Development of Cementitious Materials with High Resistance to Sulfate Attack by a Combination of Emulsified Asphalt and Fly Ash

2012 ◽  
Vol 450-451 ◽  
pp. 8-13
Author(s):  
Guang Cheng Long ◽  
Zhe Li ◽  
Kun Lin Ma ◽  
You Jun Xie
Keyword(s):  
Fly Ash ◽  
High Resistance ◽  
High Performance ◽  
Chemical Interaction ◽  
Hydration Product ◽  
Cementitious Materials ◽  
Sulfate Attack ◽  
Sulfate Salt ◽  
Chemical Attack ◽  
Emulsified Asphalt

Attack of sulfate crystallization and chemical interaction between sulfate and hydration product is one of the most important factors responsible for degradation of cementitious materials. This study investigates the effects of emulsified asphalt and fly ash as well as their combination on resistance of mortar to physicochemical attack of sulfate in order to develop high performance cementitious materials with high resistance to sulfate attack. The partly-submerged experiment with 5% Na2SO4 solution is designed to simulate physicochemical attack of sulfate salt on sample. Results indicate that, compared with fly ash, addition of emulsified asphalt is more effective in improving the resistance of mortar sample to physical crystallization role and chemical attack of sulfate. Moreover, a combination of fly ash and emulsified asphalt can further enhance the resistance of cementitious materials to physicochemical attack of sulfate, which results from the improvement of microstructure, reduction of CH product and increase of ductility of sample.

Study on Sulfate Resistance of Concrete with Compound Mineral Admixture

2011 ◽  
Vol 99-100 ◽  
pp. 420-425 ◽  
Author(s):  
Qian Rong Yang ◽  
Xiao Qian Wang ◽  
Hui Ji
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Blast Furnace Slag ◽  
Steel Slag ◽  
Sulfate Attack ◽  
Mineral Admixture ◽  
Sulfate Resistance ◽  
Chemical Attack ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

The strength, expansion and amount of scaling of concrete with compound mineral admixture (CMA) from steel slag, granulated blast furnace slag and fly ash were studied. The result shows that damage by crystallization press from sulfate attack when concrete was exposed to sulfate environments under wetting–drying alternation is much larger than that from sulfate chemical attack. Adding CMA to concrete could reduce the damage from expansion of concrete caused by sulfate chemical attack, but the resistance of concrete to damage by crystallization press from sulfate attack was remarkably reduced.

The Effect of Homogenization Procedure on Mechanical Properties of High-Performance Concrete with Partial Replacement of Cement by Supplementary Cementitious Materials

2019 ◽  
Vol 292 ◽  
pp. 102-107 ◽  
Author(s):  
Josef Fládr ◽  
Petr Bílý ◽  
Karel Šeps ◽  
Roman Chylík ◽  
Vladimír Hrbek
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Water Content ◽  
High Performance ◽  
High Performance Concrete ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Partial Replacement ◽  
Depth Of Penetration ◽  
Cement Additive

High-performance concrete is a very specific type of concrete. Its production is sensitive to both the quality of compounds used and the order of addition of particular compounds during the homogenization process. The mechanical properties were observed for four dosing procedures of each of the three tested concrete mixtures. The four dosing procedures were identical for the three mixes. The three mixes varied only in the type of supplementary cementitious material used and in water content. The water content difference was caused by variable k-value of particular additives. The water-to-binder ratio was kept constant for all the concretes. The additives used were metakaolin, fly ash and microsilica. The comparison of particular dosing procedures was carried out on the values of basic mechanical properties of concrete. The paper compares compressive strength and depth of penetration of water under pressure. Besides the comparsion of macro-mechanical properties, the effect of microsilica and fly ash additives on micro-mechanical properties was observed with the use of scanning electron microscopy (SEM) and nanoindentation data analysis. Nanoindentation was used to determine the thickness and strength of interfacial transition zone (ITZ) for different sequence of addition of cement, additive and aggregate. The thickness obtained by nanoindentation was further investigated by SEM EDS line scanning.

