Rapid Chloride Penetration Test Research Articles

Performance of mortar incorporating calcined marine clays with varying kaolinite content

This study is an attempt in exploring the feasibility of low-grade kaolinite clays, generated as waste from excavation works, as supplementary cementitious materials and potential candidate for cement replacement. Clays from five sources were investigated for composition, pozzolanic reactivity and effect on mortar strength and durability. Clays were grinded and calcined at 700 °C to convert kaolinite into metakaolin. Thereafter, 30% by wt. of cement was replaced with a combination of calcined clay and limestone in a 2:1 wt ratio. The pozzolanic nature of the clays was studied through thermo-gravimetric analysis (TGA), isothermal calorimetry (ITC) and X-ray diffraction (XRD). The effect on corrosion resistance was examined using electrical resistivity and rapid chloride penetration tests (RCPT). Results show that marine clays in Singapore in general have low to moderate kaolinite content (20–40%). In the ITC tests, blended mixes displayed accelerated hydration and 20–30% higher heat of hydration per gram of cement at 7th day compared to the reference mix without any substitution. The bound water per gram of cement calculated from the TGA results showed a noticeable increase in blended mixes, indicating additional hydration products in those samples. Though a 10–20% decrease in strength was observed in blended mortars compared to reference samples at 28-days, their corrosion resistance showed remarkable improvement. The charge passed during RCPT reduced by 20–60% while the electrical resistivity increased by 50–200% depending on the clay and its properties. Overall, the results were encouraging to suggest the use of low-grade marine clays as viable alternative to replace cement thereby producing a sustainable and low carbon concrete.

Role of red mud as a cementing material in concrete: a comprehensive study on durability behavior

Red mud (RM), a semi-solid residual of the alumina refinery process, has higher alkalinity, and its disposal leads to environmental imbalance. To overcome this issue, RM is partially replaced with cement in the range of 0% to 20% at an interval of 5%. The present research work majorly focused on durability and micro-level concrete studies containing pre-calcined (600 °C in 2 h) RM. The tests on red mud concrete, viz. compressive strength, sorptivity test, open porosity test, rapid chloride penetration test, accelerated corrosion test, water absorption test, X-ray diffraction, scanning electron microscope (SEM), and energy-dispersive spectroscope (EDS) analysis, have been conducted to investigate the comprehensive characterization of concrete with RM. From the compressive strength test results, maximum strength was observed at 10% replacement. Open porosity, chloride ions permeability, water absorption, and sorptivity values showed reduction at an increment of RM replacement level. RM concrete offered more corrosion resistance due to high alkalinity, which possessed a pH of more than 12.5. From the micro-level investigations such as SEM and EDS, higher C–S–H gel formation was observed in RM 10% replacement concrete. In the meantime, less number of pores was observed in all RM replaced concrete mixes.

Removing arsenate from water using modified manganese oxide ore: Column adsorption and waste management

There is a need to remove arsenic (As) in drinking water supplies by simple and cost-effective techniques. A column adsorption study was conducted to remove As(V) from water employing an iron (Fe) and zirconium (Zr) grafted Vietnamese manganese oxide ore (Fea-VMO and Zra-VMO). At a flow rate of 0.15 L/h, the bed volumes of water (As(V) concentration 0.1 mg/L) treated by Zra-VMO and Fea-VMO to produce water with As(V) concentration below the WHO guideline concentration (10 μg/L) were 6 and 8 times higher than for VMO, respectively. An increase in influent As concentration increased the adsorption capacity, but the increase of flow rate reduced the adsorption capacity. The maximum adsorption capacities derived from the Thomas model for VMO, Fea-VMO, and Zra-VMO at an influent concentration of 0.25 mg As(V)/L and flow rate of 0.15 L/h were 0.151, 1.145, and 0.925 mg/g, respectively. These values fell when influent As concentration decreased or the flow rate increased. Solidification/stabilisation method was applied to immobilise As(V) in the exhausted absorbent wastes by replacing 5, 10, 15, and 20 % of sand in a sand/cement concrete mixture by the adsorbent waste. This solidified material had satisfactory compressive strength, rapid chloride penetrability test, and volume of permeable voids, which indicated the material had good stability, making it suitable for use as a building material in construction work. The As(V) leaching from these materials, as measured by Method 1313 of the Leaching Environmental Assessment Framework of USEPA, proved to be very negligible.

