Sand Ratio Research Articles

Eco Friendly Plastic Sand Bricks

Abstract: Since the large demand has been placed on building material industry especially in the last decade owing to the increasing population which causes a chronic shortage of building materials, civil engineers were challenged to transform waste to useful constructing and production substances. Recycling of such waste as raw materials alternatives might also make a contribution inside the exhaustion of the herbal assets; the conservation of non renewable sources; development of the population health and protection preoccupation with environmental matters and discount in waste disposal expenses. Use of plastic has grown substantially in recent years all over the world. It is inexpensive and without problems available and can be moulded into any form. But, plastic is non-biodegradable; it causes pollutants and create problems in coping with even for a wealthy kingdom., because of this have a look at changed into to investigate the surroundings-pleasant capacity use of plastic and display usefulness of plastic sand bricks as opportunity structural elements, replacing well known clay brick physical and mechanical homes of plastic sand bricks have been studied in distinctive plastic sand ratios.

Enhancing durability and sustainability of industrial floors: A comparative analysis of dry-shake surface hardeners

This study investigates the development of a cost-effective and sustainable dry-shake surface hardener for enhancing the durability of industrial concrete floors. Utilizing locally sourced materials, the research aimed at not only ensuring the hardener's strength and finish but also its economic viability and environmental friendliness. Fourteen unique mixtures were formulated by altering the sand ratios and incorporating superplasticizers to optimize the composition. These mixtures underwent rigorous testing over 7, 14, and 28 days, evaluating their compressive and flexural strengths, flowability, water absorption, and impact resistance. The findings revealed that the modified floor hardener, specifically the FH-12 mixture, exhibited superior performance across all tested parameters. It showed higher compressive and flexural strengths, enhanced impact resistance, and reduced water absorption compared to other variants and commercially available hardeners. Notably, the use of finer coarse sand and the adjustment of superplasticizer quantities significantly contributed to these outcomes. This breakthrough demonstrates the potential of employing locally available materials to create a durable, cost-effective, and environmentally friendly solution for industrial flooring. The study underscores the importance of material characterization and methodical formulation in developing construction materials that meet the dual criteria of performance and sustainability. This option is preferred for its lower environmental impact and compatibility with sustainable practices, contributing to Sustainable Development Goal 9 on industry, innovation, and infrastructure. It highlights the role of floor hardeners in global sustainability efforts.

A Review of Weak Gel Fracturing Fluids for Deep Shale Gas Reservoirs.

Low-viscosity slickwater fracturing fluids are a crucial technology for the commercial development of shallow shale gas. However, in deep shale gas formations with high pressure, a higher sand concentration is required to support fractures. Linear gel fracturing fluids and crosslinked gel fracturing fluids have a strong sand-carrying capacity, but the drag reduction effect is poor, and it needs to be pre-prepared to decrease the fracturing cost. Slick water fracturing fluids have a strong drag reduction effect and low cost, but their sand-carrying capacity is poor and the fracturing fluid sand ratio is low. The research and development of viscous slick water fracturing fluids solves this problem. It can be switched on-line between a low-viscosity slick water fracturing fluid and high-viscosity weak gel fracturing fluid, which significantly reduces the cost of single-well fracturing. A polyacrylamide drag reducer is the core additive of slick water fracturing fluids. By adjusting its concentration, the control of the on-line viscosity of fracturing fluid can be realized, that is, 'low viscosity for drag reduction, high viscosity for sand-carrying'. Therefore, this article introduces the research and application status of a linear gel fracturing fluid, crosslinked gel fracturing fluid, and slick water fracturing fluid for deep shale gas reservoirs, and focuses on the research status of a viscous slick water fracturing fluid and viscosity-controllable polyacrylamide drag reducer, with the aim of providing valuable insights for the research on water-based fracturing fluids in the stimulation of deep shale gas reservoirs.

Effects of bag characteristics and channel side slope on incipient motion of a single Geobag under river current loading

Geobag stability has not been extensively studied under river current loading. In this study, the impacts of geobag characteristics (shape, bag material, and fill ratio of sand) and channel side slope (flat and 1V:2H) on a single geobag's stability were systematically investigated in a physical model to form the solid foundation for the research of group geobags. Overall, a geobag with a higher fill ratio, combined with the more flexible cloth material, was found to be the most stable. Critical Shields parameters were estimated between 0.0018 and 0.019, and the cross-sectional averaged flow velocity at incipient motion ranged from 0.49 m/s to 1.08 m/s. A shape factor was introduced to better describe the relationship between geobag characteristics and their stability on both riverbed configurations. Both the fill ratio and the bed side slope had higher importance on the geobag's stability compared to the relative depth, bag shape, and angle of flexibility.

