Durability Of Cement Research Articles

Testing Novel Portland Cement Formulations with Carbon Nanotubes and Intrinsic Properties Revelation: Nanoindentation Analysis with Machine Learning on Microstructure Identification.

Nanoindentation was utilized as a non-destructive technique to identify Portland Cement hydration phases. Artificial Intelligence (AI) and semi-supervised Machine Learning (ML) were used for knowledge gain on the effect of carbon nanotubes to nanomechanics in novel cement formulations. Data labelling is performed with unsupervised ML with k-means clustering. Supervised ML classification is used in order to predict the hydration products composition and 97.6% accuracy was achieved. Analysis included multiple nanoindentation raw data variables, and required less time to execute than conventional single component probability density analysis (PDA). Also, PDA was less informative than ML regarding information exchange and re-usability of input in design predictions. In principle, ML is the appropriate science for predictive modeling, such as cement phase identification and facilitates the acquisition of precise results. This study introduces unbiased structure-property relations with ML to monitor cement durability based on cement phases nanomechanics compared to PDA, which offers a solution based on local optima of a multidimensional space solution. Evaluation of nanomaterials inclusion in composite reinforcement using semi-supervised ML was proved feasible. This methodology is expected to contribute to design informatics due to the high prediction metrics, which holds promise for the transfer learning potential of these models for studying other novel cement formulations.

Evaluation of Water Sorption and Solubility of Different Dental Cements at Different Time Interval

Background: The clinical durability of dental cements is determined by dimensional stability. Water sorption and solubility of dental cements in distilled water have not been tested sufficiently. Aims: To evaluate and compare the water sorption and solubility of four different dental cements for permanent cementation at different time interval. Materials and Methods: Four different dental cements were selected: 1. Resin modified glass ionomer cement (Rely X luting2), 2. Poly acid modified composite resin cement (PermaCem Compomer), 3. Self-etching, self-adhesive dual cure composite resin cement (BeautiCem SA) and 4. Self-adhesive, dual cure composite resin cement (PermaCem 2.0). 120 discs were prepared, 30 discs for each group using Teflon molds (15±0.1mm in diameter and 1±0.1 mm in thickness). The discs were dried in a desiccator at 37co and weighted daily until a stable weight (M1) was achieved using an electronic digital balance with accuracy of 0.0001g. The discs were immersed in distilled water for different time intervals (1, 7, 14, 21, 28 and 35 days) and the weight (M2) was recorded. The discs were replaced in a desiccator and weighed daily until stable weight (M3) was achieved. Water sorption and solubility in µg/mm³ were calculated using the following equations: Wsp=(M2-M3)/V; Wsl=(M1-M3)/V. Data analyzed using ANOVA and Tukey’s Post hoc test. Results: The results showed that there was a significant difference between the different dental cements and time intervals for both water sorption and solubility. RelyX luting2 exhibited the highest water sorption and solubility values at different time interval, whereas Permacem 2.0 showed the lowest values (P≤0.05). Conclusion: Four types of dental cements of different compositions showed different behavior on water sorption and solubility. Resin cements are recommended for the permanent cementation of indirect restorations. Dental cements exhibited a time dependent increase in both water solubility and sorption.

The Doping of Mineral Additions SF, FA and SL on Sulfate Corrosion Resistance of the HIPC Cements

To prepare highly durable cement concrete for marine infrastructure, the effect of silicon powder (SF), fly ash (FA) and mineral powder (SL) on sulfate corrosion resistance of the high iron and low calcium portland cement (HIPC) were studied. In this paper, a series of experiments were carried out using HIPC cements as the raw material and 20 °C, 5% Na2SO4 solution as the conservation environment. The effect on the sulfate resistance of the system is determined by analysing the mechanical properties of the sample and measuring the corrosion resistance coefficient K to characterize the system’s resistance to corrosion. The results show that the anti-erosion coefficient of HIPC systems with different mineral admixtures has been enhanced to varying degrees, among which the optimal amount of SF is 3%; the optimal amount of SL is 40%; the optimal amount of FA 20%.