Effect of Silica Fume on Permeability and Microstructure of High Strength Concrete

The important concrete structure in the vicinity of industry, thermal power plant suffers deterioration by the acid rain cause due to combination of CO2, SOx and NOx with rain water. A combined attack that is from acid as well as sulphate can be observed under impact of sulphuric acid. It attacks on Calcium hydroxide and form Calcium sulphate, which can be leached out easily and make Interfacial Transition Zone (ITZ) poor. The water retaining structure such as dam, weir should be impermeable and that can be achieved by binary cementitious blends, using Silica fume (SF). Silica fume a by product of silicon industry, proves very effective in improving the microstructure of concrete due to their finer particle size, approximately 100 times finer than cement particles. The SEM image of binary blended high strength concrete (HSC) with Silica fume shows the condensed packing of cement hydration product and a dense microstructure as compare to control mix. The water permeability test result reveals that there is about 87 percent reduction in the coefficient of permeability achieved by inclusion of 10% Silica fume (SF) by weight of cement. Rapid chloride penetration test (RCPT) has been performed to investigate the ingress of chloride ions into the concrete. There was significant reduction in chloride ions penetration recorded due to SF inclusion.

Cellulose nanofibres mitigate chloride ion ingress in cement-based systems

This study pioneers the use of cellulose nanofibres (CNF) as a means to restricting the chloride-ion ingress in cement based systems. Three CNF variants, differing in their carboxylate content from 0.13 to 1.13 mmol/g of the nanofibre, were introduced to paste and mortar mixtures alike, at up to 1.2% by volume fraction of the dry nanofibre. The reference mixture was a plain system, prepared with CSA Type GU Portland cement. The ingress of chloride ions was investigated per the Rapid Chloride Penetration Test (ASTM C1202) and further assessed by colorimetry. Companion studies were conducted to measure changes to the air-void network and the pH environment within. The results demonstrate that adding CNF significantly impedes chloride-ion penetration, most likely due to a lower porosity in the 10 nm–140 nm range. Higher amounts of carboxyl groups, [COOH], uniformly led to higher CNF efficiency, both for easy workability and for restricting the chloride ingress. So that, for 0.50% fibre volume fraction, and the CNF variant grafted with 1.13 mmol of carboxylate/g, the mortar witnessed a 50% drop in the measured electrical charge as well as in the depth of chloride penetration. The study indicates that the [COOH] groups scavenge the soluble calcium cations Ca2+, from the aqueous phase of the cement paste without, however, altering the pH therein.

A study on mechanical and durability properties of coconut shell concrete using coconut fiber and sawdust

Sawdust was used as a partial replacement material for sand in coconut shell concrete and coconut fiber were also added with concrete to enhance the properties. The mechanical and durability properties studied are compressive strength test, split tensile test, flexural test, impact test and water absorption, volume of permeable pore voids, rapid chloride penetration test, sorptivity respectively. From the test conducted, the properties of coconut shell concrete with coconut fiber and sawdust gave a better result.

