Application Of Cement Research Articles

A study for the properties of the Portland cement from different sources available in the Iraqi market

The quality of the cement used is the most important criteria for the implementation of the plain and reinforced concrete mixtures as well as the finishing works. So that the durability of concrete members and other cement applications is a function of the quality of the cement used. In recent years,the Iraqi marketimported many types of cement from another countries, most of them have no typical tests for their chemical and physical properties or not confirm with the Iraqi specifications.In this study a comparisonwas made between random types of cements which are common used in Iraq throughout an experimental investigation. All tests werecarried in a accordance with the Iraqi specifications. For this purpose the cement mix was prepared with cement content of 300 kg/m3 and W/C ratio of 0.45. Mix proportioning of 1:1.5:3 was used for all of tested mixes. The initial and find setting times and slump tests were performedin order to identify thepropertiesof fresh concrete. On the other hand, tests of compressive strengths were adoptedto evaluatethe properties of hardened concrete. The resultsobtained showed that the locally produced cement (type Al-Muthana) is the most favorable cement compared with the other tested samples (from another countries), because of its high compressive strength and less water requirements to reach the standard consistency

FLY ASH FOUNDATION REINFORCED BY CEMENT–SOIL MIXING PILES

Cement-soil mixing piles have been commonly used to enhance the bearing capacity of fly ash stratum and mitigate the settlement damage to the surrounding environment. However, only cement is used as curing agent in traditional cement-soil mixing piles. The growth rate for strength of cement-soil mixing piles decreases with the rise in the cement content. Accordingly, it is necessary to explore the combination effects of various curing agents on the strength of cement-soil mixing piles. However, rare studies for the reinforcement effect of fly ash stratum have been conducted by using lime or gypsum as effective replacement materials of cement in cement-soil mixing piles. In this study, laboratory tests were performed to compare the variation laws of unconfined compressive and shear strength of test specimens before and after replacement. Then, the reinforcement effect of cement–soil mixing piles at different lime–cement and gypsum–cement replacement ratios was evaluated. Results demonstrate that the cement–soil mixing piles with 12% cement content not only enhance the bearing capacity of cement-soil mixing piles but also decrease the amount of the cement. When the gypsum-to-cement replacement ratio is 1:2, the 28-day strength of gypsum–cement–fly ash specimens reaches the peak value of 4.5 MPa. When the lime-to-cement replacement ratio is 1:1, the 28-day unconfined compressive strength of lime–cement–fly ash specimens is 6.6 MPa, which increased by 46% compared with those of pure cement–fly ash specimens. Thus, the strength of cement–soil mixing piles in fly ash stratum can be improved due to the lime–cement combination. The rationality of design in cement-soil mixing piles on the factor is further verified by the field test. The results of this study can be referenced for the application of cement–soil mixing piles in the stratum of fly ash reinforcement. Keywords: Cement–soil mixing piles, Unconfined compressive strength, Shear strength, Fly ash stratum

Recycling of light-emitting diode waste quartz sand as a pozzolanic material

LED waste quartz sand (LEDWS), which is a prominent byproduct of the LED manufacturing process, may contaminate the environment because it comprises numerous nanoparticles of SiO2, Al2O3, and SiC, which are hazardous ingredients that are harmful to the environment and human health when disposed of improperly. Therefore, this study investigated the pozzolanic reaction behavior of these industrial byproducts to obtain a valuable processing method for LEDWS in cement. The results showed that with increased curing time, the strength of the pastes that incorporated 10% LEDWS approached that of ordinary Portland cement. A stretching broad band was centered at 1074–1081 cm−1 from chemically bound H2O in the hydrated calcium silicate (C–S–H). Thus, the correlation between the hydration degree of the paste that incorporated LEDWS and compressive strength evolution is crucial. The results implied that LEDWS can be used as a partial replacement source for cement applications; thus, LEDWS can be used as pozzolanic material.

Effect of different laser types on bonding strength of CAD/CAM-customized zirconia post to root canal dentin: an experimental study.