Study on Static Mechanical Properties and Numerical Simulation of Coral Aggregate Seawater Shotcrete with Reasonable Mix Proportion

This study aims to explore the static mechanical characteristics of coral aggregate seawater shotcrete (CASS) using an appropriate mix proportion. The orthogonal experiments consisting of four-factor and three-level were conducted to explore an optimal mix proportion of CASS. On a macro-scale, quasi-static compression and splitting tests of CASS with optimal mix proportion at various curing ages employed a combination of acoustic emission (AE) and digital image correlation (DIC) techniques were carried out using an electro-hydraulic servo-controlled test machine. A comparative analysis of static mechanical properties at different curing ages was conducted between the CASS and ordinary aggregate seawater shotcrete (OASS). On a micro-scale, the numerical specimens based on particle flow code (PFC) were subjected to multi-level microcracks division for quantitive analysis of the failure mechanism of specimens. The results show that the optimal mix proportion of CASS consists of 700 kg/m3 of cementitious materials content, a water–binder ratio of 0.45, a sand ratio of 60%, and a dosage of 8% for the accelerator amount. The tensile failure is the primary failure mechanism under uniaxial compression and Brazilian splitting, and the specimens will be closer to the brittle material with increased curing age. The Brazilian splitting failure caused by the arc-shaped main crack initiates from the loading points and propagates along the loading line to the center. Compared with OASS, the CASS has an approximately equal early and low later strength mainly because of the minerals’ filling or unfilling effect on coral pores. The rate of increase in CASS is swifter during the initial strength phase and decelerates during the subsequent stages of strength development. The failure in CASS is experienced primarily within the cement mortar and bonding surface between the cement mortar and aggregate.

Performance modulation and optimization of PE fiber reinforced 3D-printed geopolymer

This paper aims to develop an environmentally friendly and low-carbon geopolymer for 3D printing, which has excellent mechanical and rheological performance. The effect of ground granulated blast furnace slag (GGBS), NaOH and sand on mechanical strengths, 3D printing performance and rheological behavior was investigated to determine the optimum mix proportion for 3D-printed geopolymer. Moreover, polyethylene (PE) fibers were introduced to reinforce the performance of 3D-printed geopolymer. Results show that when the ratio of GGBS, NaOH and sand is 1:0.13:2.67, geopolymer exhibits superior mechanical, 3D printing and rheological properties. Increasing the dosage of GGBS and sand leads to an overall increase in the yield stress but a decrease in the consistency coefficient, indicating that it benefits the stacking and fluidity performance of 3D-printed geopolymer. However, with an increase of NaOH content, the stacking performance increases while the fluidity decreases. Although increasing NaOH and sand content benefits the viscosity recovery performance, an increase in GGBS content has an opposite effect. Incorporating PE fibers significantly increases the flexural strength with an increase of up to 27.8 % and 21.3 % in 7-d and 28-d flexural strength, respectively, given a PE fiber volume of 0.6 %. Increasing the volume of PE fibers leads to a significant rise in the stacking performance but a reduction in the fluidity. Furthermore, adding PE fibers negatively affects the geopolymerization but benefits the hydration process given an increase of Si/Al and Si/Ca ratio identified in PE fiber reinforced 3D-printed geopolymer.

Pore pressure development model of fiber-reinforced calcareous sand based on shear strain characteristics

In this study, the pore pressure buildup characteristics of fiber-reinforced calcareous sand were investigated by examining the influences of fiber contents and fiber length through a series of cyclic simple shear tests. The test results indicate that the generation mechanisms of pore pressure ratio and shear strain of fiber-reinforced calcareous sand are interrelated under cyclic loading. The fiber content and fiber length have a significant influence on the relationship of pore pressure ratio versus number of cycles. Nevertheless, the correlation of pore pressure ratio versus shear strain is independent of fiber content and fiber length. According to the unique relationship, a pore pressure development model based on shear strain was established, exhibiting excellent predictive accuracy in simulating the pore pressure generation of fiber-reinforced calcareous sand with various fiber content and fiber lengths under cyclic loading. Moreover, the proposed model is also applicable to clean calcareous sand and siliceous sand.

