Rapid Chloride Permeability Test Research Articles

Effect of fillers on the mechanical properties and durability of steel slag concrete

Using steel slag to replace natural coarse and/or fine aggregates to make concrete provides a multi-win solution in mitigating the environmental problems regarding huge depletion of natural aggregates and disposal of large amount of slag. On the other hand, the use of pozzolanic fillers, such as fly ash (FA) and silica fume (SF) could significantly improve the strength, stiffness and durability of concrete. However, there were very few research studies on the effect of pozzolanic fillers on the mechanical behaviour and durability of concrete containing steel slag. To fill up this research gap and promote the use of steel slag, a systematic and scientific experimental study was conducted, in which 29 concrete mixes with steel slag partially or totally replacing natural aggregates and FA/SF partially replacing cement in an equal volume were prepared. The slump, wet packing density (WPD), 7-, 28-, 91- and 182-day compressive strength and durability in terms of total charge passed and chloride ion’s penetration depth in rapid chloride permeability test were tested for all the specimens while the chemical composition of concrete were tested using X-ray diffraction. Test results revealed that the slump of steel slag concrete decreased due to the porous structure of slag. Besides, the use of steel slag improved the compressive strength of concrete. By adding SF to replace partial cement, the strength of steel slag concrete could be escalated further. At given composition of aggregates and filler type, the total charge passed and the chloride ion’s penetration depth of steel slag concrete decreased as the WPD increased due to the denser and impermeable microstructure of concrete that enhanced the resistance of chloride ion penetrability.

Durability and Microstructure Characteristics of Concrete with Supplementary Cementitious Materials

Considering the environmental impact of cement manufacturing industries, this paper concerns the potential of using supplementary cementitious materials (SCMs), like fly ash and ground granulated blast furnace slag, as being essential to replacing the existing Ordinary Portland Cement (OPC). The objective of this paper is to study the microstructural characteristics of concrete with SCMs and improve the durability of the product to increase the lifespan of concrete structures. Replacement SCMs in OPC are 0, 40, 50, and 60 by percentage of cement weight, and we have taken a water-binder ratio of 0.40 for M40 grade and 0.28 for M60 grade concrete. The physical properties and chemical composition of OPC, Ground Granulated Blast-furnace Slag (GGBS), and fly ash were identified, and three different experiments were conducted to determine the resistance to penetration of chloride ions and corrosion processes. The rapid chloride permeability test, accelerated corrosion, and sorptivity tests were employed to measure concrete's resistance to the effects of aggressive environments and examine the durability properties. The most performed grade samples were analyzed as individual microspheres with Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectroscopy (EDXS), and X-ray diffraction. Significant improvements in various concrete properties were achieved through the partial replacement of fly ash and GGBS with cement. Doi: 10.28991/CEJ-2022-08-04-05 Full Text: PDF

Early-age mechanical properties and microstructures of Portland cement mortars containing different admixtures exposed to seawater

This study investigated the effects of seawater exposure on the mechanical, durability, and microstructural properties of cement mortars, which contained silica fume, metakaolin, or glass powder at two different replacement ratios. Test variables included the exposure conditions, exposure periods, supplementary cementitious material types, and replacement ratios. Compressive, flexural, and pull-off strengths were measured periodically. Mass change, water absorption, and rapid chloride permeability tests were conducted to evaluate the durability performance of Portland cement mortars (PCMs). Microcomputed tomography was utilized to obtain the pore information from representative PCMs. Test results revealed that seawater exposure yielded positive effects, including flexural strength and durability improvements during short-term exposure periods while those effects might not be last for long period. Metakaolin was the most effective supplementary cementitious material to minimize the reduction in compressive strength, while silica fume contributed to durability improvements. On the other hand, PCM containing GP did not show significant changes in strength and durability. Strong correlations between the flexural strength and durability were observed, and it was explained by additional hydration (i.e., matrix densification) of PCMs (except for the GP) due to the seawater curing which filled specific size of pores ranging 50–200 µm.

