Increasing Curing Temperature Research Articles

Effects of temperature and water-to-cement ratio on autogenous shrinkage of oil well cement

The chemical shrinkage and corrugated tube test methods were used to study the shrinkage behaviour of Class G oil well cement with water-to-cement (w/c) ratios of 0.3 and 0.5, cured at temperatures from 15 to 60°C. The experimental results show that the typical linear shrinkage evolution curve of a cement slurry obtained by corrugated tube method have an obvious inflection point, beyond which the linear shrinkage increase is close to zero. The time at which the inflection point is observed decreases significantly with increasing curing temperature, but varies very little with w/c ratio. The inflection time also shows approximately linear correlation with the setting time of the cement (The two are almost equal for w/c=0.3). The degree of hydration corresponding with the initial and final setting time were estimated based on chemical shrinkage test results and the relationships between estimated volumetric bulk shrinkage and chemical shrinkage were analyzed.

Synthesis, characterisation and hydration of ternesite

Ternesite has recently been shown to exhibit reactivity, especially in the presence of aluminum. In this article, the preparation and hydration of ternesite was studied. The dopants were incorporated during the synthesis of ternesite. The incorporation of dopants affected the synthesis of ternesite and CaF2 was most effective in achieving high phase purity. X-ray diffraction, thermal gravimetric analysis, fourier-transform infrared spectroscopy and scanning electron microscopy were conducted to investigate the hydration of ternesite. The influence of curing temperature and humidity on the hydration of ternesite and ternesite-aluminate blends were also explored. The results demonstrated that the incorporation of ye’elimite resulted in the formation of ettringite and monosulfate while the incorporation of C3A caused the formation of katoite, portlandite and monosulfate. In the presence of aluminates, the hydration kinetics of ternesite was accelerated by increasing curing temperature. Curing with high humidity was advantageous to the hydration of ternesite and ternesite-ye’elimite blend but inhibited the hydration of ternesite-C3A blend.

The Influence of Ambient Temperature on High Performance Concrete Properties.

This paper presents the results of tests on high performance concrete (HPC) prepared and cured at various ambient temperatures, ranging from 12 °C to 30 °C (the compressive strength and concrete mix density were also tested at 40 °C). Special attention was paid to maintaining the assumed temperature of the mixture components during its preparation and maintaining the assumed curing temperature. The properties of a fresh concrete mixture (consistency, air content, density) and properties of hardened concrete (density, water absorption, depth of water penetration under pressure, compressive strength, and freeze–thaw durability of hardened concrete) were studied. It has been shown that increased temperature (30 °C) has a significant effect on loss of workability. The studies used the concrete slump test, the flow table test, and the Vebe test. A decrease in the slump and flow diameter and an increase in the Vebe time were observed. It has been shown that an increase in concrete curing temperature causes an increase in early compressive strength. After 3 days of curing, compared with concrete curing at 20 °C, an 18% increase in compressive strength was observed at 40 °C, while concrete curing at 12 °C had a compressive strength which was 11% lower. An increase in temperature lowers the compressive strength after a period longer than 28 days. After two years of curing, concrete curing at 12 °C achieved a compressive strength 13% higher than that of concrete curing at 40 °C. Freeze–thaw performance tests of HPC in the presence of NaCl demonstrated that this concrete showed high freeze–thaw resistance and de-icing materials (surface scaling of this concrete is minimal) regardless of the temperature of the curing process, from 12 °C to 30 °C.

Thermal kinetics of free volume in porous spin-on dielectrics: Exploring the network- and pore-properties

Comprehensive ex-situ and in-situ investigations of thermal curing processes in spin-on ultra-low-k thin films conducted by positron annihilation spectroscopy and Fourier transform infrared spectroscopies are presented. Positron annihilation lifetime spectroscopy of ex-situ cured samples reveals an onset of the curing process at about 200 °C, which advances with increasing curing temperature. Porogen agglomeration followed by diffusive migration to the surface during the curing process leads to the generation of narrow channels across the film thickness. The size of those channels is determined by a pore size distribution analysis of positron lifetime data. Defect kinetics during in-situ thermal curing has been investigated by means of Doppler broadening spectroscopy of the annihilation radiation, showing several distinct partially superposed and subsequent curing stages, i.e., moisture and residual organic solvents removal, SiOx network cross-linking, porogen decomposition, and finally creation of a stable porous structure containing micropore channels interconnecting larger mesopores formed likely due to micelle like interaction between porogen molecules, for curing temperatures not larger than 500 °C. Static (sequencing curing) states captured at specific temperature steps confirm the conclusions drawn during the dynamic (continuous curing) measurements. Moreover, the onset of pore inter-connectivity is precisely estimated as pore interconnectivity sets in at 380–400 °C.