Research on the Mechanism of Strength Improvement in Acid–Base-Activated Low Carbon Oil Absorbent Concrete

The aim of this study is to improve the compressive strength of oil absorbent concrete (OAC) and to encourage its use in slope protection projects. This study used fly ash and slag produced in thermal power plants to substitute cement in significant amounts to prepare oil absorbent concrete (OAC). The water–cement ratios were set at 0.4, 0.5, and 0.6 and the sand rates were set at 30%, 35%, and 40% to investigate the effects of these factors on the oil absorption properties of the concrete, the variation of the oil absorption rate over time, and the compressive strengths at 28 days, 60 days, and 90 days. The compressive strength of oil absorbent concrete was improved by incorporating seashell powder (SC), alkali-modified seashell powder (SSC), and acid–base-modified seashell powder (CSC). The results showed that the optimal water–cement ratio for comprehensive oil absorption performance and compressive strength was 0.5, while the optimal sand ratio was 0.35. Compared with ordinary concrete, the oil absorption performance improved by 58.69%. The oil absorption rate decreased gradually over time. However, the oil absorption time could be effectively extended and the oil absorption performance could be improved by the addition of a silane modifier. The best method for seashell modification was acid–base modification. The compressive strength reached 14.32 Mpa at 28 days and 17.45 Mpa at 90 days, which was 19.62% higher than that of OAC. Scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), and X-ray diffraction (XRD) were used to analyze the microstructure of OAC. It was discovered that the inclusion of CSC caused a reaction with hydrocalumite in the concrete, resulting in the formation of alumohydrocalcite. Additionally, Ca(OH)2 in CSC facilitated the hydration reaction of mineral admixtures like fly ash and slag. At 28 days, more amorphous gels (C-S-H, C-(A)-S-H) and Aft were produced. The three components were combined to enhance the bonding between the cementitious materials and the aggregates, resulting in a denser internal structure of the OAC and improving its strength. This study promotes the use of OAC in slope protection projects.

Parametric study, finite element analysis, and load capacity calculation for flexural behaviour of seawater and sea sand concrete beams reinforced with GFRP bars

This study sought to enhance the understanding of seawater sea sand concrete (SWSSC) structures reinforced with glass fiber-reinforced polymer (GFRP) bars. To achieve this, an experimental investigation was conducted involving the production and testing of 6 GFRP bar-reinforced SWSSC beams (GFRP beams) alongside 3 ordinary seawater sea sand concrete (OSWSSC) beams (Ordinary beams) to evaluate their flexural performance. Additionally, a subsequent analysis comprised the establishment of 11 full-scale finite element models aimed at parameter assessment on GFRP beams. The experimental and numerical findings revealed that an increase in sea sand replacement ratio in SWSSC beams, with a shear-span ratio of 2.2, led to varying degrees of shear-compression failure. Notably, owing to the superior crack resistance of SWSSC, the beams demonstrated outstanding structural coordination. Compared to OSWSSC beams, GFRP beams with a 100 % replacement ratio of sea sand or an increased in concrete strength to C55 had initial stiffness values that were 150 % and 106 % larger, respectively. Further investigation unveiled that a reduction in the shear-span ratio from 2.5 to 1.0 or an increase in the longitudinal reinforcement ratio from 1.27 % to 2.53 % significantly augmented the ultimate load-carrying capacity, resulting in increases of 88.0 % and 37.7 %, respectively. Based on these findings, several design recommendations are proposed: 1. Establish a deflection limit at l0/500 or implement more stringent measures for GFRP beams. 2. Consider reducing the diameter of GFRP bars while maintaining a 50 % sea sand replacement rate to mitigate crack formation. 3. An excessive longitudinal reinforcement ratio hampers the enhancement of specimen load-carrying capacity. 4. Consider utilizing Chinese specifications for flexural capacity calculations.

