Rapid Chloride Permeability Test Research Articles

Evaluating the rapid chloride permeability of self-compacting concrete containing fly ash and silica fume exposed to different temperatures: An artificial intelligence framework

One of the major known challenges of improving durability of concrete structures is reducing the permeability of concrete to retard the transport of chloride ions. In this regard, the utilization of self-compacting concrete (SCC) incorporating supplementary cementitious materials such as fly ash and silica fume can aid to improve the resistance against chloride ion penetration. With the aim of evaluating the effectiveness of the SCCs, existing experimental methods, such as the rapid chloride permeability test (RCPT), demand time, financial resources, and skilled technicians. This study proposes three accurate and reliable predictive models through the combination of metaheuristic optimization techniques of particle swarm optimization (PSO), ant colony optimization (ACO) and biogeography-based optimization (BBO) with artificial neural network (ANN) in order to minimize the reliance on time-consuming and costly laboratory activities. To this end, 360 RCPT results on 60 SCC mixtures incorporating various percentages of fly ash and silica fume exposed to different temperatures during the RCPT were collected. The performance of the developed models was assessed by different statistical indicators. The results reveal that the proposed ANN-BBO model exhibits a higher accuracy than the single ANN, ANN-PSO and ANN-ACO models. It is also found that the input parameter of the sample temperature during testing is the most important variable in controlling the RCPT of SCC with a contribution of 25%. Comparing the performance of the best proposed model (ANN-BBO) with that of existing models in the literature reveals that the ANN-BBO model has a higher accuracy in predicting the chloride ion penetration resistance of SCCs.

Effect of Mud Powder on the Performance of Bridge Deck Leveling Concrete in a Seasonally Frozen Region.

Mud powders in aggregates are often found to cause deterioration of concrete properties. Based on a study of the mechanical properties of bridge deck leveling concrete (BDLC) containing different mud powders at various ages, the effects of mud powders on concrete durability were evaluated through rapid chloride permeability testing, freeze-thaw testing, and the coupling of salt solution and a freeze-thaw test. The properties of the interfacial transition zone (ITZ) were also investigated via microhardness testing. The test results showed that mud powder reduced the compressive strength, static compressive elastic modulus, and bond strength at early stages of curing. Moreover, mud powder was found to reduce the tensile properties and durability of concrete, with clay powder causing a greater reduction than mud powder in river sands and coarse aggregate. In addition, the width of the ITZ of concrete containing mud powder was found to increase by 23.1-48.3%. A significant correlation between the ITZ and the tensile properties, as well as the durability of concrete, was also observed. Therefore, in order to improve the tensile properties and durability of BDLC in seasonally frozen regions, the content of mud powder in the aggregates should be minimized according to the different compositions of mud powders. The coupling effect of salt solution and a freeze-thaw cycle should also be taken into consideration.

Experimental Investigation of Snail Shell-based Cement Mortar: Mechanical Strength, Durability and Microstructure

Snail shells are the discarded bio-shell waste from restaurants, and oceans creating huge environmental problems for society. Living organisms are harmed when these shells are released. As previously stated, the work focuses primarily on the utilisation of snail shell powder as a raw ingredient in cement mortar. The mechanical and durability features of snail shell-based cement mortar were compared to the nominal mortar in this study. Snail shell powder, ranging from 0% to 35%, was used to partially substitute cement in mortar, with a variation of 5%. XRD (X-Ray Diffraction) was used to determine the chemical composition of both mixes. The mechanical properties of mortar for both mixes were determined using a compressive strength test. The tests on cement mortar viz., Water Absorption, Sorptivity, Acid Durability, and Rapid Chloride Permeability Test (RCP Test) were compared with nominal mortar mix. According to the results of the investigation, the optimum use of snail shell powder is 30%. The durability of both mixes increased by the increase of the snail shell powder. To detect the C-S-H gel formations, microstructural analysis was performed for both mixes.

