Compressive Strength Of Material Research Articles

Comprehensive investigation of bond properties of CFRP cables with concrete and mortar

This study investigated the bond properties of carbon fiber reinforced polymer (CFRP) cables with concrete and mortar. Analyses focused on the bond-slip behavior considering various factors, such as CFRP cable types (e.g., CFRP rod and strand), surface treatments, fixed end materials (e.g., concrete and mortar). Remarkably, the material type and compressive strength at the fixed end were found to have no discernible impact on bond-slip behavior. Conversely, the type of CFRP cable and its surface treatment emerged as pivotal factors influencing bonding strength outcomes. Employing the modified Bertero-Popov-Eligehanusen (BPE) model, a comparative evaluation was performed between experimental results and theoretical estimation of bond-slip behavior. Furthermore, image processing analysis revealed a similar bonding strength of CFRP cables with both concrete and mortar. This similarity can be attributed to the sparser distribution of coarse aggregates around cables in concrete samples, implying that the cementitious phase primarily governed the bond properties, resulting in consistent bonding strengths across different fixed end materials. Overall, this study sheds light on the intricate interplay between CFRP cable types, surface treatments, and material compositions, ultimately contributing to a deeper understanding of bond properties and their implications for various structural applications.

Research on Mechanical Properties and Engineering Applications of Inorganic Cementitious Filling Materials in Coal Mine Abandoned Roadways

To solve the problems of brittleness, high cost, and the complicated construction process of traditional filling materials for filling abandoned roadways, various aspects of the physical and mechanical properties of the materials were studied using laboratory tests and were applied in coal mines. The research shows that the self-developed inorganic cementitious filling material has the advantages of being low cost, easy to cut and wash, and having good filling performance. A foaming agent is a direct factor in controlling the volume expansion of inorganic cementitious filling materials; the increase in the volume of slurry foaming with the addition of a foaming agent initially showed a large and then a small trend with a foaming agent dosage of 100 g. The increase in the volume of slurry foaming is the largest at 56.28%. The effect of the B material (calcium stearate+ J85 rapid-setting agent) on the foaming time and the number of foaming times of the slurry was significant. Foam stabilizers in the B material make the slurry particles uniformly distributed inside the slurry, while quick-setting agents control the initial and final setting time by affecting the slurry setting speed. The water/cement ratio directly affects the foaming times of the slurry but has little effect on the foaming time and setting speed. When the water/cement ratio is less than 1:2, the slurry foaming effect is poor, and the foaming volume remains unchanged. The strength of the material is significantly affected by the proportion of B material and the amount of blowing agent, and the compressive strength of materials with different compositions and ratios varies greatly. A whole set of systems of new inorganic gelatinized abandoned roadway filling materials was researched and applied in coal mines, achieving good results.

Performance study of new lightweight cementitious composites with glass beads as filler

Glass beads are a kind of inorganic lightener material with low density and high strength. They can be used to prepare lightweight cement composite and significantly improve traditional cement materials' fluidity, compressive, and flexural properties after setting. In this paper, a new lightweight cementitious hole sealing material was prepared by utilizing the excellent properties of glass beads, and the new lightweight cementitious composite drilled hole sealing material was quantitatively and qualitatively analyzed by flow test, uniaxial compression, nuclear magnetic resonance, and SEM experiments, to derive the effects of the substitution of different types of glass beads with different proportions of different types of glass beads on the material's fluidity, compressive strength, pore distribution, and microstructure. The results show that the new cementitious materials have better fluidity, in which the fluidity of the optimal group is increased by 8 % compared with that of pure cement mortar; the mechanical properties of the optimal group are significantly improved with the hollow glass beads acting as the aggregate, and the peak stress reaches 55.025 MPa; the peak stress can reach 60.191 MPa with the use of modified hollow glass beads acting as the aggregate; moreover, with the incorporation of hollow glass beads, the material is more compact, and the pore distribution and microstructure of the material is improved. In addition, with the incorporation of hollow glass beads, the densification of the material showed a trend of first enhancement and then a gradual decrease, while the densification of the material weakened after the incorporation of solid glass beads. Therefore, hollow glass beads are more suitable for improving and optimizing cementitious sealing materials. The research and development of this material are conducive to improving cementitious materials' sustainability and alleviating the cement production's environmental burden. At the same time, it provides a reference for the research and development of new high-quality cementitious materials.

