Pozzolanic Portland Cement Research Articles

Global analysis of DEF damage to concretes with and without fly-ash

Abstract Delayed Ettringite formation (DEF) is an internal expansive reaction that can damage concrete. DEF is strongly influenced by the temperature, above about 60-65°C, and other factors involving cement chemistry especially, but also its physical characteristics. The exposure environment over time also promotes a condition to increase deterioration from DEF. Expansions results from secondary ettringite formation are progressive and can lead concrete to microcracking impacting its performance and durability over time. Several concrete structures are pointed to be severely attacked by DEF, and test method as well a better comprehension on this pathology is necessary to promote specific and proper preventive measures to avoid future damages. Furthermore, compared to alkali-silica reaction, DEF occurs more readily and aggressively, and sometimes prematurely, depending on several factors, such as type of cement, concrete mix design, exposure conditions, among others. This paper involves an overall analysis of the behavior of concretes with two types of Portland cements (High early-strength cement and a Portland pozzolanic cement, with fly-ash) in relation to DEF process. Several data from a laboratory study where DEF was induced through a specific thermal curing procedure are presented and discussed. The analyses involved the assessment of physical, mechanical, and expansive properties besides microstructural monitoring of samples from concretes over time. These experiments allowed detecting high values of expansions from DEF (up to 1.2%) in the concrete without fly ash. The mechanical properties were severely impacted from this deleterious process; as expansions increased, losses in the mechanic and elastic properties were verified. Expansion levels in the order of 0.5% prompted remarkably high reductions and, at about 1% the losses were relevant for both strengths (tensile and compressive) and modulus of elasticity, of 60% and 80%, respectively, in the presence of cement without fly-ash. Concrete microstructure has indicated massive formations of ettringite as well as micro-cracking and the fragility of the cement matrix because of DEF. On the other hand, expansion up to 0.2% did not promote important negative effects on the properties of concrete, especially with the pozzolanic cement tested. Furthermore, an overall approach with several correlations between physical and mechanical properties was taken to obtain different levels of deterioration for a concrete presenting DEF.

SBR-latex modified cementitious composite coatings for concrete rehabilitation and assessment of performance measure

Mortars modified with styrene-butadiene latex (SBR) and Ordinary Portland cement (OPC), Pozzolonic Pozzolanic Portland cement (PPC) and White Portland cement (WPC) are universally accepted for concrete surface preservations. However, mortar still has application and performance limitations. To overcome this, cementitious composite coatings with various cements and cement at diverse polymer to cement ratios were prepared and evaluated. The experimental results validate that the type of cement influences the performance properties of cementitious coatings. A continuous monolithic polymer cement co-matrix film was applied to achieve better water resistance and adhesion strength. The optimum P/C ratio to achieve better water resistance of PPC, OPC and WPC has found 0.2, 0.2 and 0.4, respectively. In addition, the free cementitious coating polymer film formed by blending latex and cement; WPC-based coating has 10% and 28% highest (5.2 Mpa) tensile strength than OPC and PPC. However, 399% higher slant shear strength than without polymer and confirmed by dynamic mechanical analyses. A SEM analysis confirms an enveloping phenomenon of polymer over cement grains at higher dosages results.

Effect of Water/Cement and Aggregate/Cement Ratios on Consistency and Compressive Strength of Concrete Using Volcanic Stone Waste as Aggregates

This study investigates the effect of water cement (w/c) ratio and aggregate cement (a/c) ratio on consistency and compressive strength of concrete made by using volcanic stone waste aggregates. A total of 12 (twelve) concrete mixtures were made by varying w/c ratio and a/c ratio. Portland pozzolan cement was used as a hydraulic binder while volcanic stone wastes with a maximum diameter of 40 mm granules were used as fine aggregate and coarse aggregate. The consistency test, which is expressed in term of slump, was carried out for fresh concrete, while the compressive strength test, for each concrete mixture, was realized at the age of 28 days using 5 (five) cubical specimens measuring 150x150x150mm. The results of this study show that slump increases and compressive strength decreases with increasing w/c ratio for a constant a/c ratio. Slump decreases and compressive strength slightly increases with increasing a/c ratio for a constant w/c ratio. The decrease in slump and the increase in compressive strength with increasing a/c ratio for a constant w/c ratio is more clearly noted for a w/c ratio more than 0.5. Compressive strength decreases proportionally with increasing slump due to the increase in w/c ratio. This decrease tends to be sharper in mixture with lower a/c ratio.

