Maximum Compressive Strength Research Articles

Evaluation of Compressive Strength of Concrete with Various Proportions of Stone Dust as Fine Aggregate

Concrete is the most dynamic engineering material in construction due to its durability and strength properties, which have been used in almost all types of physical infrastructure construction. Crushed stone dust is a supplementary material that can be utilized to produce sustainable concrete. The concept of replacing natural fine aggregate in concrete production with stone dust (SD) could enhance the consumption of stone dust produced during aggregate production as well as reduce the requirement for landfill area for stone dust management. The study aims to compare the compressive strength of nominal mixed M20 and M25-grade concrete by replacing fine aggregates with stone dust. The results reveal that compressive strength increases with an increase in stone dust, but the rise in SD percentages beyond a certain level has a negative impact on the strength of concrete. However, fresh density has a similar trend of compressive strength, and the workability of concrete shows a declining trend with a rise in SD levels. From the results of the experimental investigations conducted, it is concluded that the SD can be used as a replacement for fine aggregate. It is found that 40% replacement of fine aggregate by SD gives a maximum compressive strength than normal M20 and M25 grade concrete, which starts decreasing beyond 40% replacement. The compressive strength of the concrete has been quantified by replacing sand with varying percentages of stone dust and found that it does not satisfy the specification except for 40% replacement for M20 grade concrete, though it can be used for low and medium strength concrete production. The cost savings for M20 and M25-grade concrete at 40% sand replacement are 8.23% and 7.62%, respectively.

Effect of particle size distribution on the cryogenic mechanical properties of triple‐base propellants

AbstractFillers play a decisive role in the mechanical properties of polymer composites. In this paper, different particle sizes of nitroguanidine were obtained to regulate the internal filler structure of triple‐base propellants (TBP) to improve their mechanical response in different environments. A series of morphological and structural characterizations on nitroguanidine (NQ) particles were conducted using techniques. The results indicated that the obtained NQ particles maintained a high level of crystalline quality while preserving their molecular integrity. The mechanical properties of TBP were systematically evaluated under various loading conditions, including cryogenic tensile, compressive, and impact loads, as well as dynamic thermomechanical effects. Additionally, three‐point bending simulations were employed to elucidate the mechanical responses and damage mechanisms. Under axial tensile and compressive loads, reducing the particle size of NQ significantly enhanced the tensile and compressive strength. The maximum tensile strength and compressive strength can reach 344.62 MPa and 104.79 MPa. Moreover, the compressive failure mode transitioned from cracking to axial shrinkage. Conversely, when subjected to radial bending loads, TBP exhibited contrasting behavior, including a decrease in the glass transition temperature from 84.73°C to 76.93°C and a non‐monotonic trend in impact strength (initially increasing from 4.96 to 8.85 kJ/m2 and then decreasing to 2.27 kJ/m2). This study provides valuable insights into the mechanical performance of TBP, supporting the development of high‐energy, high‐strength TBP formulations.Highlights SEM analysis confirms the pronounced orientation effect of rod‐like NQ. The orientation and particle size of NQ decide TBP's radial impact resistance. Submicron NQ enhances the compression resistance property of TBP. Submicron NQ brings about a shift in the microscopic damage morphology of TBP.

Experimental Study on the Properties and Hydration Mechanism of Gypsum-Based Composite Cementitious Materials

In order to achieve the resourceful, large-scale and high-value utilization of bulk industrial solid wastes such as flue gas desulfurization gypsum (FGDG), fly ash (FA) and ground blast furnace slag (GGBS), and to reduce the dosage of cementitious materials, orthogonal experimental methods were used to prepare composite cementitious materials based on the principle of synergistic coupling and reconstruction of multi-solid wastes. Through the method of extreme difference and ANOVA, the influence law of different factor levels on the performance of the cementitious materials was studied, and the maximum compressive strength of cementitious materials was reached when the ordinary Portland cement (OPC) dosage was 20%, the FGDG dosage was 56%, the FA dosage was 19.2% and the slag dosage was 4.8%, and the W/B was 0.55. The hydration products and microscopic morphology of the cementitious materials were analyzed by means of XRD, SEM and MIP techniques, so as to elucidate the complex synergistic hydration mechanism, and then to determine the more optimal group distribution ratio. The results show that the hydration reaction between FGDG and OPC can be synergistic with each other, and C-A-H further generates AFt under the action of SO42−, and at the same time, it plays the role of alkali-salt joint excitation for FA–GGBS, generates a large amount of cementitious materials, fills up the pores of the gypsum crystal structure, and forms a dense microstructure.