ПІДВИЩЕННЯ ДОВГОВІЧНОСТІ ЦЕМЕНТОБЕТОНУ ДЛЯ ПОКРИТТЯ АВТОМОБІЛЬНИХ ДОРІГ

The article is devoted to the problem of improving the durability of cement concrete to cover the road through the use of additives. The purpose of the work-improving the durability of cement concrete to cover roads through the use of hydrophobic additives. Object of study-cement-concrete to cover roads. Method of research: statistical analysis of scientific publications, technical and normative literature. In Ukraine, there are almost no necessary types and brands of road cement, so the research and application of existing binders with effective additives is an urgent problem, the solution of which will expand the nomenclature of cement binders for road Construction, improve the durability and resistance of cement concrete covering roads, bridges and airfields, as well as to solve security issues. For this, it is possible to use chemical additives that kolatating pores, give the surface of concrete water-repellent properties, involve in the concrete mixture of air. Based on the modern representations of the physical- xiemia of superficial processes, it can be concluded that the introduction to the concrete mix of small-scale kremnijorganicnih substances together with the water of the closing, will allow to significantly improve the durability and strength against At the same time for the concrete of aggressive factors and load. The influence of hydrophobic additives on physical, mechanical properties of cement concrete to cover roads is investigated. Based on the experimental results, it is determined that the application of 0.1­0.15% hydrophobic additives 136-157 M has a significant increase in the durability of cement concrete for the seal of roads. KEYWORDS: CEMENT CONCRETE PAVEMENT, HYDROPHOBIC ADDITIVES, FROST RESISTANCE, WATER RESISTANCE, STRENGTH, DURABILITY

Basalt fiber concrete as a new construction material for roads and airfields

The presence of reinforcing fibers in concrete in terms of their optimal content increases density, uniformity and reduces the risk of cracking which allow predicting the increased dynamic resistance, frost resistance, abrasiveness and durability of both cement and asphalt concrete. This article presents the results of experimental studies of the physical-mechanical properties of cement and asphalt concrete reinforced with basalt fiber during which technological indicators of impact on the strength and durability of concrete (fiber content in mixtures, the ratio of fiber length to the size of the largest coarse aggregate) were selected, statistical analysis and optimization of the research results. To justify the choice of basalt fiber, the results of research on the determination of its chemical composition of the fiber and physico-mechanical characteristics are shown. The optimal sizes of basalt fiber, which is introduced into the mixture, are also determined. It was concluded under what conditions the studied characteristics of concrete reinforced with basalt fiber reach their maximum value with the corresponding ratios of technological indicators.

Study on Stability and Durability of Coal Gangue Used in Runway Base

Coal gangue, as industrial waste generated in the mining process, is rarely used in the construction of domestic airport runways. This paper studies the stability of coal gangue and the durability of cement stabilized coal gangue in combination with the characteristics of navigation airport construction. The coal gangue self-stability test includes: chemical composition, loss on ignition, crushing value and expansion ratio. The durability of cement stabilized coal gangue is mainly based on the freeze-thaw cycle test. The test results show that the sum of the content of coal gangue SiO2, Al2O3 and Fe2O3 in the mine is more than 70%, the loss on ignition is less than 15%, the control standard can be achieved, and the expansion ratio is not more than 0.5%. Coal gangue itself has good stability. By comparing the compressive strength values of the standard test pieces before and after 6 freeze-thaw cycles, it is found that the cement-stabilized coal gangue with different cement content has a frost resistance of more than 60%, and the overall frost resistance is good. In addition, considering the load level and safety reserve of the navigable airport, the cement content should be greater than 5%. The above conclusions can provide reference for the application of coal gangue in the field of airport construction.

