Curing Conditions Research Articles

Study on the improvement of grouting stone properties in coal mine goafs using combined denitrifying bacteria.

Grouting can effectively reduce residual deformation of coal mine goafs, but fly ash grouting materials suffer from poor flowability and slow early strength development. Microbially -induced calcite precipitation (MICP), with its high environmental compatibility and minimal disturbance to geotechnical bodies, effectively improves the injectability of grouting slurry in goafs. This study combined Castellaniella denitrificans and Sporosarcina pasteurii to induce calcite precipitation, preparing cement-fly ash slurry with varying water-solid ratios, solid ratios and denitrifying bacteria concentrations. The physical properties of the slurry and the mechanical properties of the grouted stone bodies under sealed curing conditions were measured. Results show that the dual-bacteria MICP improves stone body performance by enhancing cohesive, frictional and interlocking forces, so that the strength of the stone bodies cured by MICP increased rapidly within 7 days, and the strength reached the standard 2.03 MPa at 28 days under conditions of low solid ratio and high water-solid ratio, with the best compressive strength at a denitrifying bacteria concentration with an optical density of 0.8 at 600 nm wavelength. At a water-solid ratio of 1 : 1.2 and a solid ratio of 15%, initial and final setting times were 67.2 and 96 h, respectively, which prolonged the initial setting time and final setting time by nearly 70% and 110% compared with that of the slurry without MICP treatment, indicating that MICP enhances slurry fluidity, providing more time for grouting construction in goafs.

Multiphysical testing of strength development of cemented paste backfill containing superplasticizer

Current laboratory procedures for curing and testing the mechanical strength of cemented paste backfill (CPB) do not take into account the complex Multiphysics (thermal, T; hydraulic, H; mechanical, M; chemical, C) processes that CPB structures are subjected to in the field. This oversight can lead to unreliable measurements and unsafe designs. In this study, a multiphysical curing and testing procedures for CPB with superplasticizer (CPB-PES) has been developed to evaluate its strength development under THMC curing conditions close to those encountered in the field. The obtained results demonstrated that the strength development of CPB-PES is greatly affected by the THMC factors and their interactions. The contributions of each one of the investigated THMC factors on the strength are not equally similar and greatly depend on the interaction between these factors and curing time. CPB samples with 0.125 % PES that underwent drainage during THMC curing showed a strength increase of up to 809 % after 28 days of curing, compared to the control samples. The strength of CPB-PES samples cured under THMC can be up to 57 % higher than that of samples cured under THC conditions. The results indicate a significant interaction between thermal (T; elevated field curing temperature) and chemical (C; superplasticizer and cement hydration) factors, between chemical (C) and mechanical (M; field curing stress) factors, as well as between thermal and mechanical factors. The influence of the mechanical factor on strength development was observed to be less pronounced compared to the impact of chemical and thermal factor, and is reduced at elevated curing temperatures. The findings underscore the critical importance of accounting for field-relevant THMC factors and their interactions in the determination of the CPB-PES strength development, which is essential for the design of safer and more economical CPB structures, ultimately enhancing mine productivity and safety.

ADDITIVE MANUFACTURING OF SYNTHETIC RUBBER INK WITH HIGH SOLID CONTENT REINFORCED BY NETWORKED SILICA

ABSTRACT Silica is a reinforcing filler commonly used in the production of environmentally friendly tires, because tires reinforced with silica have lower rolling resistance that translates into reduced energy consumption and improved fuel economy. However, achieving the optimal dispersion of silica within the rubber matrix is crucial for maximizing its reinforcing effects. In this study, a three-dimensionally networked silica (NS) was introduced in various amounts to rubber inks to improve their tensile strength and increase miscibility to enable their use in additive manufacturing. The results show that synthetic rubber ink with a high content of SBR (90%) and reinforced by NS possesses adequate viscosity for use in the direct ink write (DIW) process. NS was confirmed to have an impact on the rheological properties and printability of the rubber ink as well as improve the tensile strength of the printed parts. Different formulations were tested to study and facilitate the vulcanization process and identify the optimal curing conditions as well as the print parameters to use in DIW printing. The successful printing and vulcanization of various printed structures demonstrate the potential for using the developed printable ink in additive manufacturing. This study opens up new possibilities for creating rubber products (such as tire treads) with adequate flexibility and high tensile strength.