Effect of particle size and curing temperature on mechanical and microstructural properties of waste glass-slag-based and waste glass-fly ash-based geopolymers

This paper aims to investigate the effects of waste glass particle size and curing temperature on the mechanical properties, microstructure and minerology of waste glass-slag-based and waste glass-fly ash-based geopolymers. Specimens synthesized from ground waste bottle glass of three different particle size distributions (D50 = 49.2 μm, 159.1 μm, and 302.1 μm), ground granulated blast furnace slag (GGBS) and Class F fly ash (FFA) were produced by reacting with alkaline activators potassium hydroxide (KOH) and sodium metasilicate nonahydrate (Na2SiO3·9H2O). The geopolymer specimens were cured at four temperatures (20 °C, 50 °C, 80 °C, 100 °C) for the initial 24 h and then at 20 °C. The compressive strength of the cylinders was tested. Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD) were utilized to evaluate the microstructural and mineral characterization. Curing at 80 °C, the geopolymer made by GGBS and waste glass of D50 = 49.2 μm achieved a compressive strength of 46.5 MPa on the 28th day. The glass powder with D50 larger than 300 μm showed relatively low chemical reactivity and hardly had any reaction with the alkaline solution. An increase of curing temperature in the initial 24 h generally accelerated the kinetics and reached a higher extent of reaction, especially specimens added waste glass. Increasing curing temperature from 50 °C to 80 °C improved the compressive strength of most of specimens containing waste glass effectively. The geopolymers synthesized from the mixture of glass powder and slag achieved much higher compressive strength compared to the ones made with pure glass or slag. This was, however, not observed in Class F fly ash due to low calcium content of Class F fly ash.

Influence of silica fume and low curing temperature on mechanical property of cemented paste backfill

The cementing cost accounts for 75 percent of the total operations costs in a mine if cement is used as cemented material. Silica fume (SF), as potential cementitious material, can be used as a substitute of cement to fabricate cemented paste backfill (CPB). In this study, experimental studies were executed to investigate the mechanical properties and microstructure evolution of CPB incorporating SF and in an effort to assess the applicability of using SF as a partial cement replacement in cold region. The cement replacement level was set at 0% (control), 2.5%, 5.0% and 10.0% by the mass of cement. Furthermore, the effect of curing temperature (−1, 6, and 20 ℃) on mechanical and microstructural performance of CPB within 28 days was also studied. Results indicate that the optimal replacement level of 5.0% for CPB exhibit the highest compressive strength regardless of curing temperature and age. The low curing temperature retards hydration reaction, and the strength of CPB samples with silica fume cured at room temperature is higher than that cured at 6 ℃ and −1 ℃, however, the 28-day strength of CPB with 5% silica fume at low curing temperature (−1 ℃) is larger than that CPB without silica fume at room temperature. The strength incremental rate induced by replacement of silica fume at early age (e.g., 3 days) is more significant in comparison with that cured for 28 days. The microstructural results indicate that more hydration products (e.g. C-S-H, ettringite, and CH) are generated as silica fume dosage and curing temperature increases, thereby resulting in refinement of pore structure and improvement of CPB strength.

Nanopatterned Nafion microelectrode arrays for in vitro cardiac electrophysiology.

In this study, we report nanopatterned Nafion microelectrode arrays for in vitro cardiac electrophysiology. With the aim of defining sophisticated Nafion nanostructures with highly ionic conductivity, fabrication parameters such as Nafion concentration and curing temperature were optimized. By increasing curing temperature and Nafion concentration, we were able to control the replication fidelity of Nafion nanopatterns when copied from a PDMS master mold. We also found that cross-sectional morphology and ion current density of nanopatterned Nafion strongly depends on the fabrication parameters. To investigate this dependency, current-voltage analysis was conducted using organic electrochemical transistors (OECT) overlaid with patterned Nafion substrates. Nanopatterned Nafion was found to allow higher ion current densities than unpatterned surfaces. Furthermore, higher curing temperatures were found to render Nafion layers with higher ion/electrical transfer properties. To optimize nanopattern dimensions, electrical current flows, and film uniformity, a final configuration consisting of 5% nanopatterned Nafion cured at 65°C was chosen. Multielectrode arrays (MEAs) were then covered with optimized Nafion nanopatterns and used for electrophysiological analysis of two types of induced pluripotent stem cell-derived cardiomyocytes (iPSCs-CMs). These data highlight the suitability of nanopatterned Nafion, combined with MEAs, for enhancing the cellular environment of iPSC-CMs for use in electrophysiological analysis in vitro.