Investigation of the Properties of Metakaolin-Based Geopolymer Materials Using Ferrisilicates as Additives Synthesised in Sodium Hydroxide Solution or Distilled Water

The main objective of this work is to investigate the behaviour of ferrisilicates prepared from hematite and two silica sources (rice husk ash and silica fume) on the compressive strength of geopolymer materials. Some ferrisilicates were synthesised in 2M sodium hydroxide solution. Others were prepared using distilled water as a solvent. The Fe2O3/SiO2 molar ratio contained in the ferrisilicates is set to 0.2. Metakaolin and sodium silicate solution with a molar ratio of SiO2/Na2O of 1.6 were used as the aluminosilicate and hardener in this work. The control geopolymer compressive strength is 53.34 MPa. For ferrisilicates prepared in alkaline solution using rice husk ash and silica fume, their compressive strength values are 71.91 and 77.72 MPa, respectively. The compressive strengths of the geopolymer materials made from ferrisilicates prepared in distilled water using rice husk ash and silica fume are 74.13 and 44.73 MPa, respectively. In the presence of ferrisilicate obtained by dissolving silica fume and hematite in sodium hydroxide solution, the maximum compressive strength of 77.72 MPa was obtained. When ferrisilicates from the mixture of silica fume, hematite, and distilled water are used as an additive, the minimum compressive strength of 43.73 MPa is achieved. It can be concluded that additives synthesised in an alkaline medium and those obtained in distilled water with rice husk ash improve compressive strength. On the other hand, the compressive strength of the geopolymer material that uses the additive produced with silica fume in distilled water is lower (44.73 MPa).

Strength and microstructural analysis of geopolymer prepared with coal-based synthetic natural gas slag

PurposeThe coal-based synthetic natural gas slag (CSNGS) is a solid waste remaining from the incomplete combustion of raw coal to produce gas. With the continuous promotion of efficient and clean utilization of coal in recent years, the stockpiling of CSNGS would increase gradually, and it would have significant social and environmental benefits with reasonable utilization of CSNGS. This study prepared a new geopolymer by mixing CSNGS with PC42.5 cement in a certain mass ratio as the precursor, with sodium hydroxide and sodium silicate solution as the alkali activators.Design/methodology/approachThe formulation of coal-based synthetic natural gas slag geopolymer (CSNGSG) was determined by an orthogonal test, and then the strength mechanism and microstructure of CSNGSG were characterized by multi-scale tests.FindingsThe results show that the optimum ratio of CSNGSG was a sodium silicate modulus of 1.3, an alkali dosage of 21% and a water cement ratio of 0.36 and the maximum unconfined compressive strength of CSNGSG at 7 d was 26.88 MPa. The increase of curing temperature could significantly improve the compressive strength of CSNGSG, and the curing humidity had little effect on the compressive strength of CSNGSG. The development of the internal strength of CSNSG at high temperatures consumed SiO2, Al2O3 and CaO and the intensity of corresponding crystalline peaks decreased.Originality/valueMoreover, the vibration of chemical bonds in different wavenumbers also revealed the reaction mechanism of CSNSG from another perspective. Finally, the relevant test results indicated that CSNGS had practical application value as a raw material for the preparation of geopolymer cementing materials.

