Curing Mode Research Articles

Research on Weibull Distribution Theory for Cubic Compressive Strength Test Method of Raw Earth Materials with Different Curing Methods and Time

Cube compressive strength of raw-soil based mater is an important index of mechanical property. Because the test results vary by different curing modes and trial curing time, compressive strength test on 160 cubic raw-soil test-pieces which were made by 4 curing modes (natural curing, indoor curing, indoor+ preservative film curing, curing in standard curing chamber) and 4 Curing period (4d, 14d, 21d, 28d) was designed.In this study,the failure mechanism, failure mode, force mechanism of test were analyzed.Using Weibull distribution theory, the influence of different environmental factors on material strength is discussed.The research revealed that the different curing methods and curing time had remarkable effect on failure mode of material, but the load displacement curves had not affected. The compressive strength with 21d and 28d ‘s indoor curing and standard curing method were same in the test.The strength of raw soil increases with time, and the curing temperature had a significant effect on the early strength of raw soil materials, but had little effect on the later strength. The humidity had a great influence on the later growth of material strength. Constant temperature and humidity could effectively ensure the full response of internal water loss hardening of raw soil-based materials, and the strength of specimens increases obviously.The recommended curing mode and standard curing time for standard test of raw-soil test-pieces were temperature of 25-30oC, humidity of 50%-55%, and 28day, respectively.

Optimization of the curing modes of three-layer honeycomb panels

In this paper, a method of determining rational regimes of the process of curing structures made of polymer composite materials and honeycomb filler was developed. The subject of the study was a three-layer panel where the top and bottom layers were made from carbon fiber, while the honeycomb filler was made from aluminum foil. The filler was bonded to the top and bottom layers with epoxy film adhesive. Using numerical simulation, temperature state, curing degree, and heat generation rate of all the elements of the three-layer panel were determined. The simulations revealed that the process of curing the considered honeycomb structure was uneven due to uneven temperature distribution. The optimal process modes ensuring the gradients of the degree of cure were established.

Effect of polyvinyl alcohol fiber on the cracking risk of high strength concrete under uniaxial restrained condition at early age

Fiber materials with toughening effect can enhance the tensile strength of concrete, reduce shrinkage, and decrease the possibility of concrete cracking. Despite substantial previous researches, the effect of polyvinyl alcohol fiber (PVAF) on the cracking risk of high strength concrete (HSC) under the uniaxial restrained condition and adiabatic curing mode is hardly investigated. Accordingly, the early-age temperature, autogenous shrinkage (AS), creep, and restrained stress of concrete reinforced with different volume fractions of PVAF (0%, 0.2%, 0.4%, and 0.6% of concrete by volume, respectively) under the uniaxial restrained condition and adiabatic curing mode were further investigated in the current research. The cracking risk of HSC reinforced with different volume fractions of PVAF was estimated based on the test results. The AS decreased, while the temperature drop, cracking age, cracking stress, and cracking stress/axial tensile strength of HSC increased with increasing PVAF volume fraction. The incorporation of PVAF increased the early-age compressive creep and tensile creep of HSC. The cracking risk of HSC estimated by the stress reserve or integrated criterion decreased with increasing PVAF volume fraction.

Effects of curing cycles on developing strength and microstructure of goethite-rich aluminosilicate (corroded laterite) based geopolymer composites

The present work carried out the influence of curing cycles on the performance of laterite-based geopolymer composites. To do so, the end products were obtained by altering laterite with 15, 20, and 25 wt% of rice husk ash (RHA). Alkaline solution in a constant solid/liquid ratio of 0.35 was added together with fine and coarse aggregates (representing equal and double weight of laterite, respectively). The different obtained matrices were treated in the following three curing cycles before characterization: room temperature curing (RTC), oven curing at 80 °C (OTC) and controlled humidity steam curing at 80 °C (STC). The mechanical tests carried out at 28 days give the following maximum values for each curing mode: 16.40, 28.82 and 56.41 MPa for RTC, OTC, and STC modes respectively. This means that when the samples, submitted in a moisture-controlled environment, the end products are more stable, less porous and resistant. Regarding the physical properties, the results show that the maximum value of open porosity is 11.62% corresponding to a matrix that was cured at room temperature without rice husk ash added, while the minimum value of 7% corresponds to a matrix that was cured under controlled humidity and containing 20% rice husk ash. The optimum and minimum absorption values are 2.70 and 4.60% respectively for the OTC and RTC curing modes. As for bulk densities, the optimum value is 2.64 g cm−3 for the matrix having 15% rice husk ash and the minimum value is 2.33 g cm−3 for a matrix having 20% rice husk ash, for OTC and STC curing modes respectively. The appropriate curing type for laterite-based geopolymer is when the humidity is controlled.

