Optimal Proportion Research Articles

PERFORMANCE EVALUATION OF PALM OIL CLINKER AS CEMENT AND SAND REPLACEMENT MATERIALS IN FOAMED CONCRETE

Cellular lightweight concrete (CLC), also known as foamed concrete, has been extensively used in construction for decades. Foamed concrete’s properties include low density, excellent thermal conductivity, great workability, and selfcompaction; these features enable foamed concrete to be utilized in various contexts. However, the excessive use of conventional materials in concrete production harms the environment. Therefore, using agro-waste as a material to construct ecologically sustainable structures has numerous practical and financial benefits. Palm oil clinker (POC) is a waste product resulting from solid waste combustion during palm oil extraction. This research focused on the properties of foamed concrete with POC at 0%, 25%, 50%, 75%, and 100% as the fine aggregate replacement to develop lightweight foamed concrete (LFC) with a density of 1300 kg/m3. Besides, the potential of POC powder (POCP) and thermally activated POCP (TPOCP) at 0%, 10%, 20%, and 30% as cement replacements was examined. The development of compressive strength during a 90-day curing period was investigated. In addition, tensile and flexural strengths were assessed and reported, and the elastic modulus of the LFC was discussed. The transport properties of water absorption, porosity, and sorptivity were also investigated. The durability of concrete derivatives can exhibit the product’s resistance to chemical attacks and environmental conditions. After 75 days of immersion in hydrochloric acid and magnesium sulfate, the chemical resistivity of the produced LFC was determined by measuring the loss in weight and compressive strength. In addition, the effects of elevated temperatures on the LFC were determined by analyzing the mass loss and compressive strength degradation of specimens exposed to temperatures ranging from 200 to 800 °C. The test results demonstrated that the complete replacement of sand with POC enhanced the compressive strength of LFC by more than 50%. Similarly, POC-based LFC had higher flexural and tensile strengths than normal LFC. Besides, substituting 20% of cement with TPOCP could improve the strength of LFC by 23% during the initial curing days. Utilizing the optimal proportions of POC and POCP could enhance the residual strengths of LFC. Therefore, POC has the potential to be utilized as a fine aggregate and cementitious material to produce sustainable concrete.

Reuse of engineering waste soil and recycled fine aggregate to manufacture eco-friendly unfired clay bricks: Experimental assessment, data-driven modeling and environmental friendliness evaluation

In order to explore the possible application of engineering waste soil (EWS) and recycled fine aggregate (RFA) in cement-based unfired clay bricks (CUCB), this paper utilizes the orthogonal experiment to investigate the combined utilization of EWS and RFA to fabricate eco-friendly CUCB. The study employs an L9 (34) orthogonal table with four factors and three levels for designing mix proportions. The factors include the ratios of water-to-cement (w/c), cement-to-EWS (c/e), RFA-to-EWS (r/e) and additive content. CUCB were tested for density, compressive strength, and flexural strength; and the impact of each factor on these properties was analyzed. The test results reveal that the eco-friendly CUCB exhibit lightweight characteristics and desirable mechanical properties. The ratio of flexural strength-to-compressive strength for eco-friendly CUCB ranges from 0.23 to 0.28, indicating that eco-friendly CUCB have good toughness. Data-driven models were developed to construct the relationships between target properties (i.e., density, compressive strength, and flexural strength) and four factors. The optimal mix proportion for physical and mechanical properties was determined to be w/c= 0.55, c/e = 0.3, r/e = 0.4 and additive content= 10%, with predicted compressive and flexural strengths of 19.68 MPa and 5.19 MPa, respectively. In addition, Scanning Electron Microscope (SEM) was performed to figure out the strength enhancement mechanism of eco-friendly CUCB with varying mix proportions. Environmental friendliness evaluation shows that the optimal mix pro-portion is more environmentally friendly to fabricate CUCB from the perspective of strength-normalized carbon footprint and energy consumption. Using large quantity of cement cannot increase the compressive strength and only acts as filler in the microstructure of eco-friendly CUCB.