Performance and mechanism of carbon sequestration of air-entraining wet shotcrete

CO2 curing concrete technology refers to the CO2 reacts with cement clinker minerals to obtain high-performance concrete and achieve the purpose of energy saving and emission reduction. The researches of air entrainment agent (AEA) focus on the development of new AEA and the study of concrete performance after adding some AEA. In the background of CO2 curing concrete technology, there are relatively few researches on the influence mechanism of different characteristics of bubbles introduced by different AEAs on carbon fixation performance of concrete. This paper demonstrates the characteristics of air bubbles introduced by SY-5 AEA (main component: triterpene saponin) and LAS AEA (main component: sodium dodecylbenzene sulfonate), compares the strength of concrete mixed with above two types of AEAs cured for 28 days and analyzed them by carbonization depth test, ultrasonic detection of fissure test, SEM, XRD and TG. Results show that different AEAs introduced different characteristics of air bubbles, which affected the internal pore characteristics of concrete, and then affected its mechanical properties and carbon sequestration properties. Compared with SY-5 AEA, LAS AEA had a slightly lower air-entraining effect. But the bubbles introduced were even and stable, the internal pores of the hardened concrete were uniform. Although the former had a high carbon sequestration, the latter had a higher intensity at 28 d, about 2.69 % higher. Under carbonization curing conditions, the improvement of concrete properties was more evident when appropriate AEAs were incorporated. The compressive strength and the splitting strength were increased by 5.57 % and 4.5 % respectively under the carbonization curing condition.

Evaluation of MSA mortar pore structure characteristics in water-saturated curing environment based on Talbot gradation theory

To investigate the impact of aggregate gradation on the pore structure of manufactured sand aggregate (MSA) mortar and its fractal characteristics under water-saturated curing conditions. The static pore structure characteristics of the pore structure of MSA mortar with 10 aggregate gradations were explored. The analysis is based on the Talbot gradation theory, the NMR technique, and fractal theory. The surface area and roughness of aggregate particles contribute to a reduction in the porosity of MSA mortar. The aggregate gradation is quantified using the Talbot index. The correlation characteristics and intrinsic relationships between Talbot index and different pore structure parameters, such as total porosity, pore gradation, pore fractal dimension and permeability of MSA mortar, are analyzed. Two pore division methods are employed to explore the interrelationships among pore types, fractal dimensions and Talbot index. Additionally, A correlation model between Talbot index and permeability is developed to investigate the intrinsic correlation of parameter variations from a microscopic perspective. It is found that aggregate gradation is optimal with a Talbot index of 0.4, leading to the highest number of micropores and the lowest number of larger pores, thereby enhancing resistance to seepage and dissolution. Furthermore, The contribution of pore size, content and type to permeability varies with different aggregate gradations. Overall, this study serves as a valuable guide for the design and durability evaluation of mortar concrete projects in water-saturated curing environments.

Influence of SU-8 curing parameters on the terahertz absorption characteristics

A plethora of polymers are excellent candidates that can be utilized to build various terahertz (THz) based systems for sensing and microfluidics. SU-8 is a versatile epoxy-based polymer with excellent properties, such as biocompatibility and good mechanical properties. Nevertheless, the impact of curing parameters on the THz absorption characteristics of SU-8 remains uncertain. This study explores the impact of various curing conditions on the THz absorption properties of SU-8. The aim is to establish a correlation between THz absorption and the polymer's cross-linking characteristics. Therefore, three key curing parameters have been examined: time, temperature, and ultraviolet (UV) exposure dose. The SU-8 samples that are cured under different conditions are examined using THz Time-Domain Spectroscopy (THz-TDS) to estimate the THz absorption coefficient. Next, the swelling experiment is conducted to evaluate the polymer cross-linking of the cured samples. The results show that curing conditions and, thus, cross-linking routines significantly influence THz wave propagation and attenuation within SU-8 samples. The findings recommended using an optimal curing dose for SU-8 spanning 1240 mJ/cm2 to 1860 mJ/cm2 which results in a relatively lower absorption coefficient while still maintaining a higher state of cross-linking. This research establishes a crucial link between SU-8 processing and its THz response. It can lay the foundation for tailored SU-8 polymer with optimized THz transmission for novel and customized biosensing and microfluidic devices.

