Concrete In Marine Environment Research Articles

Behaviour of Ground Granulated Blast Furnace Slag Concrete in Marine Environment under Chloride Attack

In conventional concrete, one of the ingredients Cement is partially replaced by Ground Granulated Blast Furnace Slag and its nature is studied in this project.. In the present paper, a comparison of Chloride ion penetration is been done on Concrete specimens with partial GGBS replacement. Two tests have been performed on the concrete specimens in both normal environment and artificial marine environment. One is the conventional RCPT and the other one is the chloride ion penetration test using silver nitrate. Comparison of both the tests under normal and marine environment is the main aim of this paper. After compiling the data both RCPT and the Chloride ion penetration test goes hand in hand and this proves the compatibility of the new chloride ion penetration test using silver nitrate. This work has the comparison of the concrete specimens in normal and marine environments as well with different levels of GGBS replacement.

Experimental studies on the chloride ion permeability of concrete considering the effect of freeze–thaw damage

A series of laboratory experiments were conducted to investigate the effect of freeze–thaw (FT) cycles on mechanical properties and chloride permeability of concrete with the strength class of C30 in this paper. The mechanical property tests were performed on the specimens subjected to 0, 5, 15, 30, 50, 75 and 100 standard FT cycles to determine the compressive strength, normalized dynamic elastic modulus (NDEM) and mass loss. Also, the chloride natural diffusion tests of concrete specimens, after 0, 5, 15, 30 and 50 FT cycles, were conducted in a self-design tidal cycling simulation device to investigate the chloride ingress into concrete in marine environment of tidal zone. Based on the Fick’s second law, a time-dependent model was developed to predict the chloride profiles of frost-damaged concrete. Additional FT cycling tests at different minimum temperatures of freezing process (−4 and −11 °C) and the chloride natural diffusion tests were conducted to study the effect of minimum temperature on the chloride diffusion in concrete. The experimental results revealed the significant influence of FT action on the mass loss, compressive strength and NDEM. After 50 FT cycles, the mean of NDEM dropped to 60%, indicating that the specimen was destroyed by FT action. With the decrease of minimum freezing temperature, the loss of NDEM increased apparently, performing a good linear relation. A substantial effect of FT damage on the chloride profiles was observed: compared to the counterparts of the control groups without being exposed to FT attack, chloride concentration was larger for the frost-damaged concrete, and this difference increased with the extension of exposure duration. A linear relation between the apparent chloride diffusion coefficient and the loss of NDEM was also obtained regardless of the exposure time. Moreover, it was found that the proposed model was applicable for the prediction of chloride profiles in concrete subjected to FT cycles at different minimum freezing temperatures. In other words, the proposed model can be used to describe the chloride ingress into frost-damaged concrete, regardless of the cause of the damage (due to the number of FT cycles or the minimum freezing temperature).

Study on the corrosion resistance of sisal fiber concrete in marine environment

In this paper, the corrosion resistance test of sisal fiber-reinforced concrete under simulated marine environment is carried out, and the corrosion resistance of sisal fiber-reinforced concrete is predicted by using grey theory and Verhulst model. The results show that sisal fiber can effectively improve the strength of concrete under the corrosion of marine environment. With the increase in sisal fiber content, the compressive strength of concrete increases as a whole compared with that of concrete without sisal fiber. After 15 days of corrosion cycle, the maximum strength increase ratio of concrete with sisal fiber is 18.58. After 30 days of corrosion cycle, the maximum strength increase ratio of concrete with sisal fiber is 12.72. The GM (1,1) model and Verhulst model in grey system theory are used to simulate the mechanical properties of sisal fiber-reinforced concrete and its corrosion resistance in marine environment. The results show that the average relative residual difference between the simulated and measured values is small and belongs to the first-order accuracy. It shows that the GM (1,1) model and Verhulst model in grey system theory can be used in the mechanics of sisal fiber-reinforced concrete, and prediction and analysis of performance and corrosion resistance in marine environment. A new corrosion-resistant material may be born from it.

