Bearing capacity of circular footings on multi-layered sand-waste tire shreds reinforced with geogrids

The presence of waste tires poses an environmental challenge as they occupy a significant amount of land and are expensive to dispose in landfills.However,reusing waste tires can address this issue when waste tires are used in geotechnical applications.To determine the viability of this approach,laboratoryscale tests were conducted to investigate load-bearing capacity of circular footings on sand-tire shred(STS)mixtures with shredded waste tire contents of 5%e15%by weight and three different widths of shreds.The investigation focused on analyzing the thickness of layers composed of STS mixtures,the soil cap,and the impact of geogrids on bearing capacity.The results indicate that a specific mixture of sand and tire shreds provides the highest footing-bearing capacity.In addition,the optimal shred content and size were found to be 10%by weight and 2 cm×10 cm,respectively.Furthermore,for a given tire shred width,a particular length provides the largest bearing capacity.The results agree well with that of previous research conducted by the first author and his colleagues in direct shear and California bearing ratio(CBR)tests.The primary finding of this research is that the use of two-layered STS mixtures reinforced by geogrids significantly enhances the bearing capacity.

Effects of porosity,dry unit weight,cement content and void/cement ratio on unconfined compressive strength of roof tile waste-silty soil mixtures

One of the conventional ways to improve the mechanical behavior of soils is to mix them with cementing agents such as cement, lime and fly ash. Recently, introduction to alternative materials or sub-products that can be adopted to improve the soil strength is of paramount importance. Therefore, the present study aims to investigate the effects of porosity(h), dry unit weight(gd) of molding, cement content(C)and porosity/volumetric cement content ratio(h/Civ) or void/cement ratio on the unconfined compressive strength(quor UCS) of silty soileroof tile waste(RT) mixtures. Soil samples are molded into four different dry unit weights(i.e. 13 kN/m^3, 13.67 kN/m^3, 14.33 kN/m^3 and 15 kN/m^3) using 3%, 6% and 9%cement and 5%, 15% and 30% RT. The results show that with the addition of cement, the strength of the RT esoil mixtures increases in a linear manner. On the other hand, the addition of RT decreases quof the samples at a constant percentage of cement, and the decrease in porosity can increase qu. A dosage equation is derived from the experimental data using the porosity/volumetric cement content ratio(h/C_(iv)) where the control variables are the moisture content, crushed tile content, cement content and porosity.

Performance Evaluation of Waste Stabilisation Ponds

Waste stabilisation pond system has been used more especially in developing countries for sewage treatment. The objective of this study was to investigate the hydraulic and performance efficiency of Palapye waste stabilisation ponds. The hydraulic efficiency was evaluated through drogue, pond geometry and sludge accumulation assessment. The performance efficiency was evaluated through periodic sampling and analysis of physiochemical and bacteriological parameters of individual units and of the system as a whole. Except for the maturation ponds, the depth of the anaerobic pond had reduced from 4 m to 0.45 m, for facultative ponds from 2.0 m to a range of 0.52 m - 0.91 m. The design hydraulic retention time of the system had reduced from 20 days to 7.1 days. The concentration of some physiochemical parameters in the effluent was 305 mg·L-1, 277 Nephelometric Turbidity Units (NTU), 204 mg·L-1, 156 mg·L-1, 110 mg·L-1, and 15 mg·L-1 being total suspended solids, turbidity, nitrates, chemical oxygen demand, biochemical oxygen demand and phosphate respectively. These values were more than the standard limits of the country. Effluent total coliforms concentration was 3.6 log units and within the threshold of 4.3 log units, faecal coliforms concentration was 3.5 log units, slightly higher than the threshold of 3 log units. Though Escherichia coli have no limits for discharge into other environments, the concentration in the effluent was reasonable at 2.5 log units and also within irrigation limit of 3 log counts. Palapye wastewater treatment system hydraulic efficiency is lower than the design criterion. The system was overall poor in physiochemical parameters removal but better in bacteriological removal.