Study on the Durability of Concrete with Mineral Admixtures to Sulfate Attack by Wet-Dry Cycle Method

2011 ◽  
Vol 295-297 ◽  
pp. 165-169
Author(s):  
Guan Guo Liu ◽  
Jing Ming ◽  
Xiong Wen Zhang ◽  
Ai Bin Ma
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Sulfate Attack ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Partial Replacement ◽  
Change Environment ◽  
Physical Mechanisms ◽  
Chemical Attack ◽  
Tidal Area

Sulfate attack is one of several chemical and physical mechanisms of concrete deterioration. In actual situation, concrete structures always suffer from the coupled effects of multifactor such as wet-dry cycle and sulfate attack when exposed to tidal area or groundwater level change environment. Partial replacement of cement with mineral admixture is one of the efficient methods for improving concrete resistance against sulfate attack. In this regard, the resistance of concrete with fly ash and slag to sulfate attack was investigated by wet-dry cycle method. The degree of sulfate attack on specimens after different cycles was observed using scanning electron microscopy. The results of compressive strength and percentage of compressive strength evolution factor at various cycling times show an increase in the sulfate resistance of concrete with 60% of fly ash and slag than that only with 40% fly ash. The microstructural study indicates that the primary cause of deterioration of concrete under wet-dry cycle condition is swelling of the sulfate crystal rather chemical attack.

scholarly journals Resistance to Chemical Attack of Hybrid Fly Ash-Based Alkali-Activated Concretes

Molecules ◽  
2020 ◽  
Vol 25 (15) ◽  
pp. 3389
Author(s):  
William G. Valencia-Saavedra ◽  
Ruby Mejía de Gutiérrez
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Strength Loss ◽  
Cementitious Materials ◽  
Sodium Sulphate ◽  
Unburned Carbon ◽  
Chloride Permeability ◽  
Chemical Attack ◽  
Concrete Production ◽  
Alkali Activated

The environmental impacts related to Portland cement production in terms of energy consumption, the massive use of natural resources and CO2 emissions have led to the search for alternative cementitious materials. Among these materials, alkali-activated cements based on fly ash (FA) have been considered for concrete production with greater sustainability. In the present article, the chemical durability properties (resistance to sulphates, chloride permeability, and resistance to carbonation) of a hybrid alkali-activated concrete based on fly ash–ordinary Portland cement (FA/OPC) with proportions of 80%/20% were evaluated. It is noted that the FA was a low-quality pozzolan with a high unburned carbon content (20.67%). The results indicated that FA/OPC concrete had good durability with respect to the OPC concrete, with 95% less expansion in the presence of sodium sulphate and a 2% strength loss at 1100 days, compared with the 56% strength loss of the OPC concrete. In addition, FA/OPC showed lower chloride permeability. On the contrary, the FA/OPC was more susceptible to carbonation. However, the residual compressive strength was 23 MPa at 360 days of CO2 exposure. Based on the results, FA/OPC, using this type of FA, can be used as a replacement for OPC in the presence of these aggressive agents in the service environment.

Applying Statistical Methods for Further Improvement of High-Performance Concrete for New York State Bridge Decks

1997 ◽  
Vol 1574 (1) ◽  
pp. 71-79 ◽  
Author(s):  
Peter Bajorski ◽  
Donald A. Streeter ◽  
Robert J. Perry
Keyword(s):  
New York ◽  
Fly Ash ◽  
High Performance ◽  
High Performance Concrete ◽  
Bridge Decks ◽  
New York State ◽  
Cementitious Materials ◽  
Concrete Mixture ◽  
Successful Implementation ◽  
York State

