Chloride Ion Penetration Test Research Articles

High-quality recycled concrete aggregates developed through an integrated thermomechanical approach

This study demonstrates an integrated thermomechanical treatment process to produce high quality recycled concrete aggregate (RCA) for structural concrete. RCA is mechanically treated after 90 min of heating at 250 °C in this process. The material properties of RCA produced through 15 combinations of charges and drum revolutions are compared using a statistical method. The highest ranking of an RCA identifies it as a high-quality class. Concrete composed of 100% RCA (recycled aggregate concrete, RAC) has 1.7% higher compressive strength than natural aggregate concrete (NAC). RAC has tensile and flexural strengths of 0.95 and 1.03 in fraction of NAC. RAC meets durability criteria such as UPV greater than 4.4 km/s, rapid chloride ion penetration test (RCPT) less than 1000 C, electrical resistivity greater than 208 Ohm-m, and sorptivity closer to NAC. Water absorption and abrasion resistance are similar to or superior to those of NAC. Coherent and uniform surface morphology of RCA enhances the ITZ microstructure in RAC.

Effects of induction furnace slag on the durability properties of concrete

In this study, three major properties of concrete were compared, viz: water absorption, compressive strength and chloride ion penetration. The percentage amounts of Induction furnace slag (IFS) varied in concrete to replace cement were 0%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55% and 60%. These specimens were made to undergo curing for 7, 14, 28, 56 and 90 days following which the aforementioned tests took place. The results of the three tests (i.e. compressive strength test, water absorption test and chloride ion penetration test) showed an optimal performance of concrete at 25% IFS replacement. Some of the specimens containing varying amounts of slag (i.e. 0%, 25% and 45%) were subjected to microstructural and phase identification tests in other to establish their distinguishing properties. These tests include Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). Meanwhile the IFS was also examined for its composition through X-ray Fluorescence (XRF). Predictive models were generated from all the results obtained. The models developed can predict the compressive strength of concrete (Y) if information on the percentage of IFS replaced (X1), the depth of chloride ion penetration into concrete (X2) and the amount of void left in concrete after water is absorbed (X3) are all known. There existed a high correlation; strong relationship between compressive strength and the depth of chloride ion penetration; and between compressive strength and the percentage volume of void.

Chloride Ion Penetration Resistance of Reactive Powder Concrete with Mineral Admixtures

This study employed the rapid chloride ion penetration test and the salt spray erosion method to examine electric flux changes in mineral-admixed reactive powder concrete (RPC). Variations in the chloride ion content and diffusion coefficient under different erosion durations and depths were also investigated. The impact of mineral admixtures on the chloride penetration resistance was explored. Notably, after mixing fly ash (FA) and granulated blast furnace slag (GGBS), the electric flux values of RPC of each group were significantly reduced, and the electric flux values of RPC of the mixed group were significantly lower than those of the single mixed group and the reference group, in which the electric flux of FA10G10 was reduced by 85.2% compared to the control group; at the same erosion cycle and depth, the chloride ion content and diffusion coefficient of the mixed group were significantly lower than the control group. It shows that the reasonable compounding of mineral admixtures can better exert the "superposition effect", improve the compactness inside the matrix, and effectively reduce the chloride ion penetration rate. Considering comprehensively, the FA10G10 group has the best chloride penetration ion resistance effect.

High-strength high-performance concrete incorporating different macro fiber types and contents: Engineering and durability performance

ABSTRACT Generating a synergistic response by combining the advantages of different fiber types in concrete is of current scholarly interest. This study investigated the effects of different hooked-end steel fiber (SF) volume fractions up to 1.6% and three macro fiber types including polypropylene (PP), SF, and typical hybrid fibers (HF: 50% SF + 50% PP) at a fixed dosage of 1.6% on properties of high-strength high-performance concrete (HSHPC). A novel densified mixture design algorithm was used to incorporate a high quantity of fly ash and rice husk ash as an eco-binder. Results showed the specimens with added macro SF exhibited improved mechanical strength, dynamic modulus of elasticity and rigidity, and lower drying shrinkage while the ones with added PP exhibited reductions in compressive strength and dynamic modulus. Interestingly, the incorporation of macro fibers, regardless of fiber type and content, reduced electrical resistivity, ultrasonic pulse velocity and increased the total charge passed in the chloride ion penetration test, resulting in likely underestimation of the reinforcement corrosion resistance, especially for SF specimens. The findings also confirm that HF demonstrating synergistic response may be effective and creative in improving most of the concrete characteristics, contributing to the efficient use of HSHPC in real-world structures.