An approach for environment protection by regression and cluster analysis of GGBS-based geopolymer composite at different proportion of brick dust

The study focused on the significance of ground granulated blast furnace slag (GGBS) as replacement of brick dust. Compression, tension, rapid chloride permeability test (RCPT) and water absorption test (WA) is analyzed. Study revealed that the produced geopolymer concrete showed better properties over normal concrete. Up to 10% GGBS replacement with calcined clay, exhibits enhanced compressive strength. Chloride ion permeability tests showed that GPC is superior to normal concrete of all ages in its resistance to chloride ion penetration. On increasing brick dust proportion, mass loss minimized due to sulfate attack. Compressive strength has low relationship with water absorption (0.6618).

Enhancing the properties of geopolymer concrete using nano-silica and microstructure assessment: a sustainable approach

Nowadays low calcium fly ash-based geopolymer concrete can be replaced with cement-based concrete to avoid the adverse effect of manufacturing cement on the environment. Utilization of geopolymer concrete instead of traditional concrete using low calcium fly ash and nano silica reduces a significant amount of CO­2 emission towards the atmosphere. However, the performance of geopolymer concrete is less than that of Portland cement concrete. To improve the performance of geopolymer concrete nano silica was used in the present study. In this work, geopolymer concrete was made utilizing fly ash, ground granular blast furnace slag (GGBS), and sugarcane bagasse ash. In the first instance, binary combinations i.e. fly ash and GGBS were employed as cementitious materials for the production of geopolymer concrete. In the second instance, a ternary mixture of pozzolanic material was prepared by taking 25% GGBS, 65% Fly ash, and 10% bagasse ash. In the third instance, varying percentages of nanoparticles were used for the above ternary mixture. The mechanical and durability properties of the geopolymer composite that was made earlier were tested. The compressive strength and split tensile strength of geopolymer composites were assessed for mechanical properties and a rapid chloride permeability test, water absorption test, and acid attack test were done to know about the porosity of concrete. Results showed that, with a dose of 4% nanoparticles, the durability and strength properties of the concrete had improved the most. The GCBA-N4 mixture had the highest split tensile and compressive strength was measured to be 2.91 MPa and 41.33 MPa and the rapid chloride permeability test, water absorption rate, and percentage of mass loss due to sulfate attack were found as a minimum for GCBA-N4 specimen.

Durability parameters of three low-carbon concretes (low clinker, alkali-activated slag and supersulfated cement)

The general transfer properties (water porosity, mercury intrusion porosimetry, water permeability, capillary absorption, gas permeability and resistivity) and chloride penetration resistance (natural chloride diffusion test and rapid chloride permeability test) of three low-carbon concretes C25/30 (low clinker (LCK) concrete, alkali-activated slag with sodium carbonate (Na2CO3-AAS) concrete and supersulfated cement (SSC) concrete) were evaluated and compared, in order to identify the strengths and weaknesses of each technology. The results show that the LCK concrete is characterized by “excellent” transfer properties (low water porosity, gas permeability, water permeability and capillary absorption) but high viscosity in the fresh state and very high chloride permeability. AAS and SSC concretes have similar transfer properties, comparable to classical concretes C25/30, and are extremely resistant to chloride penetration. Finally, the use of traditional protocols for durability tests applied to alternative low-carbon binders is questioned and metrology adaptations are proposed.

Influence of Optimum Particle Packing on the Macro and Micro Properties of Sustainable Concrete

In this research, the possibility of making eco-friendly concrete from available materials in the local United Arab Emirates (UAE) market was investigated. Supplementary cementitious materials, such as ground granulated blast-furnace slag (GGBS) and silica fume (SF), were utilized for decreasing the cement quantity, enhancing the particle size distribution and improving packing. In sum, 130 concrete specimens—cubes, cylinders, and prisms—from 10 different concrete mixes were tested to determine the enhancement levels in the fresh and hard properties of new concrete. The results showed the improved particle packing of the concrete, especially within the region of sizes 100–10,000 microns, produced by the Elkem Materials Mix Analyser (EMMA), closely matching the Andreassen theoretical model. The green concrete incorporating SF and GGBS possessed air content in the range 1.0–1.4% and compressive strength that is on average 11% higher than the well-packed concrete that did not contain SF or GGBS. Compared to the ACI 318 code’s predictions, the experimental findings of the optimally packed concrete’s moduli of rupture and elasticity were under-estimated by 55–69% and 0.8–8.8%, respectively. The rapid chloride permeability test (RCPT) showed results as low as 392 coulombs for mixes with supplementary cementitious materials, indicating very low chloride permeability. Microstructural analysis using a scanning electron microscope (SEM) demonstrated that concrete with supplementary materials has fewer voids, more homogeneous integration of ingredients, and an abundance of C-S-H products that supported the RCPT findings and tests of mechanical properties. The study demonstrated a significant decrease in carbon dioxide (CO2) emissions of concrete utilizing GGBS and SF and the financial feasibility of eco-friendly concrete in the UAE.

