scholarly journals Corrosion Behavior of AISI 1018 Carbon Steel in Localized Repairs of Mortars with Alkaline Cements and Engineered Cementitious Composites

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3327
Author(s):  
Erick Maldonado-Bandala ◽  
Noema Higueredo-Moctezuma ◽  
Demetrio Nieves-Mendoza ◽  
Citlalli Gaona-Tiburcio ◽  
Patricia Zambrano-Robledo ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Corrosion Behavior ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Cementitious Composites ◽  
Engineered Cementitious Composites ◽  
Cell Potential ◽  
Repair Mortar ◽  
Class F Fly Ash ◽  
Selection Of

The selection of materials for repairs of reinforced concrete structures is a serious concern. They are chosen for the mechanical capacity that the repair mortar achieves. However, several important characteristics have been left aside, such as the adhesion of the repair mortar with the concrete substrate, the electrical resistivity and—hugely important—the protection against corrosion that the repair material can provide to the reinforcing steel. The aim of this work was to study the corrosion behavior of AISI 1018 carbon steel (CS) in mortars manufactured with alkaline cements, engineered cementitious composites (ECC), and supplementary cementitious materials (SCM). Two types of ordinary Portland cement (OPC) 30R and 40R were used. The constituent materials for the mortars with ECC mixture mortars they use OPC 40R, class F fly ash (FA), silica fume (SF) and polypropylene (PP) fibers. The sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) were used as activating agents in alkali activated cements. The reinforced specimens were immersed in two different electrolytes, exposed to a 3.5 wt % of NaCl and Na2SO4 solutions, for 12 months and their electrochemical behavior was studied by half-cell potential (Ecorr) and linear polarization resistance (LPR) according to ASTM C876-15 and ASTM G59-97, respectively. The results obtained indicated that, the mortar they have the best performance and durability, is the conventional MCXF mortar, with OPC 30R and addition of 1% polypropylene PP fiber improves the behavior against the attack of chlorides and sulfates.

scholarly journals Performance of Eco Engineered Cementitious Composites Containing Supplementary Cementitious Materials as a Binder and Recycled Concrete Fines as Fine Aggregate

2021 ◽  
Vol 1200 (1) ◽  
pp. 012004
Author(s):  
M R Md Zain ◽  
C L Oh ◽  
L S Wee
Keyword(s):  
Tensile Strength ◽  
Fly Ash ◽  
Mechanical Performance ◽  
Cementitious Materials ◽  
Recycled Concrete ◽  
Supplementary Cementitious Materials ◽  
Partial Replacement ◽  
Cementitious Composites ◽  
Fine Aggregate ◽  
Engineered Cementitious Composites

Abstract Engineered cementitious composites (ECC) mixtures demand a large cement content, which is detrimental to their sustainable development because mass cement production is hazardous to the environment and human health. Thus, this paper investigates the mechanical performance of eco engineered cementitious composites (ECC) under axial compressive loading and direct tensile strength tests. The eco ECC used in this investigation was comprised of cement, superplasticizer, fly ash (FA) or ground granulated blast furnace slag (GGBS), polypropylene (PP) fibre, water and recycled concrete fines (RCF). Two (2) eco ECC mixture series were designed and prepared. GGBS70 (70 percent GGBS + 30 percent cement), FA70 (70 percent Fly Ash + 30 percent cement), GGBS80 (80 percent GGBS + 20 percent cement), and FA80 (80 percent Fly Ash + 20 percent cement) are the four Cement-GGBS and Cement-Fly Ash combinations examined in this study. Also every combination had two different RCF percentages, R0.2 (0.2 percent RCF) and R0.4 (0.4 percent RCF). The main objective of this research is to determine the optimum mix design for eco ECC that contains supplementary Cementitious Materials (SCMs) such as GGBS or FA. Additionally, recycled concrete fines (RCF) were used as a substitute for sand. The influence of different cement replacement materials and RCF content on compressive and tensile strength was experimentally investigated. The inclusion of GGBS as a partial replacement of cement in the eco concrete mixture results in greater compressive strength than Fly Ash (FA). The test results revealed that increasing the RCF content in the ECC mixture resulted in higher compressive and tensile strength. When the sand to binder ratio was adjusted between 0.2 and 0.4, the compressive and tensile strength of the ECC mixture increased.