Investigation on the accelerated pavement test track (APTT) in the development of road network using geopolymer concrete

Geopolymers produced with fly ash and ground granulated blast furnace slag (GGBFS) are beneficial and environmentally advantageous materials, but their fragility limits their applications. In this study, the acceleratory pavement test track (APTT) was constructed to evaluate the properties of geopolymer concrete (GPC) in practical field conditions. The strength and microstructural characteristics are presented to understand the applicability of GPC for pavement applications. The rapid chloride permeability test (RCPT) and accelerated corrosion test (ACPT) were conducted to find the durability properties of APTT. On the other hand, non-destructive testing (NDT) was conducted to estimate the quality of GPC. The results are indicated that the GPC has better strength and durability properties towards the construction of pavements. Meanwhile, the scanning electron microscopy (SEM) images revealed that the GPC based APTT has shown a denser microstructure and observed a steady geopolymeric matrix formation under ambient curing compared to ordinary Portland cement (OPC) concrete.

Effect of Silicon Carbide and Tungsten Carbide on Concrete Composite

Flexural strength of concrete is an important property, especially for pavements. Concrete with higher flexural strength has fewer cracking and durability issues. Researchers use different materials, including fibers, polymers, and admixtures, to increase the flexural strength of concrete. Silicon carbide and tungsten carbide are some of the hardest materials on earth. In this research, the mechanical properties of carbide concrete composites were investigated. The silicon carbide and tungsten carbide at different percentages (1%, 2%, 3%, and 4%) by weight of cement along with hybrid silicon carbide and tungsten carbide (2% and 4%) were used to produce eleven mixes of concrete composites. The mechanical tests, including a compressive strength test and flexural strength test, along with the rapid chloride permeability test (RCPT), were conducted. It was concluded that mechanical properties were enhanced by increasing the percentages of both individual and hybrid carbides. The compressive strength was increased by 17% using 4% tungsten carbide, while flexural strength was increased by 39% at 4% tungsten carbide. The significant effect of carbides on flexural strength was also corroborated by ANOVA analysis. The improvement in flexural strength makes both carbides desirable for use in concrete pavement. Additionally, the permeability, the leading cause of durability issues, was reduced considerably by using tungsten carbide. It was concluded that both carbides provide promising results by enhancing the mechanical properties of concrete and are compatible with concrete to produce composites.

Effect of Fine Aggregate Particle Size on Physical, Mechanical, and Durability Properties of Ultra-High Performance Concrete

Ultra-high performance concrete (UHPC) mixtures are typically developed using fine aggregate with a maximum size of 600 μm. From a sustainability point of view, use of larger size fine aggregate particles in UHPC mixtures should be investigated to reduce labor costs associated with sieving, to reduce wastage of sand, and to improve sustainability. This experimental research investigates the physical, mechanical, and durability properties of UHPC incorporating coarser fine aggregates with maximum particle size of 4.75 mm replacing fine sand. Both plain and fiber reinforced UHPC mixtures were developed with a target static flow of 200 mm (8 in.) and target compressive strength of 120 MPa (17,000 pounds per square inch). Three different curing regimens were investigated: moist curing, warm bath curing at 90°C, and heat curing at 90°C. Compressive and split tensile strengths, permeable porosity, and rapid chloride permeability tests were performed to study the effect of coarser fine aggregate sizes on these UHPC properties. Increasing the maximum fine aggregate particle size range did not affect the workability, compressive strength, permeable porosity, or chloride ion ingress; however, a limited decrease in split tensile strength was observed. A change in aggregate size may have a very large impact on fiber dispersion, embedment, and crack bridging. The experimental results highlight the potential of coarser fine aggregate used in UHPC.

Correlation of Electrical Resistivity and Formation Factor with Chloride and Water Permeability of Recycled Aggregate Concrete

