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International Concrete Abstracts Portal

Showing 1-5 of 44 Abstracts search results

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.


Document: 

SP-307-08

Date: 

March 1, 2016

Author(s):

Benoît Bissonnette,1* Marc Jolin, Richard Gagné, Pierre-Vincent Certain, and Fabien Perez

Publication:

Symposium Papers

Volume:

307

Abstract:

In order to be cost-effective, surface repairs carried out on concrete structures have to perform satisfactorily over a sufficient period of time. Among the factors that can affect the durability of concrete repairs, drying shrinkage is certainly one of the most significant. Shrinkage compensating concretes (ShCC’s) represent a very attractive alternative to prevent shrinkage cracking in repairs. This paper summarizes the results of a project devoted to repair ShCC’s made with an expansive component, more specifically their robustness as a function of selected parameters. The investigated expansive systems were either, a calcium sulfoaluminate-based (ASTM Type K cement or Type K component) or calcium oxide-based (ASTM Type G component). The assessment of robustness addressed the influence of the mixture design parameters (cement composition, type and dosage of expansive agent, w/cm ratio) and the curing conditions (moist curing conditions, temperature) upon the ShCC’s expansive behavior, the bond between ShCC repairs and an existing concrete substrate, and the chemical prestress generated through the bond. Overall, the results yielded in this study demonstrate the remarkable potential of ShCC’s as crack-resistant and durable repair materials.


Document: 

SP-307-02

Date: 

March 1, 2016

Author(s):

George C Hoff

Publication:

Symposium Papers

Volume:

307

Abstract:

Samples of Type K shrinkage-compensating cement from all 17 mills producing that cement in 1974 were obtained and evaluated for compliance with the specification that was proposed at that time for these types of cements. The cements were also evaluated for specific gravity, fineness, heat of hydration, and expansion and drying shrinkage in mortars. An X-ray diffraction analysis was also made for each cement in an attempt to compare cements to note significant differences in composition or relative amounts of constituents. A standard concrete mixture was also made with all the cements and evaluated for air content, slump, compressive strength, expansion, and drying shrinkage. The results from these evaluations are revisited. The application of the 1974 proposed specification called attention to several short-comings in that specification.


Document: 

SP305-45

Date: 

September 1, 2015

Author(s):

Adriano Reggia; Sergio Tortelli; Maurizio Marchi; Massimo Borsa and Giovanni A. Plizzari

Publication:

Symposium Papers

Volume:

305

Abstract:

Concrete floor on ground represents an important application for concrete use in Italy. Despite their widespread use, a large percentage of concrete floors does not meet the performance requirements in terms of functionality and durability for various reasons; among them, restrained shrinkage cracking and curling represent one of the most important causes of defects. Cracking is mainly due to the drying shrinkage in presence of internal and external restraints, while curling is due to the shrinkage gradient due to the floor thickness. An analytical approach to shrinkage cracking and curling is often overlooked by designers in lieu of the design of contraction joints that allow the cracking of concrete under controlled conditions. Nowadays, the growing needs of concrete floors purchasers in terms of durability and functionality suggests the use of special concretes for flooring. For instance, the use of shrinkage-compensating concretes reduces the number of contraction joints and enhances the concrete slab performances. This study presents the non-linear finite element analysis of a jointless floor made with a shrinkage-compensating concrete obtained with the use of a blend of calcium sulpho-aluminate cement and ordinary Portland cement.


Document: 

SP305-47

Date: 

September 1, 2015

Author(s):

Davide Sirtoli; Sergio Tortelli; Paolo Riva; Maurizio Marchi; Roberto Cucitore; Mankaa Nangah

Publication:

Symposium Papers

Volume:

305

Abstract:

Calcium-sulphoaluminate cement (CSA) represents an eco-friendly alternative to ordinary portland cement (OPC), thanks to its lower energy consumption, special production process and raw materials. Life-Cycle Analysis (cradle-to-gate) according to ISO 14040 standard series showed a potential for substantial reduction of the environmental impacts, as well as natural resource use. Nowadays, CSA cement is being used more in construction industry thanks to its high early-age compressive strength and shrinkage-compensating behavior. This paper presents concrete mixtures with pure CSA and with OPC-CSA blends both in terms of environmental impact indicators from Environmental Product Declarations, and in terms of mechanical and rheological performance focusing on workability, compressive and flexural strength development, drying shrinkage and dynamic elastic modulus evolution from very early ages.


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