scholarly journals Preparation, Physicochemical Properties, and Long-Term Performance of Photocatalytic Ceramsite Sand in Cementitious Materials

2017 ◽  
Vol 7 (8) ◽  
pp. 828 ◽  
Author(s):  
Du Zhao ◽  
Fazhou Wang ◽  
Peng Liu ◽  
Lu Yang ◽  
Shuguang Hu ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Cementitious Materials ◽  
Long Term Performance ◽  
Term Performance

Grouted Waste Leach Tests: Pursuit of Mechanisms and Data for Long-Term Performance Assessment

1989 ◽  
Vol 176 ◽  
Author(s):  
R. Jeff Serne
Keyword(s):  
Diffusion Processes ◽  
Scale Up ◽  
Liquid Waste ◽  
Effective Diffusivity ◽  
Cementitious Materials ◽  
Solidified Waste ◽  
Effective Diffusivities ◽  
Long Term Performance ◽  
Term Performance

ABSTRACTAt Hanford, low-level liquid nuclear waste is being mixed with cementitious materials (grout) to form leach-resistant solid waste. Prior to grouting each liquid waste, an assessment must be performed to evaluate the long-term environmental impact. These predictions rely upon a diffusioncontrolled release model and short-term laboratory leach data on small grout samples. This paper describes size scale-up and inventory scale-up experiments that evaluate whether diffusion does in fact control the release of contaminants. The results of the volume scale-up test suggest that tests on grout cylinders between the sizes 3 cm dia. by 3 cm length and 30 cm dia. by 29 cm length yield comparable results. These data and other available literature suggest that extrapolation of leach results to large blocks of solidified waste is defensible.The inventory scale-up tests for 125I and selenium show a constant effective diffusivity regardless of the original inventory. This suggests that diffusion processes do in fact control the release of iodide and selenium from grout. The 99Tc effective diffusivities may not remain constant with changes in inventory.

Study on the Effects of Natural Pozzolan and Limestone Powder on Mechanical Properties of Roller Compacted Concrete Pavements

2011 ◽  
Vol 250-253 ◽  
pp. 3619-3623 ◽  
Author(s):  
Morteza Madhkhan ◽  
Armin Hamidi ◽  
Navid Salehi
Keyword(s):  
Compressive Strength ◽  
Cementitious Materials ◽  
Production Costs ◽  
Limestone Powder ◽  
Concrete Pavements ◽  
Natural Pozzolan ◽  
Two Factors ◽  
Long Term Performance ◽  
Term Performance

Due to high maintenance and production costs of conventional asphalt pavements in recent years, substitution of concrete pavements has been taken into account. One important factor of such pavements is the long-term performance. The substitution of pozzolanic materials with existing cement in the mixture is a common choice to improve the durability factors and to increase the long term compressive strength. Owing to this change in cementitious materials, a general anticipation of the pozzolanic behavior to be observed is that the early age compressive strength gets decreased. On the other hand, this defect will be compensated in the long-term compressive strength. Furthermore, as conventional loads of road pavements are concerned, the tensile and flexural strengths have their own importance. Regarding these two factors, the related tests were also performed and the results were analyzed. The main purpose is to find the optimum material among these 2 types of pozzolanic supplements and its percentage of substitution with the preference of having the best average strength in both long and short term performances. Altogether, the natural pozzolan had better performance than limestone powder.

scholarly journals A new test for combined Ca-leaching and sulphate resistance of cementitious materials

2018 ◽  
Vol 199 ◽  
pp. 02005 ◽  
Author(s):  
Florian R. Steindl ◽  
Andre Baldermann ◽  
Isabel Galan ◽  
Marlene Sakoparnig ◽  
Martin Dietzel ◽  
...  
Keyword(s):  
Testing Procedure ◽  
Calcium Sulphate ◽  
Cementitious Materials ◽  
Growth Stages ◽  
Chemical Attack ◽  
Aqueous Environments ◽  
Alternative Test ◽  
Long Term Performance ◽  
Term Performance

