scholarly journals Durability of pulverised fuel ash (PFA) concrete exposed to acidic and alkali conditions

2019 ◽  
Vol 258 ◽  
pp. 05015 ◽  
Author(s):  
Saiful Baharin Duraman ◽  
Md. Fadhil Hakim Haji Omar
Keyword(s):  
Concrete Structures ◽  
Pozzolanic Reaction ◽  
Polluted Water ◽  
Alkali Silica Reaction ◽  
Acid Attack ◽  
Fuel Ash ◽  
Alkaline Environments ◽  
High Alkalinity ◽  
Acidic Conditions ◽  
Strength And Durability

Pulverised Fuel Ash (PFA) is becoming an important component in concrete due to potentially improved properties such as workability, later age strength and durability. Concrete structures may be susceptible to acid attack due to exposure to acid rain, acidic soil or polluted water. Concrete structures exposed to high alkaline environments, in addition to the alkalinity level of the cement and aggregates, may promote alkali-silica reaction (ASR) leading to swelling and reduction in durability. This study looks into the durability properties of PFA incorporated concrete at various replacement levels when exposed to highly acidic and alkali conditions. Compressive strengths and water absorption tests were compared between concrete cured under normal conditions with concrete exposed to highly acidic and highly alkali conditions. All specimens exposed to acidic conditions showed significant decreases in mass and compressive strengths compared to specimens cured normally. Higher PFA replacement resulted in improved resistance to acid attack. All specimens exposed to alkali conditions showed minor increases in mass suggesting ASR occurring. Reductions in compressive strengths were found at lower replacement levels. At higher replacement levels, increases in compressive strengths were found, suggesting the possibility of increased pozzolanic reaction of the PFA due to the high alkalinity.

scholarly journals Optimising an expansion test for the assessment of alkali-silica reaction in concrete structures

2011 ◽  
Vol 44 (9) ◽  
pp. 1641-1653 ◽  
Author(s):  
Xiao Xiao Gao ◽  
Stéphane Multon ◽  
Martin Cyr ◽  
Alain Sellier
Keyword(s):  
Concrete Structures ◽  
Alkali Silica Reaction ◽  
Expansion Test

Filler effect and pozzolanic reaction of ground palm oil fuel ash

2011 ◽  
Vol 25 (11) ◽  
pp. 4287-4293 ◽  
Author(s):  
Chai Jaturapitakkul ◽  
Jatuphon Tangpagasit ◽  
Sawang Songmue ◽  
Kraiwood Kiattikomol
Keyword(s):  
Palm Oil ◽  
Pozzolanic Reaction ◽  
Palm Oil Fuel Ash ◽  
Fuel Ash ◽  
Oil Fuel

Effects of Geopolymer Concrete Fly Ash Based on Alkali Silica Reaction (ASR)

2014 ◽  
Vol 567 ◽  
pp. 405-410 ◽  
Author(s):  
Muhd Fadhil Nuruddin ◽  
Siti Nooriza Abd. Razak
Keyword(s):  
Fly Ash ◽  
Chemical Reaction ◽  
Length Change ◽  
Alkali Silica Reaction ◽  
Geopolymer Concrete ◽  
Alkali Silica Reactivity ◽  
Mortar Bar ◽  
Class F Fly Ash ◽  
Strength And Durability ◽  
Standard Limit

Alkali Silica Reaction (ASR) is a chemical reaction which affects both strength and durability of concrete. ASR occurs due to a chemical reaction between alkali oxides presents in the cement paste and reactive silica in aggregate. This reaction could lead to the volume expansion, cracking, loss of strength and potential failure of the concrete. This research aimed to investigate the potential alkali silica reactivity on geopolymer concrete. Specimens were prepared using Class F fly ash as binder while sodium hydroxide and sodium silicate as alkaline activators. ASTM C1260 was adopted to determine potential alkali silica reactivity by measuring the length change of mortar bar as well as the decrease in compressive strength test. Results show that fly ash based geopolymer concrete is less vulnerable to ASR as the expansion of mortar bar is below the threshold of ASTM standard limit which is 0.10% of expansion. In term of strength, the geopolymer concrete did not reduced instead it increased. From the results, it has indicated that both tests ensure that the durability of geopolymer concrete is excellent and can withstand a long life span.