Comprehensive Characterization of Drying Oil Oxidation and Polymerization Using Time-Resolved Infrared Spectroscopy.

Drying oils like linseed oil are composed of multifunctional triglyceride molecules that can cure through three-dimensional free-radical polymerization into complex polymer networks. In the context of oil paint conservation, it is important to understand how factors like paint composition and curing conditions affect the chemistry and network structure of the oil polymer network and subsequently the links between the structure and long-term paint stability. Here, we employed time-resolved ATR-FTIR spectroscopy and comprehensive data analysis to study the curing behavior of five types of drying oil and the effects of curing temperature as well as the presence of a curing catalyst (PbO). Extracted concentration curves of key reactive functional groups point to a phase transition similar to a gel point that is especially pronounced in the presence of PbO, after which curing reactivity slows down dramatically. Analysis of kinetic parameters suggests that PbO induces a network structure with a more heterogeneous cross-link density, and the ATR-FTIR spectra indicate lower levels of oxidation in those cases. Finally, lower temperatures appear to favor the formation of carboxylic acid groups in oil mixtures with PbO.

High-temperature resistance of ceramic sanitaryware waste and fly ash-based geopolymer and hybrid geopolymer mortars produced at ambient curing conditions

In this study, five different hybrid geopolymer mortar mixtures were prepared, incorporating two different geopolymers and low percentages of Portland cement (PC), (16.6 % and 33.3 %). In geopolymer mixtures, 100 % ceramic sanitaryware waste (SW) and 100 % fly ash (FA) were used as precursor materials. In hybrid mixtures, the precursor materials include FA+ PC, SW+PC, and FA+SW+PC. The flexural and compressive strengths of mortars were determined up to 56 days to investigate their strength development. Additionally, the mortars were exposed to elevated temperatures up to 800 °C, separately. After the high-temperature exposure, phase (XRD) and microstructure (SEM/EDS) analyses were conducted on the selected mortars. All the hybrid geopolymers had higher flexural and compressive strengths than the geopolymers for all the curing ages. The highest 28-day flexural and compressive strength values of 5.3 MPa and 37.0 MPa were obtained on the mixture where FA+SW+PC precursors were used in equal amounts, respectively. The geopolymer and hybrid geopolymer mortars (containing 16.6 % PC) performed well under the high-temperature effect up to 800ºC. The strength values of all the mortars were obtained higher at 800ºC than at 600ºC. After high-temperature exposure, additional crystalline phases such as gehlenite were detected in hybrid mortars.

Mechanical and Drying Shrinkage Performance Study of Ultra-High-Performance Concrete Prepared from Titanium Slag under Different Curing Conditions.

This research investigates the effects of various curing regimes, the incorporation of titanium slag, and the utilization of quartz sand on the strength properties and shrinkage behavior of ultra-high-performance concrete (UHPC). By using low-heat silicate cement to prepare UHPC, this study conducted standard curing and steam curing, and comprehensively analyzed the macro and micro performance of UHPC under different curing conditions. The findings indicate that the application of steam curing markedly enhances the mechanical attributes of UHPC while efficiently decreasing its drying shrinkage. In the comparative tests, we found that the compressive strength of concrete that had undergone 2 days of steam curing was 9.15% higher than that of concrete cured for 28 days under standard conditions. In addition, under the same curing conditions, titanium slag sand had higher mechanical properties than quartz sand. Under standard curing conditions, the 28-day compressive strength of UHPC using titaniferous slag aggregate was 12.64% higher than that of UHPC using standard sand. Through the data analysis of XRD, TG, and MIP, we found that the content of Ca(OH)2 in the hydration products after steam curing was reduced compared to the standard curing conditions, and the pore structure had been optimized. The UHPC prepared with titanium slag sand has greater advantages in mechanical properties and drying shrinkage, and has a smaller pore structure than the UHPC prepared with quartz sand. Moreover, the use of titanium slag sand offers ecological and economic benefits, making it a more sustainable and cost-effective option for high-performance construction applications.