Investigating silicon nanoparticles modified sandwich polymer composites for enhanced mechanical performance

ABSTRACT This study investigates the morphology and mechanical behaviour of a bidirectional interply hybrid sandwich polymer composite panel with the addition of silica nanoparticles (SiNPs). The investigation assesses the enhanced performance of sandwich polymer composite panels, focusing on their ability to withstand compression, Euler’s buckling axial load-bearing capacity, and surface roughness when subjected to low-velocity impact events that are barely perceptible for aircraft, automobile, and wind turbines. The composite panel was constructed using interply bidirectional Kevlar, carbon, and glass fibers, an epoxy matrix, and polyurethane (PUR) foam, with the incorporation of four different weight percentages of silica nanoparticles (0%, 2%, and 4% of SiNPs). The sandwich composite panel was fabricated using the hand lay-up technique, following a novel quasi-static stacking sequence method (01 K/01 C/01 G/PUR/01 G/01 C/01 K). Among these composite panels, the addition of 4 wt.% silicon nanoparticles exhibited the highest strength and axial load-carrying capacity compared to the other sandwich composite panels (0 wt.% and 2 wt.%). The mechanical characterisation results showed maximum compressive strengths of ca. 3 MPa, ca. 5 MPa, ca. 10 MPa, and ca. 8 MPa for the 0 wt.%, 2 wt.%, 4 wt.% and 6 wt.% of silica nanoparticles-added composite panels, respectively.

Study of the preparation and properties of hydrophobic and high strength geopolymers

An excellent hydrophobic geopolymer (GP) composite modified by fatty acid and polydimethylsiloxane (PDMS) with high mechanical strength was prepared successfully. The results of this research show that, when the mass fraction of fatty acid and PDMS were 50 % and 5 % respectively, the maximum water contact angle, 24 h minimum water absorption and maximum softening coefficient of GP obtained by composite modification method could reach 143°, 0.36 % and 0.88, respectively. Meanwhile, the maximum compressive strength exceeds 47.25 MPa.

Effect of elevated temperatures on behaviour of recycled steel and polypropylene fibre reinforced ultra-high performance concrete under dynamic splitting tension

This paper investigates the dynamic splitting resistance of ultra-high performance concrete (UHPC) incorporating recycled steel (RS) and polyethene (PP) fibres at various temperatures (i.e., 20, 200, 400, 600, 800 °C) and strain rates (i.e., 2.3−7.2 s−1). A series of tests are performed to evaluate the compressive strength, elastic modulus, uniaxial tensile strength, dynamic splitting properties and microstructural characteristics of UHPC at elevated temperatures. Results reveal that the maximum compressive strength, elastic modulus and uniaxial tensile strength of UHPC appear at 400 °C due to the promoted hydration of unhydrated clinkers at elevated temperatures. When the temperature increases from 20 °C to 400 °C, the dynamic splitting strength and dissipated energy of UHPC under the strain rate range of 6.8–7.2 s−1 increases by 30.9 % and 124.2 %, respectively. However, an opposite trend occurs with the dynamic splitting properties of UHPC decreasing with elevated temperatures of 400–800 °C, and accordingly the dynamic increase factor at 800 °C is only 61.8−73.7 % of that at room temperature. The synergistic effect of RS and PP fibre on the impact resistance of UHPC at elevated temperatures can be explained by: (i) the enhanced pore connectivity by PP fibres prevents explosive spalling of UHPC at elevated temperatures; (ii) the bridging and pull-out effects of RS fibres improve residual dynamic properties of UHPC after high-temperature exposure.

Thermal Activation of High-Alumina Coal Gangue Auxiliary Cementitious Admixture: Thermal Transformation, Calcining Product Formation and Mechanical Properties.

