Structural Characterization of UHPC Waffle Bridge Deck and Connections, TR-614, 2014

The AASHTO strategic plan in 2005 for bridge engineering identified extending the service life of bridges and accelerating bridge construction as two of the grand challenges in bridge engineering. These challenges have the objective of producing safer and more economical bridges at a faster rate with a minimum service life of 75 years and reduced maintenance cost to serve the country’s infrastructure needs. Previous studies have shown that a prefabricated full-depth precast concrete deck system is an innovative technique that accelerates the rehabilitation process of a bridge deck, extending its service life with reduced user delays and community disruptions and lowering its life-cycle costs. Previous use of ultra-high performance concrete (UHPC) for bridge applications in the United States has been considered to be efficient and economical because of its superior structural characteristics and durability properties. Full-depth UHPC waffle deck panel systems have been developed over the past three years in Europe and the United States. Subsequently, a single span, 60-ft long and 33-ft wide prototype bridge with full-depth prefabricated UHPC waffle deck panels has been designed and built for a replacement bridge in Wapello County, Iowa. The structural performance characteristics and the constructability of the UHPC waffle deck system and its critical connections were studied through an experimental program at the structural laboratory of Iowa State University (ISU). Two prefabricated full-depth UHPC waffle deck (8 feet by 9 feet 9 inches by 8 inches) panels were connected to 24-ft long precast girders, and the system was tested under service, fatigue, overload, and ultimate loads. Three months after the completion of the bridge with waffle deck system, it was load tested under live loads in February 2012. The measured strain and deflection values were within the acceptable limits, validating the structural performance of the bridge deck. Based on the laboratory test results, observations, field testing of the prototype bridge, and experience gained from the sequence of construction events such as panel fabrication and casting of transverse and longitudinal joints, a prefabricated UHPC waffle deck system is found to be a viable option to achieve the goals of the AASHTO strategic plan.

Chronic Disease Connections, December 2014

IDPH has a new grant-funded program, the Health Promotion and Chronic Disease Control Partnership. This publication, Chronic Disease Connections, will be part of the communication strategy between IDPH staff and healthcare system providers throughout the state as we partner to help patients control their diabetes and high blood pressure. This is just one of the major objectives for the funding. The CDC would like to see that more patients are aware that they have pre-diabetes, diabetes or high blood pressure and that health systems are maximizing evidence-based strategies to assist patients with achieving control. Over the coming months you will hear more about the new program and how you can become involved.

Chronic Disease Connections, January 2015

IDPH has a new grant-funded program, the Health Promotion and Chronic Disease Control Partnership. This publication, Chronic Disease Connections, will be part of the communication strategy between IDPH staff and healthcare system providers throughout the state as we partner to help patients control their diabetes and high blood pressure. This is just one of the major objectives for the funding. The CDC would like to see that more patients are aware that they have pre-diabetes, diabetes or high blood pressure and that health systems are maximizing evidence-based strategies to assist patients with achieving control. Over the coming months you will hear more about the new program and how you can become involved.

Chronic Disease Connections, February 2015

IDPH has a new grant-funded program, the Health Promotion and Chronic Disease Control Partnership. This publication, Chronic Disease Connections, will be part of the communication strategy between IDPH staff and healthcare system providers throughout the state as we partner to help patients control their diabetes and high blood pressure. This is just one of the major objectives for the funding. The CDC would like to see that more patients are aware that they have pre-diabetes, diabetes or high blood pressure and that health systems are maximizing evidence-based strategies to assist patients with achieving control. Over the coming months you will hear more about the new program and how you can become involved.

Chronic Disease Connections, March 2015

IDPH has a new grant-funded program, the Health Promotion and Chronic Disease Control Partnership. This publication, Chronic Disease Connections, will be part of the communication strategy between IDPH staff and healthcare system providers throughout the state as we partner to help patients control their diabetes and high blood pressure. This is just one of the major objectives for the funding. The CDC would like to see that more patients are aware that they have pre-diabetes, diabetes or high blood pressure and that health systems are maximizing evidence-based strategies to assist patients with achieving control. Over the coming months you will hear more about the new program and how you can become involved.