Experimental study on municipal solid waste incineration fly ash as a component of coal gangue geopolymer and the feasibility of making geopolymer mortar

In this study, municipal solid waste incineration fly ash (MSWI FA) was used as a component to supplement the missing element of Ca in the coal gangue (CG) to synthesize CG-MSWI FA geopolymer (CG-MFG). The mixed NaOH and Na2SiO3 solution is adopted as alkali activator. The influence of MSWI FA content, NaOH/ Na2SiO3 ratio, liquid–solid ratio and NaON concentration on the strength and reaction on the CG-MFG is studied by unconfined compressive strength (UCS), XRD, FTIR, TGA and SEM-EDS tests. The heavy metal leaching concentration of the CG-MFG is investigated by ICP-OES test. The test results show that MSWI FA acted as a supplementary calcium source for CG is capable of effectively improving the UCS of the CG-MFG. The optimal dosage of MSWI FA is 15 %. The NaOH/ Na2SiO3 ratio significantly affects the strength of the CG-MFG and its optimal proportion is 25:75. The CG-MFG with 15 % MSWI FA content, 25:75 NaOH/ Na2SiO3, 0.45 liquid–solid ratio and 8 mol/L NaON concentration acquires the highest UCS of 30.28Mpa. The immobilization efficiency of heavy metals from MSWI FA in the CG-MFG is larger than 84.66 %. The energy consumption and carbon dioxide emission of preparing the CG-MFG is much lower than those of Ordinary Portland Cement (OPC) with reduction of 71.9 % ∼ 78.0 % and 70.1 % ∼ 82.9 %, respectively. The amorphous geopolymeric gels are observed as the main geopolymerization product of the CG-MFG. The UCS of the CG-MFG mortar reaches 4 MPa, showing possibilities of replacing cement by the CG-MFG in construction industry and shedding light on recycling of hazardous and solid wastes of MSWI FA and coal gangue.

Development of flexible grouting material for cement-stabilized macadam base using response surface and genetic algorithm optimization methodologies

To repair the voids and cracks in the Cement-stabilized macadam base (CSMB), a grouting material with lower elastic modulus, enhanced fluidity and slight expansion called Flexible Grouting Material (FGM) was developed using superfine cement, fly ash (FA), silica fume (SF), vinyl acetate-ethylene (VAE) copolymer emulsion, and polyvinyl alcohol (PVA) fiber. After that, the study optimized the proportion of FGM using Response Surface Methodology (RSM) and Non-dominated Sorting Genetic Algorithm-II (NSGA-II) in Multi-Objective Optimization (MOO). Firstly, to determine the component contents for subsequent experiments, the fluidity, setting time, compressive/flexural strength (1d + 3d), and ratio of compressive strength to flexural strength (C/F, 1d + 3d) were tested. Subsequently, the Response Surface Methodology-Box Behnken Design (RSM-BBD) was employed using VAE content, PVA content, and water-to-cement ratio (W/C) as factors. Additionally, the fluidity, setting time, compressive/flexural strength and C/F (28d), elastic modulus (28d), and drying shrinkage (28d) were considered as responses in RSM-BBD. The VAE content and W/C significantly influenced the response values, while the PVA content had a relatively minor influence. Finally, the NSGA-II was utilized to determine the optimal proportion of FGM. Compared to the control group, the optimal FGM demonstrated 16.53 % increase in fluidity, 37.86 % decrease in elastic modulus (28d), 47.98 % decrease in C/F (28d), 22.22 % reduction in drying shrinkage (28d), and 54.07 % increase in final setting time.

Enhancing concrete performance using protective coating fabricated by recycled waste material

