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International Concrete Abstracts Portal

Showing 1-5 of 259 Abstracts search results

Document: 

19-328

Date: 

July 1, 2020

Author(s):

Jedadiah F. Burroughs, Charles A. Weiss Jr., John E. Haddock, and W. Jason Weiss

Publication:

Materials Journal

Volume:

117

Issue:

4

Abstract:

This study presents the application of an analytical model to describe the rheological behavior of cement pastes containing silica fume at replacement rates of up to 30% by mass. The analytical model hypothesizes how water interacts with particles in a cementitious system. The coating thickness of water surrounding each particle in the system is estimated. This coating thickness is shown to correlate strongly with measured rheological properties when fit to the Herschel-Bulkley model. To calculate coating thickness, it is necessary to account for the water absorbed by nonhydraulic components in the system, whether aggregate, supplementary cementitious materials, or mineral. The results suggest that silica fume particles may be absorptive, and this absorption capacity, although small, must be considered when designing water-starved cementitious materials. The experimental investigation involved the rheological testing of three water-binder ratios (0.20, 0.30, 0.45), three silica fume replacement levels (10%, 20%, 30%), and eight different silica fume products.

DOI:

10.14359/51724626


Document: 

18-320

Date: 

May 1, 2020

Author(s):

Colin B. Van Niejenhuis, Ibrahim G. Ogunsanya, and Carolyn M. Hansson

Publication:

Materials Journal

Volume:

117

Issue:

3

Abstract:

The pore solution expressed from 28-day cement pastes was analyzed as part of a wider research program investigating the corrosion behavior of stainless-steel reinforcing bars in concrete, using inductively coupled plasma and ion chromatography techniques. The pastes were prepared with different water-cementitious materials (binder) ratios (w/cm), portland cement with and without supplementary cementitious materials (SCMs), and with admixed sodium chloride in the range typical of the threshold values for stainless steel reinforcement. The major anion and cation concentrations are given, showing the influence of admixed chloride on the amount of chloride retained in solution and of sulfate released into the pore solution. The results are discussed in terms of the initial compositions of the cementitious materials and their effect on chloride binding.

DOI:

10.14359/51724590


Document: 

18-417

Date: 

May 1, 2020

Author(s):

Kamran Amini, Kristen Cetin, Halil Ceylan, and Peter C. Taylor

Publication:

Materials Journal

Volume:

117

Issue:

3

Abstract:

This paper compiles results from three different laboratory studies and employs multivariate regression analyses to model the effect of mixture parameters and concrete hardened properties on saltscaling performance. The correlations between concrete hardened properties and mixture proportions were also studied. The modeled mixture parameters included water-cementitious materials ratio (w/cm), slag cement, and air content. Concrete performance was evaluated through abrasion resistance, sorptivity, compressive strength, and salt scaling tests. According to the results obtained in this study, concrete scaling performance is affected, in the order of importance, by w/cm, slag-cement replacement, and air content. In addition, concrete hardened properties, especially abrasion resistance, were found useful in making reliable salt-scaling predictions. Based on the results derived from the regression analyses and the discussions provided in the reviewed literature, recommendations are given for proportioning of concrete to obtain adequate performance with respect to compressive strength, abrasion resistance, sorptivity, and salt-scaling resistance. In addition, the relationship between concrete properties, ingredients, and effective mechanisms are investigated.

DOI:

10.14359/51724614


Document: 

19-067

Date: 

March 1, 2020

Author(s):

Seyedhamed Sadati and Kamal H. Khayat

Publication:

Materials Journal

Volume:

117

Issue:

2

Abstract:

The research presented in this paper addresses the effect of coarse recycled concrete aggregate (RCA) on drying shrinkage of concrete designated for transportation infrastructure. Six types of RCA were employed at 30 to 100% replacement rates of virgin coarse aggregate. Two binder systems, including a binary cement with 25% Class C fly ash and a ternary system with 35% fly ash and 15% slag were employed. Three different water-cementitious materials ratios (w/cm) of 0.37, 0.40, and 0.45 were considered. Test results indicate that the use of RCA increased drying shrinkage by up to 110% and 60% after 7 and 90 days of drying, respectively. Correlations with R2 of up to 0.85 were established to determine the shrinkage at 7, 28, 56, and 90 days as a function of aggregate properties, including specific gravity, water absorption, and Los Angeles abrasion resistance of the combined coarse aggregates. The water absorption of the combined coarse aggregate was shown to be a good index to showcase the effect of RCA on shrinkage. Contour graphs were developed to determine the effect of RCA content and its key physical properties on 90-day drying shrinkage of concrete intended for rigid pavement construction. A classification system available in the literature was also used to suggest the maximum allowable replacement rates for use of RCA in a hypothetical case study. Results suggest replacement rates of 100%, 70%, and 50% (% wt.) to limit the 90-day shrinkage to 500 μɛ when RCA of A-1, A-2, and A-3 Classes are available, respectively.

DOI:

10.14359/51720296


Document: 

19-196

Date: 

March 1, 2020

Author(s):

Kacie C. D’ Alessandro, Carin L. Roberts-Wollmann, and Thomas E. Cousins

Publication:

Materials Journal

Volume:

117

Issue:

2

Abstract:

Ultra-high-performance concrete (UHPC) is known for its high strength and advanced durability. Due to the unique formulation of this material, including a fine cementitious matrix and distributed steel fibers, UHPC displays different material behavior than conventional concrete. This paper examines the biaxial tension-compression behavior of UHPC using a novel biaxial test method and compares results to biaxial failure criterion of conventional concrete. A total of 62 specimens were tested to evaluate the effects of curing regimes and fiber orientations. While the compressive strength of UHPC increased significantly when steam treated, tensile strength did not increase to the same degree. Controlled fiber orientation provided more compressive stress resistance than random fiber orientation with the presence of increasing tensile stress. Comparing UHPC results to biaxial failure criterion recognized for conventional concrete, the Mohr-Coulomb biaxial failure criterion was shown to be a conservative model for UHPC for all fiber orientations and curing regimes.

DOI:

10.14359/51722404


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