Eco-friendly mix for Roller-Compacted Concrete: Effects of Persian-Gulf-Dredged marine sand on durability and resistance parameters of concrete

Dredged marine sediment (DMS) is a by-product obtained from harbours and dry dock stations harmful to the environment and marine structures. In this study, the effects of replacing sands obtained from quarries with different percentages of DMS (15%, 25%, 35%, 50%, and 100%) dredged from the Persian Gulf on the properties of a roller-compacted concrete pavement (RCCP) were investigated. Three types of Portland cement, i.e. Type II, Type V, and special Portland pozzolanic cement (PC2, PC5, and SPPC) were utilised, along with ground-granulated blast-furnace slag (GGBS_15%) and fibre-reinforced polymer (FRP_1.25%), to improve the resistance and durability properties of RCCP. Compressive strength (CS), special electrical resistance (ER), water absorption (WA), water permeability under pressure, sulphate attack and scanning electron microscopy (SEM) tests were performed after curing the concrete specimens. The maximum CS, and ER, and the minimum water penetration, WA, and weight loss (WL) of concrete in a 5% sodium sulphate solution, were observed for 15% DMS replacement in PC5. Additionally, the maximum sulphate resistance for 25% DMS and 15% GGBS contents was observed in SPPC after one year.

Effect of direct addition of two different bacteria in concrete as self-healing agent

In this paper, a suitable and practical method to make bacterial concrete on a large and bulky scale is presented. In this method, first, bacteria compatible with concrete are extracted and identified. The bacteria are then added to the concrete in solution in a simple way. To find bacteria compatible with concrete, first, the soil near the roots of plants (rhizosphere) and two types of cement called Portland pozzolanic cement (PPC) for Darab city and Portland cement type 2 (PC2) for Hormozgan-Bandar Khamir were used. After extracting the cultured samples, it was observed that bacteria grew only in the soil sample and did not grow significantly in the cement samples. Therefore, the cultivation and reproduction of bacteria from concrete fragments were investigated. At this stage, concrete samples were prepared with two types of cement (PPC and PC2). Then, some concrete powder containing all the constituent materials was used to extract bacteria. The resulting bacteria were identified by the Deoxyribonucleic Acid (DNA) testing. Bacterial samples obtained from the concrete made of PPC with certainty exhibited the genus and species of Bacillus paralicheneniformis, but in the case of bacterial samples of concrete prepared with PC2 can only be bacterial Cited by Bacillus sp. Afterward, 4 mixing designs were designed to make concrete from the two abovementioned types of cement, with the addition of bacteria and without the addition of bacteria. In this mixing design, bacterial sediments were added to the solution and directly to the concrete mixing design. Finally, the compressive strength, water absorption and crack recovery in concrete samples were investigated. The results indicated that the presence of bacteria had slight effect on the compressive strength of concrete. The water absorption percentages of bacterial concrete samples with PPC and PC2 were 0.07 and 0.19% higher than those of non-bacterial samples, respectively. Both types of bacteria had the ability to repair cracks. Uncontrolled cracks in concrete samples were repaired to a width of at least 39.82 μm.

Assessment of natural radioactivity and radiation hazards owing to coal fly ash and natural pozzolan Portland cements

The natural radioactivity in coal fly ash and natural pozzolan Portland cement samples produced in Spain was measured by gamma spectrometry. Activity concentrations of 226Ra, 232Th and 40K ranged from 15.7 to 88.3 Bq kg−1, from 12.8 to 81.0 Bq kg−1 and from 37.0 to 678.0 Bq kg−1, respectively. The radiological hazards samples owing to the mentioned natural radioactivity were inferred from determinations of the activity concentration index, I, absorbed dose rate, Dext, and annual effective dose, Ep, which falls within 0.20 mSv to 0.87 mSv (coal-cement) and 0.18 mSv to 0.50 mSv (pozzolan-cement) (≤ 1 mSv, threshold criterion). Therefore, these cements are proper to be used for building purposes as result of their radiological assessment.