Physics-mechanical and viscoelastic properties of polymer compositions based on synthetic oligomer ED-20 and epoxidized soybean oil

The work was aimed at studying the effects of combining epoxidized soybean oil (ESO) with standard bisphenol type A epoxy resin (ED-20). The ED-20 / ESO ratios were 100/0, 90/10, 95/15 and 80/20 (wt%). The system was cured with amine hardener mono(cyanethyl) diethylenetriamine (MCDT), triethanolamine (TEA) and mixture thereof (TEA + MCDT) at different curing temperatures. The choice was based on the hardener’s ability to open oxirane cycles, form a spatial network and initiate several parallel reactions. The viscoelastic properties, mechanical properties (tensile strength and elongation) were studied the density of obtained ED-20 / ESO samples was determined. The results showed that the introduction of ESO into epoxy resin ED-20 was accompanied by significant changes in the curing and final properties of the samples. It was shown that the physic- mechanical properties of polymer compositions ED-20 / ESO were determined by both the ESO content and the temperature of curing Depending on the selected curing mode, the addition of 5–10 wt.% of ESO increased the tensile strength relative to the σр value of the original epoxy matrix. The values of relative elongation increased significantly at 15-20 wt.% of ESO. By the method of dynamic mechanical analysis it was shown that the increase of ESO content leads to plasticization of epoxy composition and to reduction of crosslinking density. It was determined that 5-10 wt.% was the optimal concentration of ESO, at which the epoxy composition had improved physical and mechanical properties Further increase of ESO content reduced the crosslinking density and increased the defectiveness of the epoxy polymer, which causes premature failure in weak places of the structure under load.

Energy-saving technology of production of elements of building structures from polymer materials

Problem statement. At present, the increase in the efficiency of the technology for the production of composite structural elements is associated with high energy costs. In this regard, the implementation of ways to optimize the parameters of the technological process of manufacturing polymer composite materials is of great importance. The purpose of the article is to optimize the modes of impregnation and curing of thermosetting binders and polymer composite materials based on them in combination with the kinetics of gas evolution and control of all stages of the technological process. Results. An energy-saving technology for molding composite structural elements of buildings and structures has been developed, which provides a reduction in the duration of the curing process of polymer materials, depending on the type of binder. The technology makes it possible to control the speed and degree of curing of a thermosetting binder by changing the tangent of the dielectric loss angle and electrical conductivity. Scientific novelty and practical significance. The approach and the electrophysical method for optimizing the modes of impregnation and curing of composite products in combination with the control of all stages of the technological process have been further developed in relation to the elements of composite structures. The permissible values of the curing parameters have been established according to the optimized mode of a number of thermosetting binders: heating rates, isotherm temperatures, and holding time at them. At the same time, the achieved optimal curing times for binders BFOS, LBS-4, ENFB, 5-211B using the new technology is 2.4; 1.8; 3.0; 2.3; 2.0 and 1.2 times less than according to known technologies. The results obtained guarantee the quality of the resulting composite product and are recommended for accelerating the curing process of polymer materials.
 Keywords: optimization; technological regime; impregnation; curing; thermosetting binders; gas evolution; stage control

Rubberized geopolymer composites: Effect of filler surface treatment

Existing waste tire management strategies such as landfill, warehousing, incineration, and pyrolysis are associated with significant emissions of hazardous compounds including gases, heavy metals, and oils. A sustainable rubber waste disposal strategy is immobilizing them in a crushed form in eco-friendly geopolymer (GP) matrices. However, the implementation of this approach is constrained by the strength degradation of rubberized geopolymer composites. In order to solve this problem, this article includes a comparative investigation of the effect of various physical and chemical pre-treatments of tire crumb rubber (CR) with NaOH, H2SO4, (CH3)2CO and KMnO₄ solutions, as well as ultraviolet radiation, on the mechanical performances and microstructure of rubberized fly ash-based GP composites. It has been established that the best effects are demonstrated by treatment with an aqueous solution of potassium permanganate; oxidative reactions with the solution lead to the formation of surface-active functional groups on the rubber. As a result, there is more than a twofold increase in the hydrophilicity of CR particles, estimated from the mass of adsorbed water vapor (from 1.5 to 3.3 wt%). This provides a strong adhesive contact of the filler with the geopolymer matrix, which favorably affects the change in the mechanical properties of the composites. The compressive strength in this case has been increased from 12.8 MPa (GP/untreated CR composite) to 15.5 MPa at addition of 10.0 wt% KMnO4 treated CR. Further optimization of the composition and of the curing mode of the geopolymer binder can potentially provide an additional positive effect in this aspect.

