scholarly journals Assessment of the Sustainability of Concrete by Ensuring Performance During Structure Service Life

2021 ◽  
Author(s):  
Dan Georgescu ◽  
Radu Vacareanu ◽  
Alexandru Aldea ◽  
Adelina Apostu ◽  
Cristian Arion ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Environmental Impact ◽  
Service Life ◽  
Sustainability Assessment ◽  
Blended Cement ◽  
Life Time ◽  
Concrete Durability ◽  
Blended Cements ◽  
Carbonation Resistance ◽  
European Standards

This article presents a method to assess the sustainability of concrete based on three elements: service life, performance and environmental impact. The method proposes - to achieve similar performance and service life times, regardless of the component materials used, so that the sustainability assessment ultimately depends on the environmental impact criterion. To this end, specific experimental methods are used to determine the performance of concrete in terms of compressive strength and carbonation resistance for concrete cast with two blended cement types. The procedure needed to classify the concrete through carbonation resistance is detailed, in relationship with the performance obtained for compressive strength. The obtained results highlight the concrete formulations to be used to ensure similar performances regardless of the cement type used. In conclusion, the simplicity in the application of the method, which is closely related to the performance approach on concrete durability in the revision proposals of the European standards, is highlighted. The method is also a useful tool to encourage the widespread use in concrete formulation of blended cements with low environmental impact, without reducing the performance or service life time of the constructions.

scholarly journals Physicochemical Properties of Hydrated Portland Cement Blended with Rice Husk Ash

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Joseph Mwiti Marangu ◽  
Cyprian Muturia M’thiruaine ◽  
Mark Bediako
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Rice Husk ◽  
Elevated Temperatures ◽  
Rice Husk Ash ◽  
Blended Cement ◽  
Strength Development ◽  
Carbonation Depth ◽  
Blended Cements ◽  
Carbonation Resistance

In the presence of significant quantities of carbon dioxide (CO2) and elevated temperatures in the atmosphere due to climate change, cement-based materials are susceptible to carbonation. Blended cements are more prone to carbonation attack than Portland cement. There is a need to evaluate the carbonation resistance of blended cements in a carbonation-prone environment. This paper presents experimental findings obtained from an evaluation of carbonation resistance tests on Rice Husk Ash- (RHA-) blended cement. The blended cement was made by intergrinding of Portland Cement (PC) and RHA to make the test cement (PC-RHA). The RHA dosage in the PC-RHA was varied from 0 to 30% by mass of PC. Pozzolanicity, standard consistency, and setting time tests were conducted on PC-RHA. Mortar prisms measuring 160 mm × 40 mm x 40 mm were separately cast at a water/cement ratio ( w / c ) of 0.50 and 0.60 and cured in water for 2, 7, 14, 28, and 90 days. Compressive strength tests were conducted on the mortar prisms at each of the testing ages. The prepared mortars were also subjected to accelerated carbonation tests in two Relative Humidity (RH) curing regimes, one maintained at an RH greater than 90% and the other between 50–60%. Carbonation resistance of the mixtures was evaluated in terms of the changes in carbonation depth using a phenolphthalein test at the age of 7, 14, 28, and 56 days of curing in a continuous flow of CO2. Compressive strength measurements were also taken during each of the carbonation testing ages. For comparison, similar tests were conducted using commercial PC. The results showed that PC-RHA was pozzolanic while PC was nonpozzolanic. Higher water demand and longer setting times were observed in PC-RHA than in PC. Moreover, there was increased strength development in water-cured samples with increased curing duration. Carbonation results indicated that there was a marked increase in carbonation depth with increased dosage of RHA in PC-RHA binders, increased duration of exposure to CO2, and decreased RH (RH between 50–60%). PC-RHA binders exhibited lower carbonation resistance than PC. In conclusion, for mortars at any w / c ratio, carbonation resistance decreased with increase in RHA dosage and increased w / c ratio.

scholarly journals Effect of Soorh Metakaolin on Concrete Compressive Strength and Durability

2017 ◽  
Vol 7 (6) ◽  
pp. 2210-2214 ◽  
Author(s):  
A. Saand ◽  
M. A. Keerio ◽  
D. K. Bangwar
Keyword(s):  
Compressive Strength ◽  
Corrosion Resistance ◽  
Life Time ◽  
Natural Material ◽  
Concrete Durability ◽  
Concrete Compressive Strength ◽  
Water Penetration ◽  
Carbonation Depth ◽  
Ordinary Concrete ◽  
Strength And Durability