Mixture design applied to the development of composites for steatite historical monuments restoration

Abstract Natural rocks, as well as artificial man-made materials, undergo degradation caused by natural and man-made agents. Many pieces made of steatite that are part of magnificent monuments, listed as World Heritage Sites, are currently at an advanced level of degradation. Therefore, alternatives and actions are needed to interrupt this process and recover the deteriorated artefacts. In this context, this work aims to develop and characterise composite materials with the potential to repair surface wear, replace damaged parts and produce copies of sculptures made of soapstone. In order to produce materials with colour and texture similar to rocks, the powder residues of soapstone are used as a dispersed phase in the composites. Three different types of matrix materials (epoxy polymer, white Portland cement and pozzolanic Portland cement) are used in composites in order to identify the most suitable composition for restoration works. A statistical methodology based on the design of mixture is applied to identify the best matrix composition. Through this methodology, it is possible to investigate not only the behaviour of the different matrices that act independently but also the effect of the combination of these materials in several proportions. The physical and mechanical properties such as bulk density, apparent porosity, water absorption, compressive strength and elastic modulus are investigated. Composites made with 30% epoxy polymer and 70% steatite particles reach the greatest potential to be applied in restorations of historic monuments made of soapstone. These composites have properties superior to rocks and other composites, in addition to exhibiting texture and colouring similar to natural soapstone.

Characteristics of Pozzolan and Composite Portland Cements for Sustainable Concrete's Material

To support sustainable materials, the ordinary Portland cement production has been reduced since it left a high carbon footprint during manufacturing. As an alternative, the use of pozzolan Portland cement and composite Portland cement has been encouraged because they are more environmentally friendly. This paper examines some characteristics of cement made from pozzolan Portland cement (P.P.C.) and composite Portland cement (P.C.C.). The testing procedures were carried out on chemical and physical testing on P.P.C. and P.C.C. In addition, the mechanical testing of concrete made from both types of Portland cement and their combinations were conducted under compression load. Furthermore, the surface hardness of the concrete was evaluated using a rebound hammer measurement. Concrete testing was conducted after the curing age of 7, 28, and 42 days. According to chemical examination, P.P.C. has higher silica (SiO2) and iron (Fe2O3) than those of P.C.C., whereas P.C.C. has a higher lime (CaO) content. Compared to P.P.C., P.C.C. shows faster initial and final setting time. This result is proportionally influencing the strength development of concrete. P.C.C. concrete offers significant strength development at an earlier age. Meanwhile, P.P.C. concrete reacts slower at an earlier age, but it improves the compressive strength at a later age. The mix combination of 50% P.P.C. and 50% P.C.C. in concrete shows the highest average compressive strength and surface hardness. This combination achieves the average compressive strength of 30.27 MPa, 35.27 MPa, and 35.93 MPa respectively for 7, 28, and 42 days curing time. Furthermore, this concrete also shows the most remarkable characteristics of Young's modulus and surface hardness

ИССПОЛЬОВАНИЕ МИНЕРАЛЬНЫХ НАПОЛЬНИТЕЛЕЙ И ХИМИЧЕСКОЙ ДОБАВКИ АЦФ, ПАВ ПОЛИФУНКЦИОНАЛЬНОГО НАЗНАЧЕНИЯ, ПРИ ПРОИЗВОДСТВЕ ЦЕМЕНТА, МОНОЛИТНЫХ И СБОРНЫХ ЖЕЛЕЗОБЕТОННЫХ КОНСТРУКЦИЙ

At the Kuvasay Cement Plant, according to the developed factory technology for separate grinding of cement clinker and mineral aggregate, the production of pilot batches of Portland cement with slice, dispersion of 1500 cm2 / g, corresponding to the requirements for pozzolanic Portland cement, was produced. The use of Portland cement with a 40% mineral filler and ACF-3M admixture for concrete cladding of irrigation protocols at Ferganairstroy facilities showed high quality cladding, and the production of precast reinforced concrete hollow core slabs is characterized by good surface quality due to the improvement of the thixotropic properties of the concrete mixture.

