Excavation Waste Research Articles

Site Trials of Recycled and Secondary Aggregates in Concrete and Concrete Blocks in Qatar

Abstract A major construction programme is underway in Qatar. A shortage of local aggregate is focusing attention on the use of recycled and secondary aggregates. Site trials using locally available materials in structural concrete and concrete blocks were carried out in three small buildings. By far the largest source of recycled and secondary aggregates in Qatar is construction, demolition and excavation waste, which is generally crudely separated into excavation waste (EW) and construction/demolition waste (CDW). The other material investigated was incinerator bottom ash (IBA). The EW was used to replace 50% of the coarse aggregate in structural C40 concrete, with the CDW replacing 50% and IBA 20% of the coarse aggregate in non-load bearing concrete blocks. The control was 100% imported gabbro coarse aggregate. The trials also incorporated replacement of 60% of the local washed sand with imported crushed rock fines; this was investigated because the reserves of suitable concrete sand in Qatar are limited. Results after one year show the materials giving equivalent or better performance than the primary aggregate controls. The Qatar Construction Specification will be updated to permit greater use of recycled and secondary aggregates (RSA) and further trials are planned in a range of applications, including unbound subbase and pavement concrete. Wider use of these materials will reduce reliance on imported aggregates. The site trials won an award for the most innovative project from the Qatar Contractors Forum 2013.

Physical properties and shear strength responses of recycled construction and demolition materials in unbound pavement base/subbase applications

Construction and Demolition (C&D) materials are increasingly used as construction materials in engineering applications. Their usage currently includes applications such as pavements, ground improvement, engineered fills, pipe bedding, backfill and aggregates in concrete. A comprehensive laboratory evaluation of physical and shear strength characteristics of recycled C&D materials was undertaken using gradation, Los Angeles Abrasion, unconfined compression, California Bearing Ratio (CBR), direct shear and consolidated drained triaxial tests. The recycled C&D materials evaluated were recycled concrete aggregate (RCA), crushed brick (CB), reclaimed asphalt pavement (RAP), waste excavation rock (WR), fine recycled glass (FRG) and medium recycled glass (MRG). All the recycled C&D materials are classified as well-graded materials and their compaction curves are controlled by water absorption and surface characteristics. RAP, FRG and MRG exhibit flat compaction curves while RCA, WR and CB exhibit bell-shaped compaction curves. The shear responses of the recycled C&D materials are classified into two groups: dilatancy induced peak strength and dilatancy associated strain-hardening behaviors. RCA, WR and CB are dilatancy induced peak strength materials in that their peak strength is clearly observed after the maximum dilatancy ratio occurs. Higher dilatancy ratios in these materials are associated with higher peak friction angles. RAP, FRG and MRG on the other hand are dilatancy associated strain-hardening materials, which exhibit strain-hardening behavior even with a relatively high magnitude of dilatancy. Based on the evaluation of the shear strength characteristics, it is ascertained that the compacted C&D materials have the potential to be used in pavement base/subbase applications as they have the required minimum effective friction angles. RCA, CB and WR in particular are found to also meet the physical and shear strength requirements for aggregates in pavement base/subbase applications.

Life-Cycle Inventory and Impact Evaluation of Mining Municipal Solid Waste Landfills

Recent research and policy directives have emerged with a focus on sustainable management of waste materials, and the mining of old landfills represents an opportunity to meet sustainability goals by reducing the release of liquid- and gas-phase contaminants into the environment, recovering land for more productive use, and recovering energy from the landfilled materials. The emissions associated with the landfill mining process (waste excavation, screening, and on-site transportation) were inventoried on the basis of diesel fuel consumption data from two full-scale mining projects (1.3-1.5 L/in-place m(3) of landfill space mined) and unit emissions (mass per liter of diesel consumption) from heavy equipment typically deployed for mining landfills. An analytical framework was developed and used in an assessment of the life-cycle environmental impacts of a few end-use management options for materials deposited and mined from an unlined landfill. The results showed that substantial greenhouse gas emission reductions can be realized in both the waste relocation and materials and energy recovery scenarios compared to a "do nothing" case. The recovery of metal components from landfilled waste was found to have the greatest benefit across nearly all impact categories evaluated, while emissions associated with heavy equipment to mine the waste itself were found to be negligible compared to the benefits that mining provided.