Optimization of the curing conditions of PVC plastisols plasticized with ethyl cinnamate

The use of ethyl cinnamate, an ester of cinnamic acid present in many fruits and plants, as a bio-based plasticizer for polyvinyl chloride (PVC) plastisols has been investigated. Different temperatures (180, 190, and 200 °C) and curing times (8, 11.5, and 15 min) have been evaluated for PVC plasticized with 70 phr (parts by weight of plasticizer per one hundred weight parts of PVC resin) of ethyl cinnamate in order to optimize the curing conditions of the material, as these play a fundamental role in determining the final properties. Optimization of curing conditions has been carried out by analyzing the effect of temperature and curing time on the tensile mechanical properties, thermal stability, morphological, color changes, and migration tendency for the different plasticized materials. It has been observed that the optimal curing conditions for PVC plasticized with ethyl cinnamate are achieved at a curing temperature of 190 °C and a curing time of 11.5 min. Under these conditions, a material with high tensile strength, around 6.4 MPa, and a high elongation at break, close to 570 %, is obtained which is comparable or even superior to materials cured in the presence of other conventional plasticizers used in the PVC industry. Additionally, through field emission scanning electron microscopy (FESEM), it has been observed that for these conditions, the curing process is complete, resulting in the complete fusion of PVC microcrystals. A material with high cohesion and very low migration loss, around 2.4 %, is obtained. The effectiveness of these curing conditions has also been demonstrated using thermogravimetry. An increase in the PVC dehydrochlorination temperature has been observed due to optimum plasticizer absorption and gelation.

Investigation and Comparison of Alternative Oxygen Barrier Coatings for Flexible PP Films as Food Packaging Material

One of the EU’s ambitious goals is to ensure all plastic packaging is reusable or recyclable by 2030. However, achieving higher recycling rates, particularly in flexible multilayer food packaging, is challenging due to the combination of diverse materials. This highlights the importance of designing for recyclability and exploring alternative barrier solutions. In this study, several types of coatings, such as ORMOCER® (Fraunhofer-ISC, Würzburg, Germany) Michem® Flex B3513 (Michelman International Belgium SRL, Aubange, Belgium), and PVOH (Kuraray Europe GmbH, Frankfurt am Main, Germany), are applied on different polypropylene substrates, including cast PP (CPP70), SiOx, and AlOx-coated PP films. The effect of double coating and optimized curing conditions of ORMOCER® on the oxygen permeability of CPP70 was also investigated. The results showed significant improvements in the barrier properties of PP/SiOx and OPP/AlOx films, and OTR values less than 0.1 cm3/m2·d·bar were achieved. It was also found that ORMOCER® and Michem® Flex B3513 could enhance the oxygen barrier property of CPP70 and the OTR value reduced by a factor of 88 and 551, respectively.

Synergistic effects of Bacillus subtilis and PET fiber additions on the mechanical properties of Alkali-Activated composite mortars

This study investigates the impact of Bacillus subtilis and PET fiber additions on the mechanical properties of alkali-activated composite mortars (AACMs). Blast furnace slag (BFS) is used as the primary binder, activated by sodium hydroxide (NaOH) and sodium silicate (Na2SiO3). Controlled curing conditions at 20 °C and 100 % relative humidity for 28 days were maintained. Comprehensive tests, including compressive strength, flexural strength, and scanning electron microscopy (SEM) analyses, were conducted. Results showed that AACMs incorporating Bacillus subtilis exhibited a 25 % increase in compressive strength and a 20 % increase in flexural strength compared to control samples. The addition of PET fibers further improved these properties by 10 % and 8 %, respectively. These findings highlight the potential of bio-enhanced alkali-activated materials in sustainable construction.

