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Please note: All sessions and events take place in Central Daylight Time: CDT (UTC-5).

H=Hyatt Regency Dallas; U=Union Station

Synergy of Nanoparticles with Supplementary Cementitious Materials in Concrete, Part 2 of 2

Wednesday, October 26, 2022  11:00 AM - 1:00 PM, H-Reunion E

Recently, many researchers have revealed that addition of nanoparticles can provide synergy to improve physical and chemical properties of concrete materials. Nanoparticles can act like fillers to refine pore structure and immobilize water movement in cement paste. They can function like seeds for CSH nucleation to accelerate cement hydration, thus compensating the delayed hydration and strength development caused by commonly used supplementary cementitious materials (SCMs) like fly ash in concrete. Many nanoparticles can also interact with SCMs to produce stable and/or cementing reaction products, thus further enhancing concrete strength and durability. The objectives of this technical session are to summarize the recent progress on the use of nanoparticles in cement-based materials containing SCMs, to have a better understanding of the synergic effects of nanoparticles and SCMs, and to recognize challenges in the use of nanoparticles in cement-based materials.
Learning Objectives:
(1) Discuss effects of nanoparticles on performance of sustainable cementitious materials;
(2) Inspect extended us of high volume supplementary cementitious materials in concrete by incorporating nanoparticles;
(3) Demonstrate enhanced concrete durability resulting from use of nanoparticles in combination with supplementary cementitious materials;
(4) Develop a better understanding of synergy between nanoparticles and supplementary cementitious materials.


Complimentary Effects of Eco-Friendly Biochar and Nanosilica on the Performance of Sustainable Cements

Presented By: Maria Konsta
Affiliation: University of Texas at Arlington
Description: Presently, the environmental impact on climate change and consumption of natural resources of construction materials and more generally of building activities is matter of concern. Within this context, the focus of this study is to investigate the role of biochar (a solid carbonaceous by-product material resulting from pyrolysis of residual biomass) as a sustainable ingredient for improving the performance of cementitious mortars. Biochar has a highly porous microstructure; hence, nanosilica is added to investigate their synergistic effects on the mechanical and hydration behavior of ordinary Portland cement (OPC)-based mortars. Our findings suggest that biochar together with nanosilica have the potential to improve mechanical and hydration properties, offering an opportunity for future studies to extend biochar utilization in construction.


Nano-Silica Aqueous Suspension (Liquid Fly Ash): Pozzolanic Reactivity and Effect on ASR Mitigation

Presented By: Luna Lu
Affiliation: Purdue University
Description: Implementation of nano-technology in construction and building materials has made a great progress in the last decade. In addition to self-sensing, self-cleaning and energy conversion applications, noticeable amount of research on utilization of nano-particles in hydrated cementitious system was performed. Among them, nano-silica can be highlighted as one of the promising additives due to its pozzolanic reactivity potential together with seeding and filler effect. In this work, the study on estimation of the pozzolanic reactivity of the four different aqueous nano-silica suspensions, also known as "Liquid Fly Ash" (LFA) is presented. For characterization of the LFAs, TEM imaging with averaged EDX spectra and pH measurements were conducted. Slurries consisting of calcium hydroxide and LFAs as well as paste samples with addition of LFAs were prepared and tested by using Isothermal Calorimeter (IC), Thermogravimetric Analysis (TGA), Quantitative X-Ray analysis (QXRD), pH measurement techniques. Moreover, the development of compressive strength over time was tested on mortar cube samples. The achieved results were used to evaluate and quantify the effect of LFA parameters (particle size range and modification type) on the pozzolanic reactivity, reaction product phases, pore solution alkalinity and compressive strength of the hydrating cementitious system. Also, the mortar prisms were made by addition of LFAs and tested for ASR expansion according to ASTM C1260 and C1567 to estimate the ASR mitigation potential of the LFAs both in plain OPC and Fly Ash replaced OPC system. In addition to expansion results, the Scanning Electron Microscopy (SEM) analysis was applied upon termination of the test. The results indicated that colloidal nano-silica can be a promising solution to improve the durability of concrete and mitigate ASR.


Can Nano Technology Help to Overcome the Challenges of Using High Contents of Fly Ash?

Presented By: Jussara Tanesi
Affiliation: American Engineering Testing
Description: The interest in more sustainable concrete mixtures made with the supplementary cementitious materials has kept growing significantly in the past few years. Nevertheless, the early-age property development (e.g., setting and strength gain) of these mixtures remains a challenge and, in most cases, prevent their efficient use in practice. In the presented study, the effect of lab synthetized nano-aluminosilicates and commercially available nano-silica and C-S-H on the mixes containing up to 60% of fly ash was investigated. The heat release and setting times of paste mixtures and the compressive strength of mortar mixes were evaluated. It is observed that for the nano-aluminosilicates, the early age properties improvement requires the use of an optimal silicon-aluminum ratio. For commercial nano-silica and C-S-H, the dosage increase does not necessarily improve the properties of the mixtures.


Newly Synthesized Nanotube Hybrids for Sustainable and Multifunctional Coal Ash Based Concrete

Presented By: Panagiotis Danoglidis
Affiliation: University of Texas At Arlington
Description: Carbon nanotube hybrids/coal ash-based concrete was prepared showing unmatched mechanical/fracture properties and sensing functionalities. The newly synthesized nanotube hybrid suspensions, prepared using ultrasonication, were found to exhibit excellent dispersibility and long-term stability for a period over 90 days. The chemical structure and functional groups of the dispersed nanotube hybrids were evaluated by FTIR and Raman Spectroscopy. A considerably increased (around 65%) electrical conductivity was observed, as compared to the plain coal ash concrete, which coupled with the enhanced modulus and toughness led to a superior electromechanical response, essential for strain sensing and progressive failure monitoring.


The Effects of Nanoclays, CNTs and Their Combination on the Fresh and Hardened Properties of Systems Incorporating Fly Ash and Slag

Presented By: Shiho Kawashima
Affiliation: Columbia University
Description: This talk will cover a performance-based study on the effects of attapulgite nanoclay and carbon nanotubes (CNTs) on the fresh and hardened properties of mortars with partial cement replacement with fly ash and blast furnace slag. Shear rheology was applied to measure yield stress and viscosity, and the tack test was applied to measure static cohesion. Results show that the additives had differing effects on 100% cement mortars versus blended (50% cement, 25% fly ash, 25% slag). The nanoclays increased yield stress and static cohesion and decreased plastic viscosity in both systems, but these effects were more marked in the cement mortar than in the blended. On the other hand, CNTs increased all measured rheological parameters in the cement mortar and decreased them in the blended. The rheological results highlight the importance of considering the binder system when utilizing additives with exceptional surface. In the hardened state, electrical resistivity, compressive strength, and tensile strength were evaluated. Results indicate that although nanoclays are utilized primarily as a rheological modifier, they have the potential to enhance mechanical properties.

Upper Level Sponsors

Ash Grove
Baker
Conseal
Controls Group
Euclid Chemical
GCP
Master Builders
PoreShield
PS=0
ACI Northeast Texas Chapter

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