Effect of seashell powder as binder material on the performance and microstructure of low-carbon sustainable alkali-activated concrete

This paper proposes using waste seashells as raw materials to partially replace fly ash in alkali-activated concrete (AAC). Fifteen groups of alkali-activated mortar and concrete were designed, with seashell powder (SP) substitution and sodium hydroxide molar concentration as variables. The material's workability, compressive strength, hydration products and micropore structures were examined. The results showed that the 3 days compressive strength of AAC with SP enhanced significantly, exhibiting an increase of nearly 30 % compared to the fly ash control. The 28 days compressive strength showed that the optimal proportion of SP replacing fly ash was 45 %. SEM images showed that micro/nanoparticles of SP filled the pores in the concrete and provided nucleation sites. Nano CT and MIP analyses indicated that the addition of SP could refine the pore structure of concrete, reducing the total porosity by nearly 30 %. Finally, the carbon emission data for 1 m³ of concrete were analyzed using a life cycle assessment approach. The carbon emissions from AAC with 45 % SP were 173.4 kg CO2/m³, compared to the reference ordinary concrete reduction of approximately 60–70 %.

Influence of Starch Powder on Compressive Strength and Microstructural Properties of Geopolymer Composite Materials Based on Metakaolin

The main objective of the present study is the investigation of the behaviour of starch powder incorporated at different levels (0, 5, 10, 15, 20, 25, and 30 wt%) on the compressive strength and microstructural properties of metakaolin-based geopolymers. Sodium silicate with a molar ratio of SiO2/Na2O of 1.6 was used as the hardener and standard metakaolin was used as the aluminosilicate source. The results showed that when metakaolin was replaced by starch from 0 to 15 wt%, the compressive strength increased from 36.50 to 64.12 MPa. When metakaolin was replaced by starch above 15 wt%, the compressive strength decreased from 64.12 to 29.43 MPa. That of the reference geopolymer material is 36.50 MPa.The infrared spectra of the geopolymer composites indicate that the Si-O-C bonds are formed. The thermal behaviour of geopolymer composites containing starch shows a mass loss at around 100 and 278 °C. The geopolymer material without starch only shows a loss of mass at around 100 °C. The micrographs of the geopolymer composite with 15% by weight of starch show that the matrix is more compact, more homogeneous, and denser than the one without starch. On the contrary, possibly due to a large amount of unreacted starch in its network, the micrographs of the geopolymer composite obtained after the incorporation of 30 wt% starch show a heterogeneous microstructure. It can be concluded that suitable starch content for the synthesis of geopolymer composites would be around 15% by weight.

Lunar In Situ Large-Scale Construction: Quantitative Evaluation of Regolith Solidification Techniques

Lunar habitat construction is crucial for successful lunar exploration missions. Due to the limitations of transportation conditions, extensive global research has been conducted on lunar in situ material processing techniques in recent years. The aim of this paper is to provide a comprehensive review, precise classification, and quantitative evaluation of these approaches, focusing specifically on four main approaches: reaction solidification (RS), sintering/melting (SM), bonding solidification (BS), and confinement formation (CF). Eight key indicators have been identified for the construction of low-cost and high-performance systems to assess the feasibility of these methods: in situ material ratio, curing temperature, time, implementation conditions, compressive strength, tensile strength, curing dimensions, and environmental adaptability. The scoring thresholds are determined by comparing the construction requirements with the actual capabilities. Among the evaluated methods, regolith bagging has emerged as a promising option due to its high in situ material ratio, low time requirement, lack of high-temperature requirements, and minimal shortcomings, with only the compressive strength falling below the neutral score. The compressive strength still maintains a value of 2–3 MPa. The proposed construction scheme utilizing regolith bags offers numerous advantages, including rapid and large-scale construction, ensured tensile strength, and reduced reliance on equipment and energy. In this study, guidelines for evaluating regolith solidification techniques are provided, and directions for improvement are offered. The proposed lunar habitat design based on regolith bags is a practical reference for future research.

Research on the ratio of similar materials in water-absorbent mudstone based on fuzzy mathematics.