Research on improving the durability performance of damaged concrete with mineral admixtures

AbstractConcrete can be damaged under long‐term chloride ion action. This article uses mineral admixtures to repair the damaged concrete, and then conducts durability performance tests. Multi‐dimensional chloride ion diffusion tests were conducted under different salt solution immersion environments. The resistance of concrete to chloride ion corrosion was evaluated through RCM chloride ion penetration test, and the internal chloride ion concentration of concrete with different diffusion dimensions was detected through chemical titration analysis. Taking the SW test group as an example, after soaking for 3 months, the three‐dimensional diffusion chloride ion concentration of the SW test group is 2.55 times that of the one‐dimensional diffusion. Under the same three‐dimensional diffusion conditions, at a depth of 10 mm of concrete erosion, the chloride ion concentration of the SW test group after soaking for 3 months is 1.76 times that of the chloride ion concentration after soaking for 1 month. Experiments have shown that multi‐dimensional diffusion can significantly increase the concentration of chloride ions inside concrete, and this effect becomes more pronounced with the increase of erosion time and dimension.

Mechanical and durability studies on fly ash based fibre reinforced concrete

The purpose of this study is to determine the fresh and hardened properties of fibre reinforced concrete along with durability properties with steel fibres (SF) and jute fibres (JF). This study presents properties of concrete prepared with Fly ash (FA) as a partial replacement to Ordinary Portland Cement along with the fibres. Concrete mix of M30 grade was prepared as per IS code guidelines. The specimens were prepared with 5, 10, 15 and 20 % Fly ash replacements along with 0.5, 1.0, 1.5 and 2.0 % Steel and Jute fibre replacements with respect to the binder. For comparison, control concrete mix corresponding to M30 grade was prepared with 0% FA and 0% fibres. Variation in workability with the addition of fibres was determined with the help of slump cone test. Various mechanical strength tests were conducted on the specimens to observe that the strength was enhanced due to addition of fibres. Ultra-sonic pulse velocity test was conducted to determine the strength of prepared specimens in non-destructive way and compared with destructive compression strength values. Durability tests - Carbonation, Acid attack, Sorptivity and Rapid chloride ion penetration tests were conducted to determine the optimum percentage of fibre replacement along with fly ash replacement for long term durability. According to the experimental results, adding 15% fly ash and 1.5% fibres enhanced the mechanical properties, whereas adding 10 and 15% fly ash, 1.5 and 2.0% fibres enhanced the durability properties in comparison with the properties of conventional concrete. This paves the way for developing sustainable alternatives in the construction industry by utilization of marginal materials such as fly ash and jute fibres.

Evaluation of crack self-sealing in flexural concrete members with SAPs by chloride ion penetration resistance

Self-sealing concrete is a technology to repair cracks using swelling properties of superabsorbent polymers (SAPs) without external work. Many studies have been conducted on SAPs as self-sealing materials that fill cracks in concrete. However, because each study evaluated self-sealing performance using different experimental methods, each study reported different results. Therefore, a standardized test method to evaluate the self-sealing performance of SAPs is needed. This study evaluated the self-sealing performance of cementitious materials with SAPs through water absorption, chloride ion penetration, and water flow tests and analyzed the correlations between the results. Two SAPs with different particle sizes were used, and their contents were set to 0.3%, 0.5%, and 0.7% depending on the binder weight. The experimental results revealed that the self-sealing performance improved with increasing particle size and SAP content. In the water absorption test, the amount of water absorbed by the surface of the original specimen and that absorbed through cracks were measured. However, the influence of the self-sealing ability of the SAPs on the total water absorption rate could not be clarified. A chloride ion penetration test was conducted to measure the chloride ion penetration depth directly, and the corresponding results indicated that the self-healing ability of the SAPs enhanced the resistance of the cementitious materials against the penetration of harmful ions. Finally, a water flow test was performed, and the results revealed that the short-term self-sealing performance of SAPs can be evaluated relatively independently.