Among the methods of determining the permeability of concrete, electrical resistivity tests are the most rapid and one of the simplest techniques. Several studies have found a strong correlation between electrical resistivity and the other permeation properties, such as water permeability and rapid chloride penetrability. However, most of these comparisons used conventional concrete in which natural aggregates were used. Concrete with alternative aggregates such as recycled aggregate concrete (RAC) shows a different microstructure and higher permeability than conventional concrete. Thus, the existing correlations might not be applicable for concrete with recycled aggregates. This research measures the electrical resistivity (AASHTO T 358 & AASHTO TP 119), formation factor, rapid chloride permeability (ASTM C 1202), and water permeability (Germann water permeability test: GWT) of RAC. High chloride ion permeability was observed in all the samples. On the other hand, some samples were found to have low water permeability. It was observed that RAC could be evaluated as water-resistant when a low water/cement ratio was used. The bulk resistivity, surface resistivity, and formation factor were all found to be strongly correlated with rapid chloride permeability test and GWT measurements. Compared with the established correlation from other studies using conventional concrete, RAC shows a higher slope of electrical resistivity versus chloride permeability regression line. On the other hand, RAC can be assumed to have low water permeability when the bulk resistivity, surface resistivity, and formation factor are greater than 5.2 kΩ-cm, 9.6 kΩ-cm, and 528, respectively.

Permeability of High-Performance Fiber Reinforced Concrete Immersed in High Concentration Sodium Chloride Solution

This paper aims to study the permeability of High-Performance Concrete containing natural pozzolan and reinforced with fibers in high concentration sodium chloride solution. Optimized finely ground natural pozzolan was employed as 6% of partial substitution of the cement. Polypropylene fibers with 6 mm and 12 mm lengths were introduced individually for a volume fraction of 0.1% and 0.15% respectively. Then, in combination with a total fiber content of 0.25%. The effect of sodium chloride attack on the performance of concretes was assessed through the measurement of the compressive strength, splitting tensile strength, sorptivity, rapid chloride permeability test, apparent and intrinsic gas permeability, and visual inspection at various testing ages (28, 90, 180, and 365 days). A total of four (04) types of concretes were cast: one (01) High-Performance Concrete (HPC), and three (03) High-Performance Fiber Reinforced Concrete (HPFRC) stored in tap water and sodium chloride environment. From the experiments performed, it can be concluded that the polypropylene fibers introduction into HPC favorably affect its chemical resistance to chloride attack and long-term durability. The difference in the permeability of HPC and HPFRC stored in tap water and chloride environment is not significant. Furthermore, the visual investigation of HPFRC after 365 days of immersion in sodium chloride environment showed no sign of degradation. Based on the results obtained in this study, we recommend the use of hybrid fiber-reinforced concrete (F0-0.25%) as a low permeable material in a severe chloride environment.

Strength, durability and micro-structural assessment of slag-agro blended based alkali activated engineered geopolymer composites

Alkali Activated Engineered Geopolymer Composites (AA-EGC) usually comprises of fly ash and silica sand as per the literatures available. It is necessary for the researchers to study the effect of other precursors based on local availability. This research paper focuses on the investigation towards the maximum utilization of high-volume industrial slag wastes along with an Agro waste to develop eco-friendly AA-EGC. Here, ground granulated blast furnace slag, rice husk ash, copper slag, Manufactured-Sand (M-sand) and polyvinyl alcohol fibers formed the primary composite ingredients. The optimization of copper slag content w.r.t M-sand was investigated, while considering the best of other mix-factors, based on literatures. Sodium based alkali activators along with polycarboxylic acid ether based super-plasticizer were used as liquid ingredients to activate the geo-polymerization reaction and to improve the workability respectively. Several experimental tests were conducted such as flow table test on fresh composite properties; compression, tensile, rapid chloride permeability test and sorptivity tests on hardened composite properties to evaluate the strength and durability performances. Scanning Electron Microscope (SEM) analysis with Energy Dispersive X-Ray (EDAX) were performed to evaluate the micro-structural properties along with Non-Destructive Test (NDT) to ensure the composite quality. The experiments revealed that the volume of copper slag as fine aggregate could be limited to 60% with respect to M-sand to avoid segregation and bleeding. Maximum of 31.1 MPa compressive strength was achieved with 40% copper slag under ambient curing conditions at the age of 28 days. Increase in copper slag content helped the composite in arresting the chloride ion penetration and absorption of capillary surface water. According to NDT, as the copper slag content increases, the pores were arrested making it denser. The quality of the composite in terms of dense packing, presence of unreacted binders, absence of air pores and unexpected reactions were ascertained with micro-structural investigations.