Investigating the impact of straw-to-tailings sand ratios on combined vertical drain performance

Investigating the impact of straw-to-tailings sand ratios on combined vertical drain performance

Durability and microstructural evolution of high-performance ecological geopolymer concrete under low-pressure–salt-erosion–freeze–thaw cycling conditions

Environmental characteristics such as low pressure, high-frequency freeze–thaw cycles, and salt erosion in a plateau region have a significant impact on the mechanical properties and durability of concrete. To reveal the damage mechanism of high-performance ecological geopolymer concrete (HPEGPC) incorporating tunnel spoils, slag, and fly ash (FA) in extreme environments, this study used HPEGPC with 12 % alkali-activated binders (AABS) and a binding material to machine-made sand ratio of 0.36 and ordinary Portland cement concrete (OPCC) with 12.4 % cement and a water-cement ratio of 0.5 to simulate the deterioration process of mechanical properties and durability under the action of low-pressure–salt–erosion–freeze–thaw cycles. The mass, compressive strength, relative dynamic elastic modulus loss rate, microstructure, and pore evolution patterns of HPEGPC and OPCC were analysed using experimental and microscopic tests. The results showed that the HPEGPC was significantly more resistant to freezing and salt erosion than the OPCC in both standard and hypobaric environments. The interfaces of HPEGPC before and after the low-pressure–salt-erosion–freeze–thaw cycles underwent a developmental process from a dense structure with microcracks to microcracks expanding into fracture surfaces and the dispersion of hydration products. The cementitious materials of HPEGPC have a high percentage of non-hazardous and less hazardous pores, and their dense structure results in a high resistance to freezing and salt erosion. In addition, by establishing a damage decay model and damage accumulation model for the compressive strength and relative dynamic elastic modulus, this paper provides theoretical guidance for the application of HPEGPC under low pressure, salt erosion, and freeze–thaw cycle environments of the plateau.

Red mud modified phosphogypsum based self-leveling mortar: Hydration mechanism, heavy metal migration law and spatial distribution characteristics

In the production processes of phosphoric acid and alumina, chemical enterprises generate solid waste such as red mud (RM), phosphogypsum (PG), and fly ash (FA). The environmentally friendly utilization of these waste materials is of crucial significance. Therefore, this study focuses on investigating the impact of collaborative modification using diverse solid wastes on the macroscopic properties and internal microstructure of self-leveling mortar. Through a careful selection process, the optimal ratio for red mud and phosphogypsum self-leveling mortar(RPSM) has been identified during the research. This study not only provides substantial support for the effective utilization of solid waste but also contributes to the improvement of overall performance and structural characteristics of the mortar. Based on this, the hydration characteristics, leaching patterns, and spatial distribution characteristics of heavy metals in RPSM were evaluated. The research revealed that the optimal ratios of RM, PG, FA, PC, river sand, and heavy calcium carbonate powder in RPSM were 20.7%, 13.8%, 17.1%, 13.8%, 17.3%, and 17.3%, respectively. Under a water-binder ratio of 0.18, the flexural and compressive strength of the mortar specimens after 14 d of curing can reach 4.3 and 31.6 MPa. Through comprehensive analysis and discussion of the performance, microstructure, and dynamics of the hydration process of RPSM, the main processes of mortar hydration were elucidated. Environmental risk assessments indicated no environmental risks from heavy metals in RPSM. Human health risk assessment suggested carcinogenic risks from Cr and Cd in RPSM through oral exposure, leading to restrictions on the content of characteristic heavy metals in different application scenarios. Furthermore, fitting results of the release kinetics of heavy metals indicated that the leaching of heavy metals in RPSM can be well fitted with kinetic models, allowing the determination of the optimal safe age of RPSM containing harmful heavy metals. Finally, using interpolation and vertical distribution simulation by software such as ArcGIS, the spatial distribution characteristics of heavy metals in RPSM during use were analyzed. The research can supply fundamental academic support for the recycling of solid wastes like RM and the control of environmental risks associated with heavy metal leaching in building materials.