In this paper, a new preparation technology is developed to make high-alumina coal gangue (HACG) auxiliary cementitious admixture by calcining HACG-Ca(OH)2 (CH) mixture. HACG powders mixed with 20 wt.% CH were calcined within a temperature range of 600-900 °C, and the thermal transformation and mineral phase formation were analyzed. The hydration reaction between activated HACG-CH mixture and cement was also investigated. The results showed that HACG experienced a conventional transformation from kaolinite to metakaolin at 600 °C and finally to mullite at 900 °C, whereas CH underwent an unexpected transformation process from CH to CaO, then to CaCO3, and finally to CaO again. These substances' states were associated with the dehydroxylation of CH, the chemical reaction between CaO and CO2 generating from the combustion of carbon in HACG, and the decomposition of CaCO3, respectively. It is the formation of a large amount of CaO above 800 °C that favors the formation of hydratable products containing Al2O3 in the calcining process and C-A-H gel in the hydration process. The mechanical properties of HACG-cement mortar specimens were measured, from which the optimal calcination temperature of 850 °C was determined. As compared with pure cement mortar specimens, the maximum 28-d flexural and compressive strengths of HACG-cement mortar specimens increased by 5.4% and 38.2%, respectively.

The impact of waste brick and geo-cement aggregates as sand replacement on the mechanical and durability properties of alkali–activated mortar composites

This study explores the potential of waste brick and geo-cement aggregates as substitutes for natural sand in alkali-activated materials (AAMs) for mortar production. With a focus on achieving net-zero construction and mitigating environmental impact, the study replaces Portland Cement (OPC) and virgin aggregates with waste materials and by-products. The investigation evaluates the substitution of sand (up to 100 % by weight) in AAMs with waste brick aggregates (WBA) and waste geo-cement aggregates (WGA) obtained from demolished construction and research lab waste, respectively. The research methodology involves assessing mechanical, durability, and microstructure properties to assess the performance of the developed AAMs with waste aggregates. Notably, AAM composites containing waste brick and geo-cement aggregates surpass natural aggregate composites in terms of mechanical strength, water absorption, freeze-thaw resistance, acid ingress, and chloride attack. The 7-day 50 % waste brick mixture achieved a maximum compressive strength of 61 MPa, while a 70 % waste geo-cement mortar mixture attained a maximum flexural strength of 12 MPa. Combinations, whether comprising waste brick or geo-cement mortar aggregates, demonstrate compressive strengths well over 40 MPa, rendering them suitable for heavy load-bearing structures. The 50 % waste geo-cement mortar mixture stands out with the lowest water absorption rate of 6 % and the least compressive strength loss of 13 % after the freeze-thaw test, with reductions of 6 % and 18 %, respectively, compared to the control. Additionally, 100 % waste brick AAMs exhibit the lowest compressive strength loss after chloride and acid attack tests, with reductions of 13 % and 2.5 %, respectively. When compared to all other mixtures, the 50 % waste brick aggregates mortar mixture obtained the best overall performance. The composites developed in this study affirm their suitability for use in heavy-load structural components, showcasing favourable mechanical and durable properties. These findings underscore the need for additional exploration in this direction to advance sustainable construction practices.

Structural Characteristics and Cementitious Behavior of Magnesium Slag in Comparison with Granulated Blast Furnace Slag.

Magnesium slag is a type of industrial solid waste produced during the production of magnesium metal. In order to gain a deeper understanding of the structure of magnesium slag, the composition and microstructure of magnesium slag were investigated by using characterization methods such as X-ray fluorescence, particle size analysis, X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. In addition, the state of Si occurrence in magnesium slag was analyzed using a solid-state nuclear magnetic resonance technique in comparison with granulated blast furnace slag. An inductively coupled plasma-optical emission spectrometer and scanning electron microscope with energy dispersive X-ray spectroscopy were used to characterize their cementitious behavior. The results show that the chemical composition of magnesium slag mainly includes 54.71% CaO, 28.66% SiO2 and 11.82% MgO, and the content of Al2O3 is much lower than that of granulated blast furnace slag. Compared to granulated blast furnace slag, magnesium slag has a larger relative bridging oxygen number and higher [SiO4] polymerization degree. The cementitious activity of magnesium slag is lower compared to that of granulated blast furnace slag, but it can replace part of the cement to obtain higher compressive strength. Maximum compressive strength can be obtained when the amount of magnesium slag replacing cement is 20%, where the 28-day compressive strength can be up to 45.48 MPa. This work provides a relatively comprehensive analysis of the structural characteristics and cementitious behavior of magnesium slag, which is conducive to the promotion of magnesium slag utilization.