Influence of slag on mechanical and durability properties of fly ash-based geopolymer concrete

A geopolymer binder is measured as an alternative and elective material to customary Portland binders. Utilization of Fly ash (FA) as a primary binding material limits the waste creation of thermal power stations and reduces environmental impacts. This paper presents the strength performance of geopolymer concrete (GC) with different proportions of FA and ground granulated blast furnace slag. The potential of GC against acid resistance, porosity, water absorption, and sorptivity is presented in this paper. Apart from this, rapid chloride penetration test was performed to assess the chloride resistance of GC. XRD and SEM analysis was done on selected samples of GC to categorize microstructural performance. The results depicted that mixes M5 and M10 have attained higher compressive strengths, i.e., 49.0 and 57.6 MPa, while the acid durability loss factor values are less by 28% and 19%, respectively compared to other mixes of GC.

Prediction of rapid chloride permeability of self-compacting concrete using Multivariate Adaptive Regression Spline and Minimax Probability Machine Regression

This paper presents new models to predict chloride penetration into self-compacting concrete (SCC) using the rapid chloride penetration test (RCPT). The research mainly focuses on the effect of supplementary cementitious material (i.e., fly ash and silica fume) and elevated temperature curing of SCC on results of the RCPT. Models are developed to predict the value of RCPT using two statistical algorithms, namely Multivariate Adaptive Regression Spline (MARS) and Minimax Probability Machine Regression (MPMR). Both models incorporate the combined effect of fly ash, silica fume and elevated temperature curing on the RCPT, and a comparative study between the models is also discussed. The analysis confirms that both MARS and MPMR are promising models for the prediction of RCPT results.

Mechanical, electrical and microstructural studies on nano-TiO2 admixtured cement mortar cured with industrial wastewater

Nanotechnology has attracted the attention of building materials over the last decade. Nano-size particles—cement mortar—can positively alter their early and hardened properties. The objective of this study is the inclusion of TiO2 nanoparticles (NT) as an admixture (2 to 10% by weight of the cement) on the mechanical, electrical, and microstructure properties of cement mortar composites and cured with industrial wastewater. Nowadays, the analysis of TiO2 nanoparticles in concrete has been recognized increasingly. Nevertheless, there has been no report of the durability problems on nano-TiO2 admixtured cement mortar cured with industrial wastewater. To achieve this purpose, compressive strength, porosity, electrical resistance, rapid chloride penetration test, and scanning electron micrograph (SEM) were performed to find out the relationship between the mechanical, microstructure, and electrical properties of NT mortar composites. The test results showed that TiO2 nanoparticles treated with industrial wastewater improve early-age hydration. For increasing replacement percentages of TiO2, the setting time is reduced due to the substitution of TiO2, despite declining cement content, which again indicates accelerated hydration. However, when NT and wastewater were mixed, porosity-test results indicated significant improvements in microstructure, resulting in the development of a more compact and durable hardened structure. Consequently, the combination of NT and wastewater cure has resulted in the development of mortar strength and durability. Eventually, 10% NT seems to be a decent substitute for economic efficiency and hardened properties.

Durability performance of waste granite and glass powder added concrete

Across the world, a large amount of waste is spawned from various industrial activities. Out of this huge quantity of waste, a little is recycled and rest is dumped in open lands. This paper deals with the use of potential solid waste in concrete, particularly granite powder originating from granite industries and discarded soda-lime glass powder obtain from waste glass bottles. Experimental study conducted in this research work examines the durability of blended concrete mixes, incorporating waste glass powder and granite powder at various substitution levels. The glass powder (GP) in 5%, 10%, 15%, 20% and 25%, and granite powder (GrP) in 10%, 20%, 30%, 40% and 50%, were added in the concrete mixes as a partial supplement of cement and sand, respectively. Durability performance of a series of blended mixes was evaluated for water absorption, water permeability, acid attack, sulphate attack, and rapid chloride penetration test (RCPT). Scanning electron microscope (SEM) and X-ray diffraction (XRD) were carried out for microstructure analysis. A significant improvement was observed in durability properties of concrete containing 15% GP and 30% GrP in place of cement and sand respectively. Results indicate improvement in water permeability and water absorption of glass granite blended concrete. Response of blended mix against sulphate and acid attack was quite better than control concrete mix. Value of RCPT was also encouraging for blended mixes.

