scholarly journals Three decades of international RILEM activities to combat deleterious Alkali-Silica Reactions (ASR) in concrete.

2018 ◽  
Vol 199 ◽  
pp. 03001
Author(s):  
Børge Johannes Wigum ◽  
Jan Lindgård
Keyword(s):  
State Of The Art ◽  
Construction Materials ◽  
Performance Testing ◽  
Test Methods ◽  
Alkali Content ◽  
International Union ◽  
Field Exposure ◽  
Performance Based Assessment

Since 1988, the International Union of Laboratories and Experts in Construction Materials, Systems and Structures (RILEM) Technical Committees (TCs) have been seeking to establish universally applicable test methods for assessing the alkali-reactivity potential of aggregates, and from later on, for concrete mixes. TC 106 (1988 – 2001) focused on accelerated aggregate tests. The successor committee TC 191-ARP (2001 – 2006) also included work on diagnosis/appraisal & specification. TC 219-ACS (2006 – 2014) introduced work on performance testing & modelling. The major recommendations were published as a RILEM State-of-the-art Report in 2016. In 2014, TC 258-AAA was established, scheduling to finish the work on performance-based assessment in 2019. This current TC is focusing on the following Work Packages; WP1Performance based testing concepts, WP2 Relationship between results from laboratory and field and the establishment of field exposure sites, WP3 Testing of potential alkalis released from certain types of aggregates and measurement of internal concrete alkali content, and eventually; WP4 Verification of alkalis released from aggregates.

scholarly journals A State-of-the-Art Review on Core–Shell Pigments Nanostructure Preparation and Test Methods

Micro ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 55-85
Author(s):  
Kwok Wei Shah ◽  
Ghasan Fahim Huseien ◽  
Harn Wei Kua
Keyword(s):  
Building Materials ◽  
Elevated Temperatures ◽  
State Of The Art ◽  
Construction Materials ◽  
Test Methods ◽  
Core Shell ◽  
Coating Materials ◽  
Potential Core ◽  
Novel Technologies ◽  
Shell Nanostructures

Uses of novel technologies for improving the durability and lifespan of the construction materials have emerged as viable solutions toward the sustainable future wherein the coating industry plays a significant role in economy growth and better livelihoods. Thus, the continual innovation of various technologies to introduce diverse market products has become indispensable. Properties of materials like color stability under UV, elevated temperatures and aggressive environments, and skid and abrasion resistance are the main challenges faced by commercial coating materials, leading to more demand of natural materials as sustainable agents. Lately, nanostructured core–shell pigments with unique compositions have widely been utilized in composite materials to enhance their properties. Core–shell particles exhibit smart properties and have immense benefits when combined with building materials. Based on these facts, we comprehensively overviewed the state-of-the-art research of core–shell nanomaterials in terms of their preparation and performance evaluation methods, as well as feasible applications. The first part of this article discusses effective shell materials, including most common silica and titanium oxides. In addition, nanotechnology enabling the production and patterning of low-dimensional materials for widespread applications is emphasized. The second part deals with various potential core materials used to achieve core–shell nanostructures. The third part of this paper highlights some interesting mechanisms of core–shell structures in the modified systems that display high stability, durability, efficiency, and eco-friendliness. Finally, different applications of these core–shell nanostructures are underscored together with their test methods to evaluate their performances.

Developments in Bulb Flats and Other Hot Rolled Special Steel Profiles for Advancing Commercial and Naval Shipbuilding in the U.S.