In clinical dentistry, the strength of bonding zirconia posts to root canal dentinal walls currently needs enhancement, and laser application can be an important contribution owing to its features that accommodate adjustable modifications on dental materials. Herein, the effect of different laser treatments applied to dentin surfaces on the strength of bonding zirconia posts to root canal dentinal walls is evaluated by using the pull-out bond strength test in a laboratory setting. A total of 40 single-rooted permanent mandibular premolar teeth that were freshly extracted were used here. The root canal preparation steps were performed using the crown-down technique. Custom-made zirconia posts were produced using CAD/CAM technology. Prior to the application of resin cement, the internal surfaces of the root canals were irradiated using Nd:YAG, Er:YAG, and KTP lasers. Pull-out tests were performed on each specimen by using a universal testing machine. One-way analysis of variance and Tukey post hoc tests were used to compare the pull-out bond strength data. The bond strengths of the laser-treated specimens were greater than those of the untreated controls (p < 0.05). While the value of the pull-out bond strength after Nd:YAG laser treatment was significantly higher than the values obtained after the applications of the Er:YAG and KTP lasers (p < 0.05), the pull-out bond strength after Er:YAG laser treatment was considerably greater than that after KTP laser treatment (p < 0.05). The bond strength between the root canal dentin and the CAD/CAM custom-made zirconia post was improved upon using all the laser modalities in current laboratory settings, among which, application of the Nd:YAG laser was the most successful.

Dissimilar sintered calcium phosphate dental inserts as dentine substitutes: Shear bond strength to restorative materials.

The application of sintered calcium phosphate dental inserts in the central part of tooth cavities can reduce amount of embedded dental composite and polymerization shrinkage of final dental fillings. The aim of this study was to analyze comparatively physico-chemical and mechanical properties of dental inserts and shear bond strength (SBS) between three dissimilar hydroxyapatite-based dental inserts and different restorative materials, after application of different clinical protocols. Starting from two different hydroxyapatite nano powders and nanostructured stabilized zirconia (YSZ), monophasic two-step sintered dense HAp inserts (TSSHAp), biphasic single-step sintered controlled porous inserts (HAp/TCp), and single-step sintered reinforced HAp/YSZ inserts were processed and characterized. Obvious differences in the microstructure of inserts surface were visualized after etching with 37% phosphoric acid. Fracture toughness of sintered inserts was ranged between 1.01 and 1.85 MPam1/2 (maximum value in the case of HAp/YSZ), while hardness values were in the range of 3.71-5.22 GPa (maximum value in the case of TSSHAp). Acid etching before application improved SBS between inserts and Maxcem compared to direct cement application. TSSHAp and HAP/TCp inserts showed comparable and relatively high SBS values, certainly higher compared to HAp/YSZ inserts. Slightly higher SBS values were measured in the case of TSSHAp insert group, and the highest mean SBS value of 18.51 MPa was determined between TSSHAp inserts and Filtek Z250_SBU following the "self-etch" protocol.

Development of banana fibers and wood bottom ash modified cement mortars

Many plant wastes have been generated from agriculture for years and as the current global drive towards a green-economy continues, more agro-based wastes will be generated in the future. Some of these wastes are being used presently as a form of renewable energy and result into ashes which are sent to landfills. However, previous studies have shown that ashes could be used as cement replacement while others considered the use of these agricultural wastes from plants as fiber reinforcement in cement appli-cations. In this study, an environment friendly solution was provided to replace cement with wood bot-tom ashes at 10, 15, 20 and 25% levels and modify the mortars produced with styrene butadiene polymers for improved strength. Also, as a way of providing sustainable path towards utilization of wastes from plant fibers, banana fibers were treated with alkaline solution and used to reinforce the polymer modified cement mortars. The developed cement composites were subjected to mechanical tests, microstructural, elemental, functional group and thermal conductivity analyses. It is realistic to conclude that optimum performance of the composite can be obtained when cement is replaced by up to 10% of wood bottom ash, 1.5% of banana fiber content and of 0.3% of styrene butadiene polymer emulsion The composite developed provided good thermal insulation properties and could be used in some selected cement based applications.