Improvement on engineering properties and volumetric stability of alkali-activated slag-based composite cementitious material with rice husk ash and magnesium oxide

This study used rice husk ash (RHA) and magnesium oxide (MgO) to improve the engineering properties and volumetric stability of alkali-activated slag-based cementitious material. Experimental results found that when the amount of slag substituted by RHA increased from 0% to 20%, the initial setting time was extended from 15 to 20 min, and the final setting time was shortened from 35 to 30 min for the paste without MgO. The optimal substitution amount of RHA was 10%, which had the maximum compressive strengths at ages of 28 and 56 days to achieve 104.44 and 102.43 MPa for the paste without MgO, respectively. The drying shrinkage of paste without MgO increased with both the increase of RHA from 0% to 20% and ages from 3 to 56 days. With RHA, the drying shrinkage substantially decreased with the substitutions of MgO from 0% to 2.0% and almost remained steady after ages of 7 or 14 days. The optimal amount of RHA to replace slag was less than 10% and the optimal content of MgO was less than 1%, which can effectively improve the volumetric stability and reduce the heat of hydration of paste.

Utilizing industrial byproducts for the manufacture of clay-cellulose nanocomposite cements with enhanced sustainability

This study investigates the influence of different nano clay contents (0, 1, 3, and 5 wt% of cement) on the microstructure and the mechanical properties of cement composites reinforced with varying Nano cellulose fiber contents (0, 0.5, 0.75, and 1 wt% of cement). Unlike previous research that employed sonication to improve dispersion in the cement matrix, this study explores the effects of unsonicated nano-cellulose addition and the combined incorporation of nano-cellulose and nano-clay. The results demonstrate that these additions significantly enhance the compressive strength, abrasion resistance, and water absorption ratios of the cement composites. Furthermore, the inclusion of nano-clay improves the microstructure of the cement matrix, strengthening the interfacial transition zone and reinforcing the bond between nano-cellulose and the cement matrix. The microstructural analysis using scanning electron microscopy (SEM) reveals the presence of a dense interconnected structure characterized by rod-like crystals. This research contributes to the development of sustainable construction materials by examining the effects of nano-cellulose and nano-clay on the properties and microstructure of cement composites. The utilization of industrial byproducts, such as wood sawdust, for the extraction of nano-cellulose offers an eco-friendly approach to enhance the performance of cement-based materials. The maximum compressive strength obtained, after 28 days, was at mix with 0.75% NCL + 5%NC with a gain of 53.5% than that of the control mix. In mixes containing only nano-clay (NCL), the increase in NCL content led to a higher rate of water absorption in the cement matrix, which reaches 4%. Confirming the results obtained from compressive strength and water absorption, mix with 0.75% NCL and 5% NC had obtained the optimum values with an improvement of 20% than that of the control mix.

Early mechanical performance of glass fibre-reinforced manufactured sand concrete

The use of manufactured sand as fine aggregate in concrete has been widely adopted in engineering to alleviate the shortage of natural river sand supply. However, there are many factors that affect the properties of manufactured sand concrete (such as the early shrinkage cracking phenomenon is more common than that in natural-sand concrete). In this study, glass fibre was added to manufactured sand concrete to improve its mechanical properties and determine the optimum content of manufactured sand and glass fibre. This study investigated the effects of the replacement rate of manufactured sand and glass fibre dosage on the compressive strength, flexural strength, and shrinkage of concrete. The results show that the optimal replacement ratio of the manufactured sand and ideal glass fibre dosage ranged 60%–80 % and 0.2%–0.3 %, respectively. Concrete exhibited significant improvements in various properties, including 22.97 %, 42.6 %, 7.1 %, and 34.7 % increase in the maximum compressive strength, peak strain, elastic modulus, and flexural strength, respectively. Concrete shrinkage was reduced by 16.1 %. Moreover, a reliable compressive constitutive model for concrete was established, demonstrating high accuracy in predicting the stress-strain relationship of glass-fibre concrete with manufactured sand. The combined utilization of manufactured sand and glass fibres proved to be effective in enhancing the mechanical strength and crack resistance of concrete.