Concrete Strength and Aggregate Properties: In-Depth Analysis of Four Sources

In the field of Reinforced Concrete Construction, concrete emerges as the predominant and extensively employed construction material. Concrete comprises a solid, chemically inert granular substance called coarse aggregate (CA) bonded with cement and water. Compared to fine aggregate or cement, CA has a larger volume of concrete. By examining the characteristics of the coarse aggregate using various laboratory testing processes, the coarse aggregate may be properly used in concrete. Bangladesh is experiencing significant growth in its infrastructure industry due to the construction of mega projects nationwide. For the building of RCC in Bangladesh, coarse aggregate is mainly procured from two sources in Bangladesh, and another is imported from China. This study aims to develop a clear understanding of aggregate and concrete strength quality for different coarse aggregates and track changes in the appearance of CA from multiple sources in China and Bangladesh. Coarse aggregates were collected from four prominent sources: Jaflong and Bholaganj (Bangladesh), Shandong, and Jiangsu (China). ACV (aggregate crushing value), gradation, voids, and unit weight; AIV (aggregate impact value), absorption, specific gravity, and resistance to abrasion-induced deterioration; and Los Angeles (LA) machines’ impact tests have been conducted for all sources of CA. The concrete cylinder was made and tested for all sources of CA with the same ratio of cement, sand, and water to know the concrete strength for different CAs. Doi: 10.28991/CEJ-2024-010-04-016 Full Text: PDF

Experimental study on cement-based materials for grouting/replacement of broken rock mass in coal mine

In deep high-pressure mines, the surrounding rock of soft broken roadways often faces issues such as poor anchorability, support difficulties, high maintenance costs, and the inadequacy of traditional materials for site requirements. To tackle these challenges, this study focuses on grouting reinforcement in coal mine sites and prefabricated bearing arch form (grouting or replacement) under specific conditions, aiming to meet the material requirements. Through an orthogonal test, various properties of cement-based materials were investigated, including fluidity, initial setting time, water separation rate, early (≤1d) compressive strength, fracture strength, and later (28d as a reference) strength. The objective was to develop a cost-effective cement-based material with high strength and toughness, suitable for underground coal mines. The experimental results demonstrate that the self-developed cement-based materials exhibit rapid setting, excellent fluidity, high early strength, and strong durability compared to traditional alternatives. Analyses of the comprehensive properties reveal that the influencing factors, in order of significance, include the mass ratio of cement and sand, water cement ratio, rubber content, and bonding mortar master material content. By employing extreme treatment and efficiency coefficient methods, the comprehensive performance of materials under different ratios was evaluated. Consistent findings were obtained, indicating that the optimal mass ratio of cement-based materials is 500:500:20:15:10:5:8:10 for cement, sand, fly ash, silica fume, mineral powder, steel slag powder, bonding mortar master material, and rubber, respectively. Additionally, the best comprehensive performance was achieved with a water cement ratio of 0.5, which confirms the results of the orthogonal test. Macroscopic failure characteristics and SEM microscopic analysis further validate the superior performance of the materials under the aforementioned ratio. The reaction process of the material can be roughly divided into four stages: initial hydrolysis stage, induction stage, acceleration stage, decay and stability stage, and finally the formation of stone body. A comparison with ordinary materials highlights the advantages of the developed cement-based materials, and suggestions are proposed for the development of field-applicable materials.

Determine attenuation coefficients of saturated sand from standard penetration test, applied to Nhon Hoi economic zone

Vietnam is located in a strong earthquake zone with many areas having a ground acceleration (a<sub>g</sub>) of greater than 0.08 g (TCVN 9386:2012). According to Vietnamese standard TCVN 9386:2012, the calculation and design of construction grade III or higher in areas where have ground acceleration a<sub>g</sub> ≥ 0.08 g must include seismic design. In calculations of earthquake-resistant pile foundation, the bearing capacity of the pile including the tip resistance strength (q<sub>b</sub>) and endurance strength (f<sub>i</sub>) need to be multiplied by attenuation coefficients (g<sub>eq1</sub> and g<sub>eq2</sub>). They are the most important parameters and depend on the soil types, saturation conditions, and earthquake intensity. The article introduces a method to determine the attenuation coefficients according to the standard TCVN 10304:2014. In addition, analyzing the theoretical basis to give the expression to determine attenuation coefficients based on the durability factor (I<sub>red</sub>) and pore water pressure ratio (R<sub>u</sub>) of saturated sand under the earthquakes. Furthermore, the paper presents a method to determine R<sub>u</sub> from the results of standard penetration test (SPT) by combining the method of Seed and Alba (1986) with the method of Marcuson and Hynes (1990). In which, Seed and Alba's method was used to determine factor of safety against liquefaction (F<sub>SL</sub>), and then Marcuson and Hynes' method was used to determine R<sub>u</sub> from F<sub>SL</sub>. The application in Nhon Hoi Economic Zone shows that: The silty fine grained sand, which is medium dense and saturated, has a attenuation coefficient of tip resistance g<sub>eq1</sub> = 0.74÷0.76 and attenuation coefficient of friction g<sub>eq2</sub> = 0.90; The fine grained sand, which is dense and saturated, has g<sub>eq1</sub> = 0.79÷0.82 and g<sub>eq2</sub> = 0.94. 