The Effect of Electric Arc Furnace Dust (EAFD) on Improving Characteristics of Conventional Concrete

The steel industry is one of the key industries and its use is inevitable in many industries including construction. In addition to steel, this industry produces massive amounts of electric arc furnace dust (EAFD) that is classified as hazardous waste. Using this material as an admixture can improve the characteristics of concrete, neutralize potential risks and be beneficial to the circular economy. Considering the differences in EAFD between different steel companies, which in turn is caused by the type and percentage of input materials, the optimal percentage and specific application of EAFD from steel companies of each region is unique. In the present study, samples from 11 different sources of EAFD in Khuzestan Steel Company (KSC) were collected. Then, they were classified into three groups depending on the size and origin (fine and coarse, both obtained by filtering those particle sizes directly from furnaces, and a third class obtained in the interior of the steelmaking site close to material handling (MH) belt conveyors) based on their physical and chemical characteristics. To test the effect of EADF as an admixture, several conventional concrete samples were prepared by replacing 0% (control), 2%, 5% and 8% of cement with each EAFD group. Finally, the resulting material was characterized through several tests, namely: (i) compressive strength test at 7, 28 and 90 days, (ii) depth of water penetration under pressure test and (iii) electrical indication of concrete’s ability to resist chloride ion penetration. The result shows that replacing 2% of the cement with MH caused the largest improvement in compressive strength of 7 day concrete, but also showed negative effect on water penetration, while coarse had a negative effect in almost all tests except in the chloride ion penetration test. The best results were obtained by replacing with 2% of cement with fine EAFD, showing significant improvements in all tests, as well as in the observed trend of increasing compressive strength over time.

Evaluation of a Hydrophobic Coating Agent Based on Cellulose Nanofiber and Alkyl Ketone Dimer.

In this study, we report on the development and testing of hydrophobic coatings using cellulose fibers. The developed hydrophobic coating agent secured hydrophobic performance over 120°. In addition, a pencil hardness test, rapid chloride ion penetration test, and carbonation test were conducted, and it was confirmed that concrete durability could be improved. We believe that this study will promote the research and development of hydrophobic coatings in the future.

Sorptivity and rapid chloride ion penetration of self-compacting concrete using fly ash and copper slag

This paper represents experimental work on the mechanical and durability parameters of self-compacting concrete (SCC) with copper slag (CS) and fly ash (FA). In the first phase of the experiment, certain SCC mixes are prepared with six percentages of FA replacing the cement ranging from 5% to 30%. In the second phase, copper slag replaces fine aggregate at an interval of 20% to 100% by taking the optimum percentage value of FA. The performance of SCC mixes containing FA and copper slag is measured with fresh properties, compressive, split tensile and flexural strengths. SCC durability metrics, such as resistance against chloride and voids in the concrete matrix, is measured with rapid chloride ion penetration test (RCPT) and sorptivity techniques. The microstructure of the SCC is analyzed by using SEM and various phases available in the concrete matrix identified with XRD analysis. It is found that when replacing cement with 20% of FA and replacing fine aggregate with 40% of copper slag in SCC, higher mechanical strengths will be delivered. Resistance of chloride and voids in the concrete matrix reaches the optimum value at 40%; and with the increase of dosage, the quality of SCC will be improved. Therefore, it is recommended that copper slag be used as a sustainable material for replacement of fine aggregate.

Self–healing capacity assessment of cracked slag modified concrete under different re-curing conditions

The self-healing property of concrete is one of the unique features that can increase reinforced concrete structures’ reliability and service life and significantly reduce repair and maintenance costs. In this regard, self-healing characteristic of concrete specimens containing different quantities of slag was investigated in lime, tap, and 3% salt water. In addition, the cracked concrete specimens were cured in the mentioned solutions to investigate the effect of curing conditions on the corrosion process. Tensile strength recovery, water passing content through the cracked specimens, and chloride ion penetration tests have been performed to investigate the self-healing performance of cracked concrete. Also, the changes in the corrosion potential of embedded steel rebars in healed concrete specimens were measured via an innovative experiment. The outcomes revealed the significant impact of substituting slag with Portland cement on the healing rate. Furthermore, the tensile strength recovery in the specimens containing 15, 30, and 45% slag has improved up to 40, 46, and 59% in tap water re-cured condition. The results from the corrosion potential and the other experiments indicated an equal tendency besides the significant impact of the specimens’ curing circumstances on the self-healing process.