An experimental study on the durability properties of abaca fiber concrete

The addition of natural fibers in concrete has effectively proved to increase the mechanical strength and durability of concrete in the recent years. They help to tackle the brittle response and limiting post-yield energy absorption by forming a bridge across the cracks in concrete. This study assesses the durability properties of abaca fiber reinforced concrete (AFRC) by surface water absorption test, rapid chloride permeability test (RCPT) and sorptivity test. The optimum percentage of abaca fiber (AF) to be used was chosen to be 0.5 % as it gave the maximum compressive strength value in concrete and a small amount of superplasticizer has been added to reduce the water content in the mix design to match the high water absorption capability of AF. The respective tests were performed to observe the improved properties of water resistance and resistance to chloride ions penetration after 3, 7, 28, 56, 90 and 180 days of curing. It has been found that the addition of AF enhances the ability of concrete to reduce permeability better compared to the effect of conventional concrete (CC).

Optimizing lightweight expanded clay aggregate coating for enhanced strength and chloride resistance

Lightweight expanded clay (EC) aggregates help in decreasing the dead load of the structure and reduce the concrete demand in foundations and other major structural members. However, a major drawback is their high water-absorption and permeability which degrades the transport properties of the concrete, and low strength which results in a concrete too weak to actively participate in load bearing. The present study demonstrates a solution to improve the performance of EC aggregates by coating with different cementitious composites before adding in the lightweight concrete (LWC). Two coating mixes, cement with silica fume and cement with fly-ash, were used to coat EC aggregates with multiple layers. The effect of coat thickness on the density, strength, and cost of EC was examined. The coated EC (CEC) aggregates showed a 60% decrease in the water absorption test, and a 200% increase in the aggregate strength. The concrete made using CEC showed up to 150% increase in the specific compressive strength, and up to 50% drop in the charge passed during rapid chloride permeability tests. Among the coats, the fly-ash (FA) mixes performed at par with the silica fume (SF) mixes in all the tests. Costing index calculated using the cost and specific strength of the LWCs showed a reduction with increasing no. of coats. Considering the high cost of SF, the use of FA coated EC aggregates is recommended to improve the concrete performance and justify the cost involved in their production.

Compressive Strength and Chloride Ion Permeability Test of Concrete Incorporating Fly Ash and GGBS with Diverse Water Binder Ratio

In this study conventional concrete of M40 grade developed with diverse water binder ratio and fixed optimum dosage of 30% mineral admixture fly ash and GGBS with weight of cement .Compression test has been conducted on cube samples and Rapid Chloride permeability test (RCPT) are conducted on cylindrical specimens to acknowledge durability parameter. Compression test results has been enhanced with replacement of supplementary cementitious materials and chloride ion permeability has been reduced with substitution of fly ash and GGBS .incremental of water binder ratio also reduce the permeability value however compression value increased

Experimental analysis on alkali activated fly ash (AAFG) and GGBS based coarse aggregate in cement concrete

Many applications of fly ash have been studied and employed in various fields. Thermal power stations use pulverized coal as fuel. Thus produce large amounts of fly ash as a by-product of combustion. The present analyses investigates the manufacturing process of Alkali Activated Fly Ash (AAFG) and Ground Granulated Blast Furnace Slag (GGBS) Based Coarse Aggregate using an ordinary concrete mixer and its properties are analyzed. The flexural capacity of the Reinforce Concrete (RC) beam with AAFG increases by increasing the diameter of reinforcement and decreases in the replacement AAFG beam, and the crack width decreases as an increase in the replacement of the fly ash aggregate up to 50% in concrete. The durability property of concrete blended with AAFG shows similar results to conventional concrete. From the Rapid Chloride Permeability Test (RCPT) results, it shows that AAFG concrete and conventional concrete are both in the moderate zone only.