Optimization of Photopolymerization Process of Dental Composites

The aim of this paper is to perform optimization of photopolymerization process of dental composites in order to obtain maximum hardness. Samples (5 mm diameter; 2, 3 and 4 mm thickness) were made of Universal Composite (UC), Bulk fill Composite (BC) and Flowable Composite (FC). Light curing of specimens was performed with 600, 1000 and 1500 mW/cm2 light intensity and an irradiation time of 20, 40 and 60 s. Vickers microhardness on the top and bottom surfaces of samples was measured. Optimization was carried out via regression analysis using QStatLab software. Photopolymerization process parameters were calculated using a specially designed MatLab software-based algorithm. For all composites, regression models for hardness on top and bottom surfaces of composite layer were established. Layer thickness as well as hardness on top and bottom surfaces of each composite was calculated for 21 curing modes varying with light intensity and irradiation time. It was established that photopolymerization guidelines only of FC manufacturer guarantee the required hardness, while recommended regimes for UC and BC did not satisfy this requirement. Tables, containing recommended light curing regimes, were developed for three composite types, guaranteeing high hardness of composite restoration. They were designed to facilitate work of dentists in dental offices.

Predicting transmitted irradiance through CAD/CAM resin composite crowns in a simulated clinical model

ObjectiveTo predict the clinically relevant transmitted irradiance that is available for luting when a CAD/CAM restoration is inserted. The influence of irradiance, exposure distance, light curing unit (LCU) angulation and direction of polymerization is analyzed when curing through crowns of different thicknesses. MethodsThree modern CAD/CAM resin-based composites (RBCs) were used to produce 45 crown-shaped specimens. The distance between fissure and crown base was set at 1.0, 1.5 and 2.0 mm (n = 5). Transmitted irradiance, while using a violet-blue LCU, was measured with a photo-spectrometer. 180 exposure conditions per specimen were investigated by variation in LCU curing mode, angulation, exposure distance and direction. Data was analyzed using univariate ANOVA followed by Tukey HSD (α = 0.05) and comparison of 95% confidence intervals. ResultsThe CAD/CAM-RBC’s decadic absorption coefficient ranges from 0.317 mm−1 to 0.387 mm−1 and the reflection correcting factor for crowns ranges from 0.305 to 0.337. Transmitted irradiance decreases significantly with increasing exposure distance and decreasing incident irradiance. For tilt angles greater than 10°, transmitted irradiances are significantly reduced (−11% for 20°, −23% for 30°). Significantly lowest transmitted irradiances were measured for vestibular curing direction (up to −15%). SignificanceA calculation model can predict the transmitted irradiance through a CAD/CAM restoration in dependence of restoration thickness and radiant emittance. The practitioner can be supported by this model to adapt material choice of dental restoration and adhesive system to the individual situation. Variation in exposure conditions shows negative effect on the transmission of light and should be limited.

Repair Bond Strength of High-viscosity Glass-ionomer Cements Using Resin Composite Bonded with Light- and Self-cured Adhesive Systems.

High-viscosity glass-ionomer cements (HVGICs) used with atraumatic restorative treatment can be repaired with light- or self-cured adhesive systems; however, the repair bond strength of two-step, self-etching and one-step adhesives in the light-cure mode surpass one-step self-cure adhesives. Working on a feasible self-cure approach in the absence of such in rural areas as well as in war zones is of prime importance.

Debonding of lithium Disilicate and Felspathic Veneers with Er, Cr: YSGG laser bonded with two different curing mode resin cement.

Debonding of lithium Disilicate and Felspathic Veneers with Er, Cr: YSGG laser bonded with two different curing mode resin cement.