Application of cellulose-based polymers in oil well cementing

Cellulose-based polymers have been successfully used in many areas of petroleum engineering especially in enhanced oil recovery drilling fluid, fracturing and cementing. This paper presents the application of cellulose-based polymer in oil well cementing. These polymers work as multifunctional additive in cement slurry that reduce the quantity of additives and lessen the operational cost of cementing operation. The viscosity of cellulose polymers such as hydroxyethyl cellulose (HEC), carboxymethylcellulose (CMC) and hydroxypropyl methylcellulose (HPMC) has been determined at various temperatures to evaluate the thermal degradation. Moreover, polymers are incorporated in cement slurry to evaluate the properties and affect in cement slurry at 90 °C. The API properties like rheology, free water separation, fluid loss and compressive strength of slurries with and without polymer have been determined at 90 °C. The experimental results showed that the viscosity of HPMC polymer was enhanced at 90 °C than other cellulose-based polymers. The comparative and experimental analyses showed that the implementation of cellulose-based polymers improves the API properties of cement slurry at 90 °C. The increased viscosity of these polymers showed high rheology that was adjusted by adding dispersant which optimizes the rheology of slurry. Further, improved API properties, i.e., zero free water separation, none sedimentation, less than 50 ml/30 min fluid loss and high compressive strength, were obtained through HEC, CMC and HPMC polymer. It is concluded that cellulose-based polymers are efficient and effective in cement slurry that work as multifunctional additive and improve API properties and cement durability. The cellulose-based polymers work as multifunctional additive that reduces the quantity of other additives in cement slurry and ultimately reduces the operational cost of cementing operation. The comparative analysis of this study opens the window for petroleum industry for proper selection of cellulose-based polymer in designing of cement slurry.

Durability and Strength Analysis of Cement Treated Soils for Sub-Base and Base Layers of Pavement

Durability and Strength Analysis of Cement Treated Soils for Sub-Base and Base Layers of Pavement

An Overview of Study on Basic Magnesium Sulfate Cement and Concrete in China (2012–2019)

In this review, investigations on the product of hydration, mechanical behavior, durability and application of basic magnesium sulfate cement (BMS) have been carried out in the past seven years in China. Structural characterization of 5·1·7 phase and hydration product of BMS are introduced in the first part of this paper. The second part gives the research on the basic properties of BMS: strength, setting time, and microstructure of BMS. The third part show the durability of the cement: water resistance, chloride penetration, ability of protecting reinforcing bars and carbonization. The last part is devoted to the production and application of BMS, which indicates that basic magnesium sulfate cement has wide application potential in the construction industry.

A multi-methodological study of kurnakovite: A potential B-rich aggregate

AbstractThe crystal structure and crystal chemistry of kurnakovite from Kramer Deposit (Kern County, California), ideally MgB3O3(OH)5·5H2O, were investigated by single-crystal neutron diffraction (data collected at 293 and 20 K) and by a series of analytical techniques aimed to determine its chemical composition. The concentration of more than 50 elements was measured. The empirical formula of the sample used in this study is Mg0.99(Si0.01B3.00)Σ3.01O3.00(OH)5·4.98H2O. The fraction of rare earth elements (REE) and other minor elements are, overall, insignificant. Even the content of fluorine, as a potential OH-group substituent, is insignificant (i.e., ~0.008 wt%). The neutron structure model obtained in this study, based on intensity data collected at 293 and 20 K, shows that the structure of kurnakovite contains: [BO2(OH)]-groups in planar-triangular coordination (with the B-ions in sp2 electronic configuration), [BO2(OH)2]-groups in tetrahedral coordination (with the B-ions in sp3 electronic configuration), and Mg(OH)2(H2O)4-octahedra, connected into (neutral) Mg(H2O)4B3O3(OH)5 units forming infinite chains running along [001]. Chains are mutually connected to give the tri-dimensional structure only via hydrogen bonding, and extra-chains “zeolitic” H2O molecules are also involved as “bridging molecules.” All the oxygen sites in the structure of kurnakovite are involved in hydrogen bonding, as donors or as acceptors.The principal implications of these results are: (1) kurnakovite does not act as a geochemical trap of industrially relevant elements (e.g., Li, Be, or REE), (2) the almost ideal composition makes kurnakovite a potentially good B-rich aggregate in concretes (for example, used for the production of radiation-shielding materials for the elevated ability of 10B to absorb thermal neutrons), which avoids the risk to release undesirable elements, for example sodium, that could promote deleterious reactions for the durability of cements.