Long-term mechanical properties and durability of high-strength concrete containing high-volume local fly ash as a partial cement substitution

High-volume fly ash (HVFA) is a commonly used partial substitution for cement in mortar and concrete production. The present study was developed to examine the potential of using local HVFA as a partial substitution for cement in high-strength concrete (HSC). The effects of FA inclusion on the long-term mechanical properties and durability of concrete were investigated. The HSC samples were prepared with different FA substitution ratios, ranging from 0% to 50% by weight (ratio between FA to total weight of cement and FA) at 10% interval. Long-term properties were evaluated through compressive strength (CS) and ultrasonic pulse velocity (UPV) tests, while durability was examined through water absorption (WA), drying shrinkage (DS), and rapid chloride ion penetration (RCPT) tests. The results indicate that, at 28 and 56 days, higher FA content was associated with lower HSC performance. However, at 120 days, the 30% FA sample achieved the highest performance of all of the samples in terms of long-term mechanical properties and durability. Moreover, higher FA content was associated with less DS. Also, no significant change in the water absorptivity value of the HSC samples was observed. All of the HSC samples at 28, 56, and 120 days of curing age had UPV values of above 4100 m/s, indicating “very good quality” concrete. In addition, all of the HSC samples exhibited “very low” chloride permeability. Finally, the results of the environmental analysis found that incorporating a high volume of locally sourced FA as a partial substitution for cement in HSC reduced both CO2 emissions (CO2-E) and energy consumption (EC), which may help further promote the sustainability of the construction industry.

Durability evaluation of binary and ternary concrete mixtures by corrosion resistance approach

The use of pozzolans as cement substitutes has become widespread in concrete technology in recent years. This is due to the improvement of concrete properties as well as from the perspective of sustainable development and reduction of cement consumption. In this study, the effect of 45% ground granulated blast furnace slag, 7% silica fume, 35% fly ash, and 15% zeolite as binary and ternary mixtures on durability and corrosion resistance of Self-compacting concrete specimens were investigated. The studied parameters included compressive strength, electrical resistivity, water absorption, rapid chloride ion penetration Test and corrosion test also scanning electron microscopy images were used to analyze the microstructure of the concrete samples. Results showed that replacement cement with slag, silica fume, fly ash, and zeolite is generally increased the durability parameters and corrosion resistance of concrete. In all experiments, silica fume has shown better behavior in terms of durability, so that its electrical resistance after 90 days is more than 3.3 times that of the control specimen and other parameters such as water absorption and chloride ion penetration showed approximately 37% And 74% less than conventional concrete respectively. Also, corrosion results indicated that samples containing silica fume had the highest corrosion resistance and reduced the corrosion rate by more than 6 times after 15 test cycles.

An Insight into Durability, Electrical Properties and Thermal Behavior of Cementitious Materials Engineered with Graphene Oxide: Does the Oxidation Degree Matter?

Due to global environmental concerns related to climate change, the need to improve the service life of structures and infrastructures is imminently urgent. Structural elements typically suffer service life reductions, leading to poor environmental sustainability and high maintenance costs. Graphene oxide nanosheets (GONSs) effectively dispersed in a cement matrix can promote hydration, refine the microstructure and improve interfacial bonding, leading to enhanced building materials' performance, including mechanical strength and transport properties. Cement-based nanocomposites engineered with GONSs were obtained using two commercial nanofillers, a GO water suspension and a free-flowing GO nanopowder, characterized by fully comparable morphology, size and aspect ratio and different oxidation degrees (i.e., oxygen-to-carbon molar ratio), 0.55 and 0.45, respectively. The dosage of the 2D-nanofiller ranged between 0.01% and 0.2% by weight of cement. The electrical and thermal properties were assessed through electrochemical impedance spectroscopy (EIS) and a heat flow meter, respectively. The results were discussed and linked to micrometric porosity investigated by micro-computed tomography (μ-CT) and transport properties as determined by initial surface absorption test (ISAT), boil-water saturation method (BWS) and chloride ion penetration test. Extra-low dosage mortars, especially those loaded with a lower oxidation degree (i.e., 0.45GO), showed decreased permeability and improved barrier to chloride ion transport combined with enhanced thermal and electrical conductivity with respect to that of the control samples.

Evaluating the Influence of Carbon Fiber on the Mechanical Characteristics and Electrical Conductivity of Roller-Compacted Concrete Containing Waste Ceramic Aggregates Exposed to Freeze-Thaw Cycling

