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International Concrete Abstracts Portal

Showing 1-10 of 229 Abstracts search results

Document: 

19-328

Date: 

July 1, 2020

Publication:

Materials Journal

Volume:

117

Issue:

4


Document: 

18-307

Date: 

May 1, 2020

Publication:

Materials Journal

Volume:

117

Issue:

3


Document: 

18-450

Date: 

March 1, 2020

Publication:

Materials Journal

Volume:

117

Issue:

2


Document: 

19-044

Date: 

January 1, 2020

Author(s):

Joaquín Abellán, Jaime Fernández, Nancy Torres, and Andrés Núñez

Publication:

Materials Journal

Volume:

117

Issue:

1

Abstract:

This paper presents the experimental results of research carried out involving the compressive strength and slump flow of ultra-high-performance concrete (UHPC) made with cementitious blends of recycled glass flour, recycled glass powder, micro limestone powder, silica fume, and portland cement. The adopted second-order polynomic regression model provided an accurate correlation between the considered variables and the obtained responses. A numerical optimization was then performed to obtain an eco-friendly mixture with the proper flow, highest compressive strength, and minimum content of cement. The use of 603 kg/m3 of cement in the mixture can be considered as the most appropriate amount to be employed in UHPC mixtures, fulfilling the limit values of compressive strength and spread flow.

DOI:

10.14359/51720292


Document: 

19-039

Date: 

January 1, 2020

Author(s):

Daniel da Silva Andrade, João Henrique da Silva Rêgo, Moisés Frías Rojas, Paulo Cesar Morais, Maria José de Souza Serafim, and Anne Neiry Lopes

Publication:

Materials Journal

Volume:

117

Issue:

1

Abstract:

The present study reports on the pioneering addition of rice husk ash (RHA) and silica fume (SF) into portland cement-based (PC-based) materials, combined with nanosilica (NS), aiming to assess the impact of the RHA on the mechanical and microstructure properties of ternary mixtures. Pastes were prepared to perform compressive strength tests, thermal analysis (DTA/TG), infrared spectroscopy, and mercury porosimetry. The highest reduction in the calcium hydroxide index (CH.I) and the highest calciumsilicate- hydrate (C-S-H) formation are found in the PC-based ternary mixture containing NS plus SF and NS plus RHA after 91 days of hydration. In line with the aforementioned trends, the ternary mixtures containing NS show the highest compressive strength values and reduction of mean diameter of porous. Indeed, we found strong evidence of synergistic effect in ternary mixtures incorporating NS plus RHA or SF, thus supporting their use in fabrication of cementitious materials.

DOI:

10.14359/51720291


Document: 

18-344

Date: 

September 1, 2019

Author(s):

Ian N. Robertson and Craig Newtson

Publication:

Materials Journal

Volume:

116

Issue:

5

Abstract:

This paper presents results of a 10-year laboratory and field monitoring study to evaluate commercially available corrosion-inhibiting admixtures in terms of effectiveness at preventing or delaying corrosion. The corrosion-inhibiting admixtures used in this study included Xypex Admix C-2000, latex modifier, Kryton KIM, fly ash, silica fume, Darex Corrosion Inhibitor (DCI), Rheocrete CNI, Rheocrete 222+, and FerroGard 901. The laboratory study used accelerated corrosion testing (ASTM G109) to study 656 specimens from 100 different mixtures. Saltwater ponding and drying cycles continued until macrocell current readings indicated initiation of corrosion. Specimens were then removed from cycling and autopsied to determine the extent and location of corrosion on the reinforcing steel. After 10 years of cycling, all remaining specimens were autopsied. The field study included 25 reinforced concrete panels exposed to the tidal zone in the Honolulu Harbor. Panels were tested regularly for chloride penetration and half-cell corrosion potential. After 10 years, the panels were removed from the site and autopsied. Results of the study showed that DCI, CNI, fly ash, and silica fume improved corrosion protection compared to control specimens. Concrete mixtures using Rheocrete 222+, FerroGard 901, Xypex Admix C-2000, or latex modifier showed mixed results.

DOI:

10.14359/51716836


Document: 

18-290

Date: 

July 1, 2019

Author(s):

Rajaram Dhole, Michael D. A. Thomas, Kevin J. Folliard, and Thano Drimalas

Publication:

Materials Journal

Volume:

116

Issue:

4

Abstract:

Fly ash concrete mixtures were tested for the chemical and physical sulfate attack. Concrete mixtures consisting of ratios of fly ashes, Type I cement, silica fume, and ultra-fine fly ash (UFFA) were tested. Four exposure conditions were simulated by subjecting the concrete specimens to: 1) immersion in 5% Na2SO4 solution; 2) wet-dry cycling in 5% Na2SO4 solution at 23°C (73°F, wet) and 38°C (100°F, dry); 3) immersion in saturated CaSO4 solution; and 4) wet-dry cycling in saturated CaSO4 solution at 23°C (73°F, wet) and 38°C (100°F, dry). Control specimens were stored in water at ambient temperature. Performance of the concrete mixtures was studied through visual inspection and by monitoring the changes in mass, length, and dynamic modulus of elasticity over time. It was found that improved sulfate resistance can be provided to the fly ash concrete by controlling water-cement ratio (w/c) and blending with Class F fly ash, UFFA, and silica fume.