A new concrete mixture designated “Class HP” for high-performance has been developed for bridge decks in New York State. A modification of the state’s standard Class H concrete, it has better handling and workability characteristics, reduced permeability, and greater resistance to cracking and displays little or no surface scaling. These improvements have potential to result in twice the previously expected concrete service life. The mixture incorporates substitutions for cement of 20 percent Class F fly ash and 6 percent microsilica. It has now been established as the required concrete mixture for all decks built by the New York State Department of Transportation. Its successful implementation has triggered further research toward an even better mixture. An experiment was designed and performed to investigate the effects on cracking and permeability of microsilica and fly ash content, as well as the effects of total weight of cementitious materials. Experimental designs allowed investigation of a broad range of possible combinations while only a limited number of mixtures were tested. Statistical analysis of experimental data is presented and some concrete mixes are recommended for further study, especially those having 10 to 25 percent fly ash, 11 to 12 percent microsilica, and 327 to 375 kg/m3 (550 to 630 lb/yd3) of cementitious materials, and also those with 20 to 35 percent fly ash, 4 to 6 percent microsilica, and 392 to 428 kg/m3 (660 to 720 lb/yd3) of cementitious materials.

scholarly journals Performance of a Fly Ash Geopolymeric Mortar for Coating of Ordinary Portland Cement Concrete Exposed to Harsh Chemical Environments

2015 ◽  
Vol 1129 ◽  
pp. 573-580 ◽  
Author(s):  
Walid Tahri ◽  
Z. Abdollahnejad ◽  
Jorge Mendes ◽  
F. Pacheco-Torgal ◽  
José Barroso de Aguiar
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Epoxy Resin ◽  
High Performance ◽  
Ordinary Portland Cement ◽  
High Performance Concrete ◽  
Surface Treatments ◽  
Concrete Durability ◽  
Portland Cement Concrete ◽  
Chemical Attack

Premature degradation of ordinary Portland cement (OPC) concrete infrastructures is a current and serious problem with overwhelming costs amounting to several trillion dollars. The use of concrete surface treatments with waterproofing materials to prevent the access of aggressive substances is an important way of enhancing concrete durability. The most common surface treatments use polymeric resins based on epoxy, silicone (siloxane), acrylics, polyurethanes or polymethacrylate. However, epoxy resins have low resistance to ultraviolet radiation while polyurethanes are sensitive to high alkalinity environments. Geopolymers constitute a group of materials with high resistance to chemical attack that could also be used for coating of concrete infrastructures exposed to harsh chemical environments.This article presents results of an experimental investigation on the resistance to chemical attack (by sulfuric and nitric acid) of several materials: OPC concrete, high performance concrete (HPC), epoxy resin, acrylic painting and a fly ash based geopolymeric mortar. Two types of acids, each with high concentrations of 10%, 20% and 30%, were used to simulate long term degradation by chemical attack. The results show that the epoxy resin had the best resistance to chemical attack, irrespective of the acid type and acid concentration.

Sulfate Attack on Concrete: Is it real or just a misinterpretation of damage done by biodeterioration?

2013 ◽  
Vol 1612 ◽  
Author(s):  
Luis Emilio Rendon Diaz Miron ◽  
Montserrat Rendon Lara ◽  
Maria Eugenia Lara Magaña
Keyword(s):  
Chemical Interaction ◽  
Holistic Approach ◽  
External Source ◽  
Sulfate Attack ◽  
Salt Crystallization ◽  
Hardened Concrete ◽  
Sulfate Ions ◽  
Chemical Attack ◽  
Physical Attack ◽  
Large Numbers