Changes in mechanical properties and durability indices of concrete undergoing ASR expansion

This research focuses on correlating the degree of expansion as a result of Alkali-Silica Reaction to mechanical properties and durability indices of hardened concrete. Degradation of six concrete mixtures incorporating Spratt aggregate with and without fused silica stored at 38 °C and 95 ± 5% RH were monitored for 12 months. Compressive and tensile strength decreased with time and the decreases became very significant as expansion progressed. There was no overall relationship found between strength and expansion for all mixtures. Linear correlations were observed between expansion with a modulus of elasticity and Poisson’s ratio. Both the Stiffness Damage Index and the Plasticity Index show notable increases up to approximately 0.4% expansion with small increases beyond that level. Ultrasonic pulse velocity showed a strong correlation to expansion regardless of the mixture. Rapid chloride permeability showed an increase in the total charge passed as a function of time, and hyperbolic relationships best expressed the correlation between Rapid chloride penetration and expansion tests.

Strength and Durability of Styrene Butadiene Latex Modified Concrete with Silica Fume

This paper discussed the properties of styrene butadiene rubber (SBR) latex modified concrete. The latex modified concrete using SBR latex were prepared with various polymer-binderratios and tested for compressive strength, flexure strength, elastic modulus and rapid chloride penetration test. Latex contents were varied as 5, 10 and 15 percentages by mass of binder (cement and silica fume). The effect of the polymer-binder ratio on the properties of latex modified concrete was examined. It was concluded from the test results that the compressive strength and elastic modulus decrease with polymer binder ratio and flexural strength increasing with polymer binder ratio. Addition of latex reduces the chloride ion penetration due to latex film formation..

Durability Properties of Kaolinite Clay - Metakaolin in Concrete

Unfortunately the concrete structures are exposed to fire, which may cause reduce in strength of structural components. In this article , the research , the effect of chloride (NaCl) penetration and temperature variations on metakaolin using in concrete. Here M60 grade concrete mix used and the concrete cubes (150 mm × 150 mm × 150 mm) are cast for cement replacement by metakaolin with 0%, 5%, 10%, 15% and 20%. The 0% specimens are considered as ‘Controlled Specimen’. Then these specimens are tested after 28 and 90 days for various temperature of 100, 200, 300 and 400°C with 1, 2 and 3 hour duration and same cubes are cast for M60 mix proportion and tested for Rapid Chloride Penetration Test and use 5% Sodium Chloride ( NaCl) concentration. The graphical Presentation is clearly shows that variations in compressive strength for cement replacement by metakaolin in concrete for chloride penetration and different temperature. For chloride penetration results shows that up to 10% to 15% replacement of Metakaolin, concrete gives good compressive strength and after it goes on decreasing,. Thus 10% give a desirable percentage of replacement. And also compressive strength drastically increasing with the age of concrete for various temperature exposures.

Comparison of Material Properties of SCC Concrete with Steel Fibres Related to Ingress of Chlorides

The paper focuses on the evaluation of chloride ion diffusion coefficient of self-compacting concrete with steel fibre reinforcement. The reference concrete from Ordinary Portland Cement (OPC) and Self-Compacting Concrete (SCC) with several values of added steel fibres—0%, 1% and 2% of weight—were cast in order to investigate the effect of fibres. The three procedures of diffusion coefficient calculation are presented—rapid chloride penetration test, accelerated penetration tests with chloride as well as the surface measurement of electrical resistivity using Wenner probe. The resulting diffusion coefficients obtained by all methods are compared and evaluated regarding the basic mechanical properties of concrete mixtures.