Geo-environmental application of municipal solid waste incinerator ash stabilized with cement

The behavior of soluble salts contained in the municipal solid waste incinerator(MSWI) ash significantly affects the strength development and hardening reaction when stabilized with cement.The present study focuses on the compaction and strength behavior of mixed specimens of cement and MSWI ash.A series of indices such as unconfined compressive strength,split tensile strength,California bearing ratio(CBR) and pH value was examined.Prior to this,the specimens were cured for 7 d,14 d,and 28 d.The test results depict that the maximum dry density(MDD) decreases and the optimum moisture content(OMC)increases with the addition of cement.The test results also reveal that the cement increases the strength of the mixed specimens.Thus,the combination of MSWI ash and cement can be used as a lightweight filling material in different structures like embankment and road construction.

Impact on Acidification Characteristics of Anaerobic Digestion of Kitchen Waste by F/M

The effect of F/M on acidification characteristics during anaerobic digestion of kitchen waste was investigated. Under different F/M,p H,alkalinity,ethyl alcohol,volatile fatty acids(VFAs),and biogas production status of acidification effluent in 96 h were observed. The study results showed that the content of propionic acid + acetic acid reached 56%-80% when F/M≤1. 0,which was mainly known as propionic acid type of fermentation and was accompanied by methane. The value of alkalinity was only 3 000-4 000 mg/L,which indicated that the stability was weak in the system. When 1. 0 < F/M≤2. 5,the concentration of butyric acid + acetic acid was in the range of 77%-85%,and acid production rate per unit load was more than 250 mg VFAs/g VS,which was known as butyric acid type of fermentation. The fermentation type was stable and could provide more available VFAs for subsequent methanation processes because the value of alkalinity reached 5 650 mg/L. When F/M≥2. 5,the content of ethanol + acetic acid was 80%-92%,which was known as ethanol type of fermentation. And p H of 96 h was only 5. 0( F/M = 3. 0) and 4. 3(F/M =4.0),and acidification was serious and the stability was weak in the system,which would hinder the subsequent methanation process.Therefore,F/M influenced fermentation type,and it can provide a target product for subsequent methanation process by controlling F/M in a reasonable range.

Effect of Waste Marble Powder on Physical and Mechanical Properties of Concrete

The emission of greenhouse gases from cement production is an obstacle for sustainable development of construction industry.The use of waste materials in constructions instead of cement could be a feasible solution to green construction.Waste marble powder with good cementing property can be used in concrete partially replace cement.In this research,the effects of using waste marble powder on the physical and mechanical properties of concrete have been studied.Three groups of particle size and five levels of replacement ratio(5%,10%,15%,20%,25%)for each group have been designed.During the different stage of hydration process,the microstructure,phase composition and thermal properties of marble-cement paste have been investigated,the influence of particle size of marble powder on these properties has been discussed.The compressive strength and stressstrain relation were tested for different series prepared by partially replacing cement at proportions of 5%–25%separately.From the data analysis,it was observed that the using of waste marble powder would affect the hydration products and further affect the mechanical properties of concrete,the addition of marble powder that partially replace the cement at particular proportions in concrete is feasible.

Biochemical changes during composting of coir pith waste as influenced by different agro industrial wastes

Coir pith, a byproduct of coconut husk is difficult to decompose due to its high lignin and cellulose content. In this study, coir pith was composted with different agro industrial by products such as cow dung, vegetable market waste, poultry waste and microbial consortium. The different treatment combinations used in the present study were Control, T1 (Coir pith + Cow dung + Vegetable market waste + Poultry waste + mixed microbial culture (Trichoderma viridae + Pleurotus sajar caju), T2 (Coir pith + Vegetable market waste + Poultry waste + Tank slit + Mixed microbial culture) and T3 (Coir pith + Cow dung + poultry waste + tank slit + mixed microbial culture). At the end of 12th week, in the treatment T1, C: N ratio of 21.8:1 was observed in the composted coir pith sample. Highest P content of 0.47% and K content of 1.2% and the least Cellulose and Lignin contents of 22.8% and 10.03% were recorded in the T1 treatment after a composting period of 12 weeks. Highest pH of 7.4 was observed in the treatment T3, this was followed by T1 (7.2) treatment.