Improving chloride ion penetration resistance of cement mortar by strong base anion exchange resin

How to improve the chloride penetration resistance of reinforced concrete in marine environment has always been an important research topic. In this paper, based on the adsorption properties of strong basic anion exchange resin (SB-AER) for chloride ion, SB-AER, silica fume (SF) and fly ash (FA) were milled into ternary admixtures with particle size less than 75 μm. The effect of SB-AER on chloride ion penetration resistance of mortar was studied. In this experiment, the mechanical properties and compactness of mortar with different SB-AER content were tested by pressure testing machine and ultrasonic nondestructive flaw detector. The microstructure of mortar was observed by scanning electron microscope (SEM). The chloride ion binding capacity of mortar with different SB-AER content was qualitatively and quantitatively analyzed by chloride ion selective electrode method. All the results show that under the appropriate SB-AER content, the ternary admixture can effectively improve the chloride penetration resistance and mechanical properties of mortar. SB-AER-3 group (SB-AER, SF and FA are 3%, 5% and 10% of cement weight, respectively) has the best performance in these two aspects.

Determination of Mechanical Properties of Rubberized Concrete in Marine Environment

With an objective of saving the environment by providing crumb rubber as an alternative to natural fine aggregate this paper presents a study carried out to find the mechanical properties of rubberized concrete. Rubberized concrete is made up of waste rubber from vehicle tyres and other rubber waste which otherwise is left out polluting the environment. In this paper, 7.5% of crumb rubber (obtained by shredding the vehicle tyres) as an alternative to fine aggregate and 7.5% of fly-ash as an alternative to cement is added with other ingredients of concrete to produce an eco-friendly concrete which can be used economically and effectively for construction along the coastal areas. Various properties like workability, compressive strength, split tensile strength, and flexural strength was carried out on concrete specimens exposed to the natural marine environment along the coast of Visakhapatnam, Andhra Pradesh. The total exposure of concrete specimen was about 150 days, and various specimens were tested at 7, 28, 90, 120 and 150 days, respectively. The test results showed that with a slight compromise in strength, the workability of concrete and resistance to the effect of seawater on the strength of concrete significantly improved with the addition of crumb rubber and fly-ash.

Chloride diffusion model for concrete in marine environment with considering binding effect

This paper presents a new chloride diffusion model for concrete exposed to marine environment, which considers the effects of different types of chloride binding. The present model has following new features. (1) The bound chlorides are divided into two types. One is reversible, which is related to the physical binding, and the other is irreversible, which is related to the chemical binding. (2) The reversible bound chloride remains its charge and continues to provide its driving force to influence the movement of free chloride ions. (3) The governing equation for the mass conservation of chlorides is established on the framework of representative elementary volume of concrete and thus the diffusion coefficient used in the present model is consistent with the effective diffusion coefficient defined in the steady-state diffusion tests of chloride in concrete.

青岛滨海环境温湿度作用与混凝土内部温湿度响应

青岛滨海环境温湿度作用与混凝土内部温湿度响应

Performance-based criteria to assess the suitability of geopolymer concrete in marine environments using modified ASTM C1202 and ASTM C1556 methods

In marine or coastal zones, the most harmful exposure for reinforced concrete structures to chloride ions. The ASTM C1556 chloride diffusion test (or its European equivalent NT BUILD 443) has been widely used as the most reliable testing method to assess the performance of concrete against chloride penetration. However, this test is time demanding and labour intensive. As a result, accelerated test ASTM C1202 (RCPT) is often preferred, providing fast and acceptable assessment of chloride penetrability of Ordinary Portland Cement Concrete. This study aimed to investigate the suitability of RCPT to assess the performance of Geopolymer Concrete (GPC) in chloride environment. The correlation between several GPC properties [i.e. compressive strength, volume of permeable voids (VPV) and sorptivity] and the chloride diffusion coefficient are examined. Results indicate that the compressive strength, the VPV and the sorptivity coefficient are not suitable indicators of the GPC performance. The ASTM C1202 standard RCPT failed to measure the charges passed through most of the GPCs tested. A modified version of RCPT using 10 V (as opposed to 60 V specified by standard ASTM C1202) is proposed in this paper, allowing to successfully measure the charges passed through all GPC samples using a wide range of binders. A good correlation was observed between modified ASTM C1202 and Standard ASTM C1556 test results. Performance-based recommendations are proposed in this paper. Both experimental results from this study and appropriate reference concretes from the literature were used to calibrate the modified ASTM C1202 and ASTM C1556 performance-based requirements for GPCs.