DOI:

10.14359/51716678


Document: 

17-466

Date: 

May 1, 2019

Author(s):

Guoju Ke, Jiaqian Wang, and Bo Tian

Publication:

Materials Journal

Volume:

116

Issue:

3

Abstract:

To solve the problem of manufactured sand concrete in the pumping process being very prone to plugging, a pumping resistance tester is used to test the influences of stone dust (SD) content and megabyte (MB) value of the manufactured sand, fly ash, silica fume, superabsorbent polymer (SAP), and air-entraining agent on the pumpability of manufactured sand concrete with different intensities, including push distance and pumping resistance. Furthermore, variations in the performance of the manufactured sand concrete before and after pumping are analyzed, including slump, slump flow, density, push distance, pumping resistance, compressive strength, chloride ion anti-permeability, and air void structure. Results show that SAP has shown a significant reduction in pumping resistance, both in low-strength concrete and in high-strength concrete. In the process of pumping, the pumping pressure causes the air void structure of the hardened manufactured sand concrete to change. The number of big air voids decreases, air void ratio increases, total porosity is reduced, and the resistance to chloride ion permeability is superior to the level before pumping.

DOI:

10.14359/51714504


Document: 

18-144

Date: 

March 1, 2019

Author(s):

Yail J. Kim and Jun Wang

Publication:

Materials Journal

Volume:

116

Issue:

2

Abstract:

This paper presents the development of cost-effective ultra-high performance concrete (UHPC) using various silica admixtures. With the aim of achieving a specified compressive strength of 138 MPa (20 ksi), a UHPC mixture is formulated. The research program consists of three phases: 1) suitable constituents are identified based on the reproduction tests of nine existing UHPC mixtures selected from literature; 2) a prototype mixture design is developed; and 3) the performance of the prototype UHPC is assessed through an experimental parametric study. The implications of various constituent types are examined with an emphasis on silica compounds (silica fume, silica powder, silica sand, finer silica sand, pyrogenic silica, and precipitated silica), including steel and polypropylene fibers. The distribution of granular particles is characterized by digital microscopy alongside an image processing technique. Benchmark tests employing the nine mixtures demonstrate that silica sand and finer silica sand perform better than silica powder from a strength perspective, and the inclusion of steel fibers rather than polypropylene fibers is recommendable. Although heat curing increases concrete strength, the prototype UHPC is designed with conventional moisture curing because of practicality in the field. The steel fibers increase the flexural capacity of the UHPC more than 60% relative to the UHPC mixed without fibers, and result in a gradual failure mode. The bulk density of silica fume influences the strength gain of the UHPC at 7 days, beyond which its effect becomes insignificant. The use of pyrogenic silica and precipitated silica is not suggested. The applicability of the modulus of rupture equations specified in published specifications and codes is assessed, and new equations are proposed for the developed UHPC mixture using randomly generated statistical data. Cost analysis shows that the prototype UHPC is up to 74% less expensive than commercial products.

DOI:

10.14359/51714450


Document: 

18-006

Date: 

January 1, 2019

Author(s):

Mohamed K. Ismail, Assem A. A. Hassan, and Mohamed Lachemi

Publication:

Materials Journal

Volume:

116

Issue:

1

Abstract:

This investigation aims to study the abrasion resistance of developed self-consolidating engineered cementitious composite (SCECC) mixtures using the rotating-cutter and sandblasting abrasion tests. The fresh and mechanical properties of the developed SCECC were also investigated in this study. Additional conventional self-consolidating concrete (SCC) (with 10 mm [0.39 in.] coarse aggregate) and vibrated engineered cementitious composite (VECC) mixtures were tested for comparison. The standard engineered cementitious composites (ECCs) are commonly developed using a high volume of fly ash (FA) and microsilica sand (SS). In this study, the FA was partially replaced by varied volumes of slag (SL), silica fume (SF), and metakaolin (MK), while the SS was replaced by crushed granite sand (CS) of different sizes. The results indicated that combining SL, SF, or MK with FA resulted in developing SCECCs with adequate deformability and higher abrasion resistance, compressive strength, and flexural strength. Using 20% of MK in the development of SCECC showed the best abrasion resistance improvement in both rotating-cutter and sandblasting tests. The results of rotating-cutter and sandblasting tests also indicated that SCECC mixtures appeared to have less abrasion resistance compared to their SCC counterpart mixtures with 10 mm (0.39 in.) coarse aggregate.

DOI:

10.14359/51712239


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