scholarly journals ESIGNING OF ALKALINE ACTIVATED CEMENTING MATRIX OF ENGINEERED CEMENTITIOUS COMPOSITES

2021 ◽  
Vol 2021 (2) ◽  
pp. 52-57
Author(s):  
Uliana Marushchak ◽  
◽  
Myroslav Sanytsky ◽  
Nazar Sydor ◽  
Ihor Margal ◽  
...  
Keyword(s):  
High Performance ◽  
Negative Impact ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Partial Replacement ◽  
Cementitious Composites ◽  
Engineered Cementitious Composites ◽  
Specific Strength ◽  
Alkaline Activator ◽  
And Performance

The development of high-performance materials, which are characterized by high compressive and flexural strength, durability and performance properties, is an urgent problem of modern construction. Engineered cementitious composites are one such material. Improving of properties of composites is achieved by partial replacement of cement with supplementary cementitious materials. The ratio of binder and filler components and superplasticizer consumption were selected. The optimal ratio of cement:fly ash:sand is 1:1:1 and the dosage of polycarboxylate superplasticizer is 0.75% by weight of the binder. The reduction of the negative impact of the increased amount of fly ash, which is characterized by low reactivity, is provided by the introduction of metakaolin and alkaline hardening activator. Alkaline activated cement system is characterized by increasing of the early strength in 1.5 times comparison with equivalent mixture without alkaline activator. Strength of alkaline activated cementing matrix after 28 days is 66.1 MPa and specific strength Rc2/Rc28 is 0.61.

scholarly journals Review on investigation of corrosion behavior of reinforced concrete with supplementary cementitious materials

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
K.U. Aavani ◽  
A. Aneesha ◽  
Baby Xavier Thomas ◽  
S. Vandana ◽  
Anju Paul
Keyword(s):  
Flexural Strength ◽  
Corrosion Behavior ◽  
Saline Water ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Flexural Property ◽  
Half Cell ◽  
Cell Potential ◽  
Curing Period ◽  
Strength And Durability

Cement concrete is the most widely used material for various constructions. Properly designed and prepared concrete results in good strength and durability. Sometime these mixes are found to be inadequate, hence variety of admixtures are used along with cement. A certain percentage of cement will be replaced separately with metakaolin and silica fumes. Hence the flexural strength test of concrete and evaluation of corrosion behavior of the reinforcement can be performed. The study of flexural property of concrete will be conducted at 7 or 28 days characteristic strength with different replacement level of cement (i.e.0%, 5%, 10%, 15%, 20%). Corrosion behavior of reinforcement will be evaluated based on half-cell potential. Concrete samples will be cured in either fresh water of 4% NaCl saline water for 7 or 28 days of curing period. We assumed that the addition of silica fumes and metakaolin will improve the flexural strength characteristics of concrete and corrosion resistivity of reinforcement. Keywords: Flexural strength, corrosion, metakaolin, silica fumes.

scholarly journals Development of Ecoefficient Engineered Cementitious Composites Using Supplementary Cementitious Materials as a Binder and Bottom Ash Aggregate as Fine Aggregate

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Jin Wook Bang ◽  
G. Ganesh Prabhu ◽  
Yong Il Jang ◽  
Yun Yong Kim
Keyword(s):  
Substitution Rate ◽  
Bottom Ash ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Cementitious Composites ◽  
Fine Aggregate ◽  
Test Results ◽  
Replacement Rate ◽  
Engineered Cementitious Composites ◽  
Advantageous Effect

The purpose of this study is to develop ecoefficient engineered cementitious composites (ECC) using supplementary cementitious materials (SCMs), including fly ash (FA) and blast furnace slag (SL) as a binder material. The cement content of the ECC mixtures was replaced by FA and SL with a replacement rate of 25%. In addition, the fine aggregate of the ECC was replaced by bottom ash aggregate (BA) with a substitution rate of 10%, 20%, and 30%. The influences of ecofriendly aggregates on fresh concrete properties and on mechanical properties were experimentally investigated. The test results revealed that the substitution of SCMs has an advantageous effect on fresh concrete’s properties; however, the increased water absorption and the irregular shape of the BA can potentially affect the fresh concrete’s properties. The substitution of FA and SL in ECC led to an increase in frictional bond at the interface between PVA fibers and matrix, improved the fiber dispersion, and showed a tensile strain capacity ranging from 3.3% to 3.5%. It is suggested that the combination of SCMs (12.5% FA and 12.5% SL) and the BA aggregate with the substitution rate of 10% can be effectively used in ECC preparation.