Effect of Metakaolin on Performance of M40 Grade Concrete in Marine Environment

Effect of Metakaolin on Performance of M40 Grade Concrete in Marine Environment

Strength of Different Fiber Reinforced Concrete in Marine Environment

In this paper, the compressive strength, tensile strength and growing rate of compressive strength in 3, 7, 28 and 90 day ages for steel, polypropylene and hybrid steel-polypropylene fiber reinforced concrete with different water to binder ratios (0.4 and 0.5) in a real marine condition and tidal zone were determined. Moreover, regarding a large number of gathered data from the other researches, new equations between compressive strength, tensile strength and elasticity modulus for different types of steel fiber reinforced concrete were proposed. Finally, proposed equations were compared and verified for a marine environment. Based on marine environment results, compressive strength of polypropylene and hybrid steel-polypropylene fiber reinforced concrete were about 18 % and 5 % greater than plain concrete in 90 day ages, respectively and steel fibers had not meaningful effect on compressive strength in 90 day ages. By increasing the water to binder ratio, the compressive strength of plain concrete and steel fiber reinforced concrete was decreased about 18 % and 25 %, respectively. Also in 28 and 90 days, steel fiber reinforced concrete tensile strength was increased about 15 % in 0.4 water to binder ratio and 20 % in 0.5 water to binder ratio rather than plain concrete. Effect of steel fiber in increment of plain concrete tensile strength in 0.5 water to binder ratio was higher than 0.4. Steel fiber reinforced concrete elasticity modulus was lower than related plain concrete and with increasing the compressive strength, the difference between elasticity modulus of steel fiber reinforced concrete and plain concrete was decreased. DOI: http://dx.doi.org/10.5755/j01.ms.24.2.17909

Mechanical performance of statically loaded flat face epoxy bonded concrete joints

One of the main challenges in the offshore renewable energy industry is the reduction in the levelised cost of energy of wind, wave and tidal devices. The use of concrete as the primary construction material in such devices presents a low unit cost, high marine durability alternative to steel, however, to maximise material efficiency factors such as mix constituent design, structural detailing and manufacturing processes have to take into account the specific conditions of the marine environment. Pre-cast segmental construction can be considered as one of the fastest and cheapest construction options. However the challenges regarding performance of epoxy bonded concrete in marine environment should be taken into account. This paper presents the results of an experimental programme on the performance of shear and tensile capacity of flat face concrete joints, focussing on the effect of substrate surface preparation, joint thickness, properties of epoxy resins, exposure to seawater and presence of joint defects on the ultimate failure load. The ultrasonic pulse velocity (UPV) method for detection of defects in the adhesive layer was examined and digital image correlation is used to observe the surface strain flow through the joint. The results indicate that the epoxy joints behave monolithically and remain undamaged under different types of static loading. The joints do not significantly interrupt the flow of strain but can locally affect the distribution of strain (and thus stiffness and stresses) in a structure. An increase in the density of the epoxy (and the filler content) leads to the increase in the joint strength and thicker joints are less affected by small defects in the bonding layer. The majority of tested specimens failed by cracking of concrete rather than by debonding of the joint, whilst compressive stresses acting on the joint can help to augment its shear strength. Sandblasting of bonded surfaces can improve performance of joints, whereas UPV testing may be used for quality control of epoxy-bonded joints.

Structural behavior of GFRP reinforced concrete columns under the influence of chloride at casting and service stages

Abstract Corrosion attack due to chloride ions is a major problem found in steel reinforced concrete structures when subjected to marine environment. Glass fiber reinforced polymer (GFRP) has become an alternative reinforcement in marine concrete structures due to its excellent corrosion resistance, making it possible to combine with concrete composed of seawater and sea sand. However, the knowledge on the short-term and long-term properties of GFRP reinforced concrete columns is still limited. In order to facilitate the practical application of GFRP reinforced concrete in marine environment, the effect of chloride ions on the structural behaviors of GFRP reinforced concrete columns is investigated here. Numerous specimens consisting of GFRP reinforced concrete columns and steel reinforced concrete columns with different chloride concentrations were fabricated, conditioned and tested. The test results show that GFRP reinforced concrete columns cast with saturated water suffer a deterioration of 27.9% in load carrying capacity, but possess an enhancement of 104% in ductility when compared to those of specimens cast with distilled water. Meanwhile, it is observed that the GFRP reinforced concrete column possess a ductile failure mode, which indicates that the GFRP spirals can provide an effective confinement to the concrete core even in high chloride environment for a prolonged time. Such findings provide solid evidence to the feasibility and application of GFRP reinforced concrete in the offshore structures or artificial islands with great environmental and economic benefits.