Concrete durability is a key aspect for forecasting the expected life time of concrete structures. In this paper, the effect of compressive strength and durability of concrete containing metakaolin developed from a local natural material (Soorh of Thatta Distict of Sindh, Pakistan) is investigated. Soorh is calcined by an electric furnace at 8000C for 2 hours to produce metakaolin. One mix of ordinary concrete and five mixes of metakaolin concrete were prepared, where cement is replaced by developed metakaolin from 5% to 25% by weight, with 5% increment step. The concrete durability was tested for water penetration, carbonation depth and corrosion resistance. The obtained outcomes demonstrated that, 15% replacement level of local developed metakaolin presents considerable improvements in concrete properties. Moreover, a considerable linear relationship was established between compressive strength and concrete durability indicators like water penetration, carbonation depth and corrosion resistance.

scholarly journals Beneficial Effect of Incorporation of Slag on the Hydration Heat, Mechanical Properties and Durability of Cement Containing Limestone Powder

2020 ◽  
Vol 330 ◽  
pp. 01047
Author(s):  
Toufik Boubekeur ◽  
Bensaid Boulekbache ◽  
Mohamed Salhi ◽  
Karim Ezziane ◽  
EL.Hadj Kadri
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Ordinary Portland Cement ◽  
Blended Cement ◽  
Dilution Effect ◽  
High Strength ◽  
Limestone Powder ◽  
Blended Cements ◽  
Hydration Mechanism ◽  
Durability Performance

This paper presents the experimental results of a wide research program, tending to determine the hydration mechanism, mechanical properties and the durability performance of ternary cement containing limestone powder and slag. The limestone powder increase the hydration at early ages inducing a high strength at, but it can reduce the later strength due to the dilution effect. On the other hands, Slag (S) contributes to increase the compressive strength at later ages. Hence, at medium blended cement (OPC-LP-S) with better performance could be produced. Results show at later age the Slag is very effective in producing ternary blended cements with similar on higher compressive strength than the ordinary Portland cement at 28 and 90 days. For durability, the incorporation of the slag into the cement containing limestone powder improves remarkably resistance to attack by acids and sulfates and it has been found that the durability of the cements never depends on the mechanical strength.

Porosity In The Microstructure Of Blended Cements Containing Fly Ash

1988 ◽  
Vol 137 ◽  
Author(s):  
H. H. Patel ◽  
P. L. Pratt ◽  
L. J. Parrott
Keyword(s):  
Compressive Strength ◽  
Image Analysis ◽  
Fly Ash ◽  
Blended Cement ◽  
Total Porosity ◽  
Major Change ◽  
Relative Volume ◽  
Blended Cements ◽  
Backscattered Electron ◽  
Electron Imaging

AbstractThe changes in porosity of OPC and an OPC-fly ash blended cement during hydration have been studied at water/solids ratios of 0.35, 0.47 and 0.59, cured for times of up to 1 year at 25°C. The porosity was measured indirectly by methanol exchange and methanol adsorption techniques and, directly, by quantitative image analysis using backscattered electron imaging in the scanning electron microscope. Measurements of porosity and of remaining anhydrous material by image analysis showed good correlation with indirect methods. Measurement of the diffusion of methanol and of the compressive strength were made in parallel with the determination of the porosity during hydration and attempts were made to relate the properties to the microstructure. For both binders the reduction of total porosity with increased reaction was small. The major change in pore structure was the subdivision of coarse pores by gel to form finer pores. Compressive strength and diffusion properties were dominated by the relative volume of coarse pores.

scholarly journals Evaluation of the chloride penetration and service life of self-healing concretes activated by crystalline catalyst

2018 ◽  
Vol 11 (3) ◽  
pp. 544-563 ◽  
Author(s):  
P. HELENE ◽  
G. GUIGNONE ◽  
G. VIEIRA ◽  
L. RONCETTI ◽  
F. MORONI
Keyword(s):  
Compressive Strength ◽  
Service Life ◽  
Blended Cement ◽  
Good Alternative ◽  
Chloride Ions ◽  
Self Healing ◽  
Chloride Permeability ◽  
Concrete Mixtures ◽  
Colorimetric Indicator ◽  
Astm C1202