Effects of curing temperature on the compressive strength and microstructure of copper tailing-based geopolymers

This study sought to analyze the effect of curing temperature on mechanical strength and microstructure of a copper tailing-based geopolymer via scanning electron microscopy (SEM), HCl extraction, nuclear magnetic resonance (NMR), and X-ray diffraction (XRD). The distribution of gel formed in geopolymers tended to be uniform with increasing curing temperature from 25 to 80 °C. Moreover, the percentage of Si sites in C–S–H and N-A-S-H gels increased from 62.08% to 78.94% and more tetrahedral [AlO4] was incorporated into the tetrahedron [SiO4] backbone, leading to an increase of compressive strength from 10.2 to 39.6 MPa. When the curing temperature was increased to 120 °C, the percentage of Si sites in C–S–H and N-A-S-H gel decreased to 69.52%, and the compressive strength decreased to 27.5 MPa. Moderately elevated curing temperature promoted the dissolution of aluminosilicate while curing temperatures above 80 °C hindered it. Excessive curing temperature led to a decrease in the geopolymer alkaline medium.

Geopolymer bricks made from less active waste materials

The current study aims at investigating the production feasibility of the geopolymer bricks using the waste materials emanated from the washing process of sand and gravel in aggregate industries. Geopolymer is a material originated by inorganic polycondensation as a result of the alkali activation of aluminosilicate materials. Geopolymer bricks seem to be advantageous due to the low demand for energy and the significant incorporation of wastes. The production of geopolymers from pozzolanic or aluminosilicate rich materials is very common. However, few studies have been carried out on the less-active materials such as waste materials of aggregate industries as raw materials for producing geopolymers. For this purpose, the influence of three parameters, sodium hydroxide concentration (4, 8 and 12 M), calcium hydroxide content (5%,10%, and 15%), and curing temperature (70 °C and 105 °C), on the physical and mechanical properties of geopolymer bricks was investigated using compressive strength, SEM micrographs, XRD analysis, water absorption, and bulk density. The results indicate that higher sodium hydroxide concentration caused forming a less porous and a more amorphous microstructure, and yielded higher strengths and lower water absorption. The mixtures with higher calcium hydroxide content had higher compressive strengths (up to 75 MPa and 36 MPa at dry and wet conditions, respectively) and a more stable microstructure, however, incorporation of calcium hydroxide at levels higher than 20% results in lower compressive strengths, lower densities, and higher water absorption contents. Increasing curing temperature from 70 °C to 105 °C increased significantly the compressive strength.

Metakaolin-based geopolymer coatings on metals by airbrush spray deposition

Metakaolin-based geopolymer coatings with a thickness of about 60 μm were prepared on 2024 Al alloy and low carbon steel substrates by airbrush spray deposition. Curing in a sealed condition led to a limited geopolymerization reaction and corrosion of the uncoated surface in the metal substrates. Fourier-transform infrared spectroscopy and X-ray diffraction measurements of the coatings cured in an unsealed condition at 40–150°C confirmed the formation of the geopolymer network. Coatings cured at 80°C possessed a favorable microstructure, while some microcracks were present in the coatings after curing at 150°C due to shrinkage and residual stresses. The adhesion strength, measured by scratch tests, showed high values of critical load for samples cured at 80°C. For samples cured at 150°C, the coating was completely removed upon loading when the geopolymer was deposited on Al but not when on mild steel. Immersion tests demonstrated that the stability of the coatings in distilled water increased with increasing curing temperature.