scholarly journals Influence of quartz powder and silica fume on the performance of Portland cement

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Ludmila Rodrigues Costa Tavares ◽  
Joaquim Francisco Tavares Junior ◽  
Leonardo Martins Costa ◽  
Augusto Cesar da Silva Bezerra ◽  
Paulo Roberto Cetlin ◽  
...  
Keyword(s):  
Portland Cement ◽  
Silica Fume ◽  
Electrical Resistance ◽  
Cementitious Materials ◽  
Pozzolanic Reaction ◽  
Heat Of Hydration ◽  
Supplementary Cementitious Materials ◽  
Cementitious Composites ◽  
Quartz Powder ◽  
Hydration Properties

AbstractSupplementary cementitious materials interact chemically and physically with cement, influencing the formation of hydrate compounds. Many authors have analyzed the filler and pozzolanic effect. However, few studies have explored the influence of these effects on hydration, properties in the fresh and hardened states, and durability parameters of cementitious composites separately. This study investigates the influence of the replacement of 20% of Portland cement for silica fume (SF) or a 20-µm medium diameter quartz powder (QP) on the properties of cementitious composites from the first hours of hydration to a few months of curing. The results indicate that SF is pozzolanic and that QP has no pozzolanic activity. The use of SF and QP reduces the released energy at early times to the control paste, indicating that these materials reduce the heat of hydration. The microstructure with fewer pores of SF compounds indicates that the pozzolanic reaction reduced pore size and binding capability, resulting in equivalent mechanical properties, reduced permeability and increased electrical resistance of the composites. SF and QP increase the carbonation depth of the composites. SF and QP composites are efficient in the inhibition of the alkali-aggregate reaction. The results indicate that, unlike the filler effect, the occurrence of pozzolanic reaction strongly influences electrical resistance, reducing the risk of corrosion of the reinforcement inserted in the concrete.

PERFORMANCE EVALUATION OF VARIOUS CONCRETE MIXES SUBJECTED TO SULFURIC ACID

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Muhammad Kalimur Rahman ◽  
Hassan Ali Alkhalifah ◽  
Ali Husain Algadhib ◽  
Salah Othman Aldulaijan ◽  
Mohammed Salihu Barry
Keyword(s):  
Sulfuric Acid ◽  
Reinforced Concrete ◽  
Oil And Gas ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Sulfur Recovery ◽  
Reinforced Concrete Structure ◽  
Acid Gas ◽  
Type V ◽  
Class F Fly Ash

Concrete is an essential structural material that has long been used for the construction of buildings, bridges, tanks, pavements and variety of the other types of structures. Due to its physical properties and economical use, concrete is used extensively in the country's infrastructure. In the Oil and Gas sector, concrete infrastructures are more challenging structures, which are exposed to a highly aggressive environment. A special type of reinforced concrete structure exposed to different forms of sulfur attack is the sulfur storage structure, typically referred to as "Sulfur Pit". Sulfur Pit is an essential part of oil and gas processing facilities, where the sulfur after extraction from the hydrocarbons in Sulfur Recovery Units is stored and maintained in the liquid phase at temperatures ranging from 130 °C to 160 °C. The gas sweeting process results in the formation of acid gas consisting of H2S, water vapor in addition to residual sulfuric acid. Reinforced concrete exposed to this environment is subject to deterioration and corrosion of the reinforcing steel. This paper presents the experimental investigation of four different concrete mixes exposed to 5% sulfuric acid at ambient temperature. These mixes include normal OPC, sulfate resistant (Type V) cement, and two mixes with supplementary cementitious materials blast furnace slag (GGBFS) and Class-F fly ash. The investigation is focused on mechanical properties and mass loss of the concrete samples.

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