Mechanical and microstructural characteristics of geopolymer paste, mortar, and concrete containing local zeolite and slag activated by sodium carbonate

In this paper, the mechanical properties of geopolymer paste, mortar, and concrete containing activated zeolite and ground granulated blast-furnace slag (GGBS) were investigated and compared with those of Portland cement. Moreover, the microstructural results of the effective parameters in geopolymer paste were evaluated. Sixteen mix designs of geopolymer paste and mortar (containing only sand) and concrete (containing sand and gravel), along with corresponding specimens made with ordinary cement, were considered with two modes of curing. The test results demonstrated that the compressive strength of geopolymer mortar after 7 and 28 days was 48 and 58% higher than that of ordinary mortar. The compressive strength of geopolymer concrete at the ages of 7 and 28 days increased by 30 and 25%, compared to the ordinary cement concrete. The average 28-day tensile strength of geopolymer mortar and concrete also grew by almost equal, compared to the specimens made with ordinary cement. Furthermore, the flexural strength of geopolymer paste, mortar, and concrete at the age of 28 days grew by 25, 2, and 18%, compared to the specimens made with ordinary cement. The results of SEM images indicated that due to the presence of more raw chemical materials in the specimens with higher strengths, the hardened geopolymer gel had a dense, coherent, and crack-free structure. Moreover, the XRD results showed the presence of C–S–H gel as a binder in the mixes, calcite, hydrotalcite, and gaylussite phases. Therefore, the geopolymer has the great potential to be used as the primary substitute for cement in civil engineering projects.

Tensile Creep Model of Slab Concrete Based on Microprestress-Solidification Theory.

Tensile creep is an important factor affecting the early cracking resistance of concrete. The tensile creep model can effectively predict the development of tensile creep. In order to establish an appropriate tensile creep model, a temperature–stress testing machine (TSTM) was employed to test the development of temperature, deformation and restraint stress of benchmark concrete and concrete mixed with the MgO under different temperature curing modes. The development law of early age stress, strain and creep was analyzed via the test data of the TSTM. The early age tensile creep of concrete was predicted with the existing Kelvin creep model. The effect of variable temperature on creep was considered in this study, and an improved Kelvin creep model was proposed. The prediction accuracy of the two models was compared and analyzed. The results indicate that MgO has little influence on the creep and specific creep of concrete. The early age cracking resistance of MgO concrete is better than benchmark concrete. The improved Kelvin model based on the microprestress-solidification (MPS) theory predicts the early tensile creep of concrete more accurately in variable temperature conditions. These are significantly helpful for the application of the MgO expansion agent in dam engineering.

Adhesion strategy and curing mode of a universal adhesive influence the bonding of dual-cured core build-up resin composite to dentin

To evaluate the influence of different adhesion strategies and curing modes of a universal adhesive on shear bond strength (SBS) of a dual-cured core build-up resin composite to bovine dentin. In total, 60 bovine anterior permanent teeth were randomly divided into 6 groups (n = 10/group) according to; 1: Adhesion strategy, 3 groups (self-etching, etch-and-rinse/wet and etch-and-rinse/dry) and 2: Curing mode, 2 groups (light-curing and dual-curing). Subsequent to root and incisal half removal of each tooth, labial enamel was wet ground over #180 SiC papers, and exposed dentin surface was wet ground over #600 SiC paper for 60 s to create a standardized smear layer. Universal adhesive was applied according to its manufacturer instructions and each tooth was then restored with one dual-cured composite cylinder (2mm×2mm). Shear bond strength was run at a crosshead speed of 0.5 mm/min, and failure modes were categorized into: 1- Adhesive, 2- Mixed and 3- Cohesive failures. Statistical analysis was performed using Two-Way ANOVA/Tukey HSD test. The results showed that factor ‘adhesion strategy’ had no statistically significant effect on SBS (p = 0.525). However, factors ‘curing mode’ and ‘adhesion strategy x curing mode’ showed statistically significant effect on SBS (p = 0.020 and p = 0.002 respectively). Mixed failure represented 55%, followed by adhesive failure (43.3%) and the cohesive failure represented 1.7%. It seemed better to apply the universal adhesive used in this study in etch-and-rinse strategy rather than self-etching one, especially when the adhesive was used in light-curing mode. The use of the DC activator seemed to be unnecessary.

РЕГУЛИРОВАНИЕ СВОЙСТВ ЭПОКСИДНЫХ ПОЛИМЕРОВ НА ОСНОВЕ ДИФЕНИЛОЛМЕТАНА С ПОМОЩЬЮ ОЛИГОБУТАДИЕНОВОГО КАУЧУКА С КОНЦЕВЫМИ КАРБОКСИЛЬНЫМИ ГРУППАМИ

