This report includes the findings of acoustic emission (AE) tests on the Fremont tied arch bridge in Portland Oregon conducted by research engineers from the Infrastructure Technology Institute of Northwestern University on March 24th, 1997.
A remote global monitoring system is being operated on a 65 year old lift bridge in Sturgeon Bay Wisconsin. The system uses both strain gages and clinometers to continuously monitor the "health" of the fracture critical components of the bridge. Ruggedized miniaturized data loggers are locally mounted on the structure...
This technical report shows the findings of acoustic emission and strain gage monitoring tests conducted by research engineers of Infrastructure Technology Institute from Northwestern University on April 18, 1997 in Sacramento, California.
Non-destructive evaluation (NDE) techniques have been used for a number of years to provide quality control of construction procedures for drilled shafts and driven concrete piles. In particular sonic echo and impulse response methods have been used extensively to check lengths and continuity of newly-installed foundations. In recent years, the...
Carbonation, a neutralizing reaction in cement paste, can be used to date cracks in cementitious materials. Currently, comparison between two cracks is the only method available to predict a relative age with carbonation. These two crack studies require a crack of known age in a similar material with similar exposure...
A study is conducted to determine the effects on the early hydration kinetics and
compressive strength by seeding of Portland cement and alkali-activated blast furnace
slag with a pure form of calcium silicate hydrate (C-S-H). The effects of C-S-H seeding
during the early nucleation and growth period of each type...
The gradual evolution of the material properties of a cement-based material, i.e. the stiffness of cement paste, is the result of the continuous change of the microstructure with the progress of the hydration process. Based on an existing micromechanical model for the simulation of the shear and elastic modulus of...
In this paper, the correlation of reflection loss measured by an ultrasonic shear wave reflection
method and the microstructure in cement-based material is investigated. Three cement pastes
(Portland cement type I) with different water-cement ratios (0.35, 0.50 and 0.60) cured at 25
°C were examined. The ultrasonic shear wave reflection...
This presentation contains information about the project "The future of transportation... and how we'll pay for it" by Joseph L. Schofer, Department f Civil & Environmental Engineering. The presentation was delivered at the 40th Anniversary Seminar Day at Northwestern University on April 18, 2009.
Few would argue that concrete is an important and useful material: after all, concrete is the backbone of the world’s infrastructure, used in vast amounts to make roads, buildings, bridges, and other structures. But sometimes familiarity breeds contempt. To most people, concrete is simply that boring grey stuff that we...