The Effect of Caspian Sea Water on Corrosion Resistance and Compressive Strength of Reinforced Concrete Containing Different SiO2 Pozzolan

Many parameters are influenced by the diffusion of chloride on concrete in marine environments and these can affect concrete quality. In this study, the effect of water to cement ratio of 0.35, 0.40 and 0.45 on corrosion resistance and compressive strength of reinforced concrete was evaluated. Moreover, different percentages of micro silica (SiO2) including 5, 7.5 and 10% were utilized, in order to investigate the effect of pozzolanic materials on the corrosion of steel in concrete. Then cubic samples reinforced with steel bar spacing of 2.5, 5 and 7 cm from the cube surface were made and put in Caspian sea water for 5 months. During this period, corrosion potential of steel was measured by a calomel half cell (SCE). In order to finalize the evaluation of the mechanical strength of the samples, concrete pressure test was conducted and the result showed that after 40, 44 and 59 days for the bars with depth of 2.5, 5 and 7 cm, respectively and the samples prepared with water-cement ratio of 0.35, the corrosion potential was -350V versus SCE, while the compressive strength was approximately 450 kg/cm2. This result showed longer life span of this sample in comparison with other water-cement ratios. By adding micro silica to the samples up to 7.5%, the time for obtaining a corrosion potential of -350V, bars with depth of 2.5, 5 and 7 cm, was 43, 50 and 86 days, respectively, and the compressive strength of this sample was approximately 480 kg/cm2. Consequently, it is arguable that in order to achieve longer life span of corrosion and suitable compressive strength, the optimum ratio of water to cement should be 0.35 and the percentage of pozzolan SiO2 should be 7.5%.

Performance of high-volume fly ash concrete in marine environment

This paper presents the durability performance of concrete incorporating high-volumes of fly ash exposed to a harsh marine environment for 19 to 24years. Concrete specimens (305×305×915mm [1×1×3ft.]) were cast using W/CM in the range of 0.31 to 0.46, various types of fly ash with replacement levels of 56 or 58%, and various types of normal density and lightweight aggregates.Surface erosion/scaling was seen on all specimens; the extent of erosion was slightly worse for fly ash concrete with normal density aggregate compared to the controls (without fly ash), but fly ash concrete with two of the three lightweight aggregates exhibited severe surface erosion.Laboratory testing included taking cores from each block and determining the existing chloride profile, compressive strength and “chloride permeability” (ASTM C1202).The depth of chloride penetration was found to be in excess of 100-mm (4in.) for the concrete specimens without fly ash, whereas the presence of fly ash significantly decreased the depth of penetration to approximately 30 and 40mm in specimens containing either normal density or lightweight aggregate, respectively. The increased penetration in the concrete with lightweight aggregates is attributed to the surface erosion observed with these concretes. The results from the chloride permeability testing also indicate significant increases in the resistance to chloride-ion penetration for fly ash concrete.

Effect of Coconut Fibre on the Mechanical and Corrosion Properties of Reinforced Concrete in Marine Environment

The aim of the research was to enhance the mechanical and corrosion properties by adding coconut fibre in the concrete. Different compositions of concrete mixtures using Ravi and Chenab sand with and without fibre have been prepared. The mechanical properties were evaluated by compression and pull-out strength while corrosion properties by measuring half-cell potential before and after exposing to the different time duration in marine environment. As the different concrete possesses the complex properties, thus by the addition of fibres, improvement in all properties is not observed. The improved swell and crack resistance was also notified. However, adverse effects were observed in the compressive strength after introduction of fibres. Cumulatively, better corrosion resistance, 20% lesser compressive strength, 17 % higher pull-out strength and higher moisture absorption was observed for fibre reinforced concrete as compared with plain concrete.