2000 ◽  
Vol 16 (04) ◽  
pp. 193-206
Author(s):  
Iain Braidwood ◽  
Geoff Lofthouse
Keyword(s):  
Composite Structures ◽  
State Of The Art ◽  
Construction Materials ◽  
Structural Performance ◽  
Life Cycle Costs ◽  
Naval Vessel ◽  
Special Steel ◽  
Steel Shapes ◽  
The Uk ◽  
Hot Rolled

Special steel profiles are increasingly being used for commercial and warship construction to reduce production and life cycle costs. In particular, bulb flats (Holland profiles), manufactured by special profiles businesses, are increasingly being used for plate stiffening in warships and naval auxiliaries. Examples are the UK's Type 23 Frigates, the LPH HMS Ocean, Watson Class Sealift ships and the Dutch LPD HrMs Rotterdam, as well as, looking to the future, the UK Type 45 Destroyer. Some comparison will be made of naval vessel construction on both sides of the Atlantic, particularly looking at the advantages that bulb flats can bring to naval vessel construction. This paper will discuss the challenge of introducing new shapes, examine the state of the art in the production of special steel shapes and describe metallurgical developments that enable the delivery of shapes with required structural performance and suitability for production. Shipbuilding developments such as laser welding are being addressed with a view to the manufacture of special profiles, particularly where tolerance and chemical composition issues need to be addressed. Future lightweight vessel construction may involve a mix of aluminium, steel and composite structures. Special profiles can be developed to assist in the joining of these different construction materials.

Expedited Testing Program for Performance Characterization of Asphalt Mixtures

2019 ◽  
Vol 2673 (12) ◽  
pp. 225-233
Author(s):  
Intikhab Haidar ◽  
Charles W. Schwartz ◽  
Sadaf Khosravifar
Keyword(s):  
Permanent Deformation ◽  
Performance Testing ◽  
Testing Procedure ◽  
Test Methods ◽  
Asphalt Mixtures ◽  
Test Specifications ◽  
Research Grade ◽  
Repeated Load ◽  
Lengthy Process

The past two decades have seen significant efforts to standardize a series of simplified test methods to characterize the dynamic modulus (DM) and repeated load permanent deformation (RLPD) performance characteristics of asphalt mixtures using the asphalt mixtures performance tester (AMPT). While the current AASHTO T 79 test specifications for the AMPT are faster and easier to perform than their preceding research grade test protocols, there is still reluctance among highway agencies and industry to conduct performance testing using the AMPT. One significant reason is the lengthy process of sample preparation and testing for the DM and RLPD tests. Two studies to expedite this process are reported here. First, the potential for abbreviating the DM testing procedure was examined. It provides the option to fully exclude testing at 40°C by adding an additional frequency of 0.01 Hz at 20°C. This approach reduces time for testing as well as for sample conditioning at high temperature. Second, the possibility of reducing the total number of required specimens was evaluated. The variation of the DM under repetitive testing and the appropriateness of performing the RLPD test on samples already tested for DM were evaluated. The results showed that specimen damage or densification because of DM testing is insignificant. As a consequence, DM test specimens can be re-used for RLPD testing, reducing the required number of samples from 12 to 9.

Performance of Hot and Cold Recycled Mixtures with High Reclaimed Asphalt Pavement Content

2020 ◽  
Vol 2674 (9) ◽  
pp. 714-726
Author(s):  
Edith Arámbula-Mercado ◽  
Santiago J. Chavarro-Muñoz ◽  
Sheng Hu ◽  
Howie Moseley
Keyword(s):  
Urban Areas ◽  
Life Cycle Cost ◽  
Asphalt Pavement ◽  
Performance Testing ◽  
Hydrated Lime ◽  
Test Methods ◽  
Reclaimed Asphalt Pavement ◽  
Moisture Susceptibility ◽  
Reclaimed Asphalt ◽  
Maintenance And Rehabilitation