Effective removal of phosphorus from eutrophic water by using cement

Increasing discharge of excessive phosphorus (P) has caused widespread eutrophication and water pollution that threaten both ecological and human health. There are many ways to remove P from eutrophic water, but there are various deficiencies. Conventional P removal is based largely on the use of Al or Fe salts and few methods can be directly used in field eutrophic water. Our research revealed that direct use of ordinary Portland cement could effectively remove P from eutrophic water bodies. Laboratory experiments indicate that a one-time application of cement reduced Total Phosphorus (TP) concentration of both eutrophic urban water and synthetic solutions to below 0.2mg/L. A second application further reduced TP to below 0.04mg/L. Use of cement also caused an increase in dissolved oxygen (DO) content in samples. Cement was directly used in eutrophic water body of a river and TP concentration was reduced to an allowable level. Use of readily available cement can contribute to the clean up of water pollution in developing countries. This study provides an innovative and easy solution to widespread eutrophication.

An in vitro investigation comparing methods of minimizing excess luting agent for cement-retained implant-supported fixed partial dentures

Statement of problemThe use of cement-retained implant-supported prostheses is a well-established treatment option. Techniques have been proposed to reduce the amount of residual excess cement (REC) around cement-retained single-implant restorations. However, studies evaluating the effectiveness of such techniques related to cement-retained implant-supported fixed partial dentures (CRISFPDs) are lacking. PurposeThe purpose of this in vitro study was to evaluate the effectiveness of various cement application techniques for CRISFPDs. Material and methodsTwo implant analogs were placed in the lateral incisor sites in a maxillary, 3D printed cast with 4 missing incisors. Twenty standardized, removable, printed soft-tissue replicas, 40 milled titanium custom abutments, and 20 milled zirconia CRISFPDs were fabricated. Two cement application techniques, the brush on technique (BOT), and the polyvinyl siloxane index (PI) technique were compared. Two cementation techniques, without bib (control) (n=10) and with a polytetrafluoroethylene (PTFE) bib (test) (n=10), were used. A premeasured amount of interim cement was used to cement the CRISFPDs. The CRISFPDs were retrieved after cementation, and standardized photographs of 4 quadrants of each abutment-CRISFPD assembly were made by using a software program that is used to calculate the ratio between the area covered with REC and the total specimen area. The extension of the REC on both the abutment and soft-tissue replica was measured at sites before and after cleaning the REC. A generalized linear mixed-model procedure was used for statistical analysis (α=.05). ResultsFor cement application, the polyvinyl siloxane (PVS) index technique had significantly less REC than the brush on technique (P<.05). The use of a PTFE bib led to significantly less REC than when no bib was used (P<.05). ConclusionsThe use of the PVS index technique along with a PTFE bib was effective in reducing REC for CRISFPDs.

Identification of a calcium phosphoserine coordination network in an adhesive organo-apatitic bone cement system

Calcium phosphate-based bone cements have been widely adopted in both orthopedic and dental applications. Phosphoserine (pSer), which has a natural role in biomineralization, has been identified to possess the functionality to react with calcium phosphate phases, such as tetracalcium phosphate (TTCP) and α-tricalcium phosphate (α-TCP), and form a uniquely adhesive cement. This study investigated the chemical composition and phase evolution of a heterogeneous calcium phosphate (56% TTCP and 15% α-TCP) and pSer cement system with respect to pH. The coordination network of calcium phosphoserine monohydrate was discovered as the predominant crystalline phase of this adhesive apatitic cement system. Furthermore, it was determined that pH has a significant effect on the reaction kinetics of the system, whereby a lower pH tends to accelerate the reaction rate and favor products with lower Ca/P ratios. These findings provide a better understanding of the reaction and products of this adhesive organo-ceramic cement, which can be compositionally tuned for broad applications in the orthopedic and dental spaces. Statement of significanceThe application of self-setting calcium phosphate cements (CPCs) in hard tissue regeneration has been a topic of significant research since their introduction to the field 30 years ago. Traditional CPCs, however, are limited by their suboptimal mechanical properties due to their solely inorganic composition. Recently, it was discovered that monomeric phosphoserine (pSer) is capable of serving as a setting reagent for a subset of CPC systems, resulting in an adhesive organo-ceramic composite. Despite its adhesive functionality and biomedical potential, its reaction chemistry and product composition were not well characterized. The present study identifies a calcium phosphoserine coordination network as the primary crystalline phase of this apatitic cement system and further characterizes compositional tunability of the products with respect to pH.