Effect on mechanical, durability and micro structural properties of high strength self compacting concrete with inclusion of micro and nano silica

The aim is to study the strength, durability and microstructural properties of high strength self compacting concrete (SCC). 25% cement is replaced by fly ash (10%) and Ground granulated blast furnace slag (GGBS) (15%) for all the mixes except control mix (M1). Micro silica (MS) and Nano silica (NS) were added at different percentages to make high strength SCC. As a cost reduction and to promote renewable material Manufactured Sand (M-Sand) used as a fine aggregate instead river sand. To determine the fresh properties of SCC followed the EFNARC 2002 guidelines. The Compressive strength test was conducted to find strength properties of SCC. The results showed that addition of MS and NS drastically decreases the fresh properties but increases the strength properties of SCC. Ultrasonic pulse velocity test was conducted to find dynamic modulus of SCC. To find the resistance of chloride ingress in to concrete by conducting Rapid chloride permeability test (RCPT). Further microstructure of SCC studied using SEM images. Finally cost analysis was performed for each mix and its results indicated as ratio of strength/cost. The combination of MS and NS in a mix (M7) showed the optimum compressive value, optimum durability and improved micro structure among all the mixes. But in ratio of strength/cost a mix M2 showed optimum result.

Mass Concrete Placement of the Offshore Wind Turbine Foundation: A Statistical Approach to Optimize the Use of Fly Ash and Silica Fume

The experimental program investigated concrete with a large amount of fly ash (FA) with silica fume (SF) to replace Portland cement on the results of semi-adiabatic test, compressive strength test, and the rapid chloride permeability test (RCPT). The replacement ratios of cement by a combination of FA and SF were 30%, 35%, and 40% by mass. The percentages of SF to replace cement were 0%, 4%, and 8% by mass. Three different water-to-binder ratios (W/B) of 0.34, 0.36, and 0.38 were also investigated. Multiple linear regression was applied to construct the predicted equations (models) for the semi-adiabatic temperature rise test and the compressive strength test. Models were assessed statistically and were used to solve the concrete mixture design optimization problems. The mixture with W/B of 0.36, 31% FA, and 5% SF was found to optimally satisfy the multi-objective problem: 28-day compressive strength of 50 MPa, low heat of hydration, and very low chloride penetrability classification. Field test on the actual wind turbine foundation of the optimal mixture revealed the maximum temperature rise was 74.8 °C and the maximum temperature differential was 21.9 °C.

Modelling chloride penetration resistance of Supplementary Cementitious Concrete and compressive strength with pulse velocity

Permeability is one of the principal factors related to durability of concrete. The responsible factor for volume change is permeability. This paper attempt to mechanical and durability study of Supplementary Cementitious Concrete where cement has been replaced by fly ash & GGBS in combination of (30%, 0%), (20%,10%), (10%, 20%) and (0%, 30%).16 such concrete samples has been cast in which water binder ratio introduced as 0.35, 0.40, 0.45 & 50 for each 4 set .cubical and cylindrical concrete 16 samples has been prepared for curing period of 7 and 28 days with replacement of manufactured sand and coarse aggregates. Compressive strength, ultra sonic pulse velocity test (UPV) and Rapid chloride permeability test has been done value at the end of each curing period. The results of this research show that both UPV and compression strength have augmented with supplementary Cementitious materials (SCM) Incorporations. Various empirical models were proposed for pulse velocity and compressive strength. Models for the compressive strength and ultrasonic pulse velocity was developed at individual percentage levels (fly ash or GGBS) and then for each replacement stage four different models (FA percent + GGBS percent) were developed. Similarly after curing for 28 days, Chloride permeability test as per ASTM C1202 has been done. Diverse parameters mathematical models were developed to acknowledge the effect of various factors like SCM incorporations, water binder ratio, replacement of manufactured sand etc., and Models has been tested in full range by data and has strong precision, correlation with experimental data.

Durability studies on ready mix concrete using mineral admixtures and manufactured sand

To meet the intensifying demand of fine aggregate in construction sector, manufactured sand has become a viable alternative to the river sand. Ready mix concrete (RMC) is playing vital role in fast-track construction particularly in Tire-II cities in India. The strength and durability concerns about using 100% manufactured sand along with mineral admixtures in RMC plant needs to be addressed through suitable experimental demonstrations. This research gives the experimental results on strength and durability studies of concrete carried out on samples obtained from RMC Plant by making use of manufactured sand containing (50% of crushed sand and 50% of the crushed rock fines) as replacement for natural sand. Trials on partial replacing cement with fly ash content of 33% and GGBS of 40% has also been carried out. Compressive and split-tensile strength studies were conducted on cubes (150mmx150mmx150mm) and cylinders (150mmx300mm) at 7, 14 & 28 days of curing. Non-Destructive tests such as Ultra Sonic Pulse Velocity (UPV) and rebound hammer tests were conducted to assess the quality of these mixes. Durability tests were conducted and comparison of the % of loss in mass and % of loss in strength for concrete samples subjected to acid attack, sulphate attack, alkaline attack tests were also carried out. Rapid chloride permeability test (RCPT) was conducted to check the concrete resistance against chloride ions penetration. The experimental results revealed that the use of 100% manufactured sand along with mineral admixtures in producing ready mix concrete is a good choice in view of the non-availability of river sand to meet the demands of fast-track construction projects.