Water Quality Index of Waste Stabilisation Ponds and Downstream of Discharge Point

Water quality index has been used in various researches for the assessment of water quality for various uses and discharges into the environment. The purpose of this study was to determine the water quality index of the effluent from waste stabilisation ponds and 400 m beyond discharge point. This was achieved by evaluating concentrations of seven parameters from soil, eleven physiochemical parameters from effluent and four microbiological parameters. Corresponding water quality indices calculated from microbiological parameters were 854, 142, 96 and 1539 respectively, at sites 1, 2, 3 and 4. Reductions of magnesium, zinc, lead, sodium adsorption ratio, sodium and electrical conductivity in soil samples at site 4 were 15.5%, 57%, 81.6%, 93.5%, 93.5% and 99% respectively. The percentage increases were 21.4% and 185% respectively, for calcium and iron ions. It can be concluded that the water quality index of the waste stabilisation ponds is unsuitable for discharge into the environment. However, the results revealed improved quality downstream of discharge point.

The Implementation of Waste Sawdust in Concrete

Nowadays, sawdust has been widely regarded as a sand replacement material to produce sawdust concrete. This thesis uses orthogonal test to analyze the mechanical and heat preservation as well as heat insulation property with the sawdust replacement ratio of 0%, 3%, 5%, 7%, 10%, respectively, to get an optimal sawdust replacement ratio. Besides, it also discusses the deficiencies of this research.

Soil Improvement Using Waste Materials:A Review

With the industrialisation,industrial byproducts are produced in large quantities and create nuisance to natural habitats.The disposal of these wastes like fly ash,marble powder,construction and demolition(C&D)waste,brick powder,agricultural wastes etc.has become the potential threat to the ecosystem and need some real solutions.The direct disposal of such wastes into open land or water bodies causes circumambient pollution.One of the potential solutions is to utilise these wastes in the construction industry on large scale as subgrade rehab or additive to cement based materials.In the present study,the compaction and strength characteristics of stabilised soil have been studied by using various waste materials i.e.lime,cement,plastic waste,industrial waste,fibre,mushroom waste,wet olive pomace etc.and reviewed.The addition of additives improved the engineering properties of soil significantly.

基于无废企业工业废料充填体强度与材料配比优化研究

为了构建无废企业,某煤电一体化企业采用连采连充式充填来循环再利用其生产的工业废弃物。结合充填工艺特点,以矸石和炉渣为骨料,粉煤灰、石膏、水泥和电厂废水配成的浆液为胶结材料,用DPS数据处理系统建立回归模型,通过方差分析与响应曲面分析法分析双因素交互作用下对充填体强度影响。研究结果表明,石膏水泥比与矸石浆液比交互作用影响最大,其次是粉煤灰水泥比与矸石浆液比的交互作用,石膏水泥比与粉煤灰水泥比交互作用影响最小。根据优化结果得到最终配比为石膏水泥比0.1,粉煤灰水泥比0.35,矸石浆液比2.9,以此参数得到充填体试验最终强度为5.21 MPa,其相对误差小于5%。研究结果可为无废企业的废弃物的循环再利用提供借鉴。

泥水盾构施工循环掘进泥浆制备试验研究

为实现盾构废弃泥浆循环利用,将废弃泥浆应用于掘进泥浆制备,依托南京长江新济洲过江供水廊道项目进行室内试验,对比了废弃泥浆和膨润土所制备掘进泥浆的性能差异,分析了废弃泥浆制备掘进泥浆的可行性;研究了废弃泥浆黏粒含量及配比对掘进泥浆性能影响的规律;建立了掘进泥浆性能指标的拟合公式,并基于拟合公式进行了废弃泥浆制备掘进泥浆的配比优化分析。研究结果有效证明了废弃泥浆制备掘进泥浆的可行性,且通过配比优化,确定了依托工程利用废弃泥浆制备掘进泥浆的参考配比:固水比0.22,膨黏比0.28,羧甲基纤维素钠(CMC)掺量0.32%。经配比优化后的掘进泥浆能够满足性能要求,可为工程中利用废弃泥浆循环制备掘进泥浆的配比确定提供参考。

