Geopolymer Laboratory - Research Projects

Evaluation of a geopolymer grout using fly ash activated with a sodium hydroxide solution.

Abstract

High performance geopolymer materials have been evaluated numerous times displaying outstanding results in physical and chemical properties, overcoming Portland cement-based binders' performance. However, Geopolymer binders can be used in a wide range of applications, and be focused in other characteristics such as flowability and setting time but always trying to find the best balance between all properties. The present paper will study and evaluate geopolymer properties such as flowability, setting time and compressive strength and their interaction with following factors: age, water/binder ratio, cement content, curing temperature, sodium hydroxide concentration and sand content. Compressive strength values up to 7000 psi with good flowability and setting times from 1 to 8 hours were obtained; very interesting tendencies in the responses when varying the factors were also noticed.

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Last update: May 22, 2008

Use of geopolymer cement as a high performance sewer pipeline coating

Objectives

Main objective: Determine geopolymer's suitability as a sewer pipeline coating given geopolymer's remarkable properties over cementitious products.

Specific objectives:

1. Experimental evaluation of geopolymer's properties:

Mortar and concrete compressive strength (1, 3, 7 and 28 days).
Concrete flexural strength (1, 7, 28 days).
Sulfuric and other acids corrosion resistance. The main response variables are: mass loss, resistance loss and expansion percentage.

2. Experimental evaluation of geopolymer cement coatings:

Sulfuric and other acids corrosion resistance. The main response variables are: mass loss, resistance loss and expansion percentage.
Biogenic corrosion tests. The response variables are the same as for the sulfuric acid test, with the exception that in this case the attack is performed by sulfuric acid excreting bacteria.
Wear resistance (loss of mass). It is important to determine the average deterioration that the coating is likely to suffer under the force of a water or sewage stream.
Bond strength (loss of adhesion) with respect to substrate in both new and degraded conditions. This is a key characteristic in order to retain the materials protection for the base concrete.

3. Field tests:

Part III will be devoted to the field tests of the geopolymer as a sewer coating. Even though laboratory tests produce very valuable information about the main variables affecting the material's behavior, the most important tests for every novel product will always be the field tests. They provide a real-life environment where unrestrained variables or their combination may produce effects that are not seen during lab tests.

Development Of A Polymer-Geopolymer Composite With High Cross-Bending Strength And High Durability

Objective

The main objective of this research will be to evaluate different polymers (individually and as blends) in combination with geopolymer binders and obtain an optimum formulation to be used in foundations for seismic areas and the restoration of historical monuments. A comprehensive experimental study will be undertaken to develop polymer-geopolymer composite mixtures with high flexural and compressive strengths. Selected mixtures will be subjected to 12 months of acid and sulfate resistance tests to evaluate the chemical resistance and durability. Dynamic load tests will be conducted on bench-scale and half-scale specimens to confirm their structural behavior. During the development of this study 3 articles will be published in prestigious peer-review scientific journals. It is proposed that the performance of a polymer-geopolymer, a steel-reinforced polymer and steel-reinforced concrete be compared using static and dynamic loading .

Importance of the study

The objective of most of modern construction codes in seismic areas is to avoid collapse, accepting damage, when structures are exposed to an exceptionally severe seism that might take place during its lifetime and avoid damages of any kind in the presence of moderate earthquakes that have a significant probability of occurrence during this time. Meeting these requirements, in simple terms, implies that the structure possesses an adequate rigidity to limit lateral displacements and to provide dynamic characteristics that avoid excessive amplification of vibrations; a sufficient resistance to lateral loads to absorb forces induced by vibrations; and high energy absorbance provided by inelastic deformations, which provides ductility. The availability of low cost material with high chemical resistance, high mechanical strength and superior performance under seismic loadings that provides the required rigidity, resistance and ductility to meet the objectives of seismic area construction codes could find many applications in Mexico 's construction industry. Considering that reinforced concrete gets its ductility from the steel contained in it and that a polymer-geopolymer composite already has a certain ductility by itself, a design of reinforced polymer-geopolymer concrete would need significantly less steel, resultant in the reduction of construction costs.

The proposed study will advance the development of geopolymer cements, a new low cost and environmentally friendly cementitious binder with superior chemical and mechanical performance, which utilizes by-products as its main constitute. Specifically, a special sub-class of polymers-geopolymer materials with high flexural strength and ductile behavior will be developed and characterized. The applicability of this innovative material to the construction of foundations for buildings and transportation infrastructure in seismic areas and the restoration of historical monuments will be evaluated experimentally.

Correlation between Chemical Composition of Fly Ash Stockpiles and their Suitability for Geopolymer Related Construction Products

Abstract

The US produces 60 million tons of fly ash a year as a bi-product of energy production and other industrial activities. The annual production rates of fly-ash in India and China are estimated at 120 and 200 million tons, respectively, with global production exceeding 850 million tons. The vast majority of the fly ash produced around the world is placed in landfills, at significant cost, posing potential risk to ground water due to the presence of heavy metals and other contaminants. Thus, the development of geopolymer concrete technology could contribute to reducing the level of CO 2 emission with no economic sacrifices, while at the same time converting a potentially hazardous bi-product to a valuable construction material. An added benefit is the conservation of valuable landfill space. Many operators of coal-burning operations are interested in converting their costly-to-dispose fly-ash bi-product to a revenue generating commodity. The main obstacle is the extent and cost of pre-treatment needed to covert the fly ash of a given composition to geopolymer-grade raw material. The paper presents the results of chemical analyses and particle size distribution of five sources of fly ash obtained from co-generation plants in the Gulf coast area. Specimens were prepared from each stock pile using a mix design formulation determined to be effective from previous studies. The specimens were subjected to an array of mechanical tests including workability/setting time, compression strength, tensile strength, elastic modulus and shear modulus. A correlation study was undertaken comparing the chemical composition and fly ash particle size distribution with the mechanical characteristics of the resulting geopolymer concrete. Based on the analysis guidelines are provided to fly ash producers as to the suitability of their bi-product as raw material for three grades of geopolymer concrete, namely: a) structural applications; b) semi-structural applications; and, c) non-structural applications.

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