Abstract The main cause of concrete structures deterioration is related to the resistance against the penetration of aggressive agents. Aiming at increase the impermeability and reduce the diffusivity of concrete elements, making it less susceptible to the ingress of chloride ions, the use of crystalline catalyst emerges as a good alternative. Its mechanism of autogenous healing enhances the natural pore-filling process of concrete. The aim of this study is to investigate the influence of the use of crystalline catalyst on the chloride ions penetration and service life prediction of concrete. For the concrete mixtures production, it was used blast-furnace slag blended cement, three different water/cement (w/c) ratios (0.45; 0.55; 0.65), with and without crystalline catalyst, totaling six different mixtures. The concrete specimens were cured in a moist chamber and tested at 28 and 91 days. It was performed tests of compressive strength, rapid chloride permeability (ASTM C1202:12), and silver nitrate colorimetric indicator. The results show that, compared to the reference mixture, the use of crystalline catalyst conserved the compressive strength and reduced the chloride ions penetration up to 30%, increasing service life up to 34%.

scholarly journals Comparative Analysis of Flexural Strength and Modulus Elasticity of Sustainable Concrete Using Supplementary Cementitious Material (SCM)

2020 ◽  
Author(s):  
Shahab Samad ◽  
Attaullah Shah
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Modulus Of Elasticity ◽  
Blended Cement ◽  
Cementitious Material ◽  
Supplementary Cementitious Material ◽  
Curing Conditions ◽  
Blended Cements ◽  
Sustainable Concrete ◽  
Cement Manufacturing

The use of Supplementary Cementitious Material (SCM) is widely used in production of sustainable concrete. Blended cements, incorporating SCM such as Pulverized Fly Ash (PFA) and Ground Granulated Blast Furnace Slag (GGBFS) have been widely used to reduce the cement contents and avoid adverse environmental impacts of CO2 produced during cement manufacturing. The analysis of various structural properties of concrete such as compressive strength, flexural strength and modulus of elasticity is important for its structural application. In this research, flexural strength of 100mmx100mmx500mm beams made from blended cement were tested under three curing conditions i.e. winter, summer and under water and the flexural strength was calculated using EN-12390-5 at the ages of 28 days and 56 days. For modulus of elasticity, concrete cylinders 150mmx300mm were tested as per procedure described in BS 1881-121(1983) at the age of 28 days. The compressive strength, flexural strength and modulus of elasticity for blended cement incorporating PFA and GGBFS has been increased under summer curing environment. The experimental values of Modulus of Elasticity are compared with the provision of BS 1881.

scholarly journals Perlite Application and Performance Comparison to Conventional Additives in Blended Cement

2020 ◽  
Vol 10 (3) ◽  
pp. 5613-5618
Author(s):  
A. Sicakova ◽  
E. Kardosova ◽  
M. Spak
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Blended Cement ◽  
Performance Comparison ◽  
Freezing And Thawing ◽  
Practical Applications ◽  
Blended Cements ◽  
Granulated Blast Furnace Slag ◽  
And Performance ◽  
The Individual

This study compares the performance of perlite with that of conventional additives in blended cements. The results of the application of Perlite Powder (PP) as a component of blended cements in two different proportions (30% and 50%) are presented and compared with standard additives of fly ash (FA) and Ground Granulated Blast Furnace Slag (GGBFS). Moreover, perlite is tested as a component of ternary cement (70% cement, 15% P and 15% FA and GGBFS alternatively). Blended cements are tested in terms of flexural strength, compressive strength, bulk density, water absorption, and frost resistance. The results show that although perlite blended cements achieve lower strengths and higher absorptivity compared to conventional additives, they have significant potential for freezing and thawing durability, especially in ternary combination with GGBFS. For practical applications, the intrinsic values of the parameters of the individual binders with perlite (e.g. flexural strength of 4.1–6.2MPa or compressive strength of 18.8–38.5MPa) are sufficient for many practical applications. Perlite, when suitably combined with other pozzolanic materials, can be a suitable component of blended binders.

Relationships Between Permeability, Porosity, Diffusion And Microstructure Of Cement Pastes, Mortar, And Concrete At Different Temperatures

1988 ◽  
Vol 137 ◽  
Author(s):  
Della M. Roy
Keyword(s):  
Pore Structure ◽  
Elevated Temperatures ◽  
Mercury Porosimetry ◽  
Blended Cement ◽  
Ionic Species ◽  
Chloride Diffusion ◽  
Concrete Durability ◽  
Chloride Permeability ◽  
Cement Pastes ◽  
Blended Cements