不同碳氮比典型食品废弃物对黑水虻生长发育的影响

黑水虻处理餐厨垃圾是当前食品废弃物处理领域的热点,但存在对不同食品废弃物的处理效率差异大的问题。本研究以豆渣、餐厨垃圾和菌渣3种常见的食品废弃物作为食物源,考察不同碳氮比(C/N)值(5.00、10.00和15.00)对黑水虻幼虫体长、体质量及生物转化率等生长指标的影响。结果表明:黑水虻在不同C/N的饲料中的生长速率不同,由高至低依次为餐厨垃圾、豆渣和菌渣,幼虫喂养10 d后的平均体长分别为2.06、1.93和1.82 cm,平均体质量分别为75.0、54.2和42.1 mg,生物转化率分别为14.89%、13.11%和4.15%。当饲料的C/N值为10.00时,有利于黑水虻的高效生长和生物转化。当将菌渣和豆渣以质量比2∶8混合喂养(C/N值为10.04)时,黑水虻的生物转化率提高至15.81%。可见,调节饲料C/N值以提高黑水虻对食品废弃物的生物转化率是一条可行的研究路径。

不同碳氮比对园林废弃物堆肥中氨气和温室气体排放的影响

[目的]针对园林废弃物堆肥过程中温室气体(CO_(2)、CH_(4)、N_(2)O)及氨气(NH_(3))排放量大的问题,研究不同碳氮比对园林废弃物堆肥过程中温室气体和NH_(3)排放的影响,以期为降低堆肥产生的温室效应和NH_(3)污染提供技术支撑。[方法]在园林废弃物中添加不同质量的鸡粪,调节堆料碳氮比至25、30和35,利用傅里叶变换红外吸收光谱仪对堆肥过程中的NH_(3)和温室气体排放进行监测;采用标准方法对堆料的pH、有机碳、全氮含量进行检测。[结果]堆肥后所有处理组堆料均达到腐熟标准;园林废弃物堆肥所产生的温室效应以CO_(2)排放引起的温室效应为主,堆肥过程中CO_(2)排放量存在明显差异,碳氮比分别为25、30、35的处理组CO_(2)平均排放量分别为5.47、9.32、19.19 g/(kg·d),可见堆肥的温室效应随着碳氮比的增加而升高;NH_(3)排放量随着碳氮比的增加而明显降低,碳氮比分别为25、30、35的处理组NH_(3)平均排放量分别为680.03、442.69、193.54 mg/(kg·d)。[结论]在园林废弃物好氧堆肥时,碳氮比可以明显影响温室气体和NH_(3)的排放,温室气体的排放量随着碳氮比的增加而升高,NH_(3)的排放量随着碳氮比的增加而明显降低,所以在堆肥时要根据需求综合考虑这2项指标来确定碳氮比。

剪切增稠液增强高发泡率废纸缓冲材料的制备及性能

随着经济的快速增长和人们环保意识的不断增强,植物纤维类环保型发泡缓冲材料逐渐成为研究热点。为改善植物纤维发泡材料发泡率低、缓冲吸能效果差等问题,本研究设计半密闭型发泡模具,成功制备了具有高发泡率和优异吸能性的废纸缓冲材料并对制备工艺进行了优化。结果表明:使用质量分数为0.5%的氢氧化钠溶液预处理废纸浆,不仅可以有效去除废纸中的杂质,而且能在不降低纤维长度的情况下对废纸纤维进行适当改性,有利于提高废纸缓冲材料的发泡率和整体性能。以正交优化试验研究原料配比对废纸缓冲材料性能的影响,并据此确定了最优配方。通过设计全新半密闭型发泡模具,成功制备高发泡率的废纸缓冲材料,其膨胀率相较传统制备方式提高了3~4倍。本研究首次引入剪切增稠液(STF)增强废纸纤维,考察了STF含量对废纸缓冲材料力学性能、发泡倍率和回弹性能的影响,分析了STF对废纸缓冲材料的增强机理。结果表明:STF能够提高单根废纸纤维的强度并增强纤维之间的连结,从而提升缓冲材料吸能性,且随着STF含量的增加,材料的吸能性逐渐增强,发泡率逐渐降低,当STF含量为10%(质量分数,下同)时,STF增强废纸缓冲材料的综合性能达到最优。