Application of Coffee Husk Ash as Partial Replacement of Fine Aggregate in Concrete

The task of turning agricultural waste into practical construction and building materials has been placed before civil engineers. Coffee husk is produced in vast amounts due to the global commerce of coffee beans, which are incinerated into ash when used as fuel, producing coffee husk ash (CHA). Even though many researchers have worked on the utilization of CHA in concrete, they have been used as partial cement replacement but not as a replacement of aggregates. The experimental study of the performance of concrete on fine aggregate replaced partially with CHA is represented in this paper. The fine aggregate is replaced by 0%, 2%, 4%, 6%, and 8% by weight of CHA. The performance of the partially replaced fine aggregate with CHA is reviewed by considering the compressive strength and workability of fresh concrete and the splitting tensile strength, flexural strength, durability under acid and alkaline media, thermal conductivity, and rapid chloride permeability test of hardened concrete. The results indicate that the partial replacement of fine aggregate with 4% of CHA (CHA04) in concrete provides a positive impact to all the selected performance parameters. The compressive strength, flexural strength, and splitting tensile of the CHA04 mix were 43.4 MPa, 3.7 MPa, and 2.44 MPa, respectively, which were 28.4%, 19.35%, and 1.66%, respectively, greater than normal concrete mix (CHA00). Even the study of acid and alkaline attack on the CHA04 mix showed lesser strength reduction as compared to other mixes. The RCPT showed less chloride permeability, and the thermal conductivity is higher for CHA04, indicating lesser voids compared to other mixes. With the help of this investigation, it can be said that fine aggregate replacement with 4% CHA has the best strength and durability properties compared to regular concrete.

Durability Assessment of Alkali-Activated Concrete Exposed to a Marine Environment

This study investigated the performance of two alkali-activated concretes (AACs) subjected to marine exposure for 2 years. The AACs were synthesized from a low-calcium Class F fly ash (FA) and a blast-furnace slag. Concrete specimens were exposed in a marine environment in a port facility in southern Australia for 2 years. The specimens were subject to a range of nondestructive testing (NDT) techniques, including resistivity, Schmidt hammer, and ultrasonic pulse velocity (UPV) tests. In addition, chloride diffusion coefficients were calculated from concrete cores taken from specimens exposed in the marine environment. Microscopy analysis was undertaken using Fourier-transform infrared (FT-IR), nuclear magnetic resonance (NMR), and thermogravimetric analysis (TGA), and comparative data were taken on laboratory specimens at 28 days. Furthermore, the chloride diffusion coefficients were compared with the results of standard laboratory tests undertaken on the control samples at 28 days, including rapid chloride permeability testing (RCPT) using a 10-V driving voltage, an NT Build 492 test, and a bulk diffusion test, to determine the relationship between the 28-day laboratory tests results and the site performance. The data showed good correlation between the predicted performance based on the 28 day laboratory tests and the 2-year site data. The chloride diffusion of the ground granulated blast-furnace slag (GGBS) concrete agreed very accurately with the predicted value from the modified RCPT test, whereas the performance of FA concrete was superior to that predicted.