scholarly journals Mechanical properties of kenaf fibrous pulverized fuel ash concrete

2018 ◽  
Vol 250 ◽  
pp. 05007
Author(s):  
Norazura Mizal Azzmi ◽  
Jamaludin Mohamad Yatim ◽  
Hazlan Abdul Hamid ◽  
Azmahani Abdul Aziz ◽  
Adole Michael Adole
Keyword(s):  
Mechanical Properties ◽  
Natural Fiber ◽  
Coal Ash ◽  
Physical And Mechanical Properties ◽  
Short Fiber ◽  
Pozzolanic Reaction ◽  
Strength Development ◽  
Kenaf Fiber ◽  
Fuel Ash ◽  
Pulverized Fuel

The main objective of the experimental work is to identify the mechanical properties of Kenaf Fiber incorporate with Ordinary Portland Cement (OPC) and Pulverised Fuel Ash (PFA) in the mix proportions of concrete. Kenaf Fibrous Concrete (KFC) and Kenaf Fibrous Pulverised Fuel Ash Concrete (KFPC) will be measured on physical and mechanical properties in order to investigate the suitability of this natural fiber as a composite material. A comparison of properties between these two composites will determine the density, workability, compressive, tensile, and flexural strength of the concrete. Eight different mixes with varying percentage of Kenaf fiber were prepared with 30N/mm2 strength at 28days ,56 days and 90 days. Short fiber with 25mm and 50mm length were randomly distribute in composite to enhance the tensile and durability. PFA was obtained by the process of burning in the Power Station Coal Ash at Tanjung Bin, Johor. The unburning powder from the process is called as a PFA generally suitable for cement replacement in the concrete mix. The pozzolanic reaction will improve the adhesion of cement gel, hence increased the properties of concrete in a long-term strength development. The result shows that the inclusion of Kenaf fiber improve tensile strength of composite, furthermore the 25% PFA mix increase the durability of concrete.

Effect of Chloride-Induced Steel Corrosion on Working Life of Concrete Structures

2018 ◽  
Vol 272 ◽  
pp. 226-231 ◽  
Author(s):  
Ivan Hollý ◽  
Juraj Bilčík
Keyword(s):  
Pore Solution ◽  
Concrete Structures ◽  
Steel Corrosion ◽  
Radial Pressure ◽  
Concrete Cover ◽  
Transport Infrastructure ◽  
Reinforcing Bars ◽  
Volume Increase ◽  
Volumetric Expansion ◽  
High Alkalinity

The reinforcing steel embedded in concrete is generally protected against corrosion by the high alkalinity (pH = 12.5 to 13.5) of the concrete pore solution. The structural degradation of concrete structures due to reinforcement’s corrosion has an impact on the safety, serviceability and durability of the structure. The corrosion of reinforcements in the construction of a transport infrastructure (especially bridges), parking areas, etc., is primarily initiated by chlorides from de-icing salts. When corrosion is initiated, active corrosion results in a volumetric expansion of the corrosion products around the reinforcing bars against the surrounding concrete. Reinforcement corrosion causes a volume increase due to the oxidation of metallic iron, which is mainly responsible for exerting the expansive radial pressure at the steel–concrete interface and development of hoop tensile stresses in the surrounding concrete. When this tensile stress exceeds the tensile strength of the concrete, cracks are generated. Higher corrosion rates can lead to the cracking and spalling of the concrete cover. Continued corrosion of reinforcement causes a reduction of total loss of bond between concrete and reinforcement.

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