Production of supplementary cementitious material as a sustainable management strategy for water treatment sludge waste

This paper investigates the application of Water Treatment Sludge (WTS), the main waste generated by water potabilization activities, for the development of a Supplementary Cementitious Material (SCM). The waste has been processed by calcining at a temperature range of 600 °C–800 °C for one hour. Chemical, mineralogical, physical, and morphological characterization has been performed to identify the potential pozzolanic activity of the calcined WTS and validate the application as SCM. Compressive strength tests have been performed in cement mortars with 14%, 35%, and 50% replacement of Portland cement by WTS. The WTS is a non-hazardous and non-inert waste, composed of SiO2, Al2O3, Fe2O3 and contains essentially quartz and kaolinite. Results confirmed the transformation of kaolinite into reactive amorphous phase by calcining. WTS calcined at 600 °C shows great potential to the production of SCM, confirmed by the chemical and physical analysis and the evidence of pozzolanic activity. The mechanical properties of mortars produced with 14% and 35% WTS calcined at 600 °C suggests a promising application in the production of blended and pozzolanic Portland cement.

Study of Proportional Variation of Geopolymer Concrete which Self Compacting Concrete

Portland cement production process which is the conventional concrete constituent materials always has an impact on producing carbon dioxide (CO2) which will damage the environment. To maintain the continuity of development, while maintaining the environment, Portland cement substitution can be made with more environmentally friendly materials, namely fly ash. The substitution of fly ash material in concrete is known as geopolymer concrete. Fly ash is one of the industrial waste materials that can be used as geopolymer material. Fly ash is mineral residue in fine grains produced from coal combustion which is mashed at power plant power plant [15]. Many cement factories have used fly ash as mixture in cement, namely Portland Pozzolan Cement. Because fly ash contains SiO2, Al2O3, P2O3, and Fe2O3 which are quite high, so fly ash is considered capable of replacing cement completely.This study aims to obtain geopolymer concrete which has the best workability so that it is easy to work on (Workable Geopolymer Concrete / Self Compacting Geopolymer Concrete) and obtain the basic characteristics of geopolymer concrete material in the form of good workability and compressive strength. In this study, geopolymer concrete is composed of coarse aggregate, fine aggregate, fly ash type F, and activators in the form of NaOH and Na2SiO3 Be52. In making geopolymer concrete, additional ingredients such as superplastizer are added to increase the workability of geopolymer concrete. From this research, the results of concrete compressive strength above fc' 25 MPa and horizontal slump values reached 60 to 80 centimeters.

Steel incorporated sawdust concrete

The constant increase in rate of cement in developing countries such as India has aroused the need to relate research to production. This Paper deals with subject of reducing the overall construction cost of concrete by partial replacement of Pozzolanic Portland Cement(PPC) with an optimum content of sawdust to reduce the cost and addition of Lathe Scrap Powder (LSP) to compensate the loss of strength due to replacement of cement by sawdust. PPC was replaced with 6%, 8%, 10%, 12% and 15% of sawdust to find the optimum percentage. LSP was then added in 0.25%, 0.5%, 0.75%, 1.0% and 1.5% to the sawdust concrete. After a time period of 7 days, 14 days and 28 days curing of standard size concrete cubes a compressive strength test was carried out, and the slump test was done on freshly prepared sample of concrete. Weight of the cubes was also found to calculate the bulk density of the steel incorporated sawdust concrete. Results show that on addition of 0.25% LSP on sawdust concrete indicated compressive strength (31.33) which was comparable to that of plain concrete(32.66).

Using calcium chloride as an accelerator for Portland pozzolan cement concrete compressive strength development

The influence of calcium chloride (CaCl2) as an accelerator for the compressive strength development of concrete made with type I Portland pozzolan cement (PPC) as a hydraulic binder has been investigated. Natural sand and crushed stone were used as fine aggregate and coarse aggregate, respectively. The mix proportion of concrete, by weight, was 1.0 binder: 2.1 fine aggregate: 3.4 coarse aggregate and the water-binder ratio was 0.57. The calcium chloride added to the concrete mixture was 0%, 1.0%, 1.5%, and 2.0% by binder weight. The compressive strength test was performed at 1, 3, 7, 28, and 90 days. The test results show that adding CaCl2 to a concrete mixture accelerates the development of compressive strength. The compressive strength gain was about 36–48% at 1 day and about 29–33% at 3 days, compared to control concrete. Moreover, it increases the compressive strength of PPC concrete about 3–16% at 28 days and about 7–19% at 90 days. The optimum dose of CaCl2 to accelerate the development of compressive strength at the early age and to produce the highest compressive strength in the long-term was about 1.5%.