Self-healing capability of engineered cementitious composites with calcium aluminate cement

The reduced heating temperatures required for producing calcium aluminate cement (CAC) make it highly suitable for reducing CO2 emissions in engineered cementitious composites (ECCs) known with their significant amount of cement. However, it is not clear to what extent this can influence the advanced mechanical and self-healing ability of control ECC, especially with the risk of conversion in CAC reaction products. This study investigates the self-healing capability of ECCs produced using CAC instead of conventional ordinary Portland cement (OPC). It also assesses the impact of incorporating fly ash (FA) into CAC-ECC blends at different FA/CAC ratios. In addition to the mechanical characterisation of sound specimens, flexural properties, cracking behavior, ultra-sonic pulse velocity (UPV) and rapid chloride permeability test (RCPT) were performed on preloaded OPC- and CAC-ECCs. The study also analyzed the microstructural changes of self-healing products associated with the high alumina content of CAC. The results show that CAC can be used to produce high mechanical strengths ECCs, with more than 34% and 7% higher compressive and flexural strengths respectively than those of ECC-CTL at early age, though the addition of FA was important to reach improved patterns of mechanical properties at advanced ages. In addition, significant improvements were recorded for the recovery rates of CAC-ECCs, reaching more than 29% for flexural strengths, 11% for UPV and 75% for RCPT than the ECC-CTL. The self-healing products characterized with SEM-EDS confirmed the occurrence of conversion when FA was not included in CAC-ECCs, nevertheless with limited effect on the self-healing efficiency of these mixtures.

Performance evaluation of ternary blended cement concrete partially replacement of natural sand with granite quarry dust

Cementitious composites are the most frequently used man-made material, with a 25 billion tonne manufacturing volume and 5% greenhouse gas emissions. Concrete composites release a lot of CO2 into the environment. Thus, replacing concrete composite raw material is a priority. To reduce this industry's carbon footprint, large-scale reuse of industrial byproducts, including Fly Ash (FA), Silica Fume (SF), and Ground Granulated Blast-Furnace Slag (GGBS) in cementitious composites, is growing. This method addresses the waste management for industry byproducts in two ways. The mechanical strength and durability of cementitious composite products with many ingredients must be recognised. This study's major goal is to evaluate high-strength cementitious composites' mechanical strength and durability. FA (20%, 30%, and 40%), SF (5%, 7.5%, and 10%), and GGBS (10%, 15%, and 20%) binder were used to make high-strength cementitious composites. Waste management has developed into a problem for the environment. The illegal and unethical practices involved in mining natural river sand (NRS) have gotten worse. Therefore, by substituting Granite Quarry Dust (GQD) for fine aggregate, the lack of NRS for a building is prevented. GQD was employed to replace natural river sand at different levels of replacement as the fine aggregate phase in 10%, 20%, and 30%. The fresh cementitious composites properties were evaluated, strength properties such as compressive strength, flexural strength, and split tensile strength were also evaluated and additionally, the durability characteristics such as water sorptivity and the Rapid Chloride Permeability Test (RCPT). We shall evaluate it with normal concrete based on the results.

Pre-treated corn straw fiber for fiber-reinforced concrete preparation with high resistance to chloride ions corrosion

Chloride ions erosion is a negative factor for concrete sustainable usage. Fiber addition is a potential solution, which promotes a tight concrete structure formation resulting in the resistance of chloride ions. Corn straw is a kind of crop waste widely sourced that can be used as sustainable concrete reinforcement material. The traditional recycling method of corn straw including burnt as straw ash is not environment friendly. This work aims to pre-treat corn straw fiber (CSF) by some convenient methods (untreated, water-treated, alkali-treated) and add treated CSFs directly into concrete to prepare fiber-reinforced concrete with excellent mechanical properties and high resistance ability to chloride ions. The component content of different treated CSFs was tested to study the fibers composition and microstructure changes. The heat of hydration, compressive strength, and flexural strength were tested to study the hydration degree and the effect of different treated CSFs on the concrete mechanical performance. The rapid chloride permeability (RCPT) and chloride migration (RCM) tests were designed to study the reinforced concretes chloride ions resistance ability change. In addition, to further explore the mechanism of mechanical performance and chloride ions resistance ability change, water absorption rate (WAR) and mercury intrusion porosity (MIP) were tested to provide more supporting information from the micro-level. It is concluded that CSF treated by Na2SiO3 has the least impurities and a rougher surface with a larger specific surface area bonding with the cement substrate. Compared to the original concrete, the compressive strength of CSF concrete, WT-CSF concrete, and NT-CSF concrete increased by 15.7 %, 17.8 %, and 33.4 % respectively. The results of RCM and RCPT show a decreasing trend with different treated CSFs addition, the NT-CSF concrete shows the greatest decrease with 20.1 %, and 17.5 %, respectively. Except for the rougher surface and less impurities of CSF, the improvement of mechanical performance and chloride ions resistance ability is mainly due to treated CSF, especially the NT-CSF contributes to a denser structure formation based on the MIP and WAR test results. The viscosity of Na2SiO3 solution acts as a binder that helps to tighten the bonding between substrate and CSF. The water adsorbed by CSF and the alkaline environment provided by Na2SiO3 facilitates hydration decreasing the chloride ions migration. At the same time, the cellulose in CSF containing many hydroxyl and carboxyl groups further contributes to the concrete chloride ion resistance improvement due to its weak conductivity and the binding force of ions exchange.

