International Concrete Abstracts Portal

ABOUT THE INTERNATIONAL CONCRETE ABSTRACTS PORTAL

  • The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.

International Concrete Abstracts Portal

Showing 1-10 of 38 Abstracts search results

Document: 

18-011

Date: 

November 1, 2019

Author(s):

A. Shakir, M. Haziman Wan Ibrahim, N. Othman, A. Ahmed, and S. Shahidan

Publication:

Materials Journal

Volume:

116

Issue:

6

Abstract:

Palm oil fuel ash (POFA) is a by-product procured from the palm oil mill through the incineration of empty fruit bunches, mesocarp fibers, and shells so as to produce electricity. POFA was considerably used as a cementitous supplement in various types of concrete, bricks, blocks, mortar, and grout due to its pozzolanic content. However, using raw POFA as cementitious replacement caused a distinct deterioration on the properties of the hardened mixture. Therefore, various treatment methodologies were adopted to enhance the properties of POFA to improve the mechanical properties of the hardened mixture. This study reviews the treatment approaches performed on POFA and their effects on the physical, chemical, and microstructural properties of POFA. It was documented that grinding POFA increased its fineness and decreased the voids and porosity of the mixture. However, the optimum use of grounded POFA was ranged 5 to 25% by weight of cement. On the other hand, thermal treatment of POFA exhibited a substantial improvement on the physical, chemical, and morphological properties of POFA; consequently, the hardened properties were dramatically developed. Thermal-treated POFA could be used as binder supplement up to 70% by weight of cement, whereby environmental pollution was dropped and sustainability was achieved. It was concluded that the higher fineness of POFA contributed to a significant pozzolanic reaction and thus promoted better performance in the hardened matrix. However, future detections should address the leaching behavior of POFA and the leaching performance of the hardened mixture incorporating POFA. Besides, the durability of specimens containing POFA as binder supplement should be well covered in the prospectus research.

DOI:

10.14359/51716975


Document: 

18-415

Date: 

September 1, 2019

Author(s):

C. Gunasekera, Z. Zhou, M. Sofi, D. W. Law, S. Setunge, and P. Mendis

Publication:

Materials Journal

Volume:

116

Issue:

5

Abstract:

The increase of carbon emissions due to the annual growth of portland cement (PC) production has promoted research into the development of sustainable green concrete using a range of readily available industrial waste materials. The present study is focused on developing two high-volume fly ash (HVFA) concretes with cement replacement levels of 65% (HVFA-65) and 80% (HVFA-80). The required lime for both HVFA concrete mixtures was initially determined and the optimized mixture designs identified, based on the 28-day compressive strength, by varying the low-calcium Class F fly ash-hydrated lime composition. The optimized concrete mixtures achieved a compressive strength of 53 and 40 MPa (7.69 and 5.80 ksi) for HVFA-65 and HVFA-80 concretes, respectively. The early-stage strength development is dependent on the matrix produced in the specific HVFA concrete, which is itself dependent on the number of unreacted fly ash spheres. The increase of fly ash and hydrated lime dosage in HVFA concrete increases the rate of hydration of the C3A and C4AF phases, but decreases the hydration of the C3S phase, which resulted in lower early-age strength development than occurs in PC concrete. It was noted that the initial setting time of HVFA concretes increase with an increase of fly ash content. However, addition of hydrated lime accelerates the hydration and decreases the final setting time for HVFA concretes.

DOI:

10.14359/51716815


Document: 

18-343

Date: 

July 1, 2019

Author(s):

Wei Cheng, John R. Elliott, and Kenneth C. Hover

Publication:

Materials Journal

Volume:

116

Issue:

4

Abstract:

Crushed charcoal (biochar) was introduced into mortar as lightweight, high-carbon fine aggregate, at eight levels of sand replacement varying from 0 to 100% and up to 275% of cement content by mass. Carbon encapsulated in hardened mortar offset the carbon footprint of cement production and reduced demand for natural sand. Water content was increased to accommodate 125% biochar absorption and maintain workability. Mixture proportions affected water-cement ratio (w/c), fresh density, and compressive and splitting tensile strength of hardened mortar, with significantly diminished strength at increased biochar content. A net carbon benefit accrued when biochar content exceeded approximately 10% of the total aggregate mass or one-third of the cement mass. At this level, compressive strength is less than typically associated with structural concrete, but net sequestration of 800 kg carbon per m3 (1350 lb/yd3) could be realized at strength levels associated with controlled low-strength materials (CLSM). Multiple environmentally effective applications are suggested.

