Abstract
Bioenzymes are organic degradable materials, currently introduced as soil improvement additives. In this experimental study, three types of bioenzymes from three different countries were used to improve Universiti Kebangsaan Malaysia (UKM) soil. UKM soil has properties quite similar to soils recommended as suitable by bioenzyme suppliers. The effect of the three bioenzymes on Atterberg limits, compaction characteristics, and unconfined compressive strength was studied. Controlled untreated and treated samples for two dosages at curing times up to three months were prepared and tested after completion of the curing period. Some results showed little improvement in compaction characteristics, and unconfined compressive strength, but no notable improvement was noticed in Atterberg limits. X-ray diffraction (XRD), X-ray fluorescence (XRF), and field emission scanning electron microscopy (FESEM) tests were conducted for untreated and treated soil samples after two months of curing. XRD and XRF did not show any change in mineralogy and chemical composition between controlled untreated samples and samples treated with the three bioenzymes. However, the FESEM images revealed a denser packing of particles for soil samples treated with two of the bioenzymes.
Highlights
In the construction industry, maintaining a balance between performance and cost, while at the same time satisfying environmental regulations, has become a challenge for building material manufacturers, design engineers, and contractors
A Standard Proctor test was carried out to examine any change in optimum moisture content and maximum dry density with two doses of all three enzymes
The same test was conducted to prepare control untreated soil samples and soil samples treated with two doses of three enzymes for three curing periods (28, 56, and 84 days)
Summary
In the construction industry, maintaining a balance between performance and cost, while at the same time satisfying environmental regulations, has become a challenge for building material manufacturers, design engineers, and contractors. It is claimed by bioenzyme manufacturers that their products are effective, environmentally friendly (nontoxic), cost-effective, and convenient to use They are generally extracted by the fermentation of vegetables and sugar canes; they are degradable; that is, they break down and dissolve with time. Kestler [4] suggested that enzymes are proprietary of their supplier; unless they provide the composition, it is very difficult to determine the precise composition and stabilization mechanism He recommended that some commercial enzymes, for example, Bio Cat 300-1, EMC SQUARED, PermaZyme 11-X, TerraZyme, and UBIX No 0010, should contain protein molecules which react with soil molecules to bind the soil particles together, decreasing the affection of soils for moisture. Enzymes combine with big organic molecules to generate a reactant mediator, which swaps ions with the clay structure and breaks up the clay lattice As a result, this produces a covering effect, which blocks further absorption of water and loss in density. Untreated controlled samples were prepared and cured along with treated samples to account for gain in strength due to aging and moisture loss, if any
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