Showing papers by "Erez N. Allouche published in 2012"

Evaluation of the potential of geopolymer mortar in the rehabilitation of buried infrastructure

Abstract: Concrete pipes represent the backbone of the wastewater collection systems in many cities across North America. These pipes are in various stages of deterioration, generally due to microbiological induced corrosion and/or mechanical loading. A common method of rehabilitating these structures is the use of cementitious coatings. This paper describes the development and testing of three novel geopolymer mix designs prepared using metakaolin and fly ash (class C and F) precursors. Specimens prepared using Portland cement-silica fume blend were also tested for comparison purposes. The specimens were placed in several concentrations of sulphuric acid for a period of eight weeks. The corrosion resistance and remaining compressive strength of geopolymer mortar made from class F fly ash precursor were found to be substantially higher compared with the enhanced OPC formulation. The other geopolymer mix designs were found to perform equally or better compared with the OPC binary blend.

Rheological behavior of fly ash-based geopolymers with the addition of superplasticizers

Abstract: Geopolymers are novel cementitious binders that are finding new industrial applications every day. One of the most important aspects for the commercialization of these products is their behavior in plastic state. The workability of fresh geopolymer paste can be measured with several common tests used for Portland cement concrete, like flow and slump; however, a more in-depth characterization of their rheology is essential to understand its basic setting mechanisms. In this article, the rheological behavior of geopolymer paste prepared under different mix design formulations is studied. Special consideration is given to the rheological behavior of geopolymer paste under the action of a superplasticizer. The effect of the superplasticizers on the viscosity of fresh geopolymers was evaluated and recommendations about the use of these additives are provided.

Incinerator fly ash geopolymer and method

Abstract: A geopolymer concrete formed by mixing about 3% to about 43% by weight incinerator fly ash, about 3% to about 35% by weight coal fly ash, about 7% to about 38% by weight alkaline activator liquid, and about 31% to about 70% by weight aggregate. The incinerator fly ash may be derived from a solid waste incinerator facility. The alkaline activator liquid may include a sodium hydroxide solution and sodium silicate. The aggregate may include a fine aggregate, such as sand, and a coarse aggregate, such as gravel.

Fully Automated Decision Support System for Assessing the Suitability of Trenchless Technologies

Abstract: Decisions related to the rehabilitation of wastewater and water infrastructure are increasingly more complicated as the number and complexity of technologies in the marketplace increases. Established methods, such as cured-in-place pipe (CIPP), are constantly evolving, and new techniques continue to be developed in North America and abroad. The need to assess the suitability of these constantly changing technologies creates the need for a resource capable of evaluation and selection of appropriate methods through a Web-based source that can be kept up to date. To meet that need, the Trenchless Technology Center (TTC), in collaboration with the National Utility Contractors Association (NUCA), Australasian Society of Trenchless Technology (ASTT), and National Association of Sewer Service Companies (NASSCO), through multiple research initiatives, has developed a comprehensive and interactive software for the evaluation of more than 70 technologies that can be employed in the installation, replacement...

Influence of Activator Solution Formulation on Fresh and Hardened Properties of Low-Calcium Fly Ash Geopolymer Concrete

Abstract: The effect of the composition of activator solutions on fresh and hardened properties of geopolymer concrete was investigated. Research variables included liquid sodium silicate product (DH, NH, and StarH), sodium hydroxide molar concentration (6, 10, and 14), and sodium silicate–to–sodium hydroxide ratio (1, 2, and 3). Response variables were compressive strength, corrosion resistance expressed as remaining compressive strength and mass loss, and flowability. Results were analyzed using Minitab statistical software. Findings suggest that activator solution formulation has a significant effect on the properties of the resulting geopolymer binder. The experimental design used was found effective in establishing the optimum activator solution formulation for a given fly ash stockpile to be used for an application with specific performance requirements. f 2012 The University of Kentucky Center for Applied Energy Research and the American Coal Ash Association All rights reserved. A R T I C L E I N F O Article history: Received 20 September 2011; Received in revised form 6 January 2012; Accepted 9 January 2012

Sensor fusion framework using multiple sensors to assess buried structures

Abstract: A method of surveying the condition of an underground conduit by positioning a propelled carriage assembly within the underground conduit. The carriage assembly includes (i) at least one transmitter/receiver unit capable of transmitting a pulsed signal toward at least a portion of an inner wall of the conduit, and (ii) a secondary sensor positioned on the carriage assembly. The data derived from the pulsed signal at a given lateral location within an underground conduit is read as is a secondary sensor condition derived from secondary sensor data taken at the given lateral location. Then it is determined whether the secondary sensor condition indicates a basis for a false void detection by the data derived from the pulsed signal and if the basis for false void detection exists, providing an indication of such basis.