To determine the suitability and credibility of similar water-absorbent mudstone materials in model experiments, the prototype mudstone parameter similarity index was determined based on the similarity theory. Similar materials use cement and Plaster as binders and quartz sand as aggregate. The sensitivity of similar indicators of similar materials to control factors was analyzed through range statistics. Multiple regression analysis was used to establish the quantitative relationship between each control factor and similar indicators. Finally, the optimal matching scheme was refined through the combination of fuzzy mathematics and analytic hierarchy process. The results show that the physical and mechanical property indicators of similar materials with different proportions have a wide distribution range, and under certain similar conditions, they can meet the requirements of rock model tests with different properties. The aggregate-binder ratio is a direct indicator of material density, elastic modulus, and compressive strength. The main controlling factors, material density, elastic modulus, and compressive strength all increase with the decrease in aggregate-binder ratio. The cement-plaster ratio is the main control factor of material water absorption, and the water absorption gradually decreases with the increase of the cement-plaster ratio. The formula obtained through linear analysis can better represent the changing trend and distribution characteristics of various parameters of similar materials with the aggregate-binder ratio and cement-plaster ratio, and initially optimize the proportioning scheme of similar materials. Use fuzzy mathematics to evaluate the membership degree of each parameter index of similar materials, and the optimal ratio scheme was further determined to improve the credibility of later model experiments.

Study of Lightweight Ceramic Matrix-Less Syntactic Foam Composed of Cenosphere Using Spark Plasma Sintering.

The current investigation presents porous ceramic materials prepared with cenospheres (CS) by using spark plasma sintering. The impact of sintering temperature, mould diameter (20, 30 and 50 mm) and cenosphere size on the properties of the sintered material was investigated. Shrinkage of the samples during sintering started at 900 °C. Total sample shrinkage during sintering increases with increasing temperature and decreases with increasing mould size; increasing sample sintering temperature increases the apparent density of all sample series CS 63-150 µm in a 20 mm mould from 0.97 to 2.3 g·cm-3 at 1050-1300 °C; in a 30 mm mould, 0.81-1.87 g·cm-3 at 1050-1200 °C; in 50 mm mould, 0.54-0.75 g·cm-3 at 1050-1150 °C; while CS 150-250 µm in a 20 mm mould is 0.93-1.96 g·cm-3 at 1050-1200 °C. Total porosity decreases from 61.5% to 3.9% by increasing sintering temperature from 1050 to 1250 °C, while open porosity reduces at lower temperatures, with closed porosity being highest in samples sintered at 1150 °C. When the sintering temperature increases from 1050 to 1300 °C, the compressive strength of the CS 63-150 samples produced in a 20 mm mould increases from 11 MPa to 312 MPa. These results correlate with the Rice model, which describes an exponential dependence of compressive strength on material porosity and fully dense material compressive strength.

The development of glutin-based biocomposite materials with advanced hydrophobicity

Biocomposite materials, which contain components of natural origin, have low resistance to water absorbtion due to high lyophilicity of components. It leads to quick destruction of biocomposite products under the conditions of high humidity exploitation that defines the necessity and importance of conducting scientific research in this sphere. The aim of the article is to research the hydrophobic additives influence on the compressive strength and hygroscopicity of biocomposite materials consisting of glutin matrix (100 parts by weight) and wood flour (100 parts by weight). The technology of forming biocomposite materials includes a step-by-step pressing the composition at a pressure of 10-15 MPa and a heat treatment of the product in a press mold at a temperature of 140°C. Experimental methods of investigating the biocomposite materials compressive strength and hygroscopicity were used in the work. It was experimentally determined that the modifying additive (paraffin) optimal content is 4 parts by weight per 100 parts by weight of biopolymer matrix. At this content, there is an increase compressive strength by 2.8-4.6 times of the biocomposite materials compared to biocomposites with different paraffin content. As a result of the state analysis of biocomposite samples which were destroyed under the static loading influence, the features of the cracks occurrence and propagation in biocomposites depending on different modifying additive content, the conduct of the composition preliminary processing or biocomposites additional processing in a thermal field were determined. The use of protective hydrophobic coatings on the biocomposite samples surface provided an increase in the biocomposites resistance to the moisture negative influence. The most effective were coatings based on a paraffin solution, which provided a reduction in water absorption by 45-50% compared to biocomposites coated with wax, drying oil Oksol, and sunflower oil. The complex use of hydrophobic substances as modifying additives and protective coatings has practical significance, as they positively affect the processes of forming the structure, increasing the strength and hydrophobicity of biocomposite materials used in a humid environment