Experimental investigation on the effect of steel fiber embedded in marble dust based concrete

In the modern era, concrete is considered as synonymous with strength and durability. The application of cement and production causes the reason for pollution in the environment. To mitigate such problems, industrial waste are frequently utilized in the concrete construction as a partial replacement of cement, reducing carbon footprint in the atmosphere and leading to enhanced strength. In this study, M20 grade concrete with marble dust in 0%, 5%, 10%, 15% and 20% in proportion along with ratios of steel wires were used and tested for 7 & 28 days on mechanical parameters. The study reveals that the inclusion of 1% steel fiber and 15% replacement of marble dust with cement exhibiting the highest mechanical strength over the ordinary concrete and other proportions. Moreover, beyond this fraction, reduction in strength is greatly achieved. As results revealed, adding certain fixed amount of marble dust with steel fiber have improved and dense interlock aggregate particles, resulting in more durable over the ordinary cement concrete.

Effect of surface finishing treatments on the color stability of CAD/CAM materials.

PURPOSEThe aim of this study was to evaluate the effect of different surface finishing processes on the color stabilities of lithium disilicate glass-ceramics, zirconia-reinforced lithium silicate ceramics, and resin nanoceramics after artificial ageing.MATERIALS AND METHODS216 samples were prepared from 3 different CAD/CAM materials (LAVA Ultimate, IPS e.max CAD, VITA Suprinity) with A1 HT color at a size of 14 × 12 mm and a thickness of 0.5 ± 0.05 mm. Color measurements of the samples were performed with a spectrophotometer using color parameters and CIE Lab color system on a gray backing between baseline color and after 5000 cycles of artificial ageing in 4 stages (i.e. the first measurement before the treatment, the second measurement after polishing, the third measurement after cement application, and the fourth measurement after artificial ageing). The results were evaluated using the Variance analysis and Fisher's LSD test.RESULTSResin nanoceramics (LU) exhibited higher color change values than zirconia-reinforced lithium silicate (VS) and lithium disilicate (EC) ceramics after artificial ageing. Manual polishing and glazing resulted in similar color change for LU and VS (P>.05). In the EC group, glazing provided statistically different results as compared to the manual polishing and control groups (P<.05). Among the ceramic groups, color change values of the subgroup, which was treated by glazing, of the zirconia-reinforced lithium silicate (VS) and lithium disilicate (EC) samples were below the clinically acceptable level (ΔE < 3.5).CONCLUSIONThe lowest color change for all stages was observed in Vita Suprinity.

Monobloco – cimentação de pino e preenchimento em único passo em dente tratado endodonticamente

The literature reports several materials for the restoration of endodontically treated teeth, with coronal destruction that requires an intra-root fiber post to stabilize the prosthetic part. The intra-radicular post of composite resin reinforced with fiberglass can be used as retainers in rehabilitating endodontically treated teeth due to their adhesiveness, pleasing aesthetics, and elasticity module close to the dentin less wear on the remaining structure. This clinical case reports the step-by-step application of dual resin cement (Rebilda DC Dentine - Voco) used as the cementation material of the post and material for the filling core in a single step, in an upper right lateral incisor. Moreover, it describes the advantages and indications of the post-and-core technique, also called “monobloc” which can be used in both anterior and posterior teeth. This protocol minimizes the adhesive interfaces, the chair time, and the steps of the clinical procedure.

Experience in the Application of Jet Cementation for Arrangement of Anti-Filtration Curtains in Rocky Soils

Experience in the Application of Jet Cementation for Arrangement of Anti-Filtration Curtains in Rocky Soils

Application of micro expansion cement in Pavement Base

Cement stabilized macadam base is widely used as a road building material in various grades of highways. Based on the law that the base cracking is mainly affected by the shrinkage of cement stabilization materials, this paper introduces the method of adding micro-expanding cement to the base that can effectively reduce the hydration shrinkage coefficient and dryness shrink factor. At the same time, it is pointed out that strict control of the amount of micro-expansion cement and the quality of the construction can also effectively reduce the occurrence of cracks in the base.

