دانلود رایگان ترجمه مقاله تقویت خاک باقی مانده کره با بیوپلیمر β-1،3/1، 6-گلوکان (نشریه الزویر 2012)

تقویت خاک باقی مانده کره با بیوپلیمر β-1،3/1، 6-گلوکان

Strengthening of Korean residual soil with b-1,3/1,6-glucan biopolymer

Abstract

Soil improvement and stabilization are important geotechnical issues when using soil as an engineering material. The most widely used material for soil treatment is cement, a trend that runs counter to environmentally friendly practice. In food and medical science, various biopolymers are commonly used as thickeners, stabilizers, binders, and so on. This study explores the feasibility of using environmentally friendly biopolymers for soil improvement. A commercial β-1,3/1,6-glucan polymer product was used to improve the strength of the Korean residual soil, hwangtoh. Liquid type β-1,3/1,6-glucan polymer solutions with different concentrations were mixed with hwangtoh and cured under different temperatures. The time-dependent compressive strength was measured in order to observe the strengthening mechanism of the β-1,3/1,6-glucan polymer-treated hwangtoh. The particle surface adsorption and tensile strength of the β-1,3/1,6-glucan polymers significantly increased the compressive strength of the hwangtoh. The strength improvement was maximized under a curing temperature of 60 °C. Furthermore, a simple economic/environmental analysis revealed that the β-1,3/1,6-glucan polymer treatment had advantages not only in strengthening the hwangtoh but also in lowering its environmental impact while offering financial competitiveness over ordinary cement treatments.

1 Introduction

Soil treatment (i.e. improvement and stabilization) has always been an important consideration throughout the history of human civilization. Various materials such as straw, bitumen, lime, salts, and pozzolans are conventional additions to soil, while cement, petrochemicals, and bacteria are currently being increasingly used in an effort to improve and stabilize soil from both mechanical and chemical aspects [1,2]. Among these, cement is the most widely used material for soil treatment in relation to soil strength improvement, ground water control, and hazardous contaminant fixes [3–6].

Ordinary cement production emits carbon dioxide, a significant greenhouse gas, during chemical calcination and fuel burning. It has been reported that 5% of the global carbon dioxide emissions are induced by the cement industries [7,8]. Meanwhile, the large amount of cement demolition waste (65 million tons/year in the United States [9]) also presents significant environmental problems. Both the disuse and recycling of cement-concrete waste are potentially hazardous to the environment due to the potential for pollutant leakage into the soil and groundwater [10,11]. Meanwhile, several alternatives such as geopolymers [12], alkaliactivated cement [13], geocement [14], and inorganic polymer concrete [15] have been developed in an attempt to reduce or replace cement use. However, the CO2 reduction efficiency of these methods is insufficient due to their dependency on ordinary cement and heavy industry by-products (e.g. blast furnace slag, fly ash, etc.). Therefore, demand for the development of environmentally friendly construction materials that are relatively harmless and easily reused without environmental impacts is increasing significantly in the 21st century.

Biopolymers are polymers produced by living organisms, and most biopolymer applications are in the field of medical engineering, such as drug delivery systems, wound healing, and surgical implantations [16]. With the aim of environmentally friendly development, biopolymers such as welan gum and curdlan have been used as bio-admixtures in concrete or dry-mix mortar as water-retention agents or superplasticizers according to their pseudoplasticity properties [17]. In the fields of soil science, geotechnical engineering, and geoenvironmental engineering, biopolymers have been applied as soil stabilizers in order to control or reduce soil erosion [18,19] and are used for soil drilling mud and temporary excavation supports [20]. Aligning with this trend, theoretical and experimental verifications of the interactions between various types of biopolymers and soil media are required in the geotechnical and geoenvironmental fields.

Hwangtoh is a common residual soil in Korea and is considered to be an environmentally friendly material due to its high absorbency, self-purification, and far infrared ray radiation characteristics [21]. However, its strength and drying shrinkage problems have restricted its usage and development [22]. Thus, an environmentally friendly approach to strengthening hwangtoh is required in order to amplify its benefits and usage.

In this study, a commercial beta-1,3/1,6-glucan polymer solution (Polycan™) is introduced as a soil-treatment material. The inter-particle behavior of the b-1,3/1,6-glucan polymer and particulate material is defined. Also, the structural and engineering behavior of the b-1,3/1,6-glucan polymer-treated hwangtoh is investigated through a series of laboratory experiments. Finally, the optimized conditions for the hwangtoh engineered using the b-1,3/1,6-glucan polymer are discussed in terms of efficiency and feasibility.