ASR and sulphate performance of mortar containing industrial waste

This study investigates the potential alkali silica reaction (ASR) of ferronickel slag (FNS) aggregate, which is a by‐product of nickel production. A class F fly ash was used as a possible ASR mitigation in accelerated mortar bar test (AMBT) specimens containing 50% FNS. There were visible surface cracks on the specimens using no fly ash or 10% fly ash. Use of 20% fly ash reduced expansion by 45% as compared to that with 10% fly ash. In accordance with the expansion limits of Australian Standard, the mixtures using 20 and 30% fly ash were categorized as slowly reactive and nonreactive, respectively. Thermogravimetric analysis (TGA) and microstructural observations confirmed the effectiveness of fly ash in reducing Portlandite content that reduced the ASR expansion. Therefore, the use of 20–30% fly ash as cement replacement is considered as an adequate ASR mitigating measure of FNS fine aggregate.

Section: Introductionmentioning

confidence: 99%

“…SCMs can bind the free alkali and reduce alkalinity of the pore solution that is required for ASR to take place. 16,17 Therefore, the use of fly ash and ground granulated blast furnace slag (GGBFS) has been found to reduce ASR expansion. 18 The chemical composition of an SCM can significantly influence its effectiveness to reduce ASR.…”

Section: Introductionmentioning

confidence: 99%

Potential alkali silica reaction expansion mitigation of ferronickel slag aggregate by fly ash

Saha

Sarker

2018

“…The application of SCM reduces the portlandite content due to the pozzolanic reaction, as well as minimizes the overall volume of calcium oxide from concrete. As a result, significant alkalinity reduction can be observed in concrete pore solution, which is one of the key factors to initiate ASR . Furthermore, alkali fixation of calcium silicate hydrate (C‐S‐H) by the SCM plays a crucial role to reduce the alkalinity of pore solution .…”

Section: Introductionmentioning

confidence: 99%

A comparative study between ASTM C1567 and ASTM C227 to mitigate alkali‐silica reaction

Saha

2018

The primary objective of this study was to evaluate the two different widely adopted test methods such as american society for testing and materials (ASTM) C1567 “accelerated mortar bar method” and ASTM C227 “mortar bar method” to identify the alkali‐silica reaction (ASR) of ferronickel slag fine aggregates. The ASR mitigation measure was assessed by the application of supplementary cementing material such as fly ash. During the experimental investigation visual inspection, mortar bar expansion and tensile strength measurements were evaluated. The test results point out that mortar bar method was unsuccessful to identify the ASR due to significant alkali leaching during the experiment. On the other hand, accelerated mortar bar method was successful to identify ASR and able to determine the safe dosage of fly ash to mitigate this deleterious expansion.

“…In addition, pozzolans were found to increase the strength and chemical resistance and reduce heat of hydration, permeability, porosity and alkali-silica expansion, which was another bonus [9]. The most frequently used pozzolans in the current concrete industry are industrial by-products such as fly ashes [10], silica fume [11], metallurgical slags [12] or waste glass [13]. Agricultural wastes, represented, for instance, by rice husk ash [14], bagasse ash [15] or sugar cane leaf [16], are being increasingly used, particularly in the regions where they are produced.…”

Section: Introductionmentioning

confidence: 99%

Mechanical, durability and hygrothermal properties of concrete produced using Portland cement-ceramic powder blends

Kulovaná

Vejmelková

Keppert

et al. 2016

Blended Portland cement‐ceramic powder binder containing up to 60 % fine‐ground waste ceramics from a brick factory is used in concrete mix design as an environmentally friendly alternative to the commonly used Portland cement. The experimental analysis of basic physical characteristics, mechanical and fracture‐mechanical properties, durability properties and hygrothermal characteristics shows that the optimal amount of ceramic powder in the mix is 20 % of the mass of blended cement. The decisive parameters in that respect are compressive strength, liquid water transport parameters and resistance to de‐icing salts, which are not satisfactory for higher ceramics dosage in the blends. In the case of other parameters studied, the limits for the effective use of ceramic powder are higher: 40 % for effective fracture toughness and specific fracture energy, 60 % for frost resistance and chemical resistance to MgCl2, NH4Cl, Na2SO4, HCl and CO2. The water vapour diffusion coefficient is found to increase with increasing ceramics content, which for wet envelopes can be considered as a positive feature, but may have a negative effect for dry envelopes. The thermal conductivity of all mixes increases fast with growing moisture content; differences of up to 50 % between the dry and water‐saturated state values are observed. This has to be taken into account in energy‐related calculations.