Effects of Curing Conditions on Pore Structure of Ultra-High-Strength Shotcrete (UHSSC) Based on X-ray Computed Tomography.

Shotcrete is widely used in mine and civil engineering as supporting structure. A new type of ultra-high-strength shotcrete (UHSSC) with viscosity-enhancing agent was taken as the research object in this paper. A microstructure model of UHSSC under different curing conditions (standard curing, natural curing and film curing) was reconstructed using X-ray computed tomography (X-CT). The grey theory was used to analyze the correlation between pore characteristics and strength of UHSSC. The results showed that the porosity and the pore size of UHSSC were significantly reduced, the compressive strength was obviously improved by the new spraying process. The effects of curing conditions on the pore characteristics and compressive strength of UHSSC were obvious. Under natural curing, the hydration degree was the highest, the maximum pore size was the smallest, and the compressive strength was the highest, reaching 95.8 MPa, but the porosity was the highest. The curing condition had a certain influence on the sphericity distribution of UHSSC pores. Under film curing, the proportion of special-shaped pores (S < 0.4) was the largest and compressive strength was the smallest. There was a good correlation between pore characteristic parameters and the compressive strength of UHSSC under different curing conditions. In particular, the large pore size (D ≥ 5000 µm) and special-shaped pores (S < 0.4) had obvious effects on the strength of UHSSC, and the grey correlation coefficients were 0.8539 and 0.8080, respectively. Additionally, the pore direction of UHSSC had obvious directionality, and the anisotropy of UHSSC may be more prominent than poured specimen. The results will lay a foundation for the study of its mechanical properties and durability.

Characterization of a fly ash-based hybrid well cement under different temperature curing conditions for natural gas hydrate drilling

This paper presents a study on the temperature effect (3°C, 10°C, and 50°C, in water bath) and activator effect on the characterization of a fly ash-based hybrid well cement, with a large fraction of fly ash (approximately 70 %), which has potential for natural gas hydrate drilling due to its low heat release. The mechanical strength, micro/nanostructure characteristics were investigated through various tests, including x-ray diffraction (XRD), thermogravimetry analysis (TGA-DTG), nuclear magnetic resonance (MAS NMR), and scanning electron microscope (SEM), to reveal the hydration mechanism of the fly ash-based hybrid well cement. The results indicate that the low curing temperatures (3°C, 10°C) inhibited both the hydration of the well cement and the pozzolanic reaction of fly ash in the cement system. However, the incorporation of solid Na2SO4 significantly contributed to the pozzolanic reaction during the hydration process by consuming more calcium hydroxide, promoting more ettringite formation and reducing the apparent activation energy of the blend cement (from 53.06 kJ·mol−1 to 41.23 kJ·mol−1), resulting in better compressive strength. MAS NMR results showed that the addition of solid Na2SO4 facilitated the substitution of Al with Si atoms, leading to the formation of more C-A-S-H and C-(N)-A-S-H gels in the system with a denser microstructure. Overall, the fly ash-based hybrid well cement can be developed as a cement system for natural gas hydrate drilling in the ocean. This cement not only exhibits low heat release but also shows improved strength development, with a 72-hour compressive strength of 8.05 MPa when cured at 10 °C.