Traditional methods of removing snow and ice from pavements using chemicals are combined with mechanical removal that involves a lot of manpower, advanced machinery, chemicals that are harmful to the environment, and damage to pavements. Furthermore, annually, large quantities of ceramic materials become waste due to their fragile nature during processing, transport, and installation, and their accumulation in the nature has brought about environmental and health-related concerns. Therefore, the study aims to investigate the effect of using waste ceramic as a replacement for fine aggregate in roller compacted concrete (RCC) and the application of carbon fiber to improve the mechanical properties and electrical conductivity of RCC. To achieve this goal, several tests such as compressive strength, indirect tensile strength, electrical resistance, chloride ion penetration, specific gravity, and skid resistance tests were carried out on the fabricated samples before and after freeze-thaw cycling exposure. The experimental results illustrated that replacing waste ceramics with fine-grained aggregate increased the compressive strength and tensile strength of RCC. Furthermore, carbon fiber increased tensile strength but had no noticeable influence on compressive strength. Freeze-thaw conditioning led to a reduction in the compressive and tensile strength regardless of the aggregate type and carbon fiber utilization. In the samples containing waste ceramic aggregate, the electrical conductivity was reduced, and by adding carbon fiber, its electrical conductivity was increased. Exposure to freeze-thaw cycling resulted in an increase in electrical resistance and the passing charge. Waste ceramic incorporation created a similar mixture in terms of skid resistance, while in contrast, the carbon fiber slightly reduced the skid resistance. In addition, freeze-thaw conditioning resulted in an increase in the skid resistance. Besides, in this study, kernelized support vector regression (KSVR) and radial bias function (RBF) neural network models were proposed to estimate the indirect tensile strength (ITS) and compressive strength (CS) values. The results showed that both models have high performance in estimating these values, but RBF was a more efficient model.

Study on the chloride ion transport mechanism of recycled mixed aggregate concrete based on evolution characteristics of pore structure

• An interface model of RMA concrete considering pore structure characteristics was established. • The evolution characteristics of the microscopic pore structure for RMA concrete were studied. • The chloride ion transport mechanism of RMA concrete was studied based on microstructure parameters. The difference in pore structure characteristics is the fundamental reason that the chloride ion transport mechanism of recycled mixed aggregate (RMA) concrete is different from that of ordinary concrete. In this paper, the chloride ion penetration tests were performed on eight groups of specimens with different water-binder ratios (w/b) and coarse aggregate types. The specimens’ micromorphology, pore structure, fractal dimension, and microhardness were analyzed in detail. The results show that the pore structure of the specimen has an important influence on the chloride ion transfer process. With the increase in curing age, the porosity of new mortar (NM) and mortar attached to the surface of brick aggregate (BM) decreased, while the total fractal dimension increased, and the porosity of BM decreased more than that of NM. The brick aggregate is wrapped in a dense hydration layer, which prevents chloride ions from penetrating the brick aggregate to a certain extent. The anti-chloride ion transport performance of NM is weaker than that of BM due to the NM contains more capillary and large pores. Different pore size distribution ranges of the specimens have similar fractal characteristics. The fractal dimension first increases and then decreases with the change of the pore size range from small to large. The interface pore model of RMA concrete was established to provide a reasonable basis for further research on the durability of the specimens.

Effects of Wollastonite Fiber and Styrene–Butadiene Latex Polymer on the Long-Term Durability of Cement-Based Repair Materials

Concrete structures are constructed in various geographical environments and climates, and frequently fail to fulfill their original functions over time due to issues such as aging and damage. Research on concrete structure repair materials is being conducted to solve these problems. This study evaluated the durability of a repair material composed of ultra-rapid hardening cement, styrene–butadiene (SB) latex polymer, and wollastonite mineral fiber. The performance targets were as follows: compressive strength of 20 MPa at 1 day of age and 45 MPa at 28 days of age, chloride ion charge passed of less than 1000 Coulombs, carbonation depth of 20 mm or less, and resistance to repeated freezing and thawing (relative dynamic modulus of elasticity) of 80% or more. The ultra-rapid hardening cement:silica sand ratio of 1:1.5 was the experimental variable, and the unit weight of each material in the mix proportion was determined to satisfy the flow requirement of 200 ± 5 mm. This flow ensured sufficient fluidity for spraying, which is the most widely used method for applying repair material. Wollastonite mineral fiber and SB latex polymer were added at 3% and 5% of the unit weight of the binder, respectively. The mechanical property of the repair material was evaluated through compressive strength, and durability was evaluated through chloride ion penetration, alkali resistance, resistance to carbonation, water absorption, and repeated freezing and thawing tests. The compressive strength satisfied both target values, regardless of the addition of SB latex polymer and wollastonite mineral fiber. The chloride ion penetration test, which was used as an indicator of durability, showed that mixtures without SB latex and wollastonite mineral fiber were not satisfied the target charge passed of 1000 Coulombs, while mixtures with latex and mineral fiber reached the target value. Notably, the co-addition of latex and wollastonite fiber showed the highest resistance to chloride ion penetration, alkali ion, carbonation, repeated freezing and thawing, and the least absorption. The results confirmed that the durability of the repair material based on ultra-rapid hardening cement was most effectively improved by the co-addition of SB latex polymer and wollastonite mineral fiber.