Chronic Disease Connections, April 2015

IDPH has a new grant-funded program, the Health Promotion and Chronic Disease Control Partnership. This publication, Chronic Disease Connections, will be part of the communication strategy between IDPH staff and healthcare system providers throughout the state as we partner to help patients control their diabetes and high blood pressure. This is just one of the major objectives for the funding. The CDC would like to see that more patients are aware that they have pre-diabetes, diabetes or high blood pressure and that health systems are maximizing evidence-based strategies to assist patients with achieving control. Over the coming months you will hear more about the new program and how you can become involved.

Impacts of Internal Curing on Concrete Properties, TR-676, 2015

Conventional concrete is typically cured using external methods. External curing prevents drying of the surface, allows the mixture to stay warm and moist, and results in continued cement hydration (Taylor 2014). Internal curing is a relatively recent technique that has been developed to prolong cement hydration by providing internal water reservoirs in a concrete mixture that do not adversely affect the concrete mixture’s fresh or hardened physical properties. Internal curing grew out of the need for more durable structural concretes that were resistant to shrinkage cracking. Joint spacing for concrete overlays can be increased if slab warping is reduced or eliminated. One of the most promising potential benefits from using internal curing for concrete overlays, then, is the reduced number of joints due to increased joint spacing (Wei and Hansen 2008).

Evaluation of Mini Slump Cone Test, MLR-97-01, 2000

Early stiffening of cement has been noted as contributing to workability problems with concrete placed in the field. Early stiffening, normally attributed to cements whose gypsum is reduced to hemi⋅hydrate or anhydrate because of high finish mill temperatures, is referred to as false setting. Stiffening attributed to uncontrolled reaction of C3A is referred to as flash set. False setting may be overcame by extended mix period, while flash setting is usually more serious and workability is usually diminished with extended mixing. ASTM C 359 has been used to detect early stiffening with mixed results. The mini slump cone test was developed by Construction Technology Laboratories (CTL), Inc., as an alternative method of determining early stiffening. This research examined the mini slump cone test procedure to determine the repeatability of the results obtained from two different testing procedures, effect of w/c ratio, lifting rate of the cone, and accuracy of the test using a standard sample.

Iowa ABC Connections, RB06-013, 2015

For several years the Iowa Department of Transportation (DOT), Iowa State University, the Federal Highway Administration, and several Iowa counties have been working to develop accelerated bridge construction (ABC) concepts, details, and processes. Throughout this development, much has been learned and has resulted in Iowa being viewed as a national leader in the area of ABC. However, at this time, the Office of Bridges and Structures does not have a complete set of working standards nor design examples to accompany ABC portions of the bridge design manual (now called the Load and Resistance Factor Design/LRFD Bridge Design Manual). During the fall of 2013, the Iowa DOT constructed a bridge on IA 92 in Cass County using an ABC technique known as slide-in bridge construction. During the design of the Cass County Bridge, several questions were raised about the performance of critical design and construction details: the pile-to-pile cap connection and the polytetrafluoroethylene (PTFE) coated bearing pads on which the bridge would slide. The timing of this specific need and the initiation of this project offered a unique opportunity to provide significant short- and long-term value to the Office of Bridges and Structures. Several full-scale laboratory tests, which included several variations of the pile-to-pile cap connection and bearing pad slides, were completed. These tests proved that the connection was capable of achieving the desired capacity and that the expected coefficient of friction of the bearing pads was reasonably low. Finally, a design tool was developed for the Office of Bridges and Structures to be used on future projects that might benefit from a precast pile cap.

Chronic Disease Connections, May 2015

IDPH has a new grant-funded program, the Health Promotion and Chronic Disease Control Partnership. This publication, Chronic Disease Connections, will be part of the communication strategy between IDPH staff and healthcare system providers throughout the state as we partner to help patients control their diabetes and high blood pressure. This is just one of the major objectives for the funding. The CDC would like to see that more patients are aware that they have pre-diabetes, diabetes or high blood pressure and that health systems are maximizing evidence-based strategies to assist patients with achieving control. Over the coming months you will hear more about the new program and how you can become involved.

Chronic Disease Connections, June 2015

IDPH has a new grant-funded program, the Health Promotion and Chronic Disease Control Partnership. This publication, Chronic Disease Connections, will be part of the communication strategy between IDPH staff and healthcare system providers throughout the state as we partner to help patients control their diabetes and high blood pressure. This is just one of the major objectives for the funding. The CDC would like to see that more patients are aware that they have pre-diabetes, diabetes or high blood pressure and that health systems are maximizing evidence-based strategies to assist patients with achieving control. Over the coming months you will hear more about the new program and how you can become involved.