AbstractPermeabilities to water and diffusion of ionic species in cementitious grouts, pastes and mortars are important keys to concrete durability. Investigations have been made of numerous materials containing portland and blended cements, and those with fine-grained filler, at room temperature and after prolonged curing at several elevated temperatures up to 90°C. These constitute part of studies of fundamental material relationships performed in order to address the question of long-term durability. In general, the permeabilities of the materials have been found to be low [many <10−8 Darcy (10−13 m·s−1)] after curing for 28 days or longer at temperatures up to 60°C. The results obtained at 90°C are somewhat more complex. In some sets of studies of blended cement pastes with w/c varying from 0.30 to 0.60 and cured at temperatures up to 90°C the more open-pore structure (at the elevated temperature and higher w/c) as evident from SEM microstructural studies as well as mercury porosimetry are generally correlated also with a higher permeability to liquid. The degree of bonding and permeability evident in paste or mortar/rock interfacial studies present somewhat more conflicting results. The bond strength (tensile mode) has been shown to be improved in some materials with increased temperature. The results of permeability studies of paste/rock couples show examples with similar low permeabilities, and some with increased permeability with temperature.Ionic diffusion studies also bring important bearing to understanding the effect of pore structure. The best interrelationships between chloride diffusion and pore structure appear to relate diffusion rate to median pore size. Similar results were found with “chloride permeability” test.

Chemical Composition and Physical Characteristics of Rice Husk Ash Blended Cement

2017 ◽  
Vol 32 ◽  
pp. 25-35 ◽  
Author(s):  
Akeem Ayinde Raheem ◽  
Mutiu A. Kareem
Keyword(s):  
Compressive Strength ◽  
Rice Husk ◽  
Rice Husk Ash ◽  
Blended Cement ◽  
Physical Characteristics ◽  
Chemical Compositions ◽  
Minimum Requirement ◽  
Suitable Material ◽  
Blended Cements ◽  
Renewable Material

Applications of agricultural by-product as substitute for non-renewable material in cement production are desirable in stimulating socio-economic development. In this study, Rice Husk Ash (RHA) blended cement was produced by replacing 5%, 7%, 11.25%, 15%, 20.25% and 25% by weight of Ordinary Portland Cement (OPC) clinker with RHA. The cement without RHA serves as the control. The chemical compositions of RHA, OPC-clinker and the blended cements were determined using X-ray fluorescence analyzer. The physical characteristics of RHA blended cements that were considered are fineness, soundness, consistency, initial and final setting times and compressive strength at 2, 7, 28, 56 and 90 curing ages. The results showed that RHA is a suitable material for use as a pozzolan as it satisfied the minimum requirement by having the sum of SiO2, Al2O3 and Fe2O3 of more than 70%. Incorporation of RHA led to an increase in the composition of SiO2 and reduction in that of CaO. An increase in RHA content showed a decrease in compressive strength at early ages and slightly increase at a later age (90 days). The blended cement produced with lower levels of RHA replacement conforms to standard specifications specified in BS EN 197-1:2000, NIS 439:2000 and ASTM C 150-02. The minimum Strength Activated Index (SAI) of 75% at the age of 28 days of curing as specified by ASTM C 618 was satisfied by RHA replacement of up to 15%. It was concluded that blended cement with the maximum of 15% RHA content is suitable for use for structural purposes.

scholarly journals - Behavior of Concrete Containing Alternative Pozzolan Calcined Marl Blended Cement

2020 ◽  
Author(s):  
Yasemin Akgün
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Mass Loss ◽  
Prestressed Concrete ◽  
Blended Cement ◽  
Drying Shrinkage ◽  
Mass Concrete ◽  
Limit Values ◽  
Blended Cements ◽  
Energy Evaluation

Natural marl which is calcined at appropriate temperature has potential being alternative pozzolan. Therefore, the calcined marl is wanted to be used as replacement material in blended cements with less clinker. This situation leads to improved performance of cement/concrete, reduced CO2 emissions, saving of energy. The properties of used pozzolan positively effect to some behavior of concrete. Shrinkage is one of these properties. The shrinkage of concrete is inherent property that needs to be control. Moreover, the shrinkage of concrete becomes even more important in some applications such as mass concrete, prestressed concrete. The aim of study is to determinate how will affected shrinkage of concrete containing alternative pozzolan calcined marl blended cements. Accordingly, the natural marl was calcined at 800 °C for pozzolanic activation. The calcined marl was replaced with Portland cement at ratios of 0, 10, 30, 50 wt.%. The setting times, volume expansion, water demand, density, performance energy evaluation of blended cements were determined. The autogenous-drying shrinkage, mass loss and compressive strength tests were performed on concretes containing calcined marl blended cements. According to the results, pozzolanic activity of calcined marl and properties of blended cements containing calcined marl are comply with limit values of TS 25 and EN197-1. It was observed that autogenous-drying shrinkage and mass loss of concretes containing calcined marl blended cement were lower than that of concretes containing Portland cement. On the other hand, it was seen that compressive strength of concretes was increased up to 50 % replacement ratio.

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