Microstructure and geotechnical properties of lime-treated expansive clayey soil

Microstructural and mechanical properties of marine soft clay stabilized by lime-activated ground granulated blastfurnace slag

This paper investigated the stabilization efficacy of alkali-activated ground-granulated blast furnace slag (GGBS) for a marine soft clay, compared with that of portland cement (PC). The influence of activators, including NaOH, Na2CO3, carbide slag (CS), NaOH-CS, Na2CO3-CS, and Na2SO4-CS, on the stabilization efficacy was investigated. A range of tests were conducted to investigate the properties of stabilized clays, including unconfined compressive strength (UCS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP). The results indicated that Na2CO3-GGBS had no stabilization efficacy for this marine soft clay. NaOH-GGBS-stabilized clay yielded the highest UCS at 7, 28, and 90 days; however, the UCS decreased from 90 to 180 days because of the microcracking. CS-GGBS-stabilized clay had higher 90-day and 180-day UCS than that of PC-stabilized clay, but significantly lower 7-day and 28-day UCS. NaOH, Na2CO3, and Na2SO4 could enhance the strength devel...

Alkali-Activated Ground-Granulated Blast Furnace Slag for Stabilization of Marine Soft Clay

This paper addresses the use of ground granulated blast furnace slag (GGBS) and reactive magnesia (MgO) blends for soil stabilization, comparing them with GGBS-lime blends and Portland cement (PC) for enhanced technical performance. A range of tests were conducted to investigate the properties of stabilized soils, including unconfined compressive strength (UCS), permeability, and microstructural analyses by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influence of GGBS:MgO ratio, binder content, soil type, and curing period were addressed. The UCS results revealed that GGBS-MgO was more efficient than GGBS-lime as a binder for soil stabilization, with an optimum MgO content in the range of 5–20% of the blends content, varying with binder content and curing age. The 28-day UCS values of the optimum GGBS-MgO mixes were up to almost four times higher than that of corresponding PC mixes. The microstructural analyses showed the hydrotalcite was produced during the GGBS hydr...

Properties of Two Model Soils Stabilized with Different Blends and Contents of GGBS, MgO, Lime, and PC

Unconfined compressive strength (UCS) of synthetic biochar mixed clays (BMC) treated with lime-GGBS has been investigated. Biochar utilized in this study was produced from the slow pyrolysis of green waste residue. Treated biochar mixed clays have also been tested for microstructural and mineralogical developments. Results of this study showed that a lime content of 2 wt%, which is much lower than the conventionally used 10 wt% lime for synthetic clay, can be effectively incorporated to improve BMCs. X-ray Diffraction analysis carried out on treated BMCs showed the development of cementitious minerals (C─S─H, ettringite). Scanning Electron Microscopy with Energy Dispersive Spectrum (EDS) enabled identification of three separate types of microstructural interactions between biochar and soil particles, namely interface cementation, surface deposition and pore space filling by cementitious minerals, all of which are responsible for the enhancement of UCS with curing.

Biochar Sequestration in Lime-Slag Treated Synthetic Soils: A Green Approach to Ground Improvement

This paper describes the strength and microstructural behaviour of lime–slag-treated clay. The microstructure was investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the strength of the treated clay was measured using the unconfined compressive strength (UCS) test. Untreated clay was prepared in the laboratory by mixing commercially available kaolin and bentonite, while hydrated lime and ground granulated blastfurnace slag (ggbs) were used as binders. XRD analyses of lime–slag-treated clay showed the existence of numerous reaction products such as calcium silicate hydrate (C–S–H), calcium aluminium silicate hydrate (C–A–S–H), and hydrotalcite (HT), which facilitated the strength increment. For a fixed proportion of lime, the relative intensity of pozzolanic reaction products was found to increase with increasing slag content. Slag was found to be very active to promote the pozzolonic reaction with lime, as evidenced from the presence of crystalline reticular (C–S–H) and ...

Behaviour of lime - Slag-treated clay

Filtration behaviour of granular soils under cyclic load

In wet conditions, a sub-ballast interface between the ballast and formation soil protects migration of formation soils. reduces track settlement and allows water to drain without excessive pore water pressure development. In a clayey formation, fine mud like slurry is often generated at the formation-sub-ballast interface as water enters into the formation and facilitates upward migration of fines (also known as mud pumping) under the cyclic load. Therefore, providing a sub-ballast interface that satisfies filtration requirements is very important in maintaining an acceptable track condition under the cyclic train loading. Filtration behaviour of sub-ballast materials at various piping ratios and permeability ratios under a cyclic load frequency of 1 to 13Hz were Investigated in the laboratory. Turbidity of the effluent and permeability of the filtration system were measured at different time intervals. Test results showed that an increase in cyclic loading caused an increase in turbidity indicating that migration of formation soils was highly possible. Piping ratio of greater than 9 was found to be unsatisfactory to minimise migration of fines under a cyclic load frequency of 10Hz and pressure of 70-140 kPa.

Towards a better design guideline of sub-ballast materials for filtration purpose under cyclic load

This paper presents the strength, compressibility a nd microstructural behaviour of lime-slag treated C oode Island Silt (CIS). The microstructure was investigated using X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM), while strength and compressibility properties of the trea ted CIS were measured using Unconfined Compressive Strength (UCS) and Oedometer Consolidation tests. Bulk untreated CIS is sampled from an excavation site in Melbourne CBD, while hydrated lime and Ground Granulated Blast Furnace Slag (GGBFS) are used as binders. Results of UCS tes ts on CIS treated with fixed lime and varying slag contents showed an increase in unconfined compressive strength with i ncreasing slag contents and curing periods. The role of lime in th e activation of slag is also seen to have an upper limit whereby excess proportions fail to provide significant additional benefit. Oedometer consolidation test results of tr eated CIS showed an increase in apparent pre-consolidation pressure and decrease in void ratio with an increase in slag co ntent. This is due to the formation of more crystalline cementitious products , which accelerate the cementation effect between l ime-slag and clay particles. XRD analyses of lime-slag treated clay s howed the existence of numerous reaction products s uch as Calcium Hydrate (CH) and Calcium Silicate Hydrate (C-S-H) which facilitates the strength increment. Slag was f ound to be very active in promoting the pozzolanic reaction with li me, as evidenced from the presence of crystalline r eticular cementitious product (C-S-H) in the SEM images.

Ahm Kamruzzaman

Papers

Behaviour of lime - Slag-treated clay

Filtration behaviour of granular soils under cyclic load

Towards a better design guideline of sub-ballast materials for filtration purpose under cyclic load

Strength and compressibility behaviour of lime-slag- treated coode island silt

Towards a Better Design Guideline of Sub-ballast Materials for Filtration Purpose Under Cyclic Load