Humidity-induced curing and anti-corrosion properties of GPTMS-modified polyorganosilazane functionalized silica coating on AA2024-T3 aluminum alloy

Relative humidity (RH) is one of the key parameters that significantly affect the curing kinetics and final properties of polysilazane-based coatings. Thus, the paper discusses the effect of relative humidity during the curing process and the anti-corrosion properties of (3-glycidyloxypropyl) trimethoxysilane (GPTMS)-modified polyorganosilazane (OPSZ) functionalized silica coatings on AA2024-T3. Modified polyorganosilazane sol was prepared and then deposited on AA2024-T3 substrates varying the curing conditions. After the deposition, the coated aluminum substrates were exposed to different RH levels; 15%, 40% and 80%, and then cured at 120 °C for 2 h. Transparent and crack-free GPTMS-modified polyorganosilazane coatings with a thickness of around 15–17 μm were obtained. The exposure to the relative humidity increased the crosslinking and hydrolysis-condensation reactions of the OPSZ and GPTMS molecules, showing more Si-O-Si bonds. The incorporation of GPTMS affected the crosslinking structure, enhancing the corrosion protection properties of the coating. GPTMS-modified polyorganosilazane coatings cured at 40%RH had the best anti-corrosive properties after immersion in 3.5 wt% NaCl solution. The impedance modulus of ∼109 Ω.cm2 at a low frequency was obtained, which was five orders of magnitude higher than that for the AA2024-T3 alloy.Graphical

Electric Resistance and Curing Temperature Development of Carbon Fiber-Reinforced Conductive Concrete: A Comparative Study.

The development of electric resistance is a key factor affecting the performance of conductive concrete, especially the electrical-thermal performance. In this work, the effects of different influencing factors (including the water-to-binder ratio, coarse aggregate content and carbon fiber (CF) content) on the electric resistance of conductive concrete were systematically investigated. At the same time, ohmic heating (OH) curing was applied to fabricate CF-reinforced conductive concrete (CFRCC) under a negative temperature environment at -20 °C. The effects of different factors on the electrothermal properties (curing temperature and conductive stability) of the samples were studied. The mechanical strengths of the CFRCC cured by different curing conditions were also tested, and the feasibility of OH curing for preparing CFRCC in a negative-temperature environment was verified at various electric powers. This work aims to give new insights into the effects of multiple factors on the performance of CFRCC for improved concrete construction in winter.

Strength characteristics of cement slurry in high geothermal tunnel environment

The early-age strength of grouting material is crucial for tunnel support under high geothermal temperatures. Grouting materials (such as the most commonly used cement slurry) hydrate and solidify under the condition of variable-temperature curing after entering the real stratum. However, the development process of the early strength of cement paste under the condition of variable-temperature curing is still unclear. This aim of this study was to elucidate the environmental effects of high-ground-temperature tunnels on the early strength development of cement stone. Cement slurry was subjected to variable-temperature curing under three different temperatures (T = 40°C, 60°C and 80°C) and two different relative humidities (H = 5% and 95%) through design experiments. Compressive strength tests were conducted, along with microscopic analysis using X-ray diffraction, scanning electron microscopy and nuclear magnetic resonance. The results indicate that the strength of cement stone under variable-temperature curing was lower than that under constant-temperature curing at the same temperature. The influence of variable-temperature curing conditions on the strength variation of samples with a high water/cement ratio at later age was greater for curing at 80°C. The research results are helpful to understand the influence of environmental effects of high-ground-temperature tunnels on the properties of grouting materials.

AI-based non-linear models for mechanical and toughness properties of sustainable fiber-reinforced geopolymer concrete (FRGPC)