Soil nailing as a ground reinforcement method of a storey building constructed on weathered siltstone: Analytical and numerical evaluation

Vietnam is located in a strong earthquake zone with many areas having a ground acceleration (a<sub>g</sub>) of greater than 0.08 g (TCVN 9386:2012). According to Vietnamese standard TCVN 9386:2012, the calculation and design of construction grade III or higher in areas where have ground acceleration a<sub>g</sub> ≥ 0.08 g must include seismic design. In calculations of earthquake-resistant pile foundation, the bearing capacity of the pile including the tip resistance strength (q<sub>b</sub>) and endurance strength (f<sub>i</sub>) need to be multiplied by attenuation coefficients (g<sub>eq1</sub> and g<sub>eq2</sub>). They are the most important parameters and depend on the soil types, saturation conditions, and earthquake intensity. The article introduces a method to determine the attenuation coefficients according to the standard TCVN 10304:2014. In addition, analyzing the theoretical basis to give the expression to determine attenuation coefficients based on the durability factor (I<sub>red</sub>) and pore water pressure ratio (R<sub>u</sub>) of saturated sand under the earthquakes. Furthermore, the paper presents a method to determine R<sub>u</sub> from the results of standard penetration test (SPT) by combining the method of Seed and Alba (1986) with the method of Marcuson and Hynes (1990). In which, Seed and Alba's method was used to determine factor of safety against liquefaction (F<sub>SL</sub>), and then Marcuson and Hynes' method was used to determine R<sub>u</sub> from F<sub>SL</sub>. The application in Nhon Hoi Economic Zone shows that: The silty fine grained sand, which is medium dense and saturated, has a attenuation coefficient of tip resistance g<sub>eq1</sub> = 0.74÷0.76 and attenuation coefficient of friction g<sub>eq2</sub> = 0.90; The fine grained sand, which is dense and saturated, has g<sub>eq1</sub> = 0.79÷0.82 and g<sub>eq2</sub> = 0.94. 

Non-destructive characterization of pore structure and chloride diffusion coefficient of cementitious materials with modified non-contact electrical resistivity method

The intricate pore structure of cement-based materials passively influences chloride ion transport and mechanical properties. Existing non-contact electrical resistivity measurement (NC-ERM) methods lack precision for rigorous studies. the NC-ERM was upgraded in this research, which is suitable for assessing the pore structure and transport characteristics of hardened cementitious substrates. The results obtained from this method closely correspond to those obtained from CEMHYD3D, Mercury intrusion porosimetry (MIP), and other methods. Additionally, the impact of mixture proportions on the resistivity, pore structure parameters, and chloride ion diffusion coefficient of cementitious materials is discussed. With an increase in sand ratio and sand-to-stone ratio, the resistivity exhibits an initial rise followed by a decline. Chloride diffusion of 5 wt% NaCl-saturated specimens is 1.2–1.3 times higher than 3.5 wt% NaCl. This study provides a novel non-destructive, convenient and accurate method for characterising the pore structure and testing the transport properties of cementitious materials.

Soil Properties Variation Valued in Relation to Land Use and Management Practices in Vietnam

Background: Land use and management practices (LUMPs) have been accelerated globally to serve the increasing socio-economic requirements in recent decades. Methods: This study focuses to assess the impacts of the LUMPs on the properties and composition of soil in the Lam River Basin (LRB), Vietnam based on analysis of ninety-six soil samples collected in the soil profiles (0_60 cm). Result: The results indicated that the sand and clay ratios (34.0~35.7% and 16.2~19.9%) and bulk density (BD) (1.07±0.05~1.34 ± 0.06 Mg m-3) in the natural forest lands (NFLs) were lower and higher perturbed than the plantation forest lands (PFLs) (31.1~ 51.5%, 5.7~38.2% and 0.86 ± 0.03~1.12±0.05 Mg m-3) in the 0-20 cm topsoil layer. The soil texture is mainly sandy clay to clay loam and the BD tends slightly increase in the topsoil layer, then decrease in the 20-60 cm subsoil layer. There is no difference in soil pH between collected soil samples (CSSs) and tends to increase with increasing the subsoil layer. The base cations (BCs) (Ca2+, K+, Mg2+: 0.01~0.29, 0.06~0.11 and 0.06~0.07 Cmolc kg-1) and total organic contents (TOCs) (total carbon (TC), total nitrogen (TN), total phosphorus (TP): 24.11; 2.80 and 0.19 g kg-1) of the NFLs are higher than those of the CSSs (TC, TN, TP: 14.37~23.91, 1.62~2.28 and 0.08~0.17 g kg-1) in the topsoil layer while these values were not different in the topsoil layer.