Evaluation of Combined Excavation Waste and Reclaimed Asphalt Pavement Aggregates for Use in Road Bases and Sub-bases

More than 15 million tons of aggregates are imported each year to Qatar from neighbouring countries. Large quantities of waste materials (around 20 million tons/year) from excavation waste, demolition rubble and reclaimed asphalt pavement (RAP) are being generated. The main objective of this paper is to present the results on the use of combined excavation waste (EW) and RAP aggregates in the construction of road bases and sub-bases. Physical and chemical properties were determined. Different combinations of both materials were subjected to compaction and California Bearing Ratio (CBR) testing in accordance with Qatar Construction Specifications. Results indicated that, for the materials tested, it is not feasible to use excavation waste, RAP aggregates or a combination of the two materials in road bases and sub-bases. The materials failed to meet some Qatari standards such as Los Angeles abrasion, liquid limit, plasticity index and CBR specified for road construction.

Open Pit Slope Design of Ajabanoko Iron Ore Deposit, Kogi State, Nigeria

Abstract An appropriate open pit slope design is the one that considers both the safety and cost aspects to minimize waste excavation. Open pit slope design of Ajabanoko iron ore deposit, Nigeria was carried out using DIPS and SLOPE/W mine softwares. Compass clinometer and Geographic Positioning System (GPS) were used to determine the dip, dip direction and location respectively of joints on the iron ore deposit and this serves as an input data in the slope design. Fifty-two dip/dip direction values were plotted using DIPS mine software. The factor of safety of the designed slope was determined using limit equilibrium method included in the slope SLOPE/W program. In order to calculate the factor of safety for the designed slopes, inputs parameters, namely unit weight of the rock mass, internal friction angle and cohesion were used in the SLOPE/W program. The obtained result indicates that slope angles with orientation of 44/071, 50/270, 61/359, 46/178 were considered safe for the eastern, western, northern and southern section of the deposit respectively. The slope design carried out shows a factor of safety that varies from a lower limit of 2.89 to an upper limit of 3.84, and this indicates safe slopes in all sections of the deposit.

Sustainable Approach for Landfill Management at Final Processing Site Cikundul in Sukabumi City, Indonesia

The main problem of landfill management in Indonesia is the difficulty in getting a location for Final Processing Sites (FPS) due to limited land and high land prices. Besides, about 95% of existing landfills are uncontrolled dumping sites, which could potentially lead to water, soil and air pollution. Based on data from the Ministry of Environment (2010), The Act of the Republic of Indonesia Number 18 Year 2008 Concerning Solid Waste Management, prohibits open dumping at final processing sites and in ratification, the Local Governments have to convert the open dump sites into controlled or sanitary landfill. The Research Institute for Human Settlements has been conducting multi-year researches related to the rehabilitation of dumpsites toward sustainable landfill. The research methods are literature reviews, experiments, laboratory analysis and field observations. A pilot model of dumpsite rehabilitation was carried out in 2010 at the Final Processing Site at Cikundul in Sukabumi City, consisting of (1) mining landfill (2) construction of landfill cells in a former mining area with a semi aerobic landfill and an anaerobic landfill and (3) landfill operations using decomposed material from landfill mining as a soil cover. The purpose of the study is to develop a sustainable approach for landfill management and rehabilitation through landfill mining and implementation of semi aerobic landfill. Findings in the construction of landfill mining indicate that (1) the construction of landfill mining is constrained by leachate that is trapped in a pile of waste, therefore, the leachate needs to be pumped to leachate treatment installations, (2) the volume of waste excavation is expanding due to the high plastic content of about 26% in landfills (3) the potency of decomposed materials from landfill mining is 40– 83% for landfill operations or greening.. The performance of landfill systems shows that leachate quality of semi aerobic landfill tends to be lower than that of anaerobic landfill. Gas composition at semi aerobic landfill in FPS Sukabumi shows about 6–10% CH4 and about 15–16% O2; for an aerobic landfill, the gas composition is about 47– 57% CH4 and about 2–3% O2. In conclusion the concept mining landfill could be developed especially for big cities where it is difficult to find a new site for landfill or to get soil cover for landfill operation. In a sustainable approach, the excavated area can be turned into a new area for landfill cell so that the capacity of existing Final Processing Site can be expanded using the block landfill concept. The landfill should be divided into three blocks: compost block, composting block and active block. Usage of the three blocks are rotated with the intention of using solid waste on the compost block as soil material for the active block through landfill mining.

Geotechnical Properties of Waste Excavation Rock in Pavement Subbase Applications

AbstractThis paper presents the findings of an extensive laboratory investigation on the geotechnical properties of waste excavation rock in pavement subbases. The waste excavation rock used in this study originated from “basalt floaters,” or surface excavation basalt rock (basalt). Traditionally, this material would have been disposed as waste, often into landfill. The engineering properties of the crushed basaltic waste rock were compared with the local road authority specifications to assess its performance as a pavement subbase material. The experimental program was extensive and included tests such as particle size distribution, modified Proctor compaction, particle density, water absorption, California bearing ratio, Los Angeles abrasion loss, pH, organic content, static triaxial, and repeated load triaxial tests. The Los Angeles abrasion loss value obtained indicated that the crushed basaltic waste rock is durable. California bearing ratio values were found to satisfy the local state road authority...