Effect of partial substitution of raw gypsum with thermally treated phosphogypsum on the properties of Portland Pozzolanic Cement

For many years of production of phosphate fertilizer very large amounts of phosphogypsum (PG) occupied large area, causing chemical and radiological environmental. Using of PG in building materials represents a good method for lowering the cost of cement production and dispose of phosphogypsum as chemical and radioactive waste. Fresh wet hemihydrate phosphogypsum, cement and pozzolana additive were mechanically activated together and from mixing Portland pozzolanic cement (PPC) with PG, these mixes were prepared at different replacements (by weight) of raw gypsum (RG)with purified PG ranging from 1–5% . The purified PG was obtained by calcining PG at temperatures of 200, 400, 600, 800 and 1000 ᵒC. The compressive strength, bulk density, total porosity, combined water and free lime of different hardened mortars were obtained following 3, 7, 28 and 90 days of curing. In addition, the setting time of cement pastes. The highest percentage increase in strength was found to be for PG calcined at temperatures of 800 and 1000 ᵒC. The incorporation of PG in the cement paste has dramatically increased its initial and final setting times. FTIR spectroscopic analysis and scanning electron microscopy (SEM) were used for investigate the change in structure of mortars after curing and change in morphology and microstructure of some hardened pastes.

Evaluation of pozzolanic Portland cement as geotechnical stabilizer of a dispersive clay

ABSTRACT In this research, through a comprehensive geotechnical testing program, the pozzolanic Portland cement was investigated for its potential as treatment additive to the problematic Iranian dispersive clay. The dispersivity potential, plasticity index (PI), maximum dry density, compression index (Cc), rebound index (Cr), and sodium percentage (PS) of the clay samples were found decreased, while the unconfined compressive strength (UCS), optimum moisture content, and electrical conductivity (EC) were found increased, after treatment with the Portland cement. With 2% Portland cement and 7 days of curing, the erosion rate index (I) of the clay increased from less than 2 to more than 4, resulting in the delay of the formation of a piping failure. In terms of erosion resistance, the addition of 2% cement with 7 to 14 days curing time was found to be optimum. However, the mechanical strength developed significantly with increasing curing days and the highest strength was recorded at 90 days. Consequently, the study showed that the dispersivity behaviour, especially during the stabilization period, could be evaluated by analyzing the parameter values of I, PS, and EC.

Physical Behavior of Ternary Portland Cement Mortar Mixtures Incorporating Pozzolan and Filler

This work shows the results carried out by mixtures of Portland cement mortars with twoadditions: ash brick ovens (CELU) which acting as pozzolan, and ground expanded perlite (PEM)as filler. The objective of this research is to determine whether by adding a pozzolan and fillermixtures base Portland cement is possible to increase physical and mechanical behavior. There were3 mixtures: the control and 2 more: one with substitution of 7% CELU, and other with 7% CELU+5%PEM respectively, carrying out tests of normal consistency, setting, fluency, simple compression,indirect tension, ultrasonic pulse velocity and electrical resistivity at the ages of 3, 7, 14, 28 and 120days. The results were favorable in the mixture that incorporates both materials (CELU+PEM).