Limitations in the understanding of chemical key controls on concrete damaging mechanisms exacerbate predictions on the long-term performance and durability of cementitious materials. Therefore, the scope of the project “ASSpC Advanced and Sustainable Sprayed Concrete” is to obtain a better mechanistic understanding of the processes underlying deleterious chemical attacks. The herein presented alternative test, loosely following the regulations of the German Building Authority (DIBt) testing procedure (the so-called SVA test) for sulphate resistance, investigates the resistance of concrete mixes with high levels of limestone substitution (35%, 50% and 65%) against sulphate attack in a 10 g L-1 Na2SO4 solution at ambient temperature. Powdered samples were used in favour of prisms or drill cores to accelerate alteration reactions and to eliminate variations in microstructure or porosity. Based on throughout chemical and mineralogical characterisation of the experimental solutions and solid materials, we identified and traced several mineral reactions taking place in a chronological order: (1) dissolution of portlandite and Ca-leaching from C-S-H started immediately at the beginning of the experiments and provided the physicochemical conditions favourable for (2) the precipitation of massive calcite and ettringite during the advanced stage of chemical attack. Ongoing changes in the aqueous composition indicate that C-S-H dissolves incongruently and may be transformed into Si-bearing hydrogarnet. The amount of precipitated ettringite is apparently controlled by the availability of calcium, sulphate and aluminium and the precipitation rate correlates with the superplasticiser demand of the concrete mixes and with the pH of the solution during the nucleation and crystal growth stages, respectively. Our test allows distinguishing between competing reaction paths and kinetics and is capable to provide new insights into concrete damaging mechanisms in sulphate-loaded aqueous environments.

The Behaviours of Cementitious Materials in Long Term Storage and Disposal: An Overview of Results of the IAEA Coordinated Research Project

2009 ◽  
Vol 1193 ◽  
Author(s):  
Zoran Drace ◽  
Michael I. Ojovan
Keyword(s):  
Cementitious Materials ◽  
Research Project ◽  
Main Research ◽  
Long Term Storage ◽  
Research Organizations ◽  
And Performance ◽  
Long Term Performance ◽  
Term Performance ◽  
Cementitious Systems

AbstractCementitious materials are widely used in waste management systems with different aims and requirements for long term performance. Both conventional and novel cementitious materials are used to create reliable immobilising elements for safe storage and disposal of wastes. The barrier elements as well as interactions envisaged between various components are important to ultimately ensure the overall safety of a storage/disposal system. The behaviour and performance of cementitious materials including waste package components, wasteform and backfilling were analysed within the IAEA Coordinated Research Project which involved 26 research organizations from 21 Member States MS). The paper presents briefly the main research outcomes for conventional cementitious systems; novel materials and technologies; testing and waste acceptance criteria; and modelling long term behaviour.

scholarly journals Summary Findings of Re-engineered Continuously Reinforced Concrete Pavement: Volume 1

2021 ◽  
Author(s):  
Jeffery Roesler ◽  
◽  
Sachindra Dahal ◽  
Dan Zollinger ◽  
W. J. Weiss ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Research Effort ◽  
Cementitious Materials ◽  
Reinforced Concrete Beams ◽  
Supplementary Cementitious Materials ◽  
Initial Cost ◽  
Long Term Performance ◽  
Term Performance

This research project conducted laboratory testing on the design and impact of internal curing on concrete paving mixtures with supplementary cementitious materials and evaluated field test sections for the performance of crack properties and CRCP structure under environmental and FWD loading. Three experimental CRCP sections on Illinois Route 390 near Itasca, IL and two continuously reinforced concrete beams at UIUC ATREL test facilities were constructed and monitored. Erodibility testing was performed on foundation materials to determine the likelihood of certain combinations of materials as suitable base/subbase layers. A new post-tensioning system for CRCP was also evaluated for increased performance and cost-effectiveness. This report volume summarizes the three year research effort evaluating design, material, and construction features that have the potential for reducing the initial cost of CRCP without compromising its long-term performance.

Fine Particle Mass Monitoring with Low-Cost Sensors: Corrections and Long-Term Performance Evaluation

2019 ◽  
Author(s):  
Carl Malings ◽  
Rebecca Tanzer ◽  
Aliaksei Hauryliuk ◽  
Provat K. Saha ◽  
Allen L. Robinson ◽  
...  
Keyword(s):  
Performance Evaluation ◽  
Fine Particle ◽  
Low Cost ◽  
Particle Mass ◽  
Long Term Performance ◽  
Term Performance

Long-term performance of the Hancock bioprosthetic conduit for aortic root replacement

2008 ◽  
Vol 56 (S 1) ◽  
Author(s):  
CC Badiu ◽  
W Eichinger ◽  
D Ruzicka ◽  
I Hettich ◽  
S Bleiziffer ◽  
...  
Keyword(s):  
Aortic Root ◽  
Aortic Root Replacement ◽  
Long Term Performance ◽  
Term Performance
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