Effects of Polyvinyl Alcohol fibers in engineered cementitious composite concrete

The present work majorly focused on the effect of Polyvinyl Alcohol fibers (PVA) in engineered cementitious composite concrete. However, PVA fibers are used as added to the ECC concrete with propotion of 0% to 2% of weight to cementitious materials. All the concrete samples are prepared with mix proportion of 1 cement: 1.1 silica fume: 0.36 ratio of sand/binder: 0.30 ratio of water/binder: 0.01 water reducer. whereas compressive, flexural, split tensile, water absorption and rapid chloride permeability tests are evaluated in order find out the performance of ECC with addition of PVA fibers. Thus, the results, ECC concrete has better mechanical and durability performance than conventional concrete and also its high early strength. From this study concludes that upto 1.5% of PVA fibers can be used in the ECC concrete, which has 60.12MPa and 18% of strength increment than the reference mix.

Development and testing of cellulose nanocrystal-based concrete

Engineers are continuously looking to improve the performance of existing materials. Nanostructured cellulose (cellulose nanocrystals or nanocellulose) offers a high aspect ratio and mechanical strength that may support development of a new class of concrete adapted for extreme environmental conditions. In this study, we developed and tested various types of cellulose nanocrystal (CNC)-based concrete for application in the construction industry. Specifically, three CNC-based concrete specimens with different cellulose nanocrystal types and proportions were tested to understand the effects of nanocellulose on structural concrete performance. Destructive and nondestructive testing, along with surface morphology characterizations, were conducted to evaluate the performance of the CNC-based concrete specimens. The destructive and nondestructive tests yielded similar results. Higher CNC proportions improved the concrete’s microstructure and produced higher ultrasonic pulse velocities along the same path length. Furthermore, results from Schmidt hammer rebound tests confirmed that the CNC-based concrete specimens with higher crystallinity, higher aspect ratios, and rougher surfaces were able to sustain larger loads with smaller crack developments. Finally, results from rapid chloride permeability tests indicated that the addition of 0.25 wt% cellulose nanocrystals in the CNC-1 concrete specimen and 0.75 wt% cellulose nanocrystals in the CNC-2 concrete specimen produced the highest peak resistance against water and chloride ion penetration. These findings can guide future research and development of this novel and innovative material.

Single and synergistic enhancement on durability of geopolymer mortar by polyvinyl alcohol fiber and nano-SiO2

To determine the optimal dosage of polyvinyl alcohol (PVA) fiber and Nano-SiO2 (NS) in metakaolin (MK) and fly ash (FA) based geopolymer mortar from the perspective of enhancement on durability of geopolymer mortar, the single and binary effects of PVA fiber and NS was explored. The compressive strength tests, rapid chloride permeability (RCP) tests, freezing-thawing cycle tests, sulfate wet–dry cycle tests, and scanning electron microscope (SEM) observation were conducted to evaluate the enhancement of PVA fiber and NS on compressive strength and durability of MK-FA based geopolymer mortar. The results showed that the application of PVA fiber and NS in appropriate dosage had significant improvement on compressive strength and durability of MK and FA based geopolymer mortar no matter they were used in single or blended addition. The best modification effect can be achieved when PVA fiber and NS were used together. The optimal mixing contents of PVA fiber and NS were 0.6–0.8 v% and 1.0–2.0 wt%, respectively. The results obtained in this study will enrich the knowledge system on properties of PVA fiber and NS modified geopolymer composites, which can provide guidance for the further promotion application of MK-FA based geopolymer mortar.