Durability of Mortars with Fly Ash Subject to Freezing and Thawing Cycles and Sulfate Attack

This work explored the correlation among the physical and mechanical parameters of concrete in marine environments during corrosion. Concrete materials with varied water–cement ratios (w/c) were soaked in four kinds of simulated seawater, including a compound solution of sodium chloride (NaCl) and magnesium sulfate (MgSO4), a solution of MgSO4, a solution of sodium sulfate (Na2SO4), and clear water. The macroscopic physical and mechanical parameters, such as compressive strength, tensile strength, mass change and ultrasonic wave velocity, were measured. The damage mechanism of corrosion products and microstructures was analyzed using microscopic approaches including scanning electron microscopy (SEM), X-ray diffraction (XRD), etc. Linear correlation was carried out on the abovementioned physical parameters, and the results revealed that, during corrosion, the correlation between compressive and tensile strength and mass (excluding Na2SO4 solution) is positive (mostly highly correlated), while that with wave velocity is poor (mostly moderately correlated).

Section: Introductionmentioning

confidence: 99%

Correlation Analyses on Physical and Mechanical Parameters of Concrete in Marine Environments

Song

Yang

2022

“…There is an interaction between freeze–thaw cycling and sulphate erosion [ 2 , 3 , 4 , 5 , 6 , 7 , 8 ]. The addition of fly ash (FA), silica fume (SF) [ 9 , 10 ] and recycled brick–concrete aggregates [ 11 ] can effectively improve the resistance of concrete to combined freeze–thaw and sulphate erosion. However, a crucial characteristic of the salt lake region of Inner Mongolia is its high environmental temperatures, low RH, high wind speed, extremely dry air, with atmospheric RH generally ranging between 30% and 50%.…”

Section: Introductionmentioning

confidence: 99%

Influence of Drying Conditions on the Durability of Concrete Subjected to the Combined Action of Chemical Attack and Freeze–Thaw Cycles

Song,

Yu,

2024

The durability of concrete is critical for the service life of concrete structures, and it is influenced by various factors. This paper investigates the impact of the relative humidity (RH) of the curing environment on the durability of five different concrete types. The aim is to determine a suitable approach for designing concrete that is well-suited for use in the salt lake region of Inner Mongolia. The concrete types comprise ordinary Portland cement (OPC), high-strength expansive concrete (HSEC), high-strength expansive concrete incorporating silica fume, fly ash, and blast furnace slag (HSEC-SFB), steel fiber-reinforced high-strength expansive concrete (SFRHSEC), and high elastic modulus polyethylene fiber-reinforced high-strength expansive concrete (HFRHSEC). All these concrete types underwent a 180-day curing process at three distinct relative humidities (RH = 30%, 50%, and 95%) before being subjected to freeze–thaw cycles in the Inner Mongolia salt lake brine. The curing environment with a 95% RH is referred to as the standard condition. The experimental results reveal that the durability of OPC and HSEC decreases significantly with increasing relative humidity. In comparison with the control sample cured in 95% RH, the maximum freeze–thaw cycles for concrete cured in lower RHs are only 31% to 76% for OPC and 66% to 77% for HSEC. However, the sensitivity of the durability of HSEC-SFB, SFRHSEC, and HFRHSEC to variations in RH in the curing environment diminishes. In comparison with the corresponding reference value, the maximum freeze–thaw cycles for samples cured in dry conditions increase by 14% to 17% for HSEC-SFB and 21% for SFRHSEC. Specifically, the service life of HFRHSEC cured in a low RH is 25% to 46% higher than the reference value. The durability of HSEC-SFB, SFRHSEC, and HFRHSEC has been proven to be appropriate for structures located in the salt lake region of Inner Mongolia.

“…Khatib et al [4] indicate that municipal solid waste incineration bottom ash can partially substitute fine aggregate. In [5] durability of mortars with fly ash subjected to freezing and thawing cycles and sulfate attack was tested. Kelechi et al [6] analyzed the durability performance of self-compacting concrete containing fly ash, crumb rubber, and calcium carbide waste.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Durability of Watertight Concretes Modified with the Addition of Fly Ash

Adamus,

Langier

2023

The growing demand for watertight concrete structures is conducive to the development of research in this area, but their results are rarely published. In order to partially fill this gap, the authors of the publication present the results of research into the effect of fly ash addition on the watertightness of concrete. Prior to the tests, a recipe for a concrete mix with the addition of a sealing admixture modified with fly ash was developed. The following properties were analyzed: consistency of the concrete mix, air content in the concrete mix, compressive strength of concrete, depth of penetration of water under pressure, and frost resistance of concrete for F150 level. The work meets the expectations of the construction industry with respect to the production of concrete structures resistant not only to the penetration of water into concrete but also resistant to aggressive substances dissolved in water that accelerate the destruction of concrete and corrosion of reinforcement bars. Based on the test results, it was found that the addition of fly ash to the concrete mix enhances the positive impact of the applied sealing admixture, increasing the tightness of the concrete. It reduces the depth of penetration of water under pressure and therefore increases the frost resistance of concrete.