Mechanical, durability and fracture properties of nano-modified FA/GGBS geopolymer mortar

Fly ash (FA)-based geopolymer mortar is known to exhibit less strength development at ambient temperature due to slow progress in the polymerisation reaction. In this paper, studies are reported on geopolymer mortar made of FA, ground-granulated blast-furnace slag (GGBS) and nano silica at ambient temperature. The investigations on mechanical and durability properties of FA/GGBS-based geopolymer mortar were carried out by adding nano silica at 1% and 2% weight of FA into the mixture. For all the mixtures, the concentration of sodium hydroxide (NaOH) was maintained as 3M and the sodium silicate (Na2SiO3)/sodium hydroxide weight ratio was 2·06. The alkaline liquid/binder ratio of 0·3 and ambient curing temperature (28°C) was maintained for all the mixtures. Geopolymer mortar with an addition of 2% nano silica showed significant improvement in compressive strength, split tensile strength, flexural strength and fracture properties. The water absorption, rapid chloride penetration test and sorptivity showed better resistance in mixtures with a 2% addition of nano silica. The improved properties could have been due to an enhancement of geopolymeric reaction by the addition of amorphous nano silica, which formed additional sodium aluminosilicate hydrate (Al2H2Na2O7Si) or geopolymer gel while ultrafine particles of nano silica reduced the size of empty space in the geopolymer matrix.

Intelligent Replaced of Natural Aggregate and Cement with Recycled Concrete Aggregate, Rice Husk Ash

Annually a huge amount of construction and demolition (C&D) waste is generated. It becomes really harmful and posing an adverse effect to the environment, increasing waste generation have demanded the need for recycling the C&D Waste. Similarly, as cement accounts for 10% global CO2 emissions, it is imperative to reduce the embodied CO2 of concrete. Thus, the sustainability of concrete is a major issue which needs to be addressed. Ways of achieving this is to recycle concrete waste back into concrete to reduce waste and use of supplementary cementitious to reduce CO2 emissions. This research aims to take a two-pronged approach by investigating the effect of pozzolanic replacement with fixed proportion of recycle aggregates to evaluate the strength and potential structural application. In this research carried out M40 mix design and rice husk ash were substituted for cement at level of 5, 10, 15, 20% by using a fixed ratio of 10, 20,30% recycle concrete aggregate (RCA). Compression test, Split Tensile Test, Flexural Test and Rapid Chloride penetration test were conducted on specimens of Grade M40, for compression test the cube was cured for 28 days and 90 days for durability (RCPT). All RCA mixes and up to 15% RHA replacement satisfied M40 criteria at 90 days, however the 20% RHA replacement mix was close to achieving this. Thus, the finding of this study indicates the use of concrete containing 30% RCA and 15% RHA can be substantially reduce waste and embodied CO2 without compromising on strength and durability parameters.

Experimental investigation of strength, durability, and microstructure of red-mud concrete

Recent trends in the construction industry involve the use of industrial by-products as building materials to improve waste management and reduce excessive CO2 emissions from the cement industry. Red mud (RM) is a by-product of alumina refinery plants. When improperly disposed, red mud harms the surrounding area, owing to its highly alkaline nature. In the current work, up to 15% of the cement in concrete was replaced with red mud, in increments of 2.5%. In addition, to enhance the pozzolanic reaction, metakaolin was used as a ternary mineral; it replaces 10% of the cement. A slump cone test was conducted to evaluate the workability. Compressive, flexural, and split tensile strength tests were conducted to observe the mechanical properties. A rapid chloride penetration test and water absorption tests were conducted to determine the durability properties of the concrete. X-ray fluorescence analysis was conducted to determine the chemical composition of both the red mud and the metakaolin. A scanning electron microscope analysis was conducted to characterize the microstructure of the RM concrete. The 12.5% red-mud replacement mix showed the greatest improvement in mechanical properties among all the mixes. As the red-mud replacement increased, the chloride-ion passage was reduced. Moreover, a denser microstructure formation was observed with the red-mud replacement, as compared to standard concrete.