ABSTRACTAt the present time, no material is known that is completely inert to chemical or biochemical action and immune to weathering damage. Concrete is no exception, but, under what might be considered normal exposure conditions, it has a very long life. Concrete made by the Romans from natural cement is in excellent condition after more than 2000 years of service. The controversies generated by contradictory expert testimonies in several lawsuits involving sulfate attack on concrete, and by the large numbers of recently published papers containing data on the subject, have caused considerable anxiety about sulfate attack mechanisms and the service life of concrete structures. Furthermore, frequently the physical attack by salt crystallization is being confused with the classical sulfate attack, which involves the chemical interaction between sulfate ions from an external source and the constituents of cement paste. In addition, there is also an internal sulfate attack –a chemical attack in which the source of sulfate ions resides in the concrete aggregates or cement–. Additionally, modern concrete as been affected by the products of microorganism metabolism, in particular sulfuric acid, this damage done to hardened concrete is known as concrete biodeterioration and also known as microbiologically induced corrosion of concrete (MICC). Being perhaps this biodeterioration the most important cause of concrete decay and perhaps the true explanation of sulfate attack on concrete. Some of the controversies about sulfate attack are addressed in this article, we have studied the case applying simple considerations concerning concrete composition and flouting at the same time some of the stricter observed paradigms in the cement and concrete industry. It is concluded that a holistic approach is necessary to separate the real causes of sulfate attack on concrete from the imaginary ones.

scholarly journals Assessment of Mechanical Properties and Damage of High Performance Concrete Subjected to Magnesium Sulfate Environment

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Sheng Cang ◽  
Xiaoli Ge ◽  
Yanlin Bao
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Magnesium Sulfate ◽  
Damage Evolution ◽  
High Performance ◽  
Damage Mechanics ◽  
High Performance Concrete ◽  
Pulse Velocity ◽  
Sulfate Attack ◽  
Exponential Fitting

Sulfate attack is one of the most important problems affecting concrete structures, especially magnesium sulfate attack. This paper presents an investigation on the mechanical properties and damage evolution of high performance concrete (HPC) with different contents of fly ash exposure to magnesium sulfate environment. The microstructure, porosity, mass loss, dimensional variation, compressive strength, and splitting tensile strength of HPC were investigated at various erosion times up to 392 days. The ultrasonic pulse velocity (UPV) propagation in HPC at different erosion time was determined by using ultrasonic testing technique. A relationship between damage and UPV of HPC was derived according to damage mechanics, and a correlation between the damage of HPC and erosion time was obtained eventually. The results indicated that (1) the average increasing amplitude of porosity for HPCs was 34.01% before and after exposure to magnesium sulfate solution; (2) the damage evolution of HPCs under sulfate attack could be described by an exponential fitting; (3) HPC containing 20% fly ash had the strongest resistance to magnesium sulfate attack.

scholarly journals Tailoring Confining Jacket for Concrete Column Using Ultra High Performance-Fiber Reinforced Cementitious Composites (UHP-FRCC) with High Volume Fly Ash (HVFA)

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 4010 ◽  
Author(s):  
Alessandro P. Fantilli ◽  
Lucia Paternesi Meloni ◽  
Tomoya Nishiwaki ◽  
Go Igarashi
Keyword(s):  
Fly Ash ◽  
High Performance ◽  
Mechanical Response ◽  
High Volume ◽  
Cementitious Materials ◽  
Seismic Retrofitting ◽  
Cementitious Composites ◽  
High Performance Fiber ◽  
Mechanical Approach ◽  
Mechanical Performances

Ultra-High Performance Fibre-Reinforced Cementitious Composites (UHP-FRCC) show excellent mechanical performances in terms of strength, ductility, and durability. Therefore, these cementitious materials have been successfully used for repairing, strengthening, and seismic retrofitting of old structures. However, UHP-FRCCs are not always environmental friendly products, especially in terms of the initial cost, due to the large quantity of cement that is contained in the mixture. Different rates of fly ash substitute herein part of the cement, and the new UHP-FRCCs are used to retrofit concrete columns to overcome this problem. To simulate the mechanical response of these columns, cylindrical specimens, which are made of normal concrete and reinforced with different UHP-FRCC jackets, are tested in uniaxial compression. Relationships between the size of the jacket, the percentage of cement replaced by fly ash, and the strength of the columns are measured and analyzed by means of the eco-mechanical approach. As a result, a replacement of approximately 50% of cement with fly ash, and a suitable thickness of the UHP-FRCC jacket, might ensure the lowest environmental impact without compromising the mechanical performances.

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