The motivation behind this research is to enhance concrete using a coating fabricated from waste materials. Polyethylene terephthalate (PET) was added to asphalt (AP) cement of 60/70 penetration grade at different percentages. Scanning electron microscope (SEM) images show that 6% PET is the optimum mix proportion, and then ternary blends were done by mixing the prepared AP/PET with nano silica (nS) at different ratios (0.5, 1, 1.5, 2, and 2.5) wt./wt. The prepared coatings were evaluated by determining drying time, dry film thickness (DFT), adhesion strength, impact resistance, and flexibility. The formulated coatings were applied to concrete substrates, and the performance of coated concrete cubes was examined by determining water absorption, contact angle, and chloride diffusion. The durability of coated concrete was evaluated by measuring the changes in compressive strength after immersion in both sulfuric acid and sodium chloride solutions separately. The study proved the eco-efficient use of PET waste bottles in protective coating preparation, and the experimental results detected that nS has a significant mechanism for improving coating performance as follows; drying time of AP/PET-2 reduced with 61% as compared to AP/PET, the increment of DFT of AP/PET-2 was 25%, and adhesion strength was improved by 90%. On the same time, silica nano particles are mainly contributes for enhancing coated concretes. Where water absorption reduced with 75%, contact angle increased by 55%, and chloride permeability resistance enhanced to 40%. Finally, improvement durability of coated concrete was 25% and 20% after immersion for 28 d in both sulfuric (3%) acid and sodium chloride (5%) solutions, respectively.

Multi-objective optimization of one-part geopolymer mortars adopting response surface method

One-part geopolymers haveimmense potential in large-scale structures owing to their improved safety and convenience of handling over the conventional geopolymermixing procedure. Thus, this study aims at optimizing the mixes by assessing the influence of binder content, activator dosage and water to geopolymer solids (W/GS) ratio on the flowability, strength, and shrinkage properties of one-part geopolymer mortars (OPGM). The test results were utilized to develop models that could predict the desired properties of mixes and optimize the mix proportions of OPGMs using the response surface method. The fly ash and slag-based OPGMs were developed. The GGBS substitution was chosen as 25, 50, and 75% by volume of fly ash. The activator dosage was taken as 8, 12, and 16% by mass of total binder content at varied W/GS ratios of 0.35, 0.40, and 0.45. The responses considered were flowability, compressive and flexural strengths at 7 and 28 days, and drying shrinkage of up to 180 days. Total of 504 specimen were cast to record the observations for this optimization study. The GGBS content, W/GS ratio, and combined effect of these factors were found to be the most influential factors affecting the responses. The optimal mix proportion obtained consists of 49.8% GGBS, 13.6% activator dosage, and 0.37 W/GS ratio. This mix achieved 170.4 mm flow, 57.8 MPa and 5.9 MPa compressive and flexural strengths, respectively and also 1626 microstrain of 180 days drying shrinkage. The microstructural characterization adopting techniques like SEM, XRD, TGA and FTIR was carried out to study microstructural changes, mineral phases, thermal mass loss and molecular bonding of OPGM mixes. This study revealed that mix with 50% GGBS, 12% activator dosage and 0.40 W/GS ratio can better be characterized compared to other mixes.

Preparation of polyurethane concrete and its novel application in bridge expansion joint anchorage zone

The frequent damage and repair of bridge expansion joint anchorage zone has caused a great burden to the bridge maintenance work. The objective of this study is to prepare a steel fiber reinforced polyurethane concrete (SFPUC) with balanced multi-properties of workability, compressive strength, and flexural strength for the application in bridge expansion joint anchorage zone. A four-factor, five-level orthogonal experimental design was carried out to investigate the effects of the binder-aggregate ratio ( BA), cement content ( C), fine-coarse aggregate ratio ( FC), and steel fiber dosing ( SF) on the workability, compressive strength, and flexural strength, respectively. The multi-criteria decision-making (MCDM) method was used to transform the multi-response problem in the orthogonal experimental design into a single-response problem. Finally, a real engineering application and a finite element method were used to verify the feasibility of SFPUC for the expansion joint anchorage zone. The results show that the optimum proportion of SFPUC is BA (25%), C (20%), FC (20%), and SF (2.5%). The maximum principal stress in SFPUC anchorage zone is less than that in C50 steel fiber concrete anchorage zone under the same load. SFPUC is a highly promising material for bridge expansion joint anchorage zone repair.

