Soil Stabilization Using Waste Paper Fly Ash: Precautions for Its Correct Use

Abstract

This paper deals with the valorization of waste paper fly ash (WPFA) as a binder for soil stabilization. The mineralogical characterization shows the presence of free lime, as well as some non-reactive and cementitious phases. The hydration of lime is an expansive reaction and can be problematic in soil stabilization. Therefore, to study its effect on stabilized soil, an in-house experimental set-up is proposed to measure the possible expansion. Furthermore, to study the effect of water reduction and delay time on strength, unconfined compressive strength with different mixes is conducted. The obtained results showed that using WPFA causes expansion in stabilized soil, but a delay time of 30 min, after mixing the material with water and then compacting it, can decrease the expansion. Additionally, decreasing the water content by a point of Proctor can be essential for improving the strength in soil samples, even reaching the same strength values as control samples cured at 7 days. Finally, all the results obtained in this study have shown that WPFA is a suitable material for use as a binder for soil stabilization while reducing its optimum water content, adding a proper delay time, and taking into consideration WPFA’s expansive behavior at the moment of its use.

Potential of Soil Stabilization Using Ground Granulated Blast Furnace Slag (GGBFS) and Fly Ash via Geopolymerization Method: A Review

“…Fly ash is a material that is increasingly being used as a cement alternative in concrete mixtures and for soil stabilization [ 25 , 27 , 29 , 36 , 38 , 40 , 42 , 54 ]. The addition of fly ash is one of the methods to stabilize soil because fly ash is a pozzolan, in which it can bind to minerals in soil and make the soil stable, so as to reduce the swell shrinkage of the soil and improve soil strength [ 41 , 42 , 44 , 46 , 54 , 69 , 70 , 71 , 72 , 73 ].…”

“…It entails compacting the soil in order to change its resistance, compressibility, permeability, and porosity [ 27 , 28 ]. Mechanical stabilization of a material is typically accomplished by adding another substance, which is fly ash or GGBFS, that enhances the grading or reduces the plasticity of the original material [ 28 , 29 , 30 ]. The original material’s physical qualities will be altered, but no chemical reaction will occur [ 26 , 31 ].…”

“…However, the redistribution of the particles changes the structure [ 27 , 31 ]. Mechanical stabilization is frequently the most cost-effective method of enhancing the quality of low-grade materials (problematic soil) [ 26 , 27 , 29 , 33 ]. The stiffness and strength of the material will typically be less than those obtained through chemical stabilization and will frequently be unsuitable for heavy traffic pavements [ 33 , 34 , 35 ].…”

Long-Term Comparison between Waste Paper Fly Ash and Traditional Binder as Hydraulic Road Binder Exposed to Sulfate Concentrations

“…A precise displacement device was used to measure the swelling/shrinkage in the soil samples as described in previous work [ 36 ].…”

Using Wastepaper Sludge Ash (Wsa) as a Material for Soil Strengthening for the Construction of Layers of Pavement

“…Authors (Khalid, 2012) have discovered, that clay soil stabilized using 10 % WSA considered effective to enhance clay soil strength for long periods and to enhance the CBR value. Other research results (Baloochi, 2020) have shown that use of wastepaper fly ash as a main binder is well suited for soil stabilization, although care should be taken to avoid possible soil expansion.…”