Stabilized Guabirotuba Silt with waste from cellulose and paper industry

ABSTRACT

The unconfined compressive strength, the splitting tensile strength and the California Bearing Ratio (CBR) were systematically investigated to analyze the performance of a silt soil from the metropolitan region of Curitiba (Brazil) stabilized with cellulose ash and with hydrated dolomitic lime. A series of compaction tests on normal Proctor energy were performed to calculate the optimum compaction parameters of the soil- cellulose ash-lime mixtures: maximum dry unit weight (γ_d-max) and optimum moisture content (ω_o). Four percentages of cellulose ash (5%, 10%, 15% and 20% in relation to the dry mass of the soil) were added and used, and a fixed content of lime (L) of 5% based on the modified initial consumption of lime and established from the interpretation of pH measurements performed on several soil-ash-lime mixtures. The results demonstrate that there is an increase in the optimum moisture content and a decrease in the maximum dry unit weight of the compaction curves with increasing the cellulose ash content. On the other hand, the tests of unconfined compression, splitting tensile and CBR show that there is an increase in the mechanical strength values of the blends up to an optimal content of 15%. In addition, Energy Dispersion Spectroscopy (EDS) made in a prototype blend shows that there was a chemical interaction between soil, lime and the smallest particles of cellulose ash. Finally, dosing equations that allow estimation of the strength values of the blends were developed based on porosity/lime index (η/L_iv) considering the specific gravity and volume of the materials besides the compaction energy.

Keywords
Soil-celulose ash-lime; unconfined compressive strength; split tensile strength; porosity/lime index