Preparation of foam concrete from solid wastes: Physical properties and foam stability

The method for preparation of foam concrete from solid wastes were proposed in this study, where soda residue (SR), calcium carbide slag (CS), grand granulated blast-furnace slag (GGBS) and fly ash (FA) were used as raw materials for the binder and Al powder was used as the foam agent. The effects of Al powder, stabilisers and FA content on the dry density as well as compressive strength were assessed to determine the optimal mix proportions. Moreover, to understand the foaming process, the influence of stabilisers on the zeta potential and surface tension of the fresh mixes were measured and Low-Field Nuclear Magnetic Resonance (LF-NMR) was employed to qualitatively characterize the pore size distribution. Finally, the hydration products were analyzed by X-Ray Diffraction (XRD), Fourier transform infrared spectrometer (FTIR), Thermogravimetric Analysis-Differential scanning calorimetry (TGA-DSC), Scanning electron microscope-Energy dispersive X-ray spectroscopy (SEM-EDS). The results suggested that the optimal content of Al powder was 1–2%, and the combination of S and P (SP) stabilisers showed better stabilization effect than the single use of S or P, leading to well distributed foam with smaller size. The stabilization effect was attributed to the dissolved negative complex that absorbed on the foam film to increase the repulsion between foams as well as to reduce the surface tension of the fresh mixture. The substitution of GGBS by FA generally resulted in reduced dry density and compressive strength, while the extent varied with the addition of stabilizers, and thus the optimal amount of FA depended on the selection of stabilisers. Overall, our study highlighted the potential of using industrial waste materials for producing sustainable light weight concrete with satisfactory dry density and compressive strength.

Constructing a Z-scheme heterojunction photocatalyst I-ABN-C3N4@CDs/BiOI by synergistically in situ modified g-C3N4 via carbon dots and copolymerization for BPA degradation

The rapid recombination of photogenerated carriers and the narrow absorption range of visible light greatly limit the photocatalytic activity of graphite carbon nitride (g-C3N4). Herein, g-C3N4 was jointly modified by carbon dots (CDs) and copolymerization via in situ co-calcining of three precursors (urea, glucose and 2-amino-5-iodo-benzonitrile (I-ABN)), and named as I-ABNx-C3N4@CDsy. Then, solid-state Z-scheme photocatalysts PC1–PC9 with CDs as the electron mediators were prepared via in situ growth of BiOI on the surface of I-ABNx-C3N4@CDsy through solvothermal method. The optimal proportion of each component was explored through orthogonal experiments. The existence of CDs act as an electron transport medium to accelerate the transportation rate of photogenerated carriers, improve the light absorption capacity. The copolymerization with I-ABN introduce benzene rings and I− to g-C3N4, which enhance the light absorption capacity and photoelectric efficiency. The Z-scheme heterojunction effectively suppresses the recombination of photogenerated electron–hole pairs. Therefore, PC1–PC9 presented excellent performance for the degradation of BPA due to the synergistic effects of the above three points. Among them, PC6 showed the best photocatalytic activity, which completely degraded BPA (15 mg/L) within 40 min, and whose rate constant (0.091 min−1) was 22.8 times that of bulk g-C3N4. The active radical trapping experiment determined •O2− and h+ were the main active radicals. Finally, the BPA degradation mechanism by PC6 was proposed. This study provides new insights for the combination of heterojunction, carbon dots, and copolymerization to rationally design efficient photocatalysts to restore the environment.

Experimental Study About Effect Iron Slag on The Shear Strength of Reinforced Concrete Beams Without Shear Reinforcement

In the last decades, researchers have become more interested in the environmental aspect of investing materials harmful to the environment in various aspects of life, including construction. Slag is considered as one of the industrial wastes that are harmful to the environment. There are many studies on the use of slag as a substitute for building materials because it adds an excellent property to concrete. In this study, the iron slag was used as a partial replacement of coarse aggregate and fine aggregate in different proportions, the study conducts to know its effects on the shear strength of reinforced concrete beams. Ten R.C. beams without shear reinforcement (1100×100×200) mm were studied using iron slag as a coarse aggregate with a ratio of 10%, 20%, 30% and 40%, as a fine aggregate with a ratio of 10%, 20% and 30%, and partial substitute for coarse aggregate by 7.5% and partial substitute for fine aggregate by 7.5% in the same model, finally, partial substitute for coarse aggregate by 15% and partial substitute for fine aggregate by 15% in the same model. According to the test results, it was found that the optimal proportion of replacing slag with coarse aggregate is 20%, which resulted in a 24.58% increase in peak load. While the optimal proportion of replacing slag with fine aggregate by 20%, resulting in a 24.3% increase in peakload.