Optimization of fused deposition modeling parameters to fabricate morphogenesis light weight structure with high tensile and compression strength

Fused deposition modeling (FDM) is a contemporary approach that can produce simple and complex physical models, prototype tools, and functional components. However, the challenge is choosing the right parameters, which are essential to printing a high-quality Additive Manufactured (AM) structure with acceptable mechanical attributes, like mechanical strength. In the additive manufacturing technique, fabricating a lightweight structure without compromising the weight and shape is very difficult because the significant parameter is infill density (D) %, which is directly proportional to the strength and inversely proportional to the weight. In this research based on morphogenesis, the infill density is varied at different locations wherever it is needed to print a lightweight, high-strength structure. Parameters Layer Thickness (LT), Shell Thickness (ST), and D were chosen, and experiments were conducted as per Central Composite Design (CCD). Tensile Strength (TS) and Compression Strength (CS) samples were printed with PLA and tested. The results were used to develop a multi-objective function. To predict maximum TS and CS without compromising the weight, Particle Swarm Optimization (PSO) and Response Surface Methodology (RSM) techniques were used to solve the multi-objective function. PSO predicts that the optimum printing parameter values for achieving a lightweight, high-strength structure are LT of 0.17 mm, ST of 0.91 mm, and D of 11.3%. These predicted results were confirmed through experiments.

Soil crust development on playa surfaces of Lake Urmia and its controlling factors: New insights to combat dust sources

The recession of lake shores, including the ones of Lake Urmia (LU), and later exposure of the lake bed sediments to wind erosion as a consequence of climate change and drought, is a devastating phenomenon worldwide. In the absence of stable surface crusts, these areas can be the source of airborne dust causing health and environmental issues. The present study aims at investigating the crust formation and development on Lake Urmia playa (LUP) surfaces through physicochemical and morphological studies and to determine the major factors affecting crust stability. To achieve the above goals, 50 soil crust samples from playa surfaces of the western LU playa were collected. The soil crust thickness and compressive strength were determined by a digital micro penetrometer. By means of X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), the main morphological and chemical factors responsible for the crust development and evolution in LUP were identified. Results showed that crust samples from clay flats (CFs) and clay flats-salt crusts (CF-SC) possessed the most stable crusts with a thickness of 2.2 and 1.9 cm and maximum compressive strength of 6709 and 7399 kPa, respectively, while sand sheets (Sa-sheets) showed weak and locally restricted crust development. Evaluation of correlation coefficients (CC) between soil crust physicochemical properties and crust stability parameters revealed that clay, silt, and organic matter enhance the crust stability and decrease the erodible fraction by increasing the crust thickness, while salt content quantified as Na+ concentration and electrical conductivity increase the firmness of the crusts. Interestingly, total carbonates quantified as calcium carbonate equivalent (CCE) correlated negatively with crust stability although pedogenic calcite is known as cementing agent in soils. XRD together with FTIR spectroscopy revealed that calcite is indeed the predominant mineral form in most soils with the exception of Sa-sheets with the highest share of carbonates, in which aragonite prevailed over calcite. While carbonates of pedogenic origin act as cementing agent, geologic carbonates present as coarse aragonite particles decrease soil stability. Therefore, samples with the highest total carbonate content exhibited the weakest crust, which explains the negative correlation between soil crust and CCE. SEM coupled with Energy Dispersive X-ray (EDX) and elemental mapping revealed that NaCl is the major cementing agent of the soil particles in crusts developed on LU playa surfaces. Its coexistence with phyllosilicates has increased the crust stability and resilience against wind erosion in CF and CF-SC samples while in the Sa-sheet samples, the absence of clay-size minerals (silt and clay) along with the prevalence of geologic carbonates (dolomite and aragonite) and lower NaCl content, limited crust formation and stability. This study emphasizes the importance of the intrinsic soil physicochemical properties together with the secondary (pedogenic) carbonate formation and more importantly the presence of NaCl, as the best determining factors controlling crust formation over LU playa surfaces.