Utilization of waste from steel and iron industry as replacement of cement in mortars

The viability of combining waste slag produced from steel (Basic Oxygen furnace) and iron (Blast Furnace) industry as replacement of cement in cement mortars was investigated. The impacts on the normal consistency, setting times, soundness, compressive strength, microstructure, and durability of cement paste/mortar were studied. The results revealed that the water requirement and the setting time of cement paste increased by the addition of steel slag powder. The optimum content of steel slag and GGBS (ground granulated blast furnace slag) as a combined admixture was 40%. The 28 day compressive strength was comparable, whereas it exceeded the strength of control mortar after 90 days of curing. The microstructure of samples was studied using SEM micrographs, which indicated denser structures of ternary mortars. The durability tests of accelerated carbonation, sulphuric acid resistance, and electrical resistivity showed acceptable results. Life cycle assessment (LCA) of ternary mortar indicated visible decrease in environmental impacts in all categories. Response Surface Methodology (RSM) was adopted to find relation between partial replacement of cement by steel slag and GGBS in ternary blend and compressive strength. This research bestows a new understanding of how industrial wastes can be managed sustainably with imparting additional benefits to the concrete economically.

Performance of cement-slag-titanate nanofibers composite immobilized radioactive waste solution through frost and flooding events

Innovation of cement-based composites is a recently strongly emerging technology. Nanotechnology is one of the potential alternatives to improve cement characteristics and to decrease the amount of cement used in various applications, which consequently reduces the energy required for cement production and carbon dioxide emission caused by cement industry. The improvement of cementitious materials is still an important target to produce modified compounds of valuable mechanical, chemical and physical characterizations. In this paper, Portland cement mixed with iron slag was hydrated with an aqueous titanate nanofibers suspension to create cement nanocomposites as environmentally friendly material with novel properties. In this sense, nanoparticles as additive material allow for improving the mechanical durability of cement and retard the permeability of cement-based materials. SEM, FT-IR and X-ray diffraction analyses confirmed the Ca(OH)2 conversion towards calcium silicate hydrate. Porosity and compressive strength measurements were also performed through variable parameters and under different conditions. Durability tests and chemical stabilization were carried out at freezing/thawing condition during extended cycles of up to 6 months. The effect of flooding in various aqueous media including acidic and alkaline ones was evaluated during extended periods of immersion. Moreover, the radioactive contaminant 137Cs was immobilized by the novel cement nanocomposite to test the nanocomposite’s chemical stability by monitoring the leaching of 137Cs. Resulting data were used to positively assess the feasibility of this compound to be used for immobilization of radioactive and other hazardous wastes. The produced composite attained proper consistency when exposed to frost attack or flooding in various media up to 180 days.

Kryteria oceny podbudów związanych cementem zawierających kruszywa pochodzące z recyklingu

The paper deals with investigations into the possibility of using crushed concrete reclaimed from road pavements to produce new cement bound mixtures for roadbase courses. From the economic and technical points of view crushed concrete waste constitutes an alternative source of aggregates which can replace natural aggregates in cement bound mixtures. First, recycled concrete aggregate was tested with regard to the current requirements which aggregates for cement bound roadbases must meet. Then, the strength and frost resistance tests were carried out on cement bound mixtures based on recycled concrete aggregates and natural aggregates. The possibilities and limitations of the use of recycled concrete aggregate for cement bound roadbase courses were examined. The results of the performed tests proved that recycled concrete aggregate, even though it does not meet the water absorption and frost resistance requirements, can be used to build durable cement bound roadbases.