PENGARUH NILAI SLUMP PADA KUAT TEKAN BETON DENGAN CAMPURAN AIR PAYAU

Concrete is a combination of constituent materials which consists of hydraulic cement (portland cement), coarse aggregate, fine aggregate, water, and additives. Generally, the use of concrete starts from the bottom construction to the top construction. In use in under construction, concrete will be in a variety of environments, one of which is an aggressive environment such as brackish water. This study aims to determine the ratio of the compressive strength of concrete and the split tensile strength of concrete in a mixture of brackish water and the concrete's compressive strength at various slump values (25–50 mm), 75–100 mm), 150–175 mm), and (> 175 mm). This research method uses an experimental research method at the Civil Engineering Laboratory, Faculty of Engineering, Muhammadiyah Parepare, in June–August 2022. The research results obtained show that the brackish water mixture in concrete results in a 10% decrease in the material's compressive strength compared to normal concrete and split tensile strength. The compressive strength of brackish water-mixed concrete with slump variation (75–100) is an average of 2.67 MPa, which is 10.68% of the normal concrete compressive strength value of 25 MPa. The compressive strength of brackish water mixed concrete with slump variation (75–100) is the result of the highest concrete compressive strength compared to other slump variations, and the compressive strength of brackish water mixed concrete with slump variation (> 175) is the lowest in concrete compressive strength results compared to other slump variations.

Transverse isotropic compression behavior of aligned steel fiber UHPC produced by electromagnetic field

Aligned steel fiber ultra-high performance concrete (ASF-UHPC) demonstrates transverse isotropic mechanical properties. Specifically, when subjected to compressive stress perpendicular to the fiber orientation, surface cracks emerge proximate to the fiber tips, resulting in a significant enhancement of the material's compressive strength. Conversely, under compressive stress applied parallel to the fiber direction, fissures manifest along the fiber orientation, leading to a notable reduction in compressive strength. Consequently, the primary contributory factor underlying augmented compressive strength is the lateral restraint effectuated by the fibers. The optimization of fiber distribution for the aim of altering compressive strength is subject to the influence of the qualities of the UHPC matrix. Moreover, a comprehensive analysis extends to the examination of pertinent parameters, encompassing fiber volume fractions, fiber lengths, and fiber shapes. Investigation of these facets reveals an optimal range of fiber volume fraction, approximately 1.0% to 1.5%, which imparts maximal compressive strength in ASF-UHPC subjected to compressive stress perpendicular to the fiber orientation. When forces are applied parallel to the fiber direction, the incorporation of longer fibers or hooked-end fibers mitigates the reduction in compressive strength perpendicular to the applied stress. The consideration of the transverse mechanical attributes exhibited by aligned steel fibers, coupled with the optimization of fiber distribution characteristics, not only attenuates steel fiber consumption but also underscores a sustainable approach by curtailing CO2 emissions.

PENGARUH NILAI SLUMP PADA KUAT TEKAN BETON DENGAN CAMPURAN AIR PAYAU

Concrete is a combination of constituent materials which consists of hydraulic cement (portland cement), coarse aggregate, fine aggregate, water, and additives. Generally, the use of concrete starts from the bottom construction to the top construction. In use in under construction, concrete will be in a variety of environments, one of which is an aggressive environment such as brackish water. This study aims to determine the ratio of the compressive strength of concrete and the split tensile strength of concrete in a mixture of brackish water and the concrete's compressive strength at various slump values (25–50 mm), 75–100 mm), 150–175 mm), and (> 175 mm). This research method uses an experimental research method at the Civil Engineering Laboratory, Faculty of Engineering, Muhammadiyah Parepare, in June–August 2022. The research results obtained show that the brackish water mixture in concrete results in a 10% decrease in the material's compressive strength compared to normal concrete and split tensile strength. The compressive strength of brackish water-mixed concrete with slump variation (75–100) is an average of 2.67 MPa, which is 10.68% of the normal concrete compressive strength value of 25 MPa. The compressive strength of brackish water mixed concrete with slump variation (75–100) is the result of the highest concrete compressive strength compared to other slump variations, and the compressive strength of brackish water mixed concrete with slump variation (> 175) is the lowest in concrete compressive strength results compared to other slump variations.

Self-updatable AI-assisted design of low-carbon cost-effective ultra-high-performance concrete (UHPC)

Machine learning has exhibited high efficiency in designing concrete. However, collecting the dataset for training machine learning models is challenging. To address this challenge, this paper develops an approach to collect concrete design data automatically based on information extraction techniques. The approach enables machine learning models to automatically track, extract, and learn knowledge embedded in data from relevant publications. The approach has been incorporated into AI-assisted design of low-carbon cost-effective ultra-high-performance concrete (UHPC) via integrating the capabilities of automatically collecting and processing data, predicting UHPC properties, and optimizing UHPC properties regarding the material cost, carbon footprint, and compressive strength. A self-updating mechanism is imparted to continuously learn available data. Such a mechanism enables the self-updatable automatic discovery of low-carbon cost-effective UHPC. The results showed increasing prediction accuracy and optimization performance of the proposed approach over time when more knowledge was learned from new data, therefore accelerating the design of UHPC.