Properties of Ultra-High Performance Concrete incorporating iron tailings powder and iron tailings sand

Iron tailings (IT) is a kind of solid waste, which is usually divided into iron tailings powder (ITP) and iron tailings sand (ITS). It has been reported that IT has potentials to be used in ultra high performance concrete (UHPC). However, the recovery rate of IT is relatively low, and rare research mentioned the co-utilization of ITP and ITS to get full-scale use of IT. Therefore, in this study, ITP and ITS with different replacement ratio were used to replace cement and quartz sand, respectively, in UHPC. The effects of ITP and ITS substitution on the mechanical properties, microstructure, hydration products, durability and environmental evaluation of UHPC mixtures were studied. The optimal ITP replacement ratio is 20% that 20% ITP-contained UHPC mixtures had better mechanical properties. Further increasing the ITS replacement ratio, the mechanical properties initially increased and then suffered a reduction. The UHPC with 20% ITP and 50% ITS had the maximum compressive strength (145.6 MPa) and flexural toughness (110.99 N·m). Appropriate addition of IT could improve the microstructures of UHPC mixtures by its filler effect and pozzolanic potential. The average pore diameter was reduced from 97.00 nm to 27.04 nm, and the ratio of harmful pores (＞ 100 nm) was reduced from 85.7% to 60.9% when ITP and ITS were added. In the durability tests, the addition of IT has less effect on the electric flux passed. Owing to the pores refining effect of IT, the drying shrinkage of UHPC mixtures was reduced. According to the environmental evaluation, the amount of leached heavy metal ions can be neglected. The IT contained UHPC had relatively low green degree and ITS/ITP surplus in 1 m3 UHPC production which implies its good environmental performance. Overall, ITP and ITS can be co-used in developing environmentally friendly UHPC to minimize the environmental burdens.

Sustainable upcycling of artificial lightweight cold-bonded aggregates (ALCBAs) designed by biochar and concrete slurry waste (CSW) into porous carbons materials for CO2 sequestration

CSW (Concrete Slurry Waste) is a hazardous solid waste due to its high alkalinity, and traditional landfill disposal wastes a lot of land. To effectively recycle CSW, this project applied it, ordinary Portland cement (OPC), and Biochar (BC) into designing artificial lightweight cold-bonded aggregates (ALCBAs) by disc granulation. A new test device for evaluating the amount of carbon absorption in ALCBAs was designed and ALCBAs adding ultra-high volume of CSW (CSW-ALCBAs) with BC dosage of 0%, 5%, 10%, and 15% were designed, respectively. The compressive strength, water absorption rate, carbon-sequestration efficiency, pores, hydration phase, and ecological properties of CSW-ALCBAs were also investigated under standard, carbonation, and sealing curing conditions. The results showed that CSW-ALCBAs had obvious carbon-sequestration potential, and the maximum carbon absorption was 18.2 wt% at 15% BC dopsage and the minimum carbon absorption was 16.2 wt% at 5% BC doping. Also, the carbon absorption of CSW-ALCBAs increases with the rise in BC dosage. Besides, the compressive strength in standard and sealed curing conditions peaked at 5% BC dosage, about 2.76 MPa, and then decreased rapidly with increasing BC dosage, and the compressive strength drops to 1.86 MPa at 15% BC dosage. Carbonization condition can improve the mechnaical and physical properties of CSW-ALCBAs with water absorption rate in the range of 6%− 13%, and the maximum compressive strength was about 6.18 MPa. And the compressive strength with the lowest and highest increasing rate in the groups under 28-d carbonized condition were in groups B5 and B10, where the compressive strength increased by 56% and 215%, respectively. Additionally, the total porosity of CSW-ALCBAs is in 13%− 23%, and the BC can provide abundant harmless pores (<50 nm) and store sufficient water. The BC could result in the internal curing effect, and the hydration products such as CH, CC, C-S-H, and AFt could be clearly observed. The choice of 5% BC doping for developing green CSW-ALCBAs is very promising. Overall, this study provides a novel method for the production of carbon-negative aggregates, which not only helps to address the recycling of massive CSW, but also opens up new channels for CSW recycling and CO2 sequestration. Meanwhile, compared with the previous reports about the recycling of CSW has been explored in various ways of utilization and curing regimes, this project explores its potential for carbon capture and investigates the changes in various properties of CSW-ALCBAs after carbonization.