Surface properties of oriented strand board coated by electrostatic dry powder spray deposition technique

Use of electrostatic powder coating technology for wood-based panels has considerably increased in the last decade. In this study, oriented strand boards (OSB; OSB/2 and OSB/3 grades) were coated with powder coatings using an electrostatic corona spray gun. Epoxy/polyester (hybrid:1/1) coating that is suitable for indoor applications was applied to the surface of OSB specimens (150 g/m2) at three different curing temperatures, 120 °C for 15 min, 140 °C for 10 min, and 160 °C for 10 min using the electrostatic corona gun. The surface properties of the OSB specimens, roughness, wettability, scratch resistance, abrasion resistance, and film thickness were determined. The abrasion resistance and scratch resistance of the coated OSB specimens improved with increasing curing temperature from 120 to 160 °C. The highest mechanical surface strength was obtained from the OSB/3 specimens cured in the infrared oven at 160 °C for 10 min, while the lowest strength was found in the OSB/2 specimens cured in the infrared oven at 120 °C for 15 min. The contact angle values of the coated OSB specimens increased with increasing curing time, while the surface roughness decreased. The curing temperature of the electrostatic powder coating may be a useful indicator to users to obtain better surface quality on the substrate.

The impact mechanical characteristics of steam-cured concrete under different curing temperature conditions

In order to clarify the influence of curing temperature on the dynamic properties of steam-cured concrete, series of SHPB tests were conducted to investigate the impact mechanical characteristics of a typical steam-cured concrete applied in prefabricated components of high-speed railway in China. The index of fineness modulus was proposed to evaluate the degree of concrete breakage under different strain rates. The results showed that the peak stress of steam cured concrete increased with increasing the strain rate, while the peak strain showed a decreasing trend, the fineness modulus of broken concrete particles decreased, and the degree of fracture increased obviously. As curing temperature increases, the peak stress of steam-cured concrete decreased significantly, and the concrete specimens showed a stronger strain rate sensitivity. A statistical damage constitutive model considering the strain rate was established and agreed well with the experimental stress–strain curves. Higher temperatures lead to an increase in internal defects of concrete, which makes the impact mechanical properties different from that of normal temperature cured concrete.

Mechanical and microstructure characteristics development of hardened oil well cement pastes incorporating fly ash and silica fume at elevated temperatures

ABSTRACT The performance of oil well cement (OWC) incorporating pozzolana under diverse hydrothermal curing circumstances was inspected. OWC was partially replaced by 5 weight% of silica fume (SF) or fly ash (FA). The prepared composites were cured under different hydrothermal circumstances (60°C/0.02 MPa, 100°C/0.1 MPa and 150°C/0.48 MPa) for 7 days. The outcomes established that increasing curing temperature and pressure brought about a decline in the compressive strength magnitudes of various neat OWC pastes. This finding is correlated to the metamorphosis of CSH to the greatly crystalline phase of α-dicalcium silicate hydrate (α-C2SH). Such transformation motivates the destruction of the pore structure and promotes compressive strength decline. Admixing OWC with 5 wt.% SF or FA displayed enrichment in the mechanical aspects accompanied by the progression of highly compact microstructures. Additionally, the presence of SF or FA motivates the advancement of stable and desirable hydration products. DTG/TG, XRD and SEM analyses affirm these results.

Insights into the Microstructure of Hydrothermal Synthesized Nanoscale K2O-Al2O3-SiO2-H2O Particles

K-A-S-H (K2O-Al2O3-SiO2-H2O) gel is a key phase that forms in most alkali-activated binders (eco-friendly binders which utilize a substantial amount of industrial by-product). An in-depth understanding of the microstructure and performance of this nano-sized key phase facilitates better application to alkali-activated binders. However, such studies remain little and undetailed. Therefore, our research aims to provide insights into the microstructure of K-A-S-H particles synthesized with accurate stoichiometric control by the hydrothermal method through thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and BET surface area. The results show that for materials prepared at the curing temperature lower than 80 °C, the K-A-S-H products were completely amorphous. With increased curing temperature and time, the K-A-S-H products were transformed from the amorphous phase to the crystalline zeolite phase structure, with a reduction in the specific surface area. The TG results indicate that the crystalline phase contains more non-evaporated water or zeolite water for structural rearrangement. The degree of tetrahedral polymerization slightly decreased with an increase of the K2O/SiO2 ratio as the amount of non-bridged oxygen atoms increased, whereas it gradually increased with an increase of curing temperature and time, as suggested by the FTIR and NMR results. Various K2O/SiO2 ratios resulted in the formation of zeolite K-H and K-G zeolite, both of which exhibited highly polymerized three-dimensional network structures. However, there was no significant effect of the SiO2/Al2O3 ratio on the structure of K-A-S-H products. Overall, these results provide insight into understanding the chemical stability of K-A-S-H.