Mechanical strong and durable cement mortars reinforced by controlling the polymer phase size

The influence of polyvinyl alcohol phase size on the properties of cement mortars has been experimentally investigated. The compressive strength reduced sharply with the increase of polymer phase size. Based on Fourier transform infrared spectroscopy (FTIR) data, the existence of Al–O–H bonds indicates that there is a moderate crosslink between polyvinyl alcohol (PVA) and cement. Mechanical and durability-related properties were compared between PVA grain powder versus PVA solution combined with cementitious matrix. It was found that the mechanical performance of mortars with PVA solution was superior to those with PVA grain powder. Water absorption coefficient was improved with the incorporation of PVA. The water absorption coefficient of mortar with PVA grain powder was lower than that incorporating PVA solution. Finally, the introduction of PVA did not boost the chloride resistance of the material but provided significant enhancement to the freeze-thaw resistance compared to the control group.

Durability properties of alkali pozzolan cement (APC)

This paper compares the durability properties of alkali pozzolan cement (APC) with high volume fly ash (HVFA) cement and ordinary Portland cement (OPC). The susceptibility to durability issues was investigated through the water absorption test using 28-day-old samples. Durability against chemical attacks was investigated through sulphuric acid attack, chloride ion penetration and carbonation tests on 1-year-old samples. The results indicated that APC occupies a median position in relation to OPC and HVFA, having greater resistance than HVFA for water absorption and carbonation, and greater resistance than OPC for sulphuric acid attack and chloride ion penetration. Chemical and microstructural reasons for the above behaviours are presented. A key index of durability performance is the free calcium hydroxide available and/or generated during cement hydration and durability exposure.

The effect of metakaolin on the processes of hydration and hardening of cement

Abstract Investigated influence of a metakaolin on processes of hydration and curing of a Portland cement. It has been shown that in the presence of metakaolin the rate of hydration and hardening of the cement are changed. The metakaolin is connected by Ca(OH)2, allocated at hydration of an alite, in hydroaluminates of calcium and poorly the kristallichny of hydrosilicates of calcium of various basicity. The additive of not modified metakaolin promotes formation of the low-main HSC (C/S = 0.8–1.5). In the presence of the modified metakaolin high-main HSC (C/S = 1.5–2) are formed. The additive of the modified metakaolin increases cement durability in early terms of curing thanks to fast formation of additional quantity of the hydrate phases, which condense structure of a cement. It leads to increase of frost resistance and corrosion resistance of cement.

An experimental study on effect of Bacillus sphaericus bacteria in crack filling and strength enhancement of concrete

Abstract Objective of the present investigation is to develop a durable cement concrete by incorporating varying proportions of Bacillus Sphaericus bacteria in crack filling and strength enhancement through biomineralisation. Test samples were tested at different ages for cube compressive strength, split tension, flexural strength, modulus of elasticity and also for durability tests with Bacillus Sphaericus bacteria concentrations of 1000, 100,000, 107 cells per 1 ml, then verified by the reference test samples made without bacteria. The crack filling ability of bacteria are studied and found that at all the concentrations, the percentage loss of strength for cracked concrete specimen with bacteria was low compared to cracked concrete specimen without bacteria. For bacterial dosage of 100,000 cells/ml better results were noticed for strength and crack filling of specimens. But with further increasing the dosage of bacteria, the mechanical properties were decreased. Findings revealed that concrete with Bacillus sphaericus is much efficient for increasing the durability of concrete as percentage loss of compressive strength is low when exposed to acid attack. The development in the parameters tested for concrete with bacteria can be attributed to the precipitation of calcium carbonate which was found in SEM analysis. Incorporated bacterium into the concrete mixture do not harm in any way. Hence, it can be stated that the amalgamation of bacterium in concrete reduces the cracks there by adds durability to the concrete.

