Sustainable and Durable Performance of Pozzolanic Additions to Prevent Alkali-Silica Reaction (ASR) Promoted by Aggregates with Different Reaction Rates

The increased use of industrial wastes and by-products to produce concretes and blended cements is a lever to achieve carbon neutrality. Furthermore, they could improve their durability. Some pozzolanic additions can minimize the alkali-silica reaction (ASR), which is a well-known deleterious process that occurs between some reactive aggregates and the alkaline pore solution found in mortars and concretes. This work quantifies the efficiency of four pozzolanic materials (natural pozzolan, P, siliceous coal fly ash, V, silica fume, D, and blast-furnace slag, S) assessed by means of compressive strength testing, open porosity, ASR-expansion measurements, and SEM microscopy. Accelerated expansion tests were performed in mortar bars with a cement/sand ratio of 1/2.25 and a water/cement ratio of 0.47, two reactive aggregates and a non-reactive one. The major contributions of this paper are: (i) The more aggregate reactivity is, the higher ASR mitigation level was found when additions were added and (ii) The best additions for ASR inhibition are silica fume and fly ash.

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Durability of Blended Cements Made with Reactive Aggregates

Materials ◽

10.3390/ma14112948 ◽

2021 ◽

Vol 14 (11) ◽

pp. 2948

Author(s):

Esperanza Menéndez ◽

Miguel Ángel Sanjuán ◽

Ricardo García-Roves ◽

Cristina Argiz ◽

Hairon Recino

Keyword(s):

Fly Ash ◽

Silica Fume ◽

Coal Fly Ash ◽

Alkali Silica Reaction ◽

Hardened Concrete ◽

Natural Pozzolan ◽

Blended Cements ◽

Pozzolanic Material ◽

Level Ii ◽

Points Of View

Alkali–silica reaction (ASR) is a swelling reaction that occurs in concrete structures over time between the reactive amorphous siliceous aggregate particles and the hydroxyl ions of the hardened concrete pore solution. The aim of this paper is to assess the effect of pozzolanic Portland cements on the alkali–silica reaction (ASR) evaluated from two different points of view: (i) alkali-silica reaction (ASR) abatement and (ii) climatic change mitigation by clinker reduction, i.e., by depleting its emissions. Open porosity, SEM microscopy, compressive strength and ASR-expansion measurements were performed in mortars made with silica fume, siliceous coal fly ash, natural pozzolan and blast-furnace slag. The main contributions are as follows: (i) the higher the content of reactive silica in the pozzolanic material, the greater the ASR inhibition level; (ii) silica fume and coal fly ash are the best Portland cement constituents for ASR mitigation.

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Durability of blended cement against sodium sulphate attack and alkali-silica reaction

10.32920/ryerson.14662332.v1 ◽

2021 ◽

Author(s):

Giri Raj Adhikari

Keyword(s):

Fly Ash ◽

Silica Fume ◽

Alkali Silica Reaction ◽

Sulphate Attack ◽

Ternary Blends ◽

Replacement Level ◽

Fly Ashes ◽

Study Results ◽

High Calcium ◽

High Calcium Fly Ash

Blended cements were studied for their efficacy against sulphate attack and alkali-silica reaction using six different types of fly ashes, a slag, a silica fume and four types of General Use Portland cement of different alkalinity. The study results showed that low calcium fly ash, silica fume and ground granulated blast furnace slag enhanced the sulphate resistance of cement with increased efficacy with the increase in the replacement level. However, slag and silica fume, especially at low replacement levels, exhibited increased rate of expansion beyond the age of 78 weeks. On the contrary, high calcium fly ashes showed reduced resistance to sulphate attack with no clear trend between the replacement level and expansion. Ternary blends consisting of silica fume, particulary in the amount of 5%, high calcium fly ashes and General Use (GU) cement provided high sulphate resistance, which was attributable to reduced permeability. In the same way, some of ternary blends consisting of slag, high calcium fly ash and GU cement improved sulphate resistance. Pre-blending optimum amount of gypsum with high calcium fly ash enhanced the latter's resistance to sulphate attack by producing more ettringite at the early stage of hydration. In the context of alkali-silica reaction permeability was found to be a contributing factor to the results of the accelerated mortar bar test. High-alkali, high-calcium fly ash was found to worsen the alkali silica reaction when used in concrete containing some reactive aggregates. Ternary blend of slag with high calcium fly ash was found to produce promising results in terms of counteracting alkali-silica reaction.

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Mineralogy and thermal expansion study of mullite-based ceramics synthesized from coal fly ash and aluminum dross industrial wastes

Ceramics International ◽

10.1016/j.ceramint.2019.01.041 ◽

2019 ◽

Vol 45 (6) ◽

pp. 7488-7494 ◽

Cited By ~ 7

Author(s):

Choo Thye Foo ◽

Mohamad Amran Mohd Salleh ◽

Kok Kuan Ying ◽

Khamirul Amin Matori

Keyword(s):

Thermal Expansion ◽

Fly Ash ◽

Coal Fly Ash ◽

Industrial Wastes ◽

Aluminum Dross ◽

Thermal Expansion Study

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MECHANICAL AND DURABILITY CHARACTERISTICS OF GGBS DOLOMITE GEOPOLYMER CONCRETE

Proceedings of International Structural Engineering and Construction ◽

10.14455/isec.res.2019.108 ◽

2019 ◽

Vol 6 (1) ◽

Author(s):

Aikot Pallikkara Shashikala ◽

Praveen Nagarajan ◽

Saranya Parathi

Keyword(s):

Fly Ash ◽

Silica Fume ◽

Rice Husk ◽

Rice Husk Ash ◽

Setting Time ◽

Cementitious Materials ◽

Strength Properties ◽

Industrial Wastes ◽

Geopolymer Concrete ◽

By Products

Production of Portland cement causes global warming due to the emission of greenhouse gases to the environment. The need for reducing the amount of cement is necessary from sustainability point of view. Alkali activated and geopolymeric binders are used as alternative to cement. Industrial by-products such as fly ash, ground granulated blast furnace slag (GGBS), silica fume, rice husk ash etc. are commonly used for the production of geopolymer concrete. This paper focuses on the development of geopolymer concrete from slag (100% GGBS). Effect of different cementitious materials such as lime, fly ash, metakaolin, rice husk ash, silica fume and dolomite on strength properties of slag (GGBS) based geopolymer concrete are also discussed. It is observed that the addition of dolomite (by-products from rock crushing plants) into slag based geopolymer concrete reduces the setting time, enhances durability and improves rapidly the early age strength of geopolymer concrete. Development of geopolymer concrete with industrial by-products is a solution to the disposal of the industrial wastes. The quick setting concrete thus produced can reduce the cost of construction making it sustainable also.

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