Florida Department of Transportation yearly maintenance and rehabilitation activities include milling and resurfacing of approximately 2,000 lane miles of roadway, with an average resurfacing depth of about 2.1 in. (55 mm). These activities result in the generation and accumulation of roughly 1.8 million tons of reclaimed asphalt pavement (RAP) each year. The use of elevated quantities of RAP in asphalt pavement provides an environmentally responsible solution to the accumulated RAP surplus in some urban areas, while at the same time offering an economical pavement maintenance and rehabilitation option to local agencies facing budget constraints. The objective of this project was to compare the performance of mixtures with 60% RAP content to be used primarily on low volume roads (average daily traffic <750 vehicles) and suggest adequate test methods within the context of a balanced mix design approach. To accomplish this objective, three types of mixtures were considered: hot, cold with emulsion, and cold with foamed binder. Performance testing included intermediate temperature cracking, rutting, moisture susceptibility, and durability. The hot recycled mixtures showed good moisture susceptibility and cracking resistance, especially when rejuvenators were incorporated. The cold recycled mixtures showed poor moisture susceptibility and durability characteristics, which were alleviated when hydrated lime or Portland cement was incorporated in the emulsified and foamed mixtures, respectively. Most hot recycled mixtures, and all the cold recycled mixtures, exhibited poor rutting behavior, likely because of the harsh conditions of the test. A life-cycle cost analysis demonstrated more favorable savings when cold recycled mixtures were used.

State of the art on geopolymer concrete

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Zoi G. Ralli ◽  
Stavroula J. Pantazopoulou
Keyword(s):  
Mechanical Performance ◽  
State Of The Art ◽  
Construction Materials ◽  
Cementitious Materials ◽  
Sustainable Construction ◽  
Geopolymer Concrete ◽  
Critical Material ◽  
Content Type ◽  
Critical Requirement

PurposeImportant differentiating attributes in the procedures used, the characteristic mineral composition of the binders, and the implications these have on the final long term stability and physico-mechanical performance of the concretes produced are identified and discussed, with the intent to improve transparency and clarity in the field of geopolymer concrete technologies.Design/methodology/approachThis state-of-the-art review covers the area of geopolymer concrete, a class of sustainable construction materials that use a variety of alternative powders in lieu of cement for composing concrete, most being a combination of industrial by-products and natural resources rich in specific required minerals. It explores extensively the available essential materials for geopolymer concrete and provides a deeper understanding of its underlying chemical mechanisms.FindingsThis is a state-of-the-art review introducing the essential characteristics of alternative powders used in geopolymer binders and the effectiveness these have on material performance.Practical implicationsWith the increase of need for alternative cementitious materials, identifying and understanding the critical material components and the effect they may have on the performance of the resulting mixes in fresh as well as hardened state become a critical requirement to for short- and long-term quality control (e.g. flash setting, efflorescence, etc.).Originality/valueThe topic explored is significant in the field of sustainable concrete technologies where there are several parallel but distinct material technologies being developed, such as geopolymer concrete and alkali-activated concrete. Behavioral aspects and results are not directly transferable between the two fields of cementitious materials development, and these differences are explored and detailed in the present study.

Estimation of Liquefaction Potential by in Situ Methods

1995 ◽  
Vol 11 (3) ◽  
pp. 431-455 ◽  
Author(s):  
Steven D. Glaser ◽  
Riley M. Chung
Keyword(s):  
Seismic Velocity ◽  
State Of The Art ◽  
Test Methods ◽  
Estimation Methods ◽  
Penetration Test ◽  
Liquefaction Potential ◽  
Current State ◽  
Undisturbed Samples ◽  
In Situ Methods

This report examines the state-of-the-art of in situ methods of estimating liquefaction potential in sands. In situ methods are especially important since “undisturbed” samples of loose sand for laboratory testing are virtually unobtainable. Various penetration test methods are examined, such as the SPT, DMT, and the CPT and variants. These methods are completely empirical in nature, and have worked well to date. The current state-of-practice is an SPT-based method. Intrusive, seismic-based tests are also examined: the cross-hole, down-hole tests, and down-hole logger. The seismic velocity-based predictors have a stronger physical basis than the penetration test-based estimation methods, but need a larger database. A non-intrusive test, the Spectral Analysis of Surface Waves technique, seems especially suited for examining sites of large areal extent.

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