The objective of this program is to measure the changes in the properties of the C-S-H gel phase in cement paste as a function of the Ca/Si ratio. The motivation is to better understand the hydration products that form in blended cements with lower Ca/Si ratios than portland cement. The...
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...
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...
During the past several years an easily weldable, high strength (more than 75 ksi yield), high impact fracture toughness steel (NUCu steel) has been investigated at Northwestern University with bridge applications in mind. For good weldability without pre-heating and post-heating, the carbon content of the steel was kept low and...
Northwestern University developed copper-precipitation-hardened, high-performance weathering steel (NUCu 70W Steel) that is produced by hot rolling after casting and then air-cooling. Due to simple processing the steel is fabricated at lower cost than competing high-performance steels that require quench and tempering. NUCu 70W steel can be easily welded without pre-...
Construction is omnipresent in modern-day America. It's the sound and vibration of a nation scrambling to keep up with its burgeoning population. In most states, allowable construction-induced ground motions range from 0.5 to 1.0 inches per second (in/sec) and under certain
conditions up to 2.0 in/sec.
However, ground motion as...
In early 2001, a sinkhole formed directly under State Road 66 near the city of Sebring in Highlands County, Florida. The Florida DOT built a land bridge over the sinkhole and the road was reopened to traffic. Since SR-66 is an important regional trucking route, it was decided that the...
Cosmetic and structural cracks are a large concern for homeowners. Although these cracks can develop from a variety of causes: differential foundation settlement, occupant activity, climatological effects, as well as dynamic events, people tend to look to dynamic events like blasting, construction, or traffic vibrations to be the culprit. This...
The notion of blasting, even in a controlled setting such as a limestone quarry, can be alarming to residents and business owners within earshot. Because humans are inherently sensitive to blast-induced vibrations, they perceive that the structures in which they live in are equally sensitive. The goal of this project...