Mechanical properties and anti-efflorescence of cement-based coating containing silicon-aluminum based powder and modified-polyacrylate emulsion

The objective of this paper was to prepare a novel type of anti-efflorescence cement-based coating with excellent mechanical properties using the modified polyacrylate emulsion (MP) and silicon-aluminum based powder (SA), and provided an optimum proportion. Silica sol (SS) and polydimethylsiloxane (PDMS) were selected as modified components to incorporate into polyacrylate emulsion (PA). The synergistic effect of MP and SA on the tensile strength, water absorption, hydration process, microstructure and anti-efflorescence property of cement-based coatings were investigated. The research results demonstrated that the tensile strength and waterproof in coating containing MP and 0.3 wt% SA were increased by about 73.4% and 52.1%, respectively, compared with the reference sample. The reason could be attributed to the densification of the internal structure due to the formation of “Si-O-Si” structure and pozzolanic effect of SA. In addition, the hydrophobic PDMS can hinder the migration of water and salt, thereby limiting the diffusion of alkali ions outward. Hence, the efflorescence area of the modified-coating was decreased to 1.58%.

Construction of Z-scheme BiVO4/NaNbO3 piezo-photocatalyst with improved carrier separation for efficient removal of tetracycline

Piezoelectric catalysis combined with photocatalysis could use both solar energy and mechanical energy to degrade tetracycline pollutants, promising for application in environmental remediation but also facing challenges. This paper designed and synthesized a novel Z-scheme BiVO4/NaNbO3 heterojunction to obtain high piezo-photocatalytic activity. Under the co-acting of light radiation and ultrasound, the reaction rate constant (k) of optimal proportion BiVO4/NaNbO3(BV/NN-2) heterostructure on the tetracycline reached 0.028 min−1, which indicates that the piezo-photodecomposition ratio of TC is 1.33 times higher than the BiVO4. In addition, the degradation rate of the BV/NN-2 sample under light irradiation + ultrasonic vibration was 2.6 and 3.7 times higher than that on the condition of light irradiation and ultrasound, respectively. The results further revealed the coupling effect between piezoelectric catalysis and photocatalysis. The morphology observations revealed that the BiVO4 nanoparticles grow on the surface of the NaNbO3 nanorods. Photoluminescence demonstrated that Z-scheme BiVO4/NaNbO3 heterojunction exhibited higher current separation and transfer efficiency than BiVO4 and NaNbO3. BiVO4 produces many photogenerated carriers under visible light, which supplements the free carriers consumed by BiVO4/NaNbO3 piezoelectric catalysis and dramatically improves the catalytic activity. This study provided a promising strategy to enhance piezoelectric catalysis for removing antibiotic contaminants.

Enhanced photo-Fenton catalytic activity over Cu-doped Bi12O17-xCl2 nanotube for tetracycline degradation: Oxygen vacancies-induced mixed valent Cu

Fenton photocatalyst constructed by transition metal-doped semiconductor material seems to be a promising alternative to classic Fenton catalysts. A series of Cu-doped tubular Bi12O17Cl2 with sufficient oxygen vacancies (ov) was successfully prepared through a hydrothermal method. The formation of ov in the Bi12 crystal lattice can favor the Fenton reaction not only by serving as a reaction site and increasing the charge density in the photocatalyst but also by partially reducing the dopant Cu2+ to Cu+, which consequently enhances the H2O2 activation to a significantly higher rate. Notably, Cu-doped Bi12O17Cl2 ov with an optimal dopant proportion of 4 % exhibited a preferable Fenton catalytic rate 4.5 times higher than pure photocatalytic degradation. This work investigates the mutual promotion of oxygen vacancies and dopant ions in the Fenton reaction and provides a novel development scheme for the advanced oxidation process.