Estudo da Utilização da Reciclagem de Concreto Asfáltico como Camada de Pavimento

The present study aims to analyze the performance of milling material mixed with binders and mineral additions for tensile strength by diametrical compression, with the purpose of evaluating its application in the base layers and sub-base of pavements and in the search for satisfactory solutions in terms of pavement. The materials used were the milled material of asphalt pavement and stone powder, with the CP-IV pozzolanic Portland cement and the dolomite hydrated lime CH-II, with mineral additions of rice husk and fly ash. Cylindrical specimens measuring 10cm in diameter and 5cm in height were molded with modified energy from the Proctor test and tensile strength tests were carried out by diametrical compression, and the additions were performed at different levels. The results indicated that the quantitative of the mixture that obtained the highest tensile strength by diametrical compression was composed of 80% of milled material and 20% of stone powder, containing 5% cement and 5% silica content of the rice husk. This mixture obtained tensile strength by diametrical compression of more than 1.15 MPa. Therefore, this mixture comes to be the one of better technical and environmental performance, reusing residues of the pavement itself and also of rice production .

Monitoring reinforcement corrosion of concretes designed for nuclear facilitie

ABSTRACT The facilities designed for the peaceful activities of nuclear energy are made with different materials, among them, reinforced concrete. This material, in addition to being structural, is a barrier for isolation and confinement from the environment of the radioactive materials. One of its degradation mechanisms is the corrosion of the reinforcement, a frequent cause of premature failure in service. Consequently, it is essential to study this degradation mechanism in formulations developed for this purpose, as well as the development and implementation of monitoring techniques. The objective of this work is to compare, from the corrosion of reinforcement point of view, two concrete formulations, one made with ordinary portland cement and the other with pozzolanic portland cement. Both formulations are candidate for some nuclear applications, such as the Low Radioactive Waste disposal facilities, whose durability requirement is higher than 300 years. The results of approximately four years of monitoring are presented. The parameters followed are: corrosion potential and corrosion rate of the reinforcements, electrical resistivity, oxygen flow, internal temperature and carbonation rate of concrete. These parameters were measured and monitored in reinforced concrete specimens by embedded sensors previously developed in our laboratory. Also, unreinforced specimens were prepared to measure the carbonation rate. The presence of reinforcements provides the possibility of monitoring directly on them the corrosion potential, the corrosion rate and electrical resistivity of concrete, using on-surface electrodes provided by a commercial instrument. This allows the comparison of the parameters monitored by embedded sensors and the on-surface electrodes.

Green quaternary concrete composites: Characterization and evaluation of the mechanical properties

Industrial byproducts such as fly ash (FA), silica fume (SF), ground granulated blast furnace slag (GGBS), metakaolin (MK), and lime powder (LP), popularly known as supplementary cementitious materials (SCMs), have been extensively used in the manufacturing of cement and cement products in binary and ternary modes. In the present study, attempt has been made to develop a new sustainable green quaternary binder by partially replacing ordinary Portland cement (OPC) with different percentages of SCMs and find the optimum mix that can provide the best results in terms of mechanical as well as durability properties. The motivation is to reduce our dependency on OPC to reduce carbon foot print and utilizing these industrial byproducts for the sustainable development. Different compositions of quaternary binders were prepared and their physical, mechanical, and durability properties were studied and compared with the OPC and binary cement product pozzolanic Portland cement (PPC). The mechanical properties of concrete prepared with these OPC, PPC, and quaternary binders were also studied and it is established that the concrete mixtures prepared with quaternary binders provided better results and proved to be more economical. It is concluded that quaternary binders (a) OPC70% + FA15% + SF7.5% + GGBS7.5%, (b) OPC70% + FA15% + SF7.5% + MK7.5%, (c) 50%OPC + 30%FA + 10%SF + 10%GGBS, and (d) 50%OPC + 30%FA + 10%SF + 10%MK have produced relatively better strength, improved durability, and resistance to sulfate attack. These findings were also supported with the microstructural studies of hardened concrete of M20 grade using scanning electron microscope (SEM) and X‐ray diffraction (XRD).

Study of natural carbonation of concrete incorporating marble dust

This paper describes an experimental investigation on the carbonation of Portland pozzolan cement (PPC) concrete with marble dust (MD). The five PPC concrete mixes containing MD (up to 20%) were prepared with three different water–cement ratios (0·5, 0·6 and 0·7). All the concrete cube specimens were exposed to natural atmospheric carbonation after 28 d of moist curing. It was observed that the use of 10% MD enhanced the compressive strength of concrete and the carbonation coefficient decreased with an increase in MD content.