DOI:

10.14359/51716716


Document: 

17-456

Date: 

January 1, 2019

Author(s):

Hayder H. Alghazali and John J. Myers

Publication:

Structural Journal

Volume:

116

Issue:

1

Abstract:

This paper presents an experimental study on bond behavior between steel reinforcement and high-volume fly ash self-consolidating concrete (HVFA-SCC). HVFA-SCC is a new concrete grade of HVFA concrete with the rheology of self-consolidating concrete that satisfies the quality of construction work, environment aspects, and concrete sustainability. Mixtures with different cement replacement levels of fly ash and hydrated lime (50%, 60%, and 70% [by weight]) were used. Twelve full-scale reinforced concrete beams were cast and tested using a four-point load test setup. This study focused on observing the effect of factors such as cement replacement level, confinement conditions, and casting position on the beam flexural behavior. All beams were 10 ft (3048 mm) in length, 18 in. (457 mm) in thickness, and 12 in. (305 mm) in width. Rheological and mechanical properties of the mixtures were monitored. During testing, cracking and ultimate load, deflection, crack pattern, and mode of failure were recorded. Furthermore, test results were compared to a database of different concrete types such as conventional concrete and self-consolidating concrete. The findings of this study show that HVFA-SCC mixture with 70% replacement is not only feasible in terms of acceptable bond behavior, but also is superior in other certain attributes.

DOI:

10.14359/51706920


Document: 

17-240

Date: 

May 1, 2018

Author(s):

Seyedhamed Sadati and Kamal H. Khayat

Publication:

Materials Journal

Volume:

115

Issue:

3

Abstract:

This paper evaluates the effect of recycled concrete aggregate (RCA) on concrete durability. Six RCA types procured from different sources were employed at 30 to 100% replacement rates by volume of virgin coarse aggregate. One fine RCA was also investigated and was used for up to 40% replacement by volume of virgin sand. In total, 33 mixtures were proportioned with these aggregates in concrete made with a binary or a ternary binder system and a watercementitious materials ratio (w/cm) of 0.37 to 0.45. The mixtures were investigated for frost durability, electrical resistivity, sorptivity, and abrasion resistance. Test results indicate that concrete made with up to 100% coarse RCA from an air-entrained source can exhibit proper frost durability. No significant reduction (limited to 3%) in frost durability factor was observed when the fine RCA volume was limited to 15% of total sand. Increase in mass loss due to deicing salt scaling was observed in concrete made with 50% of RCA with high (over 4%) deleterious materials content and high mass loss during soundness test. For a given w/cm and binder type, the use of 50% coarse RCA resulted in up to 32% reduction in electrical resistivity. The reduction in w/cm from 0.40 to 0.37 and the use of ternary binder containing 35% Class C fly ash and 15% slag proved to be effective in mitigating the potentially negative impact of RCA on sorptivity and abrasion resistance, compared to concrete made without any RCA with w/cm of 0.40 and binary cement with 25% fly ash.

DOI:

10.14359/51702190


Document: 

17-019

Date: 

January 1, 2018

Author(s):

Adam M. Knaack and Yahya C. Kurama

Publication:

Structural Journal

Volume:

115

Issue:

1

Abstract:

This paper describes the development and validation of a time-dependent fiber-based (that is, layered) numerical model for the service-load deflection analysis of reinforced concrete structures. Specifically, the model is applied to analyze the effect of recycled concrete aggregates (RCA) on the deflections of beams. Previous research has shown that increased deflections (rather than reduced strength) may be a greater limitation for the use of RCA to replace natural coarse aggregates (for example, gravel and crushed limestone) for increased sustainability. Analysis and design tools are needed to quantify this increase in deflections so that limits on the use of recycled aggregates can be established. To aid in quantifying these increased deflections, a new time-dependent concrete fiber including creep and shrinkage strains was developed in the open-source structural analysis program, OpenSees (Open System for Earthquake Engineering Simulation). This paper describes the validation of the model, including recent data from service-load tests of slender cracked and uncracked RCA concrete beams. The model was able to predict the time-dependent deflections of reinforced concrete structural members under various load scenarios; however, the initial (instantaneous) deflections were generally underestimated because of underestimations in the extent of cracking. The model was also able to predict the total strains and increased neutral axis depth over time as a result of creep and shrinkage strains, except for the tension strains that were underestimated because of the inability of the model to accurately predict the amount of cracking. It was found that the shrinkage strains had a large effect on the time-dependent deflections of the beam test specimens, which was not a finding available from the experimental measurements. While the paper focuses on RCA concrete applications, the numerical model is a general-purpose tool that can be used to analyze the time-dependent axial-flexural deformations of conventional reinforced concrete structures as well.