High-temperature mechanical properties of calcium sulfate whisker-reinforced high-alumina cement

Brittleness and low flexural or tensile strength limit the applications of calcium aluminate cement (CAC)-based composites in high-temperature oil or gas well cementing. The reinforcement of the CAC with whiskers substantially enhances its strength and toughness and is a sophisticated approach to overcome the mechanical limitations of the CAC. In this study, the effect of calcium sulfate whiskers (CSWs) on the mechanical properties of the CAC-based composites was investigated; six cement specimens, with whisker contents of 0–5%, were prepared and tested. The results exhibited an improvement in the compressive and tensile strengths and the toughness of the whisker-reinforced samples over the control samples. The compressive strength of the samples cured at 50°C and then subjected to high temperature (500°C) increased by 25·93% at 14 d and the tensile strength increased by 93·63% with the addition of 4% CSW to the cement. The cement slurry properties were stable when 0–5% of CSWs was added. Finally, X-ray diffraction and scanning electron microscopy were used to determine the phase compositions and micromorphology of the cement composites. The results indicated that the CSWs improved the toughness of the cement binders by forming a stable phase and deflecting cracks in the cement matrix.

Towards a clean environment: The potential application of eco-friendly magnesia-silicate cement in CO2 sequestration

Abstract The key point of this study is the fabrication of magnesia-based cement with promising mechanical properties and high efficiency of CO2-capture. The naturally occurring volcanic ashes (white & red ashes) and reactive magnesium oxide are the main materials used in the synthesis of eco-friendly CO2-capture materials. Volcanic ashes were individually mixed with reactive magnesium oxide at ash to magnesium oxide ratio of 25:75 wt %. The dry blends can react with water to yield hardened materials (at ambient temperature) with compressive strength depends on the type of volcanic ash. A considerable change in the features of the hardened samples was recorded when the fabricated materials exposed to 100% CO2 gas for 28-days. This change is mainly due to CO2-capture by magnesium hydroxide Mg(OH)2 within the fabricated materials, resulting in the formation of Nesquehonite minerals MgCO3.3H2O as proved by X-ray diffraction, thermo-gravimetric, and infra-red instrumental techniques. The thermo-gravimetric analysis demonstrates that, the fabricated sample containing low amorphous red ashes has higher CO2-capture capacity (∼260 kg/ton) compared to that having high amorphous white volcanic ashes (∼220 kg/ton) at 28-days of CO2-exposure. Accordingly, the fabricated magnesia-based cement is not only used as cementitious material with outstanding mechanical properties, but also used as a super CO2-absorbent precursor. This can strongly contribute in the mitigation of global warming potential caused by different industrial activities.

Comparative analysis of the effect of tricalcium silicate cement and mineral trioxide aggregate on the cellular composition of the pulp after the vital amputation in experimental animals.

The purpose of the study was to determine the effect of tricalcium silicate cement on the protective process of pulp in the treatment of reversible pulpitis. There was carried out an experiment on 3-month-old male rabbits to study morphofunctional changes in the pulp tissue with modeling of reversible pulpitis followed by vital amputation with coating of the pulp with tricalcium silicate (8 animals, study group) and mineral trioxide aggregate (MTA) (8 animals, comparison group). In 2 and 6 weeks dental tissues were fixed by 10% formalin solution and after decalcification and done routine procedures, histological sections were made, stained with hematoxylin and eosin. After the application of tricalcium silicate cement in 2 weeks, the odontoblast density changed to 3.92±1.03×103/mm2 from 8.3±1.02×103/mm2 of cell density in the intact group. The number of neutrophils also plays a big role in the regeneration of inflamed pulp. Thus, in 2 weeks the number of neutrophils made up 6.39±2.61x102 per 1 mm2, which is 3 times less than after mineral trioxide aggregate usage – 19.49±2.85x102per 1 mm2. It was established that the processes of rheological disorders with impaired lymph circulation are replaced by the restoration of the cellular component. In such a way the proposed vital amputation was examined for reversible pulpitis and it revealed similar clinical and pathological effectiveness with a positive regenerative process with formation of a sufficient number of odontoblasts (7.98±1.51×103/mm2) for the subsequent formation of a hard tissue bridge, which consists of collagen fibers in the form of a frame. The main goal of vital amputation procedure is regeneration (proliferation) of the pulp with a short-term signs of alteration and exudation, which is provided by the choice of material for the pulp covering. Thus, after the vital amputation of the pulp, followed by the use of tricalcium silicate cement 6 weeks after, the number of neutrophils was 1.39±0.72x102per 1 mm2, which is 5 times less than after using mineral trioxide aggregate.

