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International Concrete Abstracts Portal

Showing 1-5 of 277 Abstracts search results

Document: 

23-055

Date: 

February 8, 2024

Author(s):

Sangyoung Han, Thanachart Subgranon, Hung-Wen Chung, Kukjoo Kim, Mang Tia

Publication:

Materials Journal

Abstract:

A compressive laboratory testing program, field testing program, numerical analysis, and life-cycle cost analysis were conducted to evaluate the beneficial effects of incorporating shrinkage-reducing admixture (SRA), polymeric microfibers (PMF), and optimized aggregate gradation (OAG) into an internally cured concrete (ICC) mix for rigid pavement application. Results from the laboratory program indicate that all ICC mixes outperformed the standard concrete (SC) mix. All ICC mixes showed a decrease in drying shrinkage compared to the SC mix. Based on the laboratory program, three ICC mixes and one of the SC mixes were selected for the full-scale test subjected to a heavy vehicle simulator for accelerated fatigue testing. Extensive testing and analysis have shown that ICC mixes incorporating SRA, PMF, and OAG can be beneficially used in pavement applications to achieve increased pavement life.

DOI:

10.14359/51740564


Document: 

23-101

Date: 

February 8, 2024

Author(s):

Le Teng, Alfred Addai-Nimoh, Kamal H. Khayat

Publication:

Materials Journal

Abstract:

This study evaluates the potential to use shrinkage-reducing admixture (SRA) and pre-saturated lightweight sand (LWS) to shorten the external moist curing requirement of ultra-high-performance concrete (UHPC), which is critical in some applications where continuous moist curing is challenging. Key characteristics of UHPC prepared with and without SRA and LWS and under 3 days, 7 days, and continuous moist curing were investigated. Results indicate that the combined incorporation of 1% SRA and 17% LWS can shorten the required moist curing duration since such mixture under 3 days of moist curing exhibited low total shrinkage of 360 µε at 56 days and compressive strength of 135 MPa (19,580 psi) at 56 days and flexural strength of 18 MPa (2,610 psi) at 28 days. This mixture subjected to 3 days of moist curing also had a similar hydration degree and 25% lower capillary porosity in paste compared to the Reference UHPC prepared without any SRA and LWS and under continuous moist curing. The incorporation of 17% LWS promoted cement hydration and silica fume pozzolanic reaction to a degree similar to extending the moist curing duration from 3 to 28 days and offsetting the impact of SRA on reducing cement hydration. The lower capillary porosity in the paste compensated for the porosity induced by porous LWS to secure an acceptable level of total porosity of UHPC.

DOI:

10.14359/51740566


Document: 

21-335

Date: 

January 4, 2024

Author(s):

Zainab Hashim Abbas Alsalami, Fatima Hashim Abbas,

Publication:

Materials Journal

Abstract:

Ultra-high-performance concrete (UHPC) is considered a sophisticated concrete construction solution for infrastructure and other structures because of its premium mechanical traits and superior durability. Fibers played a special effect on the properties of UHPC, especially this type of concrete suffered from high autogenous shrinkages due to high cementitious content, so the properties and volume fraction of fibers are more important in UHPC. This study will describe the previous related works on the mechanical behavior of UHPC specimens reinforced with micro and Nano scale fibers, comparison of the behavior of UHPC reinforced with microfibers and that reinforced with Nanofibers. Compressive strength, flexural behavior, and durability aspects of UHPC reinforced with nano and/or micro scale of variable types of fibers were studied to highlight the issues and make a new direction for other authors.

DOI:

10.14359/51740369


Document: 

22-200

Date: 

September 1, 2023

Author(s):

S. Fernando, C. Gunasekara, D. W. Law, M. C. M. Nasvi, S. Setunge, and R. Dissanayake

Publication:

Materials Journal

Volume:

120

Issue:

5

Abstract:

The creep and drying shrinkage of two alkali-activated concretes produced with low-calcium fly ash and rice husk ash (RHA) were investigated over a period of 1 year. The compressive strength of 100% low-calcium fly ash (100NFA) concrete and the concrete having 10% RHA replacement (10RHA) decreased from 49.8 to 37.7 MPa (7.22 to 5.47 ksi) and 30.2 to 18.3 MPa (4.38 to 2.65 ksi), respectively, between 28 and 365 days. The imbalance in the dissolution rate of the raw materials in the blended system (10RHA) could negatively influence the strength properties, which leads to poor matrix integrity and a highly porous structure when compared with 100NFA. The presence of the micro-aggregates due to the block polymerization provides the effect of increasing the aggregate content in the 100NFA concrete compared with the 10RHA concrete, which is hypothesized as one of the reasons creep and shrinkage properties deteriorated in 10RHA.

DOI:

10.14359/51738891


Document: 

22-190

Date: 

May 1, 2023

Author(s):

Hossein Karimi and H. J. H. Brouwers

Publication:

Materials Journal

Volume:

120

Issue:

3

Abstract:

In this paper, the applicability of the modified Andreasen and Andersen (A&A) particle packing model for designing pumpable flowing concretes, according to ACI 211.9R-18, is analyzed. An experimental investigation is undertaken to evaluate consistency, compressive strength, and shrinkage of flowing concretes designed with this model. The results show that the modified A&A model optimizes the particle size distribution of concrete ingredients and produces pumpable concretes according to ACI 211.9R-18. The distribution modulus of the model controls the combined grading, the ratio of coarse-to-fine aggregate, and the percentage of fine aggregate passing 300 and 150 μm. At a distribution modulus of 0.35, the model serves as the ACI’s recommended boundary limit for ideal-for-pumping combined grading. A high distribution modulus results in a high coarse-to-fine aggregate ratio and lowers the drying shrinkage of concrete. This insight enables a straightforward mixture design methodology that results in concrete that meets ACI 211.9R-18 recommendations.

DOI:

10.14359/51738685


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