Fresh and Hardened Properties of Self-Compacting Concrete Comprising a Copper Slag

Recycling trash and protecting natural resources are two of the many benefits of using copper slag as a fine aggregate in a concrete building. However, stakeholders need proven research output to build trust and initiate or enhance the use of such industrial waste in buildings. This study evaluated self-compacting concrete’s fresh and hardened characteristics (SCC) comprising a copper slag aggregate (CSA). For this purpose, six mixes were prepared by substituting river sand with CSA up to 50%, with a 10% increment. The properties of fresh SCC were evaluated using slump flow, V-funnel, and L-box tests. Several parameters of SCC were examined, including water absorption, sorptivity, chloride ion penetration, sulphate attack, and acid attack tests. Energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM) were used to investigate the concrete microstructure. The results indicated that the fresh characteristics of SCC were enhanced as the amount of CSA increased consistently. The durability properties showed a considerable enhancement in SCC mixes comprising up to 20% of CSA.

Novel recycling application of high volume municipal solid waste incineration bottom ash (MSWIBA) into sustainable concrete

Since municipal solid waste incineration bottom ash (MSWIBA) contains some heavy metals that are harmful to the groundwater and soil, this study proposes an effective and new approach to deal with high-volume MSWIBA. Selecting 70% MSWIBA, 10% ordinary Portland cement (OPC), 10% fly ash/ground granulated blast furnace slag (FA/GGBFS), and 1% volume of polypropylene (PP) fiber as the raw materials, this project designed and manufactured cold-bonded fiber aggregates (CBFAs) and applied them into sustainable concrete. It was found that the water absorption of CBFAs was between 12 and 14%, the bulk density was between 900 and 1100 kg/m3, and the compressive strength of single particle was greater than 1.8 MPa. And it was found that the mechanical strength and bulk density of CBFAs were positively correlated, while the mechanical strength and water absorption were negatively correlated. The leaching behaviors of CBFAs on Cu, Pb, Cd, and Cr were successfully suppressed to less than 1% of that originally from MSWIBA, which can be in line with the Chinese standards. Additionally, it is also found that the green concrete with adding GGBFS-CBFAs has higher overall fluidity and better mechanical properties than the concrete with FA-CBFAs. The mechanical properties of concrete were the best under the replacement rate of 60% of CFBAs, and the strength of green concrete added with GGBFS-CBFAs reached 96% of that of ordinary concrete. In this study, the rapid chloride ion penetration test, mercury intrusion and electron microscope tests found that the bonding effect between the CBFAs and the green concrete matrix was better, and the pore structure in the transition zone of the surrounding interface was refined. The proportion of transition pores in the pore structure was up to 59%. This shows that the concrete added with CBFAs has better resistance to chloride ion diffusion, and has some improvement on the durability. This research suggests that CBFAs including high volume MSWIBA has the potential to be successfully applied as the alternative to natural aggregates in sustainable concrete, and this can also advance waste recycling, and solidify high volume heavy metals in infrastructures.

The impact of using rice husk ash as a replacement material in concrete: An experimental study

Rice husk ash (RHA) is a promising pozzolanic alternative material for partial replacement of ordinary Portland cement to increase the durability and strength of concrete and, at the same time, to decrease the corrosion effect caused by the harsh environment conditions. In this study, the impact of adding RHA in different ratios (0%, 7%, and 14%) as a replacement of ordinary Portland cement with different water–cement ratios (0.3, 0.5, and 0.7) and cured in water for different periods (10, 20, and 30 days) both on the durability and strength of the concrete and on its corrosion was investigated. The prepared specimens were tested by flexural, compressive, and tensile strength tests, slump test, and Rapid Chloride Ion Penetration test to determine the suitability of the partial replacement of ordinary Portland cement by RHA in concrete. The most important findings of this work, which is considered novel in this field, are that adding fine (instead of more extensive) RHA particles enhances the flexural, compressive, and tensile strength values and limits the chloride ion penetration with time. An adverse impact was found to increase the water–cement ratio, which is assigned to the effect of water on RHA and as a result on the porosity of the concrete.