The influence of modifying additives of oligobutadiene rubber with terminal carboxyl groups of the SKD-KTR brand on the deformation-strength and adhesive properties of epoxy polymers based on the EDFM-19 product, which is a diglycidyl ether of diphenylolmethane, is studied in a wide range of concentrations. The compositions are cured with triethylentetramine methylphenol UP-583T and triethylentetramine THETA without heat supply from the outside and when heated to a temperature of 120°C. It is found that with increasing rubber concentration, the tensile strength and elastic modulus indicators monotonously decrease, especially intensively when the modifier content is up to 15 mass parts. The dependence of the glass transition temperature and adhesion strength on the amount of introduced rubber is extreme. In the range of modifier concentrations from 5 to 15 parts by weight peaks are observed, the position of which depends on the chemical nature of the hardener of the epoxy resin and the curing mode of the composition. The deformation at break increases monotonously with the increase in the elastomer content, most rapidly in the range of modifier concentrations of 5-25 mass parts. The effect is shown both for samples cured at room temperature and heat-treated compositions. Due to a significant increase in the ability of the sample to develop deformation, despite the decrease in the strength parameter, the work of destruction of modified samples increases significantly. It contributes to improving the performance of composites modified by SKD-KTR rubber under the action of shock and vibration loads.

A new approach to estimate the curing mode of thermosetting polymer films with regard to physical aging and slow chemical processes

AbstractWe propose an original method to determine the temperature and time required for additional curing of physically aged partially cured glass‐shaped systems, based on the example of epoxy amine systems. The approach consists of the plotting of temperature–time–transformation (TTT) diagrams, supplemented with lines, which illustrate the shift in glass transition temperature (Tg) as a result of the processes of physical aging (enthalpy relaxation) and with isoconversion curves. Then we should determine Tg of partially cured and aged sample at a certain temperature. Having known this Tg value, the position of the isoconversion curve at a given point and Tg,∞ as well, we can determine the postcuring time at T = Tg,∞ + 5 K. Thus, the method provides information about the temperatures and the duration of these two consecutive steps. The TTT diagrams are based on experimental results obtained by differential scanning calorimetry in dynamic mode with preliminary heated samples in an external thermostat. The proposed approach based on epoxy amine systems allows the prediction of the optimal curing mode for thermosetting systems to provide the highest degree of cure. Our method is applicable to a wide range of thermosetting polymer systems that complete transition to a glassy state before full conversion is achieved.

Effect of dispensing method and curing modes on the microleakage of composite resins

Background: Vibration decreases the viscosity of composite, making it flow and readily fit the walls of the cavity. This study is initiated to see how this improved adaptation of the composite resin to the cavity walls will affect microleakage using different curing modes
 Materials and methods: Standard Class V cavities were prepared on the buccal surface of sixty extracted premolars. Teeth were randomly assigned into two groups (n=30) according to the composite condensation (vibration and conventional) technique, then subdivided into three subgroups (n=10) according to light curing modes (LED-Ramp, LED-Fast and Halogen Continuous modes). Cavities were etched and bonded with Single Bond Universal then restored with Filtek® Z350 (3M ESPE, USA). In the vibration group, condensation was done using CompothixoTM (Kerr, Switzerland). In the conventional group, condensation was done with hand plugger. Curing modes for all groups were LED-Ramp, LED-Fast and halogen continuous modes, respectively. Samples stored in distilled water at 37°C for seven days, and painted completely with two layers of nail varnish with only 1 mm around the composite restoration left. Samples were thermocycled, immersed in 2% methylene blue solution for 3 hours, and sectioned longitudinally. Dye penetration was assessed under a stereomicroscope. Data were analyzed by Kruskal-Wallis and Mann-Whitney U tests with p <0.05 considered significant.
 Results: Vibration group showed less microleakage (P=0.028). In the conventional group there were no differences by using different curing modes (P=0.277). In the vibration group no differences were found between LED-Ramp and LED-Fast mode (P=0.989). However, there were significant differences between LED-Fast and halogen (P=0.05) and between LED-Ramp and halogen group (P=0.001). Microleakage scores of all cervical walls were higher than the occlusal walls (P=0.001). Occlusal walls leakage for conventional and vibration groups were not different (P=0.475), while there were significant differences between them at cervical walls (P=0.001).
 Conclusion: Vibration with LED-Ramp curing mode may decrease marginal leakage of composite restoration placed in Standard Class V tooth preparations.
 Keywords: Composite resin, Vibration, Condensation, Compothixo, Microleakage,

Microstructural Properties of Alkali-Activated Metakaolin and Bottom Ash Geopolymer