Effect of Wood Ash on salt Crystallization and Rapid Chloride Permeability Test (RPCT) in Mortar

Abstract: Ash by-products obtained from combustion of wood biomass are generally used in land filling for embankments, road/highway construction. It can be used as soil supplementing material to reduce the alkalinity of soil in agricultural lands. And it can also be used as raw material in the manufacturing of cement in cement industries. Many researches had been carried out to incorporate wood waste ash as a cement replacement material in the production of greener construction material (concrete/mortar) and also as a sustainable means of disposal for wood waste ash. Results of these researches indicated that wood waste ash can be effectively used as a cement replacement material for the production of structural concrete/mortar of acceptable strength and durability parameters. In the present study salt crystallization, rapid chloride permeability test are performed. The results shows As wood ash contains more amount of calcium oxides which are soluble in water and leached out and further react with sodium sulphate. That is why, on increasing the percentage of wood ash, loss in weight as well as loss in compressive strength and chloride ion permeability is high in all the cases but as we increase the percentage of wood ash, chloride ion permeability decreases

Characterization of fiber reinforced self-compacting concrete by fly ash and cement

Self-compaction concrete is huge flow capable kind of concrete that flows through the appearance lacking of any shaking. Self-compacting concrete is a non-separating concrete those can be located by its own mass. It has fresh properties approximately passing capacity, flowing ability, filling ability and segregate resistance which can be estimated by conducting workability tests like L-Box, V-Funnel, U-Box, J-Ring and Slump cone flow. The characteristics of self-compacting concrete replacing by fly ash to improved the fresh state stability, rheological properties and compressive strength and steel fibers generating a highest compression and splitting tensile strengths in self-compaction concrete. The effects of fly ash as 5%, 10%, 15%, 20%, 25%, 30% weight of cement and of steel fibers as 0.5%, 1.0%, 1.5, 2% with taking of the highest (optimum) value of fly ash to get maximum strength. The strength characteristics like compression, split, tensile and flexural strengths. And longevity (durability) properties like sorpitivity, rapid chloride permeability test (RCPT) of self-compacting concrete.

Corrosion inhibitors for enhanced strength, durability, and microstructure of coastal concrete structures

The prevalence of catastrophic structural member failure caused by steel corrosion in civil infrastructure underscores the importance of reducing reinforcement corrosion to enhance overall infrastructure costs, reliability, and sustainable development. The present research investigates the potential of corrosion inhibitors to enhance the durability and strength of concrete structures, with a focus on their long-term effectiveness in resisting corrosion in reinforced concrete structures. Multiple approaches such as inhibitors, repairing processes, and coatings have been explored to prevent concrete corrosion damage, with an emphasis on concrete corrosion performance in coastal and corrosive situations. This study investigates the effect of six different corrosion inhibitors (zinc oxide, magnesium oxide, urea, sodium nitrate, sodium molybdate, and diethyl ether) on the compressive strength and durability of concrete samples. The compressive strength is assessed using both destructive (28 days cube compressive strength) and non-destructive (Ultrasonic Pulse Velocity) test methods, while concrete durability is evaluated using the rapid chloride permeability test (RCPT). The compressive strength of the admixture incorporated samples are found to be higher than the control sample by almost 50% and above with excellent concrete quality. The RCPT values of inhibitor-incorporated samples are moderate and low with control samples having high permeability even in adverse conditions of freezing, thawing, and deicing. The samples incorporated with inhibitors also show less negative half-cell potential which is 1.43 times less than that of the control sample indicating the lesser probability of occurrence of corrosion. SEM imaging is also conducted to analyze the microstructure of each mix. The findings of this study highlight the importance of inhibitors in enhancing the durability of reinforced concrete structures.