Experimental examination of selected limit states of structural liners at locations of ring fracture

Abstract: While designing rehabilitation solution for deteriorated pressurized potable water mains, presence discontinuities in the pipe’s walls must be considered. This experimental work involves investigation of three limit states e.g. flexure, shear and axial that could cause liner instability as a result of internal water pressure and uneven ground movement at a broken location e.g. ring fracture - frequently found in small diameter cast iron pipes suffering from loss of beam support. It is reasonable to assume that natural settlement of the bedding materials has long been completed for pipes that have been buried for many years. Therefore, the differential ground movements induced by frost, moisture changes in ‘reactive’ clays or a nearby excavation causes a transverse fracture on the brittle cast iron pipes. The liner product needs to be able to accommodate such movements, which tend to take the form of flexure, shear or axial displacement. Six testing specimens were prepared (each comprised of two 4 ft long sections of a 70-year old 6 in. ID cast iron pipe) by forming a simulated transverse ring break at their lengthwise middle point and then lining them with a fiber reinforced CIPP liner. For pressurized condition test, three specimens were capped and subjected to three-point flexural, pull, and shear loading using custom-built testing apparatus. In the non-pressurized condition similar steps were followed except the caps were hollow. The behavior of the pipe and the liner was monitored with increased deflection, and geometrical changes in the liners were noted. Strain and stress measurements in the axial and hoop directions within the liner structure at the location of the ring failure were also monitored. Conclusions were made regarding governing failure mechanisms for fiber-reinforced CIPP liners subjected to angular and axial displacement.

Decision Support System for Lateral Pipe Rehabilitation: Case Study Analysis

Abstract: Laterals, connecting between the mainline sewer and individual households, have long been considered as a great source of infiltration and inflow (I/I) to municipal wastewater networks. This paper discusses decision support system focusing on a case study database that provides guidelines for the selection of technically viable and cost-effective lateral rehabilitation methods. The objective of this study was to find (1) how a case study database can be utilized to combine a list of parameters regarding lateral rehabilitation, (2) what is the average cost per linear foot per inch diameter ($/lf-in) for lateral rehabilitation, and (3) what are the most popular rehabilitation methods as well as host pipe materials. In order to accomplish these objectives, a questionnaire-based survey was conducted with municipalities and consulting companies across the USA, Canada, and Europe. Based on the data collected from survey and literature study, a list of 34 lateral rehabilitation case studies was summarized in a project database. The typical range of maximum and minimum values were presented for parameters such as lateral diameter, rehabilitated length, duration, and cost per linear foot per inch diameter ($/lf-in) of rehabilitation. It was computed that the average cost per linear foot-inch diameter for lateral rehabilitation methods using CIPP relining, pipe bursting, and flood grouting was about $20, $12, and $8 respectively. Furthermore, the most popular methods of sewer laterals renewal were CIPP relining and pipe bursting. Finally, it was observed that the most common lateral host pipe material was vitrified clay pipe (VCP).

Beam steerable UWB radar

Abstract: An adaptive UWB radar front-end that can a) automatically tune the pulse width for target type and depth; b) automatically sweep specific area by controlling the timing (delay); and, c) for each steering direction, it can automatically adjusts the power distribution for improving radiation pattern and thus improving signal quality for clutter free imaging

Universal impedence probe for detection of side-connections through thermoplastic, thermosetting and cementitious liners

Abstract: A conduit survey apparatus having a carriage capable of movement axially down a conduit. The carrier includes a radio frequency (RF) signal generator and an RF signal detector positioned on the carriage along with a controller controlling the signal generator and signal detector. The carrier further includes a waveguide with an open throat transmitting signals from the signal generator and directing received signals to the signal detector. Finally, the carrier includes a waveguide positioner mounted on the carrier and adapted to selectively engage an interior wall of the conduit, wherein the waveguide guide is connected to the positioner such that the open throat of the waveguide is within about 1 inch of the interior wall when the positioner engages the interior wall.

Estimating residual strength of deteriorated 96" interceptor and strength enhancement provided by lining methods using computer modeling and forensic investigation tools

Abstract: In 1985¸ the Trinity River Authority of Texas (TRA) completed the construction of Elm Fork Relief Interceptor Segment 1-Aconsisting of 17,200 linear ft of a 96-in. diameter reinforced concrete pipe. A 1999 investigation revealed significant wall losses triggering the installation of a parallel 104-in. pipeline of similar capacity in 2007. In 2008 Espey Consultants were retained by TRA to evaluate different avenues for restoring the structural integrity and functionality of the original pipeline. Their investigation revealed that up to 30% of the wall thickness had been lost to corrosion for the majority of the length of the pipeline, and in some limited sections even greater wall loss, mainly in the crown region. The severe degree of corrosion demonstrated partially deteriorated and limited fully deteriorated pipe condition; however, completely neglecting the contribution of the host pipe resulted in a wall thickness that was likely to compromise the required hydraulic capacity. In an attempt to estimate the remaining structural capacity of the pipe, an extensive forensic engineering investigation was undertaken consisting of mechanical and chemical testing of physical cores taken from the pipe in 1999. Information from laboratory testsalong with information from a laser profiler study of the pipe's inner geometrygeotechnical information, ground and surface water loads, and data regarding original design parameters were used to construct a detailed 3-D finite element (FE) model of the in-situ pipe. Structural enhancement provided by two common rehabilitation methods, CIPP and GIPP, was superimposed on the FE model. An extensive parametric study was undertaken to gain insight as to possible contribution of the host pipe in resisting the various external loads and the anticipated structural capacity of the rehabilitated structure.