This paper presents a study on the use of alkali-activated metakaolin (MK) and Bottom Ash (BA) blend in geopolymer concrete. A preliminary attempt was made on alkali-activated metakaolin and bottom ash-based geopolymer (MK–BA-GPM) mortar with river sand as fine aggregate to find a suitable mix to produce geopolymer concrete (GPC). The liquid alkaline activator is a combination of sodium silicate and sodium hydroxide solution. The molarity of NaOH was 8 M. Molar ratio of Na2O and SiO2 was 2, and ambient curing mode was selected. Also, M30 grade control concrete was made using OPC and cured in water. Further, GPC and control concrete specimens were tested for compressive strength, split tensile, flexural strength and modulus of elasticity. Also, XRD, SEM and EDAX studies were carried out to analyse element/mineral compounds present and the microstructure and morphological characteristics of GPC to substantiate the strength development. MK–BA GPC demonstrated 49% higher compressive strength than that of control concrete at 28 days. More so, the early as well as later strength gain of GPC was remarkably higher than that of OPC. Strength was due to densification of microstructure over a period of time and due to the formation of additional crystalline phases in geopolymer concrete.

Effect of Shortened Light-Curing Modes on Bulk-Fill Resin Composites.

Shortened light curing does not affect volumetric polymerization shrinkage or cohesive tensile strength but negatively affects the shear bond strength of some bulk-fill resin composites. When performing shortened light curing, clinicians should be aware of the light output of their light-curing units. Purpose: To evaluate volumetric polymerization shrinkage (VPS), shear bond strength (SBS) to dentin, and cohesive tensile strength (CTS) of bulk-fill resin composites (BFRCs) light activated by different modes.Methods and Materials: Six groups were evaluated: Tetric EvoCeram bulk fill + high mode (10 seconds; TEC H10), Tetric EvoFlow bulk fill + high mode (TEF H10), experimental bulk fill + high mode (TEE H10), Tetric EvoCeram bulk fill + turbo mode (five seconds; TEC T5), Tetric EvoFlow bulk fill + turbo mode (TEF T5), and experimental bulk fill + turbo mode (TEE T5). Bluephase Style 20i and Adhese Universal Vivapen were used for all groups. All BFRC samples were built up on human molar bur-prepared occlusal cavities. VPS% and location were evaluated through micro-computed tomography. SBS and CTS tests were performed 24 hours after storage or after 5000 thermal cycles; fracture mode was analyzed for SBS.Results: Both TEC H10 and TEE H10 presented lower VPS% than TEF H10. However, no significant differences were observed with the turbo-curing mode. No differences were observed for the same BFRC within curing modes. Occlusal shrinkage was mostly observed. Regarding SBS, thermal cycling (TC) affected all groups. Without TC, all groups showed higher SBS values for high mode than turbo mode, while with TC, only TEC showed decreased SBS from high mode to turbo modes; modes of fracture were predominantly adhesive. For CTS, TC affected all groups except TEE H10. In general, no differences were observed between groups when comparing the curing modes.Conclusions: Increased light output with a shortened curing time did not jeopardize the VPS and SBS properties of the BFRCs, although a decreased SBS was observed in some groups. TEE generally showed similar or improved values for the tested properties in a shortened light-curing time. The VPS was mostly affected by the materials tested, whereas the SBS was affected by the materials, curing modes, and TC. The CTS was not affected by the curing modes.

Composite Cements with Mineral Additives of Intrusive and Metamorphic Rocks of Central Aldan (Yakutia)

The creation of new compositions with mineral additives requires fundamental research of the chemical activity of mineral additives. As an active mineral additive used waste production of chromdiopside and phlogopite –dunite and diopside Aldan region (Yakutia). The use of overburden reduces the cost of production of building materials and improves the environmental situation in the region. The obtained dependence of the strength developed in cements, their composition, preparation of the raw mix, modes of curing and keeping maturing. For the first time, using a set of technological approaches including pre-annealing, mechanical activation and autoclave synthesis, a high-strength composite cement with additives of magnesium silicates exceeding the strength of Portland cement by 56.8% was obtained. In our previous experiments, the introduction of up to 40% diopside in Portland cement did not increase the strength of the cement stone due to the chemical inertness of the additive. Magnesium chloride - MgCl2 was used for mixing in order to activate hydration. It is shown that the high rate of formation of the solid phase during the closure with magnesium chloride leads to the development of stresses and strains leading to a decrease in strength in the later stages of hardening. The optimal technological approach is water mixing and autoclave synthesis. Possible consumers can be cement plants, enterprises for the production of building materials, representatives of medium and small businesses, as well as enterprises of the mining industry interested in the disposal of waste production.