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International Concrete Abstracts Portal

Showing 1-5 of 10 Abstracts search results

Document: 

SP-307-05

Date: 

March 1, 2016

Author(s):

Edwin McLean and Seth Roswurm

Publication:

Symposium Papers

Volume:

307

Abstract:

Owners, engineers, and contractors have been forced to contend with drying shrinkage for as long as portland cement has been used in slabs-on-ground, containment structures, and other concrete elements. The resulting cracks and warping have long-lasting impacts on both the performance of the concrete and the lifetime maintenance cost. Various construction methods have historically been used to mitigate this issue including modified mix designs, curing compounds, joint detailing, and transfer devices to reduce warping (curling). With advances in type K shrinkage compensating cement technology, however, designers and contractors now have access to a concrete that can eliminate shrinkage cracks, extend joint spacing to extremes, vastly reduce costly joint construction, and shorten construction schedules. This solution reduces not only construction costs but also maintenance costs on the structure for years to come. Shrinkage compensating concrete (SCC) produced using ASTM C845 Type K cement has been used in floors, elevated building decks, bridge decks, post-tensioned concrete, and containment structures since the mid 1960’s. Today, Type K SCC cement technology is even better understood, making way for higher performing concrete elements.

DOI:

10.14359/51688878


Document: 

SP-307-06

Date: 

March 1, 2016

Author(s):

Ed McLean, Chris Ramseyer, and Seth Roswurm

Publication:

Symposium Papers

Volume:

307

Abstract:

In the modern transportation industry, nearly all bridge decks are constructed of concrete. Of the concrete bridge decks currently in service across the US, almost all contain large numbers of cracks. These cracks are the bane of deck longevity. They allow the ingress of salts that cause corrosion of the reinforcing steel, exacerbating concrete cracking and loss of structural capacity. A survey conducted several years ago by Folliard et al. (2004) for the FHWA found that more than 100,000 bridges suffered from early-age cracking. This paper presents a case study of bridge decks in Ohio and Michigan that are essentially crack-free. Some of these bridge decks are located on high volume highways/interstates and are up to 30 years of age. In addition, several of these bridges have adjacent standard Portland cement concrete sister bridges built at the same time, with identical spans and construction details handling traffic flowing in the opposite direction. Comparison of these bridges offers unique insight into a simple, effective solution for mitigation of bridge deck cracking.

DOI:

10.14359/51688879


Document: 

SP-307-09

Date: 

March 1, 2016

Author(s):

Alma Reyes

Publication:

Symposium Papers

Volume:

307

Abstract:

Expansive component systems provide the possibility to control the effects of concrete drying shrinkage in civil engineering applications, promoting durability for new construction and repair alternatives. Drying shrinkage is a natural consequence of concrete upon water loss after hardening. When there are restrictions such as internal reinforcement, adjacent structural elements and subgrade friction, concrete drying shrinkage can lead to cracking if no provisions are considered on the mix design or on the construction procedure. Expansive component Type G reacts chemically with Portland cement and water in the concrete mix to produce calcium hydroxide platelet crystals, which after setting, produce a volume increase. Providing internal or external restrictions, a concrete, that contains an expansive component system, can induce compression stress in the concrete mass and tension stress in the reinforcement. Concrete cracking can be reduced because such induced compression stress counteracts the tensile stress in the concrete mass caused by drying shrinkage. This article comprises a variety of applications of concrete, including the expansive component Type G, in Mexico as a solution means of improved functionality and durability of modern construction.

DOI:

10.14359/51688882


Document: 

SP-307-07

Date: 

March 1, 2016

Author(s):

Chris Ramseyer, Kyle Renevier, and Seth Roswurm

Publication:

Symposium Papers

Volume:

307

Abstract:

Type K Shrinkage Compensating Concrete (SCC) concrete is uniquely suited for use in slabs and walls because it typically requires fewer expansion joints than a convention portland cement (PC) concrete. This allows for continuous placement of much larger slabs and walls and facilitates the construction of high performance smooth slabs with few interruptions. Typically shrinkage-compensating concrete construction practice is to pour adjoining wall sections a minimum of five days apart in order to allow for the initial expansion of the material. The need for unrestrained expansion is implied in the ACI 223R-10 Design Guide in Chapter 5 in a discussion on sequencing the placement of wall segments. This paper discusses testing that was performed at two different locations, spanning both two different times of year and two unique climates. The tests used vibrating wire strain gages (VWSG) to investigate the restrained behavior of a wall segment in a six million gallon clear well tank in Springfield, IL, as well as the unrestrained behavior of two slabs-on-grade in Los Angeles, CA. Measurements were taken for a minimum of 30 days and a maximum of 170 days. Testing results are then compared to similar scenarios using ordinary PC concrete.

DOI:

10.14359/51688880


Document: 

SP-307-04

Date: 

March 1, 2016

Author(s):

Shideh Shadravan, Thomas H.-K. Kang and Chris Ramseyer

Publication:

Symposium Papers

Volume:

307

Abstract:

This paper reexamines the authors’ experimental results on the dimensional stability of concrete slab-on-ground under a variety of environmental conditions. The experiments considered the dimensional properties of concrete slab materials using both Demec targets and vibrating wire strain gages. Realistic slab-on-ground sections were investigated in this study in that the concrete slabs were exposed to a controlled environment on the top surface and to actual ground moisture on the bottom surface. The concrete materials tested were normal Portland cement concrete (PCC), high strength concrete (HSC), concrete with shrinkage reducing admixtures (SRA), and concrete with calcium sulfoaluminate cement (CSA). The compiled database contains: 1) standard concrete material test results; 2) joint movements in concrete slab-on-ground; and 3) internal relative humidity and temperature through the slab-on-ground depth. The experimental results revealed that CSA was quite stable with little long-term shrinkage/cracking or warping, whereas PCC and HSC had continuing crack growth during 600 days of curing. The SRA exhibited a modest reduction in shrinkage/crack at the early stage, and while this decrease extended for the length of the testing no further decrease in the shrinkage growth or sectional stability was noted when compared to PCC at the end of 2 years. Evaluation of the vibrating wire strain gage method of measuring long term concrete shrinkage was found to be less prone to user bias and more accurate than the Demec target method or the ASTM C157 method.

DOI:

10.14359/51688877


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