The incorporation of fibers into geopolymer concrete (GPC) produces FRGPC which mitigates brittle failure and restrains macro crack propagation; however, research on predicting the mechanical and toughness properties of FRGPC remains limited. This study addresses this gap by developing prediction models for compressive strength (CS), flexural strength (FS), flexural toughness (FT), and fracture toughness (FR). A dataset of 600 data points was compiled from the published literature, encompassing various constituent proportions, fiber shapes, fiber dosages, aspect ratios, and curing conditions. Employing an artificial neural network (ANN) methodology, 10 independent variables (g1, g2, …., g10) were utilized to predict four dependent variables (CS, FS, FT, and FR), resulting in the development of eight non-linear ANN models for both straight fibers (SFs) and hooked fibers (HFs). Each model has shown a higher R 2 value and lower root mean square error (RMSE) for training (70%), testing (15%), and validation (15%) datasets. The prediction model for the CS of FRGPC with HFs (CS-HF) and SF (CS-SF) showed R 2 values of 0.983 and 0.973, and RMSE of 2.088 and 2.435 MPa highlighting the accuracy of the ANN models. Similarly, the comparative analysis for FR models exhibited R 2 values of 0.997 and 0.987, and RMSE values of 0.045 Mpa √m and 0.032 Mpa √m for FR-HF and FR-SF, highlighting that fiber addition strongly impacts improving toughness properties. To identify the most influential independent variable(s), sensitivity analysis revealed g10, g1, g8, and g9 as the most influential parameters for mechanical and toughness properties with SFs. For HFs, g1, g2, and g3 were most influential for mechanical properties, and g8, g9, and g10 for toughness. This study also presented the mathematical formulation of the developed models for better interpretability and to facilitate optimal and economical FRGPC mix design selection, highlighting the potential of AI-based models in advancing sustainable construction materials.

Study on High-Ductility Geopolymer Concrete: The Influence of Oven Heat Curing Conditions on Mechanical Properties and Microstructural Development.

Low carbon and high performance have become key trends in the development of construction materials. Understanding the mechanism by which curing conditions affect the mechanical properties of high-ductility geopolymer concrete (HDGC) is of significant importance. This study investigated three sealing curing temperatures (room temperature, 45 °C, and 60 °C) and four curing durations (1 day, 3 days, 5 days, and 7 days), while considering two final curing ages (7 days and 28 days) to explore their effects on the axial tensile and compressive properties of HDGC. The results showed that both 45 °C and 60 °C could improve the brittle failure of HDGC under axial compressive loading. However, curing at 60 °C and for durations longer than 1 day in an oven would catalyze the formation of eight-faced zeolite crystals within the slag-fly ash geopolymer matrix, and it could weaken the matrix's pore structure and subsequently affect the material's later strength development. Nevertheless, oven heat curing enhanced the bridging effect between the fibers and the matrix, partially compensating for the reduction in the initial tensile strength of HDGC. This follows the pseudo-strain-hardening material's saturation cracking criterion to enhance the strain-hardening behavior of HDGC and improve its tensile energy absorption capacity. A curing condition of 45 °C for 5 days is recommended to maximize the ductility of HDGC. This study provides important theoretical support for the design and promotion of green, low-carbon, high-ductility composite materials.

Investigation Of Strength Development In Conventional And High Strength Concrete Under Different Curing Conditions

The composite material obtained by blending cement, aggregate, water and, when necessary, an additive, placing a mixture with carefully adjusted proportions into molds of the desired shape and size without gaps and hardening under appropriate maintenance conditions, is called concrete or traditional concrete. In the 1960s, concretes with compressive strengths of 41 MPa and 52 MPa were used on the market in the USA. In the recent past, concretes with compressive strengths varying between 80 MPa and 100 MPa have been commercially applied in structures made with in-situ concrete and prestressed concrete structural elements. Strength developments of traditional and high-strength concretes under different curing conditions will be examined. For this purpose, central pressure tests were carried out on cube samples produced. For concrete production; For each aggregate class, cement, saturation water, mixed water and high strength concretes; It was prepared by weighing silica fume and superplasticizer. The prepared samples were stored in standard or cold water for 3 days, 7 days, 28 days and 90 days. In this study, the strength development of traditional and high-strength concretes under different curing conditions was examined experimentally. In accordance with the experimental work plan determined for this investigation, concrete cube samples were produced and these samples were subjected to the central pressure test. The concretes produced are in C55, C20 and C12 classes. As a result, although similar behaviors were observed in high-strength and conventional concretes cured in different environments, it was determined that the difference in curing temperature was more effective on the strength development than the inadequacy of curing in water. It should be noted here that it would be beneficial to conduct similar studies on different types of concrete.