Chemical Kinetics Analysis of Strength Development of Mortar Containing Fly Ash Based on Various Curing Temperatures

Due to large size and high internal temperature of hydraulic dams, the strength development process of damming materials is often faster than those under standard curing conditions. In order to further study the strength development features of damming materials under internal temperature conditions, two kinds of fly ash mortars were investigated, of which fly ash content is 40% and 30%. The compressive strength of mortars under three curing temperatures containing 20, 30 and 38°C was tested at 3 days, 7 days, 14 days, 28 days, 56 days and 90 days, respectively. Then chemical kinetics equation was employed to describe the strength development features under different temperature conditions. The results show that the compressive strength of fly ash mortar increases with the increase of curing temperature in the range of 20 to 38 °C. The main reason is that the chemical reaction rate of cementitious materials is accelerated by increasing curing temperature. For example, the hydration rate at 30° is 1.6 to 1.9 times of that at 20°, and the hydration rate at 38° is 3.1 to 3.9 times of that at 20°. In addition, the hydration rate of mortar with higher fly ash content is accelerated more. It can be seen that the apparent activation energy of mortar containing 40% of fly ash is 1.2 times of that with 30% of fly ash, and its chemical reaction barrier is higher. Therefore, the equivalent age of mortar with 40% of fly ash is longer and its compressive strength is improved more greatly under temperature-raising conditions.

Effect of acid-temperature-pressure on the damage characteristics of sandstone

The primary objective of this study is to experimentally study the effects of different curing temperatures (25, 50 and 75 °C) and pressures (5, 10 and 15 MPa) on the mechanical properties and damage deterioration mechanism of sandstone samples subjected to pH3 H2SO4. The responses of mass loss, aperture structure based on NMR, deformation behaviour and mechanical parameters of sandstone were compared and analyzed. The microstructure change in sandstone samples was observed and analyzed with SEM-EDS. The deterioration mechanism of sandstone after treatment with acid-temperature-pressure (ATP) was discussed considering pH and ion concentration in acidic solution. The results indicated that mass, uniaxial compressive strength and elastic modulus of the samples decreased and sandstone sample porosity as well as pH and ion concentration of corrosion solution increased after treatment with APT. Under the same conditions, increasing curing temperature had apparent deterioration effect on acid-corroded sandstone, yet increasing pressure had little effect on it, especially the pressure increased from 10 MPa to 15 MPa. The results of SEM and electron spectroscopy showed that the microstructure, defects and mineral content of sandstone changed after treatment with ATP. The secondary pores increased and the surface structures became loose. The chemical reactions between sandstone samples and acidic solutions with different curing temperatures and pressures as well as the damage mechanism underlying the interaction were discussed in the theoretical context of chemical kinetics.

GMCs stabilized/solidified Pb/Zn contaminated soil under different curing temperature: leachability and durability.

In this study, the impact of the curing temperature on leaching behaviour and durability of GGBS-MgO-CaO (GMC)-stabilized/GMC-solidified Pb/Zn-contaminated clay soils was investigated. Toxicity characteristic leaching procedure (TCLP) test, wetting-drying cycles, freeze-thaw cycles and unconfined compression strength (UCS) test were carried out. The influence of curing temperature, binder dosage and curing time on the performance of these samples was investigated. The results show that the leachability and the durability of all samples were improved by increasing curing temperature, curing time and binder dosage. GMCs are more functional in immobilizing Pb compared with Zn, especially in immobilizing high Pb-contaminated soils. The mass loss and Pb/Zn leachability of all samples increased, while their strength decreased after cyclic wetting-drying and cyclic freeze-thaw. Furthermore, curing at 21 °C and 45 °C, the freeze-thaw resistance of 10% GMC-treated soil (GMC10) was found better than that of 10% Portland cement-treated soil (PC10). After 10 cycles of wetting-drying, GMC10 is more chemically stable than PC10.