Fresh, hardened and durability properties of concrete made with flyash and limestone based Portland composite cement

Clinker substitution with alternative cementitious materials is one of the way to develop low clinker cement. In this work, three compositions of Portland composite cement (PCC) were prepared by inter-grinding of clinker, gypsum, flyash and limestone where limestone content were kept as 5 %, 7 % and 10 % and flyash content kept as 25% & 35 %. In the present work, study was conducted at 0.60 w/c and in total 4 concrete mixes were designed including one control mix (made with PPC). Fresh properties like air content & fresh density, hardened properties like compressive strength, flexural strength & drying shrinkage and durability behaviour of concrete made with PCC was compared with control concrete. Various durability tests like Rapid chloride permeability test (RCPT), electrical resistivity, accelerated carbonation and sulphate resistance test were carried out to evaluate the performance of concrete made with PCC. The study indicates that with limited addition of limestone i.e., up to 10%, early strength as well as later age strength increases marginally. This may be due to the synergistic effect of flyash and limestone. However, durability aspect was influenced by limestone addition. Test results of RCPT, electrical resistivity as well as sulphate attack indicates the dilution effect of limestone dominates over other physical effects that leads to an overall increase in effective w/c ratio whereas carbonation depth is predominantly affected by the fly as content.

Impact of slag‐fly ash cementitious system on thermal controls and durability of high‐strength mass concrete

AbstractThe rise in temperature due to the heat of hydration in the high‐strength mass concrete poses serious issues such as thermal cracking and delayed ettringite formation. The present experimental investigation is to optimize the proportions of SCMs like fly ash (FA) and ground granulated blast‐furnace slag (GGBS) for the same grade of high‐strength mass concrete with a focus on controlling the peak temperature rise and improving sustainability. For this purpose, one 100% ordinary Portland cement (OPC)‐based sample (T1) and five SCMs‐based samples viz. T2, T3, T4, T5, and T6 in which OPC was replaced by 20% FA, 35% FA, 50% GGBS, 70% GGBS, and 33%FA + 33% GGBS, respectively, were cast in the insulated blocks having one cubic meter volume. Analyzing critically, it is observed that for the same grade of concrete, the right blend of SCMs greatly reduces the peak core temperature (~33.2% and ~ 39.4% for T5 and T6 samples, respectively) than the sample prepared with 100% OPC. This is due to the reduction in the total heat of hydration in the SCMs‐based system than that of the OPC‐based system at early age. The amount of hydration products formed at early age varies for different percentages of SCMs, which is investigated by X‐ray diffraction (XRD), Fourier‐transform infrared spectroscopy (FTIR), and Field emission scanning electron microscopy (FESEM) analyses. Additionally, compressive strength analysis reveals that all the samples achieved almost similar strength (71.4, 74.6, 73.5, 71.5, 69.2, and 68.2 MPa, respectively, for T1 to T6 samples) at 56 days. Moreover, the rapid chloride permeability test (RCPT) values of the T2 to T5 samples are measured to be 597, 461, 672, 584, and 621 coulombs; while, the same is measured to be 2637, coulombs for the T1 sample, indicating higher durability of SCMs‐based samples. Finally, based on the analyses, a plausible model has been presented to explain the phenomenon, and industrial viability analysis is done to adjudge its suitability for an onsite application.

