Development of a new ternary blended cementitious binder produced from waste materials for use in soft soil stabilisation

Abstract

Soil stabilisation using traditional binders such as Ordinary Portland Cement (OPC), has a serious negative environmental impact, specifically carbon dioxide (CO 2) emissions as a result of the manufacture of OPC. Because of this, the use of sustainable binders has become a critical issue to help reduce cement production through the use of by-product materials. This research seeks to develop a new ternary blended cementitious binder (TBCB) to replace cement for soft soil stabilisation. Different ternary mixtures containing wastes i.e., high calcium fly ash (HCFA), palm oil fuel ash (POFA) and rice husk ash (RHA) along with flue gas desulphurisation (FGD) gypsum used as a sulphate activator and grinding agent, were examined. The results illustrate that ternary mixtures improved the engineering and mechanical properties of stabilised soil. The results indicated that the plasticity index (PI) was reduced ACCEPTED MANUSCRIPT from 20.2 to 13.0 and the unconfined compressive strength (UCS) increased after 28 days of curing from 202kPa to 944kPa using the optimum non-FGD activated mixture. FGD contributed significantly by increasing the UCS to 1464kPa at 180 days of curing, which surpassed that for the reference cement (1450kPa), and by improving the soil consistency limits; where the PI decreased to 11.7 using TBCB compared with 14.5 for the soil treated with the reference cement. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis revealed substantial changes in the diffraction patterns and microstructure components of the TBCB paste over the curing period, confirming the formation of cementitious products. A solid, coherent and compacted structure was achieved after treatment with TBCB as evidenced by the formation of C-S-H, CH and ettringite.

The development of a low carbon binder produced from the ternary blending of cement, ground granulated blast furnace slag and high calcium fly ash: An experimental and statistical approach

“…From Table 2, it can be seen that the amount of CaO, SiO2 and Al2O3 in the HCFA exceeds that in the OPC. The chemical composition of the HCFA in this study are consistent with those of Dulaimi et al [41] and Jafer et al [30]. GGBS has significant proportions of most principle oxides (CaO, SiO2, MgO and Al2O3) and its (CaO+MgO)/SiO2 is greater than 1.0, which meets BS EN 197-1:2000 requirements for granulated blast furnace slag [42].…”

“…In contrast, HCFA has larger particles relative to OPC, which could retard the performance of the mortars during hydration reactivity [30]. These results are in agreement with the findings obtained by Jafer et al [30] and Dulaimi et al [31] The elemental composition of OPC, GGBS and HCFA was analysed by an Energy Dispersive X-ray Florescence Spectrometer (EDXRF) type Shimadzu EDX-720. This test identifies the major oxide and trace elements in raw materials by breaking down the chemical composition.…”

“…HCFA is classified as fly ash class C. It has some self-cementing properties attributed to a high proportion of free lime, in addition to its pozzolanic properties [28,29]. HCFA has been used by the authors in the production of binary and ternary blended binders as an alternative to cement in different applications [15,30,31].…”

“…NaOH. Jafer et al [30] found that the ternary blending of HCFA, palm oil fuel ash (POFA) and rice husk ash (RHA) can be used as a cement replacement in the stabilisation of soft soil giving a superior performance to that of OPC. The efficacy of HCFA in road construction has been evidenced by Dulaimi et al [31] who established that the combination of 4.5% HCFA with 1.5% fluid catalytic cracking catalyst (FC3R), improved the stiffness modulus by around 9% in comparison to a mixture treated with OPC alone.…”

The recycling and reuse of steelmaking slags — A review

“…Researchers began to look at if the slag could be used as a soil stabilization material because of its successful use as a fertilizer (Jafer et al, 2018). Soil stabilizers are used to enhance the physical properties of soft soils that are not considered very useful due to their low compressive strength.…”