Effect of four-component binder on characteristics of self-compacting and fibre-reinforced self-compacting mortars

AbstractThe hydration heat of a four-component binder consisting of Portland cement (CEM I 42.5 R), blast-furnace slag (BFS), metakaolin (MK), and silica fume (SF) was investigated using a conduction calorimeter and thermal analytical method to optimize the material composition of self-compacting mortar (SCM). Then, the influence of material composition with different substitution levels (0, 25, 30, and 35% labelled as SCM100, SCM75, SCM70, and SCM65) on physical and mechanical properties of the mortars with two volumetric binder sand ratios of 1:1 and 1:2 (cement: sand) was evaluated. Furthermore, two mortar compositions comprising SCM75 and sand at 1:1 and 1:2 ratios were used to prepare fibre-reinforced self-compacting mortars in five combinations (0, 0.25, 0.5, 0.75, and 1%) of two fibres (polypropylene-PPF and basalt-BF) at a constant content of 1.00 vol%. The properties of the prepared samples were investigated with respect to the characteristics of self-compactibility and mechanical properties of fresh and hardened states, respectively. The rheology characteristics expressed by slump flow, V-funnel, and T20 were found following the EFNARC guidance. The partial replacement of cement by supplementary cementitious materials has enhanced the performances (compressive and flexural strengths, dynamic modulus of elasticity) of self-compacting mortars from the 7th day through pozzolanic activity. Furthermore, adding fibres has enhanced the DME and microstructure of the self-compacting mortars.

Responses of different growing media ratios growth performance of spinach (Spinacia oleracea L.) under greenhouse conditions

Spinach (Spinacia oleracea) vegetables are an important constituent of the diet of rural communities worldwide. It is a suitable substitute for several indigenous leafy vegetables, as it has more or less the same texture after cooking. Consequently, growers tend to grow spinach in any soil type or mixture available to them without modifying it, leading to reduced growth performance and yields. The use of animal manure is common in South Africa and helps to improve soil fertility when used in the correct ratio mixture. Therefore, the study’s objective was to investigate which of the growing media mixture (GMM) ratios of sand, Hutton soil, and goat manure would improve the growth and yield of S. oleracea under greenhouse conditions. The experiment was laid out in a randomized complete block design (RCBD), with 10 replicates (n=60). Six treatments comprised of different types of GMM namely, sand, Hutton soil, and goat manure at T1 (1:3:0 -control), T2 (1:2:1), T3 (1:1:1), T4 (1:1:2), T5 (2:1:2) and T6 (2:3:2), respectively. Growing media mixture had significant (P ≤ 0.05) effect on plant height (PH), number of leaves (NL), chlorophyll content (CC) and root length (RL) of S. oleracea, contributing 78, 62, 76 and 54% of the total treatment variation (TTV) in the respective variables. Relative to the control (T1), treatment T2, T3, T4, T5 and T6 increased PH by 22.75 cm, 24.03 cm, 27.92 cm, 22.84 cm and 24.35 cm, respectively. Similarly, the NL in all the treatments T2, T3, T4, T5 and T6 was increased by 10.90, 11.70, 11.90, 11.70 and 11.60, respectively, compared to T1. A related trend was observed in the CC, treatments T2, T3, T4, T5 and T6, increased the CC by 14.99, 15.08, 26.45, 21.38 and 15.83, respectively when compared to T1. The GMM treatment T4 obtained the highest 27.92, 11.9, 26.45 and 42.38 in PH, NL, CC and RL. In conclusion, GMM T4 had a positive effect on the growth and yield of S. oleraceae, and it is recommended for use to grow the vegetable crop.