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International Concrete Abstracts Portal

Showing 1-5 of 183 Abstracts search results

Document: 

20-254

Date: 

March 1, 2021

Author(s):

Vineet Shah and Allan Scott

Publication:

Materials Journal

Volume:

118

Issue:

2

Abstract:

Magnesium silicate hydrate (M-S-H) formed by the reaction between magnesium oxide and amorphous silica in water imparts strength-binding characteristics similar to that of portland cement (PC). Analysis of both the mechanical and durability parameters of MgO-SiO2 binder is essential for its adoption as an alternative cementitious material. This study investigates the mechanical and transport properties of MgO-SiO2 binder concrete. Silica fume and metakaolin were used as amorphous silica sources in the binder. The implications of the addition of magnesium carbonate in MgO-SiO2 binder concrete was also investigated. Along with the compressive strength, other hardened properties of concrete including elastic modulus, shrinkage, porosity, sorptivity, permeability, and resistivity were measured at 7, 28, and 90 days. The overall performance of the concrete was improved through the use of metakaolin instead of silica fume in terms of compressive strength, elastic modulus, and shrinkage. The transport properties of the magnesium oxide and metakaolin mixture were found to be better or similar compared to PC, which was attributed to the refined pore structure and lower porosity. The addition of magnesium carbonate further helped to improve the overall performance of the concrete through likely the formation of hydrotalcite type phases.

DOI:

10.14359/51730418


Document: 

19-503

Date: 

March 1, 2021

Author(s):

Ablam Zidol, Monique T. Tognonvi, and Arezki Tagnit-Hamou

Publication:

Materials Journal

Volume:

118

Issue:

2

Abstract:

It has been demonstrated in recent studies that, unlike general-use cement (GU), glass powder (GP) performs better in concrete mixtures with high water-binder ratios (w/b) in terms of both mechanical properties and chloride ion permeability. This paper aims to deepen investigations on the behavior of concrete incorporating GP in aggressive outdoor environments such as chloride ion diffusion, carbonation, and sulfates as a function of w/b. For comparison purposes, concretes containing conventional supplementary cementitious materials (SCMs) such as Class F fly ash (FFA) and ground-granulated blast-furnace slag (GGBFS) along with control concrete were also studied. In general, GP-based concretes behaved as those containing SCM. Indeed, despite their high w/b, concrete incorporating GP better withstands sulfate attack than the reference. This was mainly attributed to the low chloride permeability of such concretes. Also, as commonly observed with SCM concretes, carbonation was higher with GP-based concrete and increased with w/b.

DOI:

10.14359/51729326


Document: 

18-308

Date: 

January 1, 2021

Author(s):

M. Almarshoud, H. Mosavi, R. Alrashidi, M. H. M. Alyami, C. C. Ferraro, H. D. DeFord, and K. A. Riding

Publication:

Materials Journal

Volume:

118

Issue:

1

Abstract:

In this study, the concrete penetrability properties were measured for both the older test methods and the new resistivity-based test methods. To consider different materials, four types of cement were used, including an ASTM C150/C150M Type I/II low alkali cement, Type V cement, Type I cement with high alkali content, and an ASTM C595/C595M Type IL cement. Silica fume, slag cement, Class F fly ash, and metakaolin were used as supplementary cementitious material (SCM) in binary and ternary blends with different replacement ratios to evaluate the correlation between electrical and transport properties. The tests included AASHTO TP 119 for bulk resistivity, AASHTO T 358 for surface resistivity measurement, rapid chloride permeability test (ASTM C1202/C1202M), rapid chloride migration test (NT Build 492), concrete water absorption rate (ASTM C1585/C1585M), concrete volume of permeable voids (ASTM C642/C642M), and a constant-head water permeability test. The results showed good correlation between the electrical-based tests and water permeability, but poor correlation between the electrical-based tests and the volume of permeable voids.

DOI:

10.14359/51729334


Document: 

19-449

Date: 

November 1, 2020

Author(s):

Sarah De Carufel, Andrew Fahim, Pouria Ghods, and Rouhollah Aalizadeh

Publication:

Materials Journal

Volume:

117

Issue:

6

Abstract:

This paper presents a model developed to predict the internal relative humidity (RH) of concrete during drying. The model makes use of simplified inputs, including the concrete mixture design and the cement Bogue composition, thus making it accessible to engineers and practitioners. These inputs are used to separately determine the permeability of both liquid and vapor phases, hence solving for moisture transport through an empirical derivation of the (de) sorption isotherm, total porosity, and pore tortuosity. The model is validated using previously published literature data as well as experiments designed specifically for model validation. The model was found successful in predicting RH profiles for the validation data with the simple inputs required. However, it was found that in cases where the standardized ASTM F2170 method is used to measure RH, the agreement between the model and experimental data decreases. This was found to be related to errors associated with performing humidity measurements within cavities drilled in concrete. Such errors are discussed, and room for improvement in in-place humidity measurements is proposed. Finally, the model is used to validate the use of RH measurements at a specific concrete depth to evaluate the susceptibility of moisture-sensitive flooring to failures.

DOI:

10.14359/51728146


Document: 

19-438

Date: 

November 1, 2020

Author(s):

Sarah C. Baxter, Katherine A. Acton, and Rita E. Lederle

Publication:

Materials Journal

Volume:

117

Issue:

6

Abstract:

Pervious concrete is a specialty concrete with a high pore volume fraction. The porosity and microstructure that give pervious concrete its characteristic permeability also limit aspects of performance, such as strength and durability. Microstructural parameters used in computational models of mechanical behavior can be quantified using image analysis. However, because pervious concrete has a random microstructure, measured values from a single image may not reflect the “effective” behavior of the material. The appropriate size of a sample, known as a Representative Volume Element (RVE), may vary depending on the parameter under consideration. In this work, six microstructural parameters are measured using image analysis. Average values of these parameters were calculated as a function of sample size to illustrate convergence to a representative value. Representative values from image analysis were also compared with experimentally measured porosity. Results suggest appropriate RVEs for porosity, specific surface area, characteristic length, mean free spacing, characteristic pore diameter, and interfacial perimeter.

DOI:

10.14359/51728124


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