Surface treatment systems for concrete in marine environment: Effect of concrete cover thickness

There are some ways to extend the service life of a reinforced concrete structure. This paper focuses on the extension of the service life by treating the surface of reinforced concrete, specifically on the effect of the concrete cover thickness on the surface treatment system efficacy. Thus, chloride migration tests were performed and diffusion chloride coefficients were calculated. The service life of each case (treated or non-treated concrete) was estimated using these data and Fick's second law of diffusion. Results indicated that the thicker the concrete cover is, the greater the efficacy of the concrete surface treatment system will be. The dissemination of this information is important, since it is almost intuitive to think that the effect of a surface treatment system depends only on itself and this study shows the opposite.

Effect of Ca(OH)2, NaCl, and Na2SO4 on the corrosion and electrochemical behavior of rebar

The corrosion of rebar in reinforced concrete in marine environments causes significant damage to structures built in ocean environments. Studies on the process and mechanism of corrosion of rebar in the presence of multiple ions may help to control damage and predict the service life of reinforced concrete structures in such environments. The effect of interactions between sulfate and chloride ions and calcium hydroxide on the electrochemical behavior of rebar are also important for evaluation of structure durability. In this work, electrochemical impedance spectroscopy (EIS) plots of rebar in Ca(OH)2 solution and cement grout, including NaCl and Na2SO4 as aggressive salts, were measured for diff erent immersion times. The results show that corrosion of rebar was controlled by the rate of charge transfer as the rebar was exposed to chloride solution. In the presence of high concentrations of sulfate ions in the electrolyte, generation and dissolution of the passive film proceeded simultaneously and corrosion was mainly controlled by the diff usion rate. When Na2SO4 and NaCl were added to Ca(OH)2 solution, the instantaneous corrosion rate decreased by a factor of 10 to 20 as a result of the higher pH of the corroding solution.

Strength and Durability of Concrete incorporating Natural Pozzolan in Aggressive Solomon Sea Environment

This paper reports the results of a comparative study on the performance of natural pozzolana (volcanic ash) based blended cement concrete in marine environment. Variables were volcanic ash (VA) content and curing environment. VA contents as cement replacement was varied from 0 to 35% and the samples were cured in the actual sea in two different conditions and in normal water. Volcanic ash concrete (VAC) showed better performance in terms of strength and durability (related to seawater ion diffusivity) compared to control normal concrete (NC) due to pozzolanic action of VA in marine condition.

Experimental Study on Influence of Bending Load on Chloride Ion Concentration of Concrete in Marine Environment

This paper mainly determined free chloride ion concentration of concrete beams of two kinds of water cement ratio (0.45and0.60) and bending load (0.00Fmax, 0.30Fmax, 0.45Fmax and 0.60Fmax) after 240 d in marine environment and compared the effect of different load conditions in the same water cement ratio on the free chloride ion concentration. The results show that the concentration of free chloride ion in tension zone of concrete increases with the increase of load level, the concentration of free chloride ion in compressed zone of concrete decreases with the increase of load level; under the same bending load level, the concentration of free chloride ion in concrete increases with water cement ratio.

Assessment of some parameters of corrosion initiation prediction of reinforced concrete in marine environments

Chloride ion ingress is one of the major problems that affect the durability of concrete structures such as bridge decks, concrete pavements, and other structures exposed to harsh saline environments. Therefore, durability based design of concrete structures in severe condition has gained great significance in recent decades and various mathematical models for estimating the service life of rein-forced concrete have been proposed. In spite of comprehensive researches on the corrosion of rein-forced concrete, there are still various controversial concepts in quantitation of durability parameters such as chloride diffusion coefficient and surface chloride content. Effect of environment conditions on the durability of concrete structures is one of the most important issues. Hence, regional investigations are necessary for durability based design and evaluation of the models. Persian Gulf is one of the most aggressive regions of the world because of elevated temperature and humidity as well as high content of chloride ions in seawater. The aim of this study is evaluation of some parameters of durability of RC structures in marine environment from viewpoint of corrosion initiation. For this purpose, some experiments were carried out on the real RC structures and in laboratory. The result showed that various uncertainties in parameters of durability were existed.