Alkali-activated materials

Geopolymer concrete: A review of some recent developments

A review of the multi-component utilisation of coal fly ash

Advances in understanding alkali-activated materials

The development of new, sustainable, low-CO2 construction materials is essential if the global construction industry is to reduce the environmental footprint of its activities, which is incurred particularly through the production of Portland cement. One type of non-Portland cement that is attracting particular attention is based on alkali-aluminosilicate chemistry, including the class of binders that have become known as geopolymers. These materials offer technical properties comparable to those of Portland cement, but with a much lower CO2 footprint and with the potential for performance advantages over traditional cements in certain niche applications. This review discusses the synthesis of alkali-activated binders from blast furnace slag, calcined clay (metakaolin), and fly ash, including analysis of the chemical reaction mechanisms and binder phase assemblages that control the early-age and hardened properties of these materials, in particular initial setting and long-term durability. Perspectives fo...

Geopolymers and Related Alkali-Activated Materials

State-Of-The-Art-Review Of No-Dig Technologies for New Installations

The Trenchless Technology Center, in collaboration with industry associations, has developed comprehensive, yet easy to use interactive software for the evaluation of alternative construction methods that can be employed in the installation and rehabilitation of buried pipes (gravity driven and pressurized) and manhole structures utilized in municipal applications. The decision support software was implemented in an on-line format, so it can be accessed simultaneously by multiple users over the internet via a web-portal named TTWorld. A Social Cost calculator was added to the web-portal to assist users in estimating the social costs associated with the various construction methods. The software is updated regularly to include emerging and evolving technologies and materials, and is available in both, English and Spanish. Future developments will focus on enabling the software to accept input data directly from relational databases associated with commonly used GIS software packages.

TTWorld: A Web-Portal for Assessing the Suitability of Trenchless Construction Methods for Utility Projects and Associated Social Cost Savings

This paper presents an overview of quality management theory and its application in the area of trenchless technology in general, and horizontal directional drilling (HDD) in particular. Current practices that support quality management in the HDD industry are described and are classified using the relevant clauses of ISO 9000. The development of load cell technology aimed at enhancing the quality control/quality assurance (QC/QA) of HDD is then described. Based on load cell data collected during 20 commercial installations, electronic records of installation loads are demonstrated to be a powerful tool for implementing QC/QA programs. The records provide installation rates, the average pull load per unit length of pipe, the maximum load exerted on the pipe, as well as the entire load history of the installation. Radio transmitting capability provides real-time load cell data that can be used to adjust drilling practices to match the level of installation effort to the parameters of the given installation, thereby maximizing productivity. Load cell data are expected to benefit owners, contractors, and consulting engineers.

Real-Time Monitoring for Quality Delivery of Directional Drilling Installations

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.

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

This paper focuses on developing a rapid and cost effective evaluation methodology for the condition assessment of culverts to estimate their remaining service life. Nondestructive inspection methods are selected based on their reliability and effectiveness. A synthesis of current and emerging non-destructive technologies (NDT) for culverts assessment management is presented. The information presented intends to serve as a database for a generalized algorithm for selecting a NDT scheme for condition assessment of culverts and their embedment.

Erez N. Allouche

Papers

State-Of-The-Art-Review Of No-Dig Technologies for New Installations

TTWorld: A Web-Portal for Assessing the Suitability of Trenchless Construction Methods for Utility Projects and Associated Social Cost Savings

Real-Time Monitoring for Quality Delivery of Directional Drilling Installations

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

Evaluation of Non-Destructive Methods for Condition Assessment of Culverts and Their Embedment