Study of Making Concrete Block Using Gawan River Sand and Coal Waste (Bottom Ash) with Portland Cement Padang Viewed from the Perspective of Strength and Production Costs

Data from the DPUPR of Sragen district, the price of Merapi sand in 2020 is IDR 1,590,000 then in 2021 the price of Merapi sand is IDR 1,680,000. The increase in the material price of Merapi sand in Sragen Regency has forced the brick maker UD. Cerah, whose address is in Dayu village, Jurang Jero sub-district, Karangmalang subdistrict, Sragen district, is again racking her brains to set a selling price for the bricks to avoid losses. The making of the brick itself cannot be separated from the costs incurred for purchasing raw materials, purchasing equipment for making bricks, and labor costs. So with the high price of Merapi sand material, it requires that the brick maker, UD. Sunny innovates by replacing the cheaper sand material. In this study using experimental methods for making bricks, using the full costing method for calculating production costs and using the depreciation method to obtain the annual depreciation load for brick machines. Based on research on the characteristics of fine aggregate river sand from Ngipang village, Gawan subdistrict, Tanon sub-district, Sragen district, the results of testing for silt content, testing for organic matter content, testing for specific gravity and water absorption, gradation testing met the requirements while testing for saturated surface dry (SSD) did not meet the requirements. Then research on the characteristics of fine aggregate from coal waste (bottom ash) obtained the results of testing for mud content, testing for organic matter content, testing for gradation that met the requirements while testing for specific gravity and water absorption, testing for saturated surface dry (SSD) did not meet the requirements. Based on the research on the compressive strength test of the bricks, it was found that the compressive strength of the bricks from river sand, Ngipang village, Gawan sub-district, Tanon sub-district, Sragen district was greater than the compressive strength of the bricks from coal waste (bottom ash), the maximum average compressive strength value of bricks from river sand in the village Ngiang, Gawan sub-district, Tanon sub-district, Sragen district obtained a value of 6.51 MPa on the 1PC : 5PS FAS mixture variation of 0.5, while the maximum compressive strength value of bricks made from coal waste (bottom ash) obtained a value of 5.10 MPa on the variation mix 1PC : 5BA FAS 0.6. Based on research on the production costs of making bricks, it was found that the production costs of making 1 m3 of river sand bricks in Ngipang village, Gawan sub-district, Tanon sub-district, Sragen district were greater than the production costs of making 1 m 3 of coal waste (bottom ash) bricks, the production costs of 1 m3 river sand bricks in Ngipang village, village Gawan, Tanon sub-district, Sragen district, the highest is in the mix variation of 1PC: 5PS FAS 0.6 with the production cost of IDR 962,237.49, while the largest 1 m3 coal waste (bottom ash) brick production cost is in the 1PC mix variation: 5BA FAS 0.6 with a production cost of IDR 659,285.51.

Microstructure and properties of a shape memory alloy Ti–Ni–Al–V fabricated by double-wire arc additive manufacturing

In this study, a novel heterogeneous double-wire arc additive manufacturing method was used for the in-situ synthesis of a novel Ti–Ni–Al–V alloy wall. The results indicated that the synthesis wall was composed of the NiTi2, B2, and Ni4Ti3 phases from the bottom to the top. With an increase in deposition layers, the Ti2Ni content decreased. The hardness at the bottom was ∼685.4 HV0.2, while that of the middle and stable regions was 553 HV0.2. The maximum compressive strength was 2100 MPa. The fracture morphology was brittle. After cyclic compression, the recoverable and unrecoverable strains were 4.79 % and 1.21 %, respectively, indicating excellent recovery characteristics.