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International Concrete Abstracts Portal

Showing 1-5 of 197 Abstracts search results

Document: 

23-096

Date: 

March 15, 2024

Author(s):

Zoi G. Ralli and Stavroula J. Pantazopoulou

Publication:

Materials Journal

Abstract:

In light of the effort for decarbonization of the energy sector, it is believed that common geopolymer binding materials such as fly ash may eventually become scarce, and new geological aluminosilicate materials should be explored as alternative binders in geopolymer concrete. A novel, tension-hardening geopolymer concrete (THGC) that incorporates high amounts of semi-reactive quarry wastes (Metagabbro) as a precursor and coarse quarry sand (granite) was developed in this study using geopolymer formulations. The material was optimized based on the particle packing theory and was characterized in terms of mechanical, physical, and durability properties (i.e., compressive, tensile, flexural resistance, Young’s Modulus, Poisson’s ratio; absorption, drying shrinkage, abrasion, and coefficient of thermal expansion; chloride ion penetration, sulfate, and salt-scaling resistance). The developed THGC with an air-dry density of 1,940 kg/m3 [121 lb/ft3], incorporates short steel fibers at a volume ratio of 2% and is highly ductile in both uniaxial tension and compression (uniaxial tensile strain capacity of 0.6% at an 80% post-peak residual tensile strength). Using DIC, multiple crack formation was observed in the strain-hardening phase of the tension response. In compression the material maintained its integrity beyond the peak load, having attained 1.8% compressive strain at 80% post-peak residual strength whereas upon further reduction to 50% residual strength, the sustained axial and lateral strains were 2.5% and 3.5%, respectively. The material exhibited low permeability to chloride ions and significant abrasion resistance due to the high contents of Metagabbro powder and granite sand. The enhanced properties of the material, combined with the complete elimination of ordinary Portland cement from the mix, hold promise for the development of sustainable and resilient structural materials with low CO2j, emissions while also enabling the innovative disposal of wastes as active binding components.

DOI:

10.14359/51740704


Document: 

21-381

Date: 

December 1, 2023

Author(s):

Othman AlShareedah and Somayeh Nassiri

Publication:

Materials Journal

Volume:

120

Issue:

6

Abstract:

Pervious concrete is a stormwater management practice used in the United States, Europe, China, Japan, and many other countries. Yet the design of pervious concrete mixtures to balance strength and permeability requires more research. Sphere packing models of pervious concrete were used in compressive strength testing simulations using the discrete element method with a cohesive contact law. First, three mixtures with varied water-cement ratios (w/c) and porosities were used for model development and validation. Next, an extensive database of simulated compressive strength and tested permeability was created, including 21 porosities at three w/c. Analysis of the database showed that for pavement applications where high permeability and strength are required, the advised porosity is 0.26 to 0.30, producing average strengths of 14.4, 11.1, and 7.7 MPa for w/c of 0.25, 0.30, and 0.35. The model can guide the mixture design to meet target performance metrics, save materials and maintenance costs, and extend the pavement life.

DOI:

10.14359/51739157


Document: 

22-388

Date: 

December 1, 2023

Author(s):

R. M. Ghantous, V. Bui, S. Schaef, B. Fronczek, C. B. Jablonski, S. R. Reese, and W. J. Weiss

Publication:

Materials Journal

Volume:

120

Issue:

6

Abstract:

This study uses neutron radiography (NR) and visual inspection to quantify water penetration in concrete samples exposed to water pressure on one face. It provides experimental data regarding the impact of mixture proportions on the hydraulic permeability of concrete. Specifically, it illustrates the influence of water-cement ratio (w/c), curing duration, entrained air content, and coarse aggregate (CA) size and volume on water transport. In addition, this paper quantifies the impact of permeability-reducing admixtures (PRAs) on water transport in concrete. It was observed that decreasing the w/c and/or increasing the curing duration reduced the fluid transport. Liquid and powder PRAs efficiently reduced fluid transport in concrete without impacting the compressive strength. The liquid PRA showed more consistent results, likely due to better dispersion than the powder PRA. Fluid ingress in concrete samples appears to increase with entrained air content due to a lower degree of saturation (DOS) at the start of the test. Increasing the CA volume fraction or decreasing the CA size will increase the fluid transport in concrete due to an increase in the connectivity of the interfacial transition zone. The influence of entrained air content, curing duration, CA volume fraction, and CA size was less noticeable on mixtures with PRAs due to the higher density and low permeability of these samples compared to control samples.

DOI:

10.14359/51739150


Document: 

22-221

Date: 

September 1, 2023

Author(s):

C. F. Hollmann, L. Zucchetti, D. C. C. Dal Molin, and A. B. Masuero

Publication:

Materials Journal

Volume:

120

Issue:

5

Abstract:

Self-healing is a process by which concrete is able to recover its properties after the appearance of cracks, which can improve mechanical properties and durability and reduce the permeability of concrete. Self-healing materials can be incorporated into concrete to contribute to crack closure. This study aims to evaluate the influence of crystalline admixtures and silica fume on the self-healing of concrete cracks. The rapid chloride penetration test was performed on cracked and uncracked samples, from which it was possible to estimate the service life of concretes. The concretes were characterized by tests of compressive strength and water absorption by capillarity. The use of crystalline admixtures did not have a negative influence on concrete properties, but did not favor the chloride penetration resistance. The concrete with silica fume showed the lowest charge passed and highest values of estimated service life.

DOI:

10.14359/51738892


Document: 

22-340

Date: 

September 1, 2023

Author(s):

Uwazuruonye Raphael Nnodim

Publication:

Materials Journal

Volume:

120

Issue:

5

Abstract:

This study clarifies the effects of moisture (expressed as percentage saturation degree of permeable pore voids, PSD) on water ingress properties of concrete and establishes a region where PSD does not affect the quantitative water absorption. Experimental measurements and finite element model (FEM) simulation results for ordinary portland cement (OPC) concretes preconditioned to equilibrium moisture formed plateaus between 21 and 58% PSD. Non-continuous finer capillary pores (ϕ10 nm [3.937 × 10–4 mil, thou] to ϕ100 nm [3.937 × 10–3 mil, thou]) constitute the empty pores within the plateau region before tests. Water sorptivity of OPC and slag cement concrete blocks at several degrees of surface moisture with internal moisture gradients validate the existence of the plateau within the PSD range. Measuring short-term water absorption within this plateau region eliminates the effects of initial surface moisture content on the measured properties and evaluates the continuity and connectivity of pores, which is the major indicator of the durability of concrete.

DOI:

10.14359/51739018


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