Curing Kinetics and Mechanism Research of E44/T31 Insulation Paint

Epoxy resin insulation paint was prepared with epoxy resin (E44) as binder and with proper inorganic fillers and curing agent (T31) as additives. The isothermal curing reaction process of paint was studied by the differential scanning calorimetry method (DSC), and the curves of curing reaction rate versus time of paint were obtained. The curing reaction kinetics was investigated by using the phenomenological method, and the corresponding parameters of the n-order model, autocatalytic model and Kamal model were determined by fitting the experimental data, respectively. According to the values of R2 and the sum of square due to error (SSE), a suitable curing reaction kinetic model was determined. The curing reaction mechanism of paint was ascertained by the dynamic temperature DSC method and IR spectroscopy (FTIR) method. The results show that the Kamal model can be used to describe the curing kinetics of epoxy resin paint, and the total reaction orders increase from 1.30 to 2.14. The two rate constants increase with the increase of the curing temperature. The activation energy is 90.5832 kJ/mol and 68.3733 kJ/mol respectively, and the pre-exponential factors are 6.521 × 1015 s-1 and 6.3807 × 109 s-1. The curing reaction of paint consists of two steps: the first step is the addition reaction of epoxy group and primary amine or secondary amine; the second step is the etherification reaction of epoxy group and phenolic hydroxyl or alcoholic hydroxyl.
 Epoxy resin insulation paint was prepared with epoxy resin (E44) as binders and with proper inorganic fillers and curing agent (T31) as additives. The isothermal curing reaction process of paint was studied by differential scanning calorimetry method (DSC), and the curves of curing reaction rate versus time of paint were obtained. The curing reaction kinetics was studied by using the phenomenological method, the corresponding parameters of the n-order model, autocatalytic model and Kamal model were determined by fitting the experimental data, respectively. According to the values of R2 and the sum of square due to error (SSE), a suitable curing reaction kinetic model was determind. The curing reaction mechanism of paint was ascertained by dynamic temperature DSC method and IR spectrogram (FTIR) method. The results show that the kamal model can be used to describe the curing kinetics of epoxy resin paint, the total reaction orders increase from 1.30 to 2.14. The results also show that the two rate constants increase with increasing curing temperature, The activation energies are 90.5832 kJ/mol and 68.3733 kJ/mol, and the pre-exponential factor are 6.521×1015 s-1 and 6.3807×109 s-1. The curing reaction of paint in two steps, the first step is the addition reaction of epoxy group and primary amine or secondary amine. The second step is the etherification reaction of epoxy group and phenolic hydroxyl or alcoholic hydroxyl.

Effects of temperature on performances and hydration process of sulphoaluminate cement-based dual liquid grouting material and its mechanisms

In order to find out the rules of the effect of temperature on performances and hydration process of sulphoaluminate cement-based dual liquid grouting material, the performances of the grouting material were studied by determining its setting time, compressive strength and setting temperature. Its hydration process, hydration products and microstructure were analyzed by using XRD, TG–DTA and SEM–DES. The results show that water temperature has a significant effect on the setting time and setting temperature. The higher the water temperature, the shorter the setting time and the higher the setting temperature. In addition, as the water temperature and curing temperature increase, the hydration rate grows faster and the early strength becomes higher. However, the later strength of samples which are with lower temperature is higher. The results of TG–DTA, XRD and SEM–DES show that ettringite (AFt) is the main hydration product. Higher water temperature and curing temperature accelerate the formation of AFt, but also restrict the later hydration rate. The type of hydration product does not change as the temperature changes, but the microstructure of hydration product does.

The effect of curing regimes on the mechanical properties, nano-mechanical properties and microstructure of ultra-high performance concrete

This study addresses the effect of curing regimes on the mechanical properties, hydration and microstructure of ultra-high performance concrete (UHPC). The results demonstrate that the mechanical properties are strengthened by increasing curing temperature, but the flexural/tensile to compressive strength ratio shows an unusual increasing tendency with increasing temperature and compressive strength, which is opposite to normal concrete. The nano-mechanical properties are also enhanced by heat treatment. The ultra-high density phase is dominated hydrates. Microstructure observation indicates that heat treatment promotes the formation of additional hydrates with high-packing density and stiffness such as tobermorite and xonotlite, enhancement of transition zone around steel fiber, quartz and clinker, average chain length of hydrates and pozzolanic reaction between quartz/silica fume and Ca(OH)2. The evolution of hydrates and microstructure due to curing regimes and the presence of quartz play key roles in controlling the unusual behavior of the strength ratio and improvement of mechanical properties.