农林废弃物循环流化床空气气化特性实验研究

【目的】考察生物质种类在不同参数下对循环流化床空气气化特性的影响,为宽燃料适应性的生物质循环流化床气化技术和生物质气化耦合燃煤发电技术提供相关数据参考。【方法】在自行搭建的小型常压循环流化床气化实验装置上,开展了以空气当量比(equivalent ratio,ER)、气化温度为参数,农林废弃物(稻壳、木屑、玉米秸秆和稻草)为原料的空气气化实验研究。【结果】稻壳、木屑、玉米秸秆和稻草气化气组分在不同空气当量比下的变化规律基本一致,随着空气当量比不断增加,稻壳、木屑、玉米秸秆和稻草的气化燃气低位热值和冷煤气效率均呈现先增后减的变化趋势,对于稻壳、木屑和玉米秸秆,ER为0.20时均为最优工况,最高冷煤气效率分别为46.19%、38.07%和37.71%;而对于稻草,ER为0.25时为最优工况,最高冷煤气效率可达39.55%;稻壳、木屑、玉米秸秆和稻草气化气组分中的三大可燃气体(CH4、CO、H2)在不同气化温度下的变化规律也一致,随着气化温度不断升高,稻壳、木屑、玉米秸秆和稻草的气化燃气低位热值和冷煤气效率也均呈现先增后减的变化趋势,其中稻壳和玉米秸秆冷煤气效率在气化温度为750℃时达到峰值,分别为46.19%和37.71%,而木屑和稻草在气化温度为760℃时达到峰值,分别为38.07%和37.56%。【结论】研究结果可为宽燃料适应性的生物质循环流化床气化技术和生物质气化耦合燃煤发电技术提供相关数据参考。

稻壳灰-废旧砖再生透水混凝土的配合比研究

为探究稻壳灰-废旧砖再生透水混凝土的配合比,采用4因素3水平正交试验,探究水灰比、目标孔隙率、废旧砖骨料取代率、稻壳灰掺量对透水混凝土的强度、透水性、抗冻性的影响。结果表明:水灰比为0.3、目标孔隙率为10%、废旧砖骨料取代率为40%、稻壳灰掺量为6%时,稻壳灰-废旧砖再生透水混凝土的性能更优,其抗压强度为11.28 MPa、劈裂抗拉强度为1.99 MPa、透水系数为0.56 cm/s、孔隙率为37.5%、50次冻融循环后抗压强度为3.74 MPa。

废塑料催化裂解直接生产化学品技术分析和研究

介绍了废塑料催化裂解直接生产化学品技术研究情况。废塑料催化裂解直接生产化学品可以在废塑料溶解进料过程中高效脱除原料中的含氯化合物,其余少量含氯化合物在催化裂解反应过程中进一步脱除,能够实现废塑料脱氯和催化裂解生产化学品同时进行。利用金属氧化物催化剂,聚丙烯废塑料一步催化裂解能够实现多产乙烯的目标,乙烯、丙烯、丁烯产率分别为19.7%、11.5%、5.2%,芳烃产率为20.1%,高价值产品收率超过50%。利用ZSM-5分子筛催化剂,聚丙烯废塑料一步催化裂解能够实现多产丙烯的目的,乙烯、丙烯、丁烯的产率分别为10.13%、35.06%、19.55%,芳烃产率为19.44%,化学品总收率超过80%。废塑料通过ZSM-5分子筛催化剂催化裂解生产化学品具有明显的技术经济优势。