia, DMS are considered as wastes and are currently not
being recycled. Solidification of DMS needs to be undertaken before the materials can
be reused. Soil solidification involves the use of solidification agents or binders in soft
soils to improve the geotechnical properties. This study focused on the development of
strength of three solidified fme-grained DMS admixed with cement and bottom ash
(BA). The factors that could influence the strength development are curing period
effects, water-binder ratio, percentage of binders and percentage of granular admixture
were examine. The DMS were collected fkom dredge sites in Melaka and Kelantan,
while the binder used were ordinary Portland cement (C) and the granular admixture
bottom ash (BA) retrieved fiom a local coal power plant. The standard unconfined
compression, bender element and synthetic precipitation leaching procedure (SPLP)
test were conducted to determine the improvement of strength, stifihess and leaching
behaviour of solidified DMS. The water-binder ratio used in this study was 1,3 and 5.
The results show the strength and stifl5ess increased with prolonged curing. As for
water-binder ratio, the strength and stiftkess increased when the water-binder ratio
decreased. The results show that, high plasticity clay (CH) samples with water-binder
(wh) ratio =1 has the highest strength that is up to 4.7 MPa. The optimal dosage of BA
or granular admixture for effective solidification of the DMS was found to be 25 %.
With higher BA dosages strength and st iaess of the solidified DMS would increase
till it peaked at the optimal dosage. After exceeding the optimal BA dosage, the
strength was observed to decrease rather dramatically. All of the elements tested using
the SPLP method does not exceed the allowable limit for drinking water. In
conclusion, solidification of DMS with cement-bottom ash improved the original
properties of the DMS, with the added 'green' value of partial substitution of cement
with an industrial waste product.
Keywords: Dredged marine soils, soZidiJication, OPC, bottom ash, water-binder ratio
Tanah kerukan dari laut @MS) addah sgdimen dm serpihan yang d i k e d semasa
proses pengerukan. Di Malaysia, DMS dianggap sebagai bahan buangan dan pada masa
ini tkhk dikitar semula lagi. Pmejalan DMS perlu dijdankan seblum DMS dapat
digunakan semula. Pemejalan tanah melibatkan penggunaan agen pemejalan atau
pengikat dalarn m a h lernbut untuk memperbaiki sifat-sifat geoteknikal. Kajian ini
memberi tumpuan kepada kaedah untuk mengukuhkan DMS yang telah dicampur
dengan simen dan abu bawah @A). Faktor-falctor yang boleh mempengaruhi
peningkatan kekuatan adalah kesan tempoh pengawetan, nisbah air-pengikat, peratusan
pengikat dan peratusan pengisi digunakan, DMS dikumpulkan dari bpak pengerukan
seperti di Melaka dan Kelantan, manakala pengikat yang digunakan ialah simen Portland
biasa (OPC) manakala pengisi yang ctigunakan adalah abu bawah yang telah diambil dari
loji kuasa arang batu tempatan. Ujian mampatan tak terkurung, ujian unsur terbengkok
(BE) dan ujian hujan sintetik (SPLP) telah dijalankan untuk menentukan peningkatan
kekuatan, kekukuhan dan tingkah laku larut lesap DMS pejal. Nisbah air-pengikat yang
digunakan &lam kajian hi adalah 1, M a n 5. Keputusan menunjukkan kekuatan dan
ketegangan meningkat dengan tempoh awetan. Bagi nisbah air-pengikat, kekuatan dan
kekukuhan meningkat apabila nisbah air-pengikat berkurangan. Keputusan menunjukkan
bahawa, sampel tanah liat dengan kelekitan yang tinggi (CH) dengan air pengikat (w 1 b)
nisbah = 1 mempunyai kekuatan paling tinggi iaitu sehingga 4.7 MPa. Campuran
optimum BA atau bahan tambah untuk pemejalan DMS yang berkesan didapati 25%.
Kekuatan bagi DMS akan meningkat sehiigga mencapai tahap optimum. Selepas
melebihi peratusan BA optimum, kekuatan dilihat akan semakin berkurangan secara
drarnatik. Semua elemen yang diuji menggunakan SPLP adalah dibawah takat minimum
air minuman yang dibenarkan. Kesimpulannya, pemejalan DMS dengan simen-abu
bawah memperbaiki sifat-sifat asal DMS, dengan nilai tambah 'hijau' penggantian separa
simen dengan bahan buangan industri.
Kata kunci: Tanah Kertrkan, pemejalan, OPC, abu bawah, nisbah air-pengikat
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