Effect of different activation techniques on the engineering properties of cement-free binder containing volcanic ash and calcium carbide residue

This study developed a cement-free binder using volcanic ash (VA) and calcium carbide residue (CCR) as an alternative binder to cement. First, the optimal proportions of VA and CCR were determined to achieve superior flow, compressive strength, and bulk electrical resistivity. After that, various activation techniques, namely physical (sieving the CCR on sieve No. 325), chemical (adding 1 % NaOH by binder mass to the paste), and thermal (curing the paste in an oven at 65℃ for 24 h), were used either exclusively or synergically to enhance the performance. The results show that the optimum VA:CCR was 95:5. The flow increased by chemical activation but decreased with physical activation. Using subsequent physical and chemical activation led to a slight increase in flow. Binders subjected to physical activation followed by thermal activation had the highest compressive strength of 31.2 MPa at 28 days of curing. In contrast, subsequent combined chemical and thermal activation produced superior bulk resistivity of 193 Ω.m at the same age compared to other activation techniques. Nevertheless, all activation techniques improved the strength and bulk resistivity. The calorimetric analysis confirmed that the emitted heat increased with different activation methods compared to the mix without activation, which agreed with compressive strength results. X-ray diffraction (XRD) analysis showed that the reaction products were calcium-silicate-hydrate and calcium-aluminate-silicate-hydrate gels. Scanning electron microscope (SEM) images confirmed that different activation techniques resulted in a denser microstructure than the inactivated VA-CCR paste. This cement-free binder contributes to the ongoing efforts to reduce the carbon footprint of cement-based materials by finding sustainable alternative binders to cement.

The Combination of Citicoline and Nicotinamide Mononucleotide Induces Neurite Outgrowth and Mitigates Vascular Cognitive Impairment via SIRT1/CREB Pathway.

Vascular dementia (VD) is characterized with vascular cognitive impairment (VCI), which currently has few effective therapies in clinic. Neuronal damage and white matter injury are involved in the pathogenesis of VCI. Citicoline has been demonstrated to exhibit neuroprotection and neurorepair to improve cognition in cerebrovascular diseases. Nicotinamide adenine dinucleotide (NAD+)-dependent sirtuin (SIRT) signaling pathway constitutes a strong intrinsic defense system against various stresses including neuroinflammation in VCI. Our hypothesis is that the combined use of citicoline and the precursor of NAD+, nicotinamide mononucleotide (NMN), could enhance action on cognitive function in VCI. We investigated the synergistic effect of these two drugs in the rat model of VCI by bilateral common carotid artery occlusion (BCCAO). Citicoline significantly enhanced neurite outgrowth in Neuro-2a cells, and the combination of citicoline and NMN remarkably induced neurite outgrowth in Neuro-2a cells and primary cortical neuronal cells with an optimal proportion of 4:1. In the rat model of BCCAO, when two drugs in combination of 160mg/kg citicoline and 40mg/kg NMN, this combination administrated at 7days post-BCCAO significantly improved the cognitive impairment in BCCAO rats compared with vehicle group by the analysis of the Morris water maze and the novel object recognition test. This combination also decreased microglial activation and neuroinflammation, and protected white matter integrity indicated by the increased myelin basic protein (MBP) expression through activation of SIRT1/TORC1/CREB signaling pathway. Our results suggest that the combination of citicoline and NMN has a synergistic effect for the treatment of VD associated with VCI.

Formulation and properties of a new cleaner double liquid alkali-activated grouting material

Herein, a new cleaner double liquid alkali-activated grouting material (DLAG) was successfully developed, which could be applied similarly to cement by adding water. Desulphurisation gypsum (DG) was selected to activate ground granulated blast-furnace slag (GGBFS) and fly ash (FA) to completely replace cement. The optimum proportion of the basic materials and admixtures were determined by a series of orthogonal and single-factor controlled variable experiments. The mechanism for the strength enhancement of the materials was interpreted by microscopic experiments. The optimum proportion of the basic materials was determined that slurry A comprised of only GGBFS, whereas DG, FA, and metakaolin (MK), were present in a mass ratio of 6:3:1 in slurry B. The single slurry maintained good workability over a long period before mixing, and the fluidity of mixed slurry could be dynamically adjustable from 138 mm to 215mm. The strength of solidified specimens reached 45.7 MPa at 28 days curing time, which was 220% higher than that of Portland cement. Microscopic analyses showed that Al2O3 and SiO2 in the precursor materials were continuously dissolved and reorganised to produce hybridised phase gels (C, N)-A-S-H (calcium, sodium aluminium silicate hydrate), and also hydrated with Ca2+, SO42− provided by DG to produce ettringite and calcium silicate hydrate (C-S-H) in the alkaline environment. The size and content of hydration products gradually increased with increasing curing time and acted together to enhance the strength of solidified body. The proposed material can promote the development of alkali-activated technology in the field of special grouting materials.