Application of BMP-Bone Cement and FGF-Gel on Periodontal Tissue Regeneration in Nonhuman Primates.

The ultimate challenge of tissue engineering research is the translation of experimental knowledge into clinical application. In the preclinical testing phase of any new therapy, animal models remain the gold standard. Therefore, the methodological choice of a suitable model is critical to meet the requirements for a safe clinical application of the developed treatment. For instance, we have shown in rats that the application of calcium phosphate cement (CPC)/propylene glycol alginate (PGA) with bone morphogenetic protein (BMP)-2 or fibroblast growth factor (FGF)-2 resulted in the regeneration of periodontal defects. However, it is debated whether using small models form a predictive method for translation to larger species. At the same time, the 3R framework is encouraged as guiding principles of the ethical use of animal testing. Therefore, based on the successful rat study, the objective of this study was to further investigate the periodontal regenerative efficacy of the CPC/BMP and PGA/FGF system in a periodontal defect model with a low number of nonhuman primates (NHPs). Three Macaca fascicularis-overstocked from breeding for other purposes-were used (reuse of animals and appropriateness of the experimental animal species according to 3R framework). Three-wall periodontal defects were surgically created in the mandible. In total, 10 defects were created and distributed over two groups: (1) control group: PGA+CPC (n = 5) and (2) experimental group: PGA/FGF+CPC/BMP (n = 5). After 3 months, tissue regeneration was evaluated by histomorphometry and radiographic measurements. Data showed that epithelial downgrowth, cementum, and ligament regeneration were significantly enhanced in the experimental group compared with the control group (n = 5; p = 0.013, p = 0.028, and p = 0.018, respectively). However, the amount of newly formed bone did not differ (p = 0.146). Overall, as a translational proof-of-principle study, the hybrid periodontal regenerative method of CPC/BMP+PGA/FGF promoted periodontal regeneration in NHPs. This study warrants the application of CPC/BMP/PGA/FGF in clinical trials. Impact Statement This study validated an earlier successful periodontal regeneration strategy from a rat model into a few spare nonhuman primates (NHPs). The hybrid periodontal regenerative method of calcium phosphate cement (CPC)/bone morphogenetic protein (BMP)-2/propylene glycol alginate (PGA)/fibroblast growth factor (FGF)-2 promoted periodontal regeneration in NHPs, which corroborated the previous rat results. This translational approach was a very practical option and thus reduced the number and species of experimental animals in translational research. These results found in NHPs indicate a consistent conclusion with the earlier findings in the rat model. It further warrants the application of CPC/BMP-2+PGA/FGF-2 in human clinical trials.

Alkali-activated Portland cement with adjustable proper deformations for anchoring application

The application of alkali-activated Portland cement (hereinafter AAPC) for anchoring grouts was investigated with obtaining of non-shrinking high performance cementing systems. The AAPC system “ordinary Portland cement clinker – sodium metasilicate” was modified by the complexes of mineral and organic compounds to ensure specified properties of anchoring grouts. It was revealed that the most effective multifunctional additives are represented by the system “salt-electrolyte – surfactant”. Alongside with slowing down of AAPC paste setting time, the effect of compensated shrinkage of AAPC mortar, i.e. expansion within 0.062 mm/m and slight shrinkage within 0.017 mm/m, was ensured when Na2SO4 and NaNO3 were used in the mentioned system respectively. The effect of compensated shrinkage is explained by greater crystallization of hydrosilicates and hydroaluminates, additional formation of sulfate-containing sodium-calcium hydroaluminate (for Na2SO4-based system) and crystalline calcium hydronitroaluminate (for NaNO3-based system). The advantages of the modified AAPC for anchoring application are indicated in the paper.

Study of service properties of alkali-activated cement using wastewater treatment residues

The paper discloses the results of the study of treatment of galvanic wastewater residues by incorporation into the alkali-activated cement matrix. Leaching of heavy metals from the artificial stone was studied. It is set that immobilization level of the matrix is 99.96 % by mass of heavy metal (97.83 using traditional methods). Application of alkali-activated cement makes it possible to obtain compressive strength of compound up to 40 MPa even when 30 % of wastewater residues are involved. Immobilization level of alkali-activated cement matrix met requirements of the standard.