Experimental investigation on electrical response and mechanical performance of cementitious materials at low temperatures

In cold regions, concrete structures suffer from low temperatures, where damage will initiate due to the expansion of ice formation and accumulate with water supply to keep penetrating into the pores and cracks. Meanwhile, it is found that the mechanical properties of cementitious materials can be enhanced owing to the pores filled by ice. Therefore, it is important to evaluate the freezing process, in which the freezing action can have both strengthening and damaging effects on the mechanical properties of concrete material, depending on several environmental and material factors. Besides, if temperature remains negative, the capacity of cementitious materials in service with ice presented inside pores and cracks are also important. However, there is still lack of effective evaluation methods for the mechanical properties of frozen concrete. In this study, cementitious materials with/without air entraining agent (AEA) of different water-to-cement ratios (W/C) are prepared and tested at low temperatures (−10, −20, −30 and −40 °C). The results show that the mechanical properties of the materials (compressive strength, splitting tensile strength, dynamic elastic modulus) are closely related to electrical resistivity, which is further explained by the impact of air voids and pore structures from a multiscale scheme. It proves that the change of resistivity could be adopted as the index to evaluate the performance of frozen concrete, and an empirical model is derived based on the experiment results.

INFLUENCE OF FINENESS MODULUS AND PREHEATED SAND ON COMPRESSIVE STRENGTH OF ALKALI ACTIVATED GEOPOLYMER MORTAR

Geopolymer mortar is a complex material, and its strength and durability fundamentally depend on its main constituent properties, grading and grain size distribution of a fine aggregate. The Fineness Modulus (FM) of fine aggregates (sand) is an empirical figure obtained by adding the total percentage of the sample of sand retained on each of a specified series of sieves and dividing the sum by 100. The purpose of this research is to analyze the effect of the Fineness Modulus (FM) of preheated sand at 100°C on geopolymer material (GPM) compressive strength (Cs). The current research used natural river sands of fineness modulus 1.85, 2.41, 2.79, 3.32 to prepare geopolymer material paste. The 36 cube specimens of 50 x 50 x 50 mm size were used to calculate the Cs of GPM paste at 3 h, 1 d, and 7 d. All specimens were kept in hot curing at 40°C for 3 h. The outcomes of the research showed that the sand fineness modulus has a significant impact on the GPM flow rate (%). The results indicated that rising the fineness modulus of sand enhanced the flow rate (%) of GPM paste. The GPM paste made with preheated sand of FM 1.85 (fine sand), and FM 2.79 (medium sand) at 100°C attended the highest compressive strength growth rate (%)and showed up to 47% and 51%, 85.6% and 87.27% increased in compressive strength in 3 h and 1 d, accordingly. Additionally, the fineness modulus has a significant impact on the Cs of GPM paste in the case of preheated sand. Fine sand and mild sand are the best type of fine aggregate to develop early-high-strength geopolymer material.

Evaluating the effects of steel and polypropylene fibers reinforced concrete using mechanical tests

Concrete has excellent compressive strength. However, it has low tensile strength, which depends on factors such as the size, shape and surface roughness of the aggregates, as well as the resistance of the cementitious paste. This study suggested incorporating two distinct fibres into concrete. Steel and propylene are two types of fibres with different properties. An experimental investigation mainly focuses on a ratio of 1.5% fibres to the volume of concrete; the ratio of steel-to-propylene is adjusted to percentages of C1:(100:0), C2:(75:25), C3:(50:50), C4:(25:75), and C5:(0:100) from steel to propylene. So, this research is expected to answer the basic question of whether, if one style of construction is sensitive to fire, others can be used to prevent catastrophic structural failure. Experimental experiments were conducted to explore the effect that adding fibre would have on the material's compressive strength, tensile strength, and flexural strength.