Comparative Study of Rapid Chloride Penetration Test (RPCT) on Self Compacting Concrete (SCC)

Abstract: To check resistance to chloride ions penetration, we used Electrical resistivity techniques to give an indication of the relative permeability of concrete. The ASTM C 1202 (Standard Test Method for Electrical Indication of concrete’s ability to resist chloride Ion Penetration), more commonly known as the rapid chloride permeability test (RCPT). Self-compacting concrete (SCC) is a very fluid concrete and a homogeneous mixture. In this research work, M40 grade of concrete mixes were made using IS 10262:2019 method. The fresh and harden properties of SCC was taken at the ages of 3,7 and 28 days. After experimental investigation, we can conclude that SCC was more workable than the normal concrete and it did not show any major reduction in compressive strength up to 2% replacement of Super plasticizer. The RCPT is performed on Normal & SCC mix after 28th days and SCC mix showed less values of charges passed than that for the normal concrete mix. Hence, SCC has more resistance to chloride ions penetration.

Properties of Sustainable Concrete Containing Different Percentages and Particles of Oil Palm Ash as Partial Sand Replacement

Oil palm shell (OPS) in concrete is well studied as an alternative material of fine aggregate in concrete, as a way to use agricultural waste, and helps to contribute to environmental sustainability and economical construction cost. However, OPS addition will lead to lower properties of the concrete, and much research focuses on treating the OPS to overcome it. Many previous works focused on replacement without examining the effect of different particle sizes of OPS. Hence, this study focuses on the performance of concrete with different particle sizes of OPS as sand replacers in concrete at 25% and 50%. The physical and permeability properties of concrete prepared with OPS particle sizes in the ranges between 600μm to 4.75mm (L), 300μm to 1.18mm (M), and of less than 600μm (S) and two different percentages of 25% and 50% by weight as sand replacement are examined. More than 200 cubes, cylinders, and prisms were tested to determine their physical, mechanical, and permeability properties. The workability was measured by the slump height, the mechanical properties by the compressive strength test, flexural strength test, splitting tensile test, ultrasonic pulse velocity (UPV) test, and rebound hammer test. While the permeability properties by the water penetration test, sorptivity test, and rapid chloride permeability test. The findings showed that increasing the particle sizes of OPS would reduce concrete’s physical and permeability properties. The optimum OPS particle size for structural concrete grade 30 is less than 600μm. With OPS particles of 600um, green concrete using OPS can be made for medium to low-strength applications in the construction industry.

Influence of Calcined Clay Pozzolan and Aggregate Size on the Mechanical and Durability Properties of Pervious Concrete

Pervious concrete has been reported as a viable solution to reduce stormwater run-off, the heat-island effect, road noise, and pavement flooding. Previous researchers have focused on analysing the structural properties and functionality of pervious concrete. However, relatively few studies have been conducted into the addition of supplementary cementitious materials (SCMs), such as calcined clay, in pervious concrete and its effect on long-term durability. This paper has studied the effect of calcined clay pozzolan as a partial substitute for Portland cement in pervious concrete, together with the influence of coarse aggregate size. A water–binder ratio of 0.4 and aggregate–binder ratio of 4.0, as well as a superplasticiser content of 0.95%, were maintained for all mixes. Two sizes of coarse aggregates were used for this study: 9.5 mm and 20 mm. CEM-I cement was partly substituted with calcined clay in dosages of 0 to 30% in replacement intervals of 5%. The mechanical tests conducted included the split tensile test, compressive strength test, and flexural strength test. Durability measurements such as the rapid chloride permeability test (RCPT), thermal conductivity and sulphate resistance tests were also carried out. The mechanical properties of the pervious concrete followed a similar trend. The results showed that at 20% replacement with calcined clay, the compressive strength increased by 12.7% and 16% for 9.5 mm and 20 mm aggregates, respectively. The flexural strength improved by 13.5% and 11.5%, whereas the splitting tensile strength increased by 35.4% and 35.7%, respectively, as compared to the reference concrete. Beyond 20% replacement, the tested strengths declined. The optimum calcined clay replacement was found to be 20% by weight. Generally, pervious concrete prepared with 9.5 mm obtained improved mechanical and durability properties, as compared to those of 20 mm aggregates.