Study of the Cement Additives Effect on the Physical and Mechanical Characteristics of Rubber Material

The materials of the article are devoted to obtaining the material based on a mixture of natural rubber with the refractory cement filler in a certain proportion and the study of its physical and mechanical characteristics. The samples with different cement contents were formed to determine the optimal proportion of cement additives in the mixture. The resulting analysis showed that the material with a cement proportion of 15 (pphr) has the best characteristics, in which an increase in the values of the maximum tensile pressure (8.98 MPa) was achieved, a decrease in the values of elongation, while an increase in the value of hardness and wear resistance, and minimum level of absorption was observed when the samples were immersed in technical oil - by 1.29%.

An investigation of the bio-medical waste ash on cement mortar bricks

Personal protective equipment (PPE), and particularly face masks, have become widespread during the COVID-19 epidemic. One of the most pressing ecological, monetary, and social problems facing the world today is the proper disposal and management of solid waste. There may be incinerators in different parts of the globe, but biomedical waste (BMW) has always been a problem. The effect of using biomedical waste ash in lieu of fine aggregate on the compressive strength of cement mortar is discussed. Cement mortar mixes were created with ratios of 1:1, 1:2, and 1:2:4, as well as 5:15:5, 25%, and 35%. Results for 15% and 25% replacement of Bio-Medical Waste ash in concrete were favourable, but those for 35% replacement resulted in a decrease in compressive strength. The 15% replacement level is chosen as the optimal proportion after comparing all the experimental test findings.

Compressive Strength of Concrete using Rice Husk Ash Produced at Different Temperatures

This study focuses on the optimization of the burning temperature of furnace-incinerated rice husk ash (RHA) into a concrete mix design. The primary objective of this study is to investigate the optimum proportion of incineration temperature required to develop an amorphous silica from rice husk wastes and to determine the compressive strength of blended cement replaced partially at the ratio of 5%, 7.5%, 10.0%, and 12.5% of RHA, incinerated at temperatures of 600 °C, 700 °C, and 800 °C. The experimental test specimens, consisting of concrete cubes, were prepared and tested after 7, 14, and 28 days of water curing. The pozzolanic reactivity of RHA highly depends on the silica form. The silica form in the RHA is analyzed by chemical composition analysis and x-ray diffraction analysis based on the incineration period to decide if it is in the amorphous or crystalline form, with the identifying sample having a greater influence on the compressive strength. This study shows that the presence of RHA in concrete tends to improve compressive strength, especially at the early stages of curing, and the optimum replacement of cement with RHA in the concrete was 7.5% at the incineration temperature of 700 °C.

Multi-objective optimization of sponge facility layout in built-up urban areas

In order to effectively cope with the destruction of natural hydrological cycle mechanism, frequent urban flood, serious water pollution and other problems, which are caused by the rapid urbanization process, the ‘sponge city’ concept has been widely used in China. This paper mainly focuses on how to rationally arrange the sponge grey and green facilities in built-up urban areas. With background analysis as the premise, model construction as the platform and swarm intelligence optimization as the method, the optimal proportion of sponge green facilities is determined. Furthermore, gray facilities are strengthened for the problem area, and the optimal allocation scenario of sponge facilities with the combination of gray and green is obtained through continuous circulation. The final results show that the optimal layout proportion of rain garden, sunken green space, permeable pavement and green roof are 3.88%, 7.95%, 2.01% and 0.99% respectively, which can meet the 80% runoff control rate and 40% pollution load control rate in the standard. Based on the simulation results of 50a rainfall, regulation and storage facilities are arranged near the severely overloaded node and the diameter of the overloaded pipes are increased. It can be proved that runoff and pollution can be effectively controlled and urban flood can be alleviated with grey facilities by model. The research results of this paper are expected to provide the overall idea and method of layout optimization of grey-green facilities for sponge city construction in built-up urban areas.