KARAKTERISTIK PENGGUNAAN ABU SERBUK KAYU SEBAGAI SUBTITUSI FILLER PADA CAMPURAN LASTON LAPIS AUS

Most of the filler material is a natural product such as rock ashes that increasingly limited and possesses high economic value. The further innovations in filler substitute by using alternative materials are demanded such as waste saw dust to become economical and unlimited resources. This study aims to determine the effect of the use of sawdust and Portland cement as a filler over AC-WC aggregate mixture characteristics. Further, sawdust and the Portland cement includes as the substitution. The filler substitution sawdust and Portland cement respectively amounted to 75% ASK - 25% SP, 50% ASK - 50% SP, 25% ASK - 75% SP and 0% ASK - 100% SP. Moreover, the experiment produced Substitution of 6.1% KAO for 75% sawdust - 25% Portland cement, Substitution of 6% for 50% sawdust - 50% Portland cement, Substitution of 5.85% for 25% sawdust - 75 % Portland cement and Substitution of 5.31% for 0% sawdust - 100% Portland cement. The best resulted KAO found in 0% sawdust substitution and 100% portland cement with 5.31%. The high-grade stability value with 30 minutes of regular water immersion is 1300,38 kg within 0% ash of sawdust substitution and 100% of Portland cement. The lowest stability value with 30 minutes of regular water immersion is 1056.09 kg within 75% sawdust substitution and 25% of Portland cement. The sawdust and portland cement durability value accomplished the Bina Marga 2014 specification (≥ 90%). The ANOVA test proved the addition of sawdust and portland cement in the asphalt mixture affects the stability value of the regular water immersion.

Express Forecast of Portland Cement Strength Using Conductimetric and Thermogravimetric Analyses

Questions of express (within 15 minutes or 24 hours) instrumental forecast of Portland cement strength by means of conductivity and (or) gravimetric measurements are considered. It is shown that the specific resistivity of the sample of cement-sand mortar of standard composition (1:3, W/C=0.5) or the determination of the degree of hydration of cement stone (W/C=0.3-0.32) for interval losses during thermogravimetric analysis in the period of 24 hours provides fairly reliable results in the range of 40 to 70 MPa for R28 and 12-30 MPa for R3 days during the first 15 minutes.A comparison of the different nature of the forecast methods adequacy for Portland cement durability (for “ion” power and transformation of cement-framework of grains) demonstrates the compatibility of these practices and ensures the convergence of the strength results. The use of these different techniques also provides additional information about a number of important construction and technical characteristics (the period of cement setting in the solution, the number of mineral additives, the content of Ca(OH)2, etc.).

Effect of early age curing carbonation on the mechanical properties and durability of high initial strength Portland cement and lime-pozolan composites reinforced with long sisal fibres

This paper presents the results of a study about the mechanical behaviour, before and after aging, of two cement-based composites reinforced with long sisal fibres cured at early age in a CO2 environment. After curing, samples of both composite systems were submitted to wetting and drying cycles to accelerate the aging of the materials allowing the evaluating of the efficiency of the CO2 treatment. Besides promoting CO2 capture, the used cure also allowed the increase in the durability of the sisal fibre-cement based composites by the Calcium Hydroxide (CH) consumption and pH decrease promoted by the carbonation reactions. The lime-pozzolanic material composite was also treated with CO2 at early stages of formation, with the carbonation and pozzolanic reactions acting simultaneously to deplete the Ca(OH)2 thus improving its durability. Four-point bending test, thermogravimetry analysis of the matrix and SEM analysis of the fibres were done before and after aging to study the durability mechanisms of the composites. The obtained results showed that the CH free cement-based composite containing metakaolin and fly ash presented the best mechanical behaviour before and after accelerated aging. The early age carbonation of the lime-pozolan composites improved its mechanical response, before and after accelerated aging, when compared with the non-carbonated samples. The thermogravimetry test showed that the increase of the carbonation time of the reference Portland cement-based composite consumed the CSH, compromising the ductility and strain capacity of this composite family after aging. The SEM pictures showed petrified fibre effect by the migration of hydrated products after 10 and 20 cycles of ageing for this composite system.