Study on a Convenient Method for Monitoring Hazardous Gas Based on Methane Determination during Waste Excavation at Reclamation Sites

Study on a Convenient Method for Monitoring Hazardous Gas Based on Methane Determination during Waste Excavation at Reclamation Sites

Environmental problems caused by Istanbul subway excavation and suggestions for remediation

Many environmental problems caused by subway excavations have inevitably become an important point in city life. These problems can be categorized as transporting and stocking of excavated material, traffic jams, noise, vibrations, piles of dust mud and lack of supplies. Although these problems cause many difficulties, the most pressing for a big city like Istanbul is excavation, since other listed difficulties result from it. Moreover, these problems are environmentally and regionally restricted to the period over which construction projects are underway and disappear when construction is finished. Currently, in Istanbul, there are nine subway construction projects in operation, covering approximately 73 km in length; over 200 km to be constructed in the near future. The amount of material excavated from ongoing construction projects covers approximately 12 million m3. In this study, problems—primarily, the problem with excavation waste (EW)—caused by subway excavation are analyzed and suggestions for remediation are offered.

Phytotechnology – is there a possibility to use it for land reclamation of areas contaminated by Technologically Enhanced Naturally Occurring Radioactive Materials?

Presently, excavation and shipping to a distant waste disposal site is the most commonly used method for handling waste contaminated with radionuclides. Due to international recommendation waste containing enhanced concentration of natural radioactivity should be treated in the same way. In case of TENORMs, which usually occur in huge quantity, this method would be very expensive and can be disruptive to the environment in which the contamination was found as well as direct effects of this pollutant occurrence.Biological treatment methods, such as phytoextraction or at last phytostabilisation could provide an attractive alternative to the excavation of waste. It is entirely possible that methods successful for heavy metals may be successful for the radioactive elements. Seven-years observation of the a settling pond contaminated with radium isotopes showed that even natural plant transgression into contaminated area can be an effective tool to stabilize pollutants. On the other hand, the assessment of the effectiveness of phytoextraction based on natural plants gave not so promising results.

Architects’ perspectives on construction waste reduction by design

The construction, demolition and excavation waste arising in England was estimated at 91 million tonnes in 2003. The current thinking on construction waste minimisation is heavily focussed on several issues relating to physical construction waste and recycling guides. Indeed, much had been published on ways to improve on-site waste management and recycling activities but very few attempts made to address the effect of design practices on waste generation. However, there is a consensus in the literature that the architect has a decisive role to play in helping to reduce waste by focussing on designing out waste. This paper examines previous studies on architects' approach towards construction waste minimisation; and by means of a postal questionnaire, investigates: the origins of waste; waste minimisation design practices in the UK; and responsibilities and barriers within the UK architectural profession. The findings reveal that waste management is not a priority in the design process. Additionally, the architects seemed to take the view that waste is mainly produced during site operations and rarely generated during the design stages; however, about one-third of construction waste could essentially arise from design decisions. Results also indicate that a number of constraints, namely: lack of interest from clients; attitudes towards waste minimisation; and training all act as disincentives to a proactive and sustainable implementation of waste reduction strategies during the design process.

Mixing Water Treatment Residual with Excavation Waste Soil in Brick and Artificial Aggregate Making

A large quantity of water treatment residual is generated each year from fresh water treatment plants in Taiwan. Landfill disposal of the nonhazardous sludge is impractical because of the high cost of transportation and an increasing scarcity of landfill sites in Taiwan. The water treatment residual was characterized; the ceramic bodies were prepared and sintered to formulate into building bricks and artificial aggregates. The sintering temperature requirement by the water treatment residual was higher than normally practiced in brick works due to the higher Al2 O3 and lower Si O2 content. The excavation waste soil, practically clay, was blended with water treatment residual to improve the brick quality. Under the commonly practiced brick-making condition, up to 15% of water treatment residual could be added to produce first grade brick specified by the National Science Council (NSC). Test results of specific gravity, water absorption, and compressive strength of the artificial aggregates confirmed its ap...

道路工事に伴う掘削残土リサイクルの運営と改良土の道路工学的特性 大阪市の場合

道路工事に伴う掘削残土リサイクルの運営と改良土の道路工学的特性 大阪市の場合