DOI:

10.14359/51701153


Document: 

16-238

Date: 

January 1, 2018

Author(s):

Hasan Sahan Arel and Ertug Aydin

Publication:

Materials Journal

Volume:

115

Issue:

1

Abstract:

This work investigated the effects of Class F fly ash (FA), coconut husk ash (CHA), and rice husk ash (RHA) as cement replacements at various proportions on the workability, setting time, compressive strength, and pullout strength of concrete. Concretes containing partial replacement of cement by 20 and 40% FA and 10, 15, and 20% CHA and RHA were investigated. The results revealed that FA, CHA, and RHA can be used as replacements for cement in concrete production to produce sustainable and ecological products. The mixed composition of 20% FA and 20% RHA had 15.3% greater compressive strength than that of the reference composition after 180 days, while a slight reduction in this parameter was observed in FA-CHA combinations. FA and RHA mixtures showed the highest compressive and pullout strengths for all aging times tested.

DOI:

10.14359/51700991


Document: 

16-259

Date: 

March 1, 2017

Author(s):

Jay Shannon, Isaac L. Howard, V. Tim Cost, and Will Crawley

Publication:

Materials Journal

Volume:

114

Issue:

2

Abstract:

Portland-limestone cement (PLC) has recently been found useful in improving concrete’s synergy with some supplementary cementitious materials (SCMs), relative to ordinary portland cement (OPC), and in reducing early-age performance impacts of higher levels of cement replacement with SCMs. Use of PLC extends sustainability benefits by reducing concrete’s carbon footprint via reduced clinker content. This study explores how the performance of concrete using higher cement replacement with SCMs may be improved through use of PLCs in place of traditional OPCs in support of improved sustainability. PLCs were found to be able to enhance strength and setting in mixtures with higher levels of SCM replacement of cement, especially in certain combinations, while maintaining or improving later-age strengths. Results were notably productive in balancing mixture early performance, late-age strengths, and economics, with performance generally improved using PLCs relative to OPCs.

DOI:

10.14359/51689596


Document: 

15-265

Date: 

March 1, 2017

Author(s):

M. C. Caruso, C. Menna, D. Asprone, A. Prota, and G. Manfredi

Publication:

Structural Journal

Volume:

114

Issue:

2

Abstract:

This study aims to define a methodological framework that could guide construction community stakeholders in conducting environmental sustainability comparisons among building systems at the design stage. The study proceeds on the basis that the design of new structures starts with specific requirements, including national technical standards. An application of the proposed framework for the comparative life-cycle assessment (LCA) concerning a residential building is presented; three different structural materials are compared—namely, reinforced concrete (RC), steel, and wood. Starting with functional, architectural, and structural requirements, the building is designed and verified to take into account how structural solutions change depending on each building material. A cradle-to-grave LCA study is conducted for the three alternative structures using SimaPro software; both IMPACT2002+ and EPD2008 methodologies are used to quantify environmental impacts.

DOI:

10.14359/51689426


Document: 

15-243

Date: 

March 1, 2017

Author(s):

Maddalena Carsana and Luca Bertolini

Publication:

Materials Journal

Volume:

114

Issue:

2

Abstract:

Although concrete has a significant environmental impact, it also offers interesting opportunities of recycling waste materials that may improve its sustainability. Together with different other industrial residues that are normally recycled in concrete, expanded glass can be used as a lightweight aggregate. However, the use of glass in concrete raises concerns about durability because of its poor stability in alkaline environments. This paper presents a study aimed at investigating the durability of lightweight concrete (LWC) made with expanded glass and silica fume used, respectively, for the replacement of the fine fraction of aggregate and as mineral addition. Expanded glass particles were characterized in terms of alkali-aggregate reaction, density, absorption, and microstructure. The combination of expanded glass and silica fume led to a structural lightweight concrete that was able to maintain its strength under exposure to moist and hot conditions and showed high resistance to the penetration of aggressive agents.

DOI:

10.14359/51689472


1234

Results Per Page