Stabilisation of soft soil using binary blending of high calcium fly ash and palm oil fuel ash

Abstract

Lime and/or Ordinary Portland cement (OPC) are the traditional binders used in soft soil 17 stabilisation. However, their manufacture has a negative impact on the environment. This 18 paper reports the results of experimental work for the optimisation of a binary blended 19 cementitious binder (BBCB) using two types of fly ash as an alternative for use in soft soil 20 stabilisation. The optimum content of the high calcium fly ash (HCFA) was initially 21 determined along with the effect of grinding activation on the performance of HCFA. 22 Subsequently, the effect of palm oil fuel ash (POFA) pozzolanic reactivity on the engineering 23 properties of soft soil, stabilised with HCFA, was investigated by producing different binary 24 mixtures of HCFA and POFA. Based on the Atterberg limits and unconfined compressive 25 strength (UCS) tests, the combination of POFA with HCFA results in a considerably lower 26 plasticity index (PI) and higher compressive strength than those obtained from the soil treated 27 with HCFA alone. Substantial changes in the microstructure and binders of the stabilised soil 28 over curing time were evidenced by SEM imaging and XRD analysis. A solid and coherent 29 *Revised manuscript with no changes marked Click here to view linked References structure was achieved after treatment with BBCB as evidenced by the formation of C-S-H, 30 portlandite and ettringite as well as secondary calcite.

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

“…This leads to a successful hydration reaction, transforming the calcium hydroxide of HCFA into calcium silicate hydrate (C-S-H) [15,61]. This gel tends to fill pores and grow into capillary spaces, resulting in a more impermeable, dense and higher-strength structure [61][62][63]. It can be seen from Fig.…”

“…of HCFA, which enhanced the dissolution of the glassy phases of GGBS producing additional C-S-H gel [14,61,62]. This leads to a successful hydration reaction, transforming the calcium hydroxide of HCFA into calcium silicate hydrate (C-S-H) [15,61].…”

“…of HCFA, which enhanced the dissolution of the glassy phases of GGBS producing additional C-S-H gel [14,61,62]. This leads to a successful hydration reaction, transforming the calcium hydroxide of HCFA into calcium silicate hydrate (C-S-H) [15,61]. This gel tends to fill pores and grow into capillary spaces, resulting in a more impermeable, dense and higher-strength structure [61][62][63].…”

Future of clay-based construction materials – A review

“…This was due to the chemical reaction occurring between the CaO from the cement, lime and other stabilisers and amorphous silica provided by clay together with the high alkalinity environment of cement or lime [37,39,45,46]. These gels tend to fill pores and grow into capillary spaces, resulting in a more impermeable, dense and higher-strength structure [48,49]. However, high dosage of stabiliser with high CaO content might negatively affect the performance of the product because this might resulted in free CaO that could lead to expansion and cracks in the final product [9].…”

Experimental Research on Resilient Modulus of Silty Clay Modified by Oil Shale Ash and Fly Ash after Freeze-Thaw Cycles

“…In fact, the great engineering property of OSA-stabilized soils is mainly attributed to the cementing property of OSA [10,12,13]. It has been revealed in previous literature that the combination of fuel ash waste and FA as additives has a significant effect on soil stabilization [14,15]. However, research on the application of soils stabilized by both OSA and FA is scarce, especially on the dynamic resilient modulus of the modified soil.…”