Effect of carbonation on the mechanical and durability properties of sandstone modified self-compacting concrete

Sandstone is one of the most used dimensional stone in the construction industry. Rajasthan is producing More than 90% of sandstone from all over India. Eastern Rajasthan is one of the dominant areas where sandstone waste was obtained and used in this study. This stone waste was produced during the shaping of sandstone and due to very fine particle size, this waste was named as sandstone slurry (SS). Excessive open dumping of stone waste creates environmental pollution through air and water, which also need to be addressed. This study aims to utilise sandstone waste in the concrete sector as an alternative building material. In this research work, Pozzolana Portland Cement (PPC) was partially replaced by SS at a percentage of 0, 10, 20 and 30. Rheological properties were tested to determine the flowability and viscosity of concrete mixes. To evaluate the effect of carbonation concrete specimens were carbonated. Compressive, splitting tensile strength and rapid chloride penetration test (RCPT) was conducted on the carbonated sample (CS) as well as a non-carbonated sample (NCS). The impact of CO2 concentrations was also determined by performing accelerated carbonation test. The test results revealed that carbonation enhances the compressive and splitting tensile strength properties of concrete by reducing pore structures. The depth of chloride penetration of CS is less as compared to NCS. However, accelerated carbonation displayed an increased depth of carbonation.

Evaluating the durability of recycled concrete made of coarse recycled aggregate concrete containing silica-fume and natural zeolite

This experimental study evaluates the durability of recycled aggregate concrete (RAC) containing silica-fume (SF) and natural zeolite (NZ). For this purpose, four levels of recycled coarse concrete aggregates (RCA) were replaced with natural coarse aggregates (NCA). To compare the effect of pozzolans, three levels of SF (5%, 10%, and 15%) and three levels of NZ (10%, 20%, and 30%) were replaced with cement. To evaluate the durability of RAC, 28 mixed designs were made and the following were measured: compressive strength (CS), water absorption by immersion (WA by immersion), water absorption by capillary (WA by capillary), electrical resistance (ER), electrical conductivity (EC) and rapid chloride penetration test (RCPT). The results indicated that WA by immersion and WA by capillary of RAC increased with enhanced RCA incorporation. On the other hand, the pozzolanic reaction of 10% of SF and 10% of NZ decreased capillary pores and structural weakness of full-scale RAC. However, due to the internal chemical changes of RAC, contrary to the WA by immersion and WA by capillary, compared to conventional concrete (CC), a lower EC and unchanged ER values of RC100 containing pozzolans were seen. The scanning electron microscopy (SEM) revealed that compared to NZ, a 10% of SF significantly improved the microstructure of full scale RAC.

The Effect of Mix-Design and Corrosion Inhibitors on the Durability of Concrete

The deterioration of concrete over time is the result of various mechanical, physical, chemical and biological processes, with the corrosion of reinforcement being the most serious problem of durability of reinforced concrete structures. Over the last 50 years, a tremendous effort has been spent by the international scientific community with laboratory research and experimental field studies in order to increase the resistance of concrete over corrosion. This paper presents an experimental study of the corrosion behavior of 5 different concrete mix designs. The compositions were developed as per the latest concrete regulations and International Standards which are as follows: conventional concrete C30/37, conventional concrete with corrosion inhibitor as an additive, conventional concrete with surface spray sealant, fine aggregate concrete and self-compacting concrete. Their behavior against corrosion was determined via the following tests: water absorption test, water permeability test, mercury intrusion porosimetry, rapid chloride penetration test (RCPT), and accelerated carbonation test. The experimental results showed that the corrosion systems examined in the study provide anti-corrosion protection on steel rebars against corrosion comparing with the reference group. Also, an inversely proportional relationship of the water/cement ratio of a composition with its corrosion behavior was observed. Smaller w/c values (0.4 instead of 0.5) lead to better anti-corrosion resistance. In addition, an analogous relationship between the cement content of a composition and its corrosion behavior was observed.