Compressive strength prediction of carbon fiber-reinforced pultruded profiles including realistic volumetric fiber orientations

A compressive strength prediction method considering 3D fiber orientation distributions is developed. The method quantifies volumetric fiber orientations using the structure tensor image analysis method on X-ray computed micro-tomography data. The estimated fiber orientations are subsequently mapped to a finite element mesh. The finite element model is solved using a three-dimensional non-linear constitutive model implemented as a user-subroutine in AbaqusTM. A model capable of describing the elastic–plastic behavior of fibrous composites and simulating strain localization in the form of kink bands. The compressive strength of a carbon-epoxy pultruded profile is predicted based on three volumetric subsets of the profile and compared with experimental obtained compression test measurements. The strength predictions of the three volumetric subsets are in the range of 16%–42% higher than the experimental results. It is argued that the experimental results do not represent the full potential of the material compressive strength due to stress concentrations at the load introduction and that the model predictions can describe a potential for the actual compressive strength of the carbon-epoxy pultruded profile.

EFFECT OF RESAM FIBER ADDITION (Dicranopteris Linearis) ON THE CHARACTERISTICS OF CONCRETE

This study discusses the effect of the addition of resin fibers (Dicranopteris linearis) on the characteristics of concrete. The purpose of fibers to the characteristics of concrete. horns, anti-termite, not easily broken and resistant to humid air and is a plant that grows a lot in Pagar Alam City area. Therefore, the researchers decided to examine the effect of adding resin rod fibers to the characteristics of concrete. characteristics of this concrete is an experimental method that is tested, namely the physical material test, slump test, compressive and flexural strength of concrete. Experiments with the addition of resin rod fibers to the concrete mix of 0.5% of the weight of normal concrete cement. All samples were tested at the age of 3,7,14,21 and 28 days. Based on the test results, 3 cm and 5 cm long resin fibers were used. At 3 cm compressive strength of 28 day old concrete decreased by 0.36% from normal concrete with flexural strength increased by 0.02% of normal concrete while at 5 cm compressive strength of 28 day old concrete decreased by 0.66% of concrete normal while the flexural increase as much as 0.04% of normal concrete. The decrease in compressive strength is due to the addition of impregnated fibers into the concrete which will create more voids or voids in the concrete, the reduced density of concrete and disruption of the bond between cement and other concrete aggregates and the increase in flexural strength is caused because the resin fibers play a role in resisting cracks due to the pressure exerted by them. occurs in the concrete so as to increase the flexural strength of the concrete.

High thermal inertia mortars: New method to incorporate phase change materials (PCMs) while enhancing strength and thermal design models

This study proposes and tests a new method to incorporate Phase Change Materials (PCMs) into construction materials to increase building envelopes' thermal inertia without causing a decrease in the material's compressive strength. Mortars with three water-to-cement ratios (0.45, 0.55, 0.65) and, therefore, different porosity were used in this study as base materials. Following our novel procedure, PCM was incorporated into the pore structure of hardened samples through immersion into heated PCM in a liquid state and vacuum application for three different vacuum periods (15 min, 1 h, and 4 h). Final porosity, absorbed PCM volume, thermal conductivity, thermal effusivity, and compressive strength were determined. An increase in all studied properties was observed. The maximum enhancement was observed in samples with 0.65 w/c and 4 h of vacuum, which corresponded with the samples with the highest PCM incorporated (7.01 % of PCM by sample volume). This maximum increase was 17.86 % in thermal conductivity, 24.68 % in thermal effusivity, and 22.59 % in compressive strength. Besides, estimation models for the thermal properties and compressive strength were developed, showing high accuracy (errors lower than 10 %). These estimation models were combined to create a target-by-design system that determines the initial porosity and PCM content required to obtain a desired combination of compressive strength and thermal conductivity or effusivity. The thermal conductivity and effusivity of the solid part of the mortar (excluding the air) were obtained based on these models. These values can be very useful as an input for simulating the thermal behavior of cementitious composites using computational models.

Predicting mechanical development of mine functional mortar: experiment and thermodynamic analysis

Shotcrete mortar is an imperative material for tunnel surface supporting. The mine environment with different temperature affects the mechanical development of mortar, resulting in a difficult to predict its compressive strength development at high temperature. In this investigation, the compressive strength, hydration heat, mineral evolution, pore content of mortar samples at 20 and 60 °C, containing partial steel slag powder, were comprehensively compared by experiment and simulation in order to provide a reliable approach for underground materials compressive strength prediction. Results show that the compressive strength development of the samples cured at 20 and 60 °C, is consisted with the corresponding cumulative hydration heat, and the correlation coefficient is higher than 0.96. The hydrates and heat of the samples are significantly affected by the cement type, mineral admixture, and temperature. Indeed, increasing temperature significantly accelerates the minerals’ hydration and heat release. Combining the composition, pore and single mineral hydration heat simulation, the mortar compressive strength development of the mortar in deep mine can be predicted by a thermodynamic model.