scholarly journals A study of the Hot-Mix Asphalt layer thickness reduction when applied over lateritic soils cement base in airfield

Exacta ◽  
2009 ◽  
Vol 7 (1) ◽  
pp. 121-132
Author(s):  
Alex Alves Bandeira ◽  
Rita Moura Fortes ◽  
João Virgilio Merighi
Keyword(s):  
Hot Mix Asphalt ◽  
Construction Material ◽  
Federal Aviation Administration ◽  
Lateritic Soil ◽  
Tropical Region ◽  
Lateritic Soils ◽  
Aluminum Hydroxides ◽  
Yellow Coloration ◽  
Base Course ◽  
The Cost

In tropical region, in upper layers, soils having red or yellow coloration are generally found and are denominated lateritic soils. They are rich in aluminum hydroxides and ferric hydrates that give an elevated mechanic resistance. When the lateritic soils are used as a construction material in the structural pavement, the exceptional mechanical characteristic reduced the cost over 50% when associated with the sub-base and base layers, or over 25% when the lateritic soil is treated with cement. In São Paulo State, it was made more than ten thousands kilometers of roads where the base or sub-base was made using lateritic soils or lateritic soils treated with cement. In this study, it is showed, through Finite Element Method, a critical analysis of the sub-base and base of airfield pavement using lateritic soils cement base course and Hot-Mix Asphalt thickness surface less than recommended for critical area in according to Federal Aviation Administration (1996). Considering the results, it is possible to propose a reduction of thickness Hot-Mix Asphalt layer, resulting in a reduction of the final cost of implantation of hundreds of airfields in South America.

scholarly journals A study of the Hot-Mix Asphalt layer thickness reduction when applied over lateritic soils cement base in airfield DOI: 10.5585/exacta.v7i1.798

Exacta ◽  
2009 ◽  
Vol 7 (1) ◽  
pp. 121-132
Author(s):  
Alex Alves Bandeira ◽  
Rita Moura Fortes ◽  
João Virgilio Merighi
Keyword(s):  
Hot Mix Asphalt ◽  
Construction Material ◽  
Federal Aviation Administration ◽  
Lateritic Soil ◽  
Tropical Region ◽  
Lateritic Soils ◽  
Aluminum Hydroxides ◽  
Yellow Coloration ◽  
Base Course ◽  
The Cost

In tropical region, in upper layers, soils having red or yellow coloration are generally found and are denominated lateritic soils. They are rich in aluminum hydroxides and ferric hydrates that give an elevated mechanic resistance. When the lateritic soils are used as a construction material in the structural pavement, the exceptional mechanical characteristic reduced the cost over 50% when associated with the sub-base and base layers, or over 25% when the lateritic soil is treated with cement. In São Paulo State, it was made more than ten thousands kilometers of roads where the base or sub-base was made using lateritic soils or lateritic soils treated with cement. In this study, it is showed, through Finite Element Method, a critical analysis of the sub-base and base of airfield pavement using lateritic soils cement base course and Hot-Mix Asphalt thickness surface less than recommended for critical area in according to Federal Aviation Administration (1996). Considering the results, it is possible to propose a reduction of thickness Hot-Mix Asphalt layer, resulting in a reduction of the final cost of implantation of hundreds of airfields in South America.

scholarly journals Improvement of deltaic lateritic soil using river sand and cement for use as pavement construction material

2021 ◽  
Vol 40 (2) ◽  
pp. 168-176
Author(s):  
D. Imafidon ◽  
O.R. Ogirigbo ◽  
J.O. Ehiorobo
Keyword(s):  
Soil Stabilization ◽  
Construction Material ◽  
Strength Properties ◽  
Lateritic Soil ◽  
Natural Soil ◽  
Chemical Stabilization ◽  
Stabilization Method ◽  
River Sand ◽  
Lateritic Soils ◽  
Mechanical Stabilization

This study examined the effect of mechanical and chemical improvement on deltaic lateritic soils in Warri East in Delta State, Nigeria. Mechanical stabilization was carried out by adding river sand to the natural soil in various proportions, while chemical stabilization was carried out using cement and a mixture of cement and sand. Compaction and CBR tests were conducted on the natural soil before and after stabilization. From the results obtained, it was seen that the mechanical stabilization method improved the strength properties of the soil making it suitable for use as subbase materials, though not as much as the chemical stabilization method or the mixed method of stabilization. It was concluded that using a combination of cement and sand as a stabilizing agent for deltaic lateritic soils can lead to significant reduction in the amount of cement required for soil stabilization thus saving costs.

Assessment of Bentonite Influence on Hydraulic Conductivity of Lateritic Soil

2010 ◽  
Vol 3 ◽  
pp. 84-93 ◽  
Author(s):  
Agapitus A. Amadi ◽  
K.J. Osinubi
Keyword(s):  
Hydraulic Conductivity ◽  
Construction Material ◽  
Dry Weight ◽  
Optimum Moisture Content ◽  
Test Method ◽  
Lateritic Soil ◽  
Hydraulic Structures ◽  
Lateritic Soils ◽  
Compactive Effort ◽  
Soil Mixtures

Lateritic soils are pedogenic surface deposits which occur in vast areas of tropical and subtropical regions of the world and find use as construction material in diverse civil engineering aspects. But, the predominance of kaolinitic 1:1 lattice clay mineral and coating of the clayey constituents with sesquioxides limits the ability of the soil from achieving very low hydraulic conductivity, (k) required for some geotechnical/geoenvironmental structures. The present study investigates the influence of low percent bentonite on the hydraulic conductivity of a residually derived lateritic soil. Accordingly, the test programme involved specimens of lateritic soil - bentonite mixtures containing 0, 2.5, 5, 7.5 and 10% bentonite (by dry weight of soil) prepared at different compaction states (optimum, dry and wet of optimum content), compacted with British Standard Heavy, (BSH) compactive effort and permeated in compaction mould permeameter using falling head test method. Results indicate that reductions in hydraulic conductivity values ranged from 1 x 10-9 to 6.79 x 10-11 m/s (i.e. two orders of magnitude) as the percentage of bentonite increased from 0 to 10%. Soil mixtures with up to 5% bentonite content recorded the lowest k values at 2% wet of optimum moisture content, beyond which an increase in k followed. For soil mixtures containing 7.5 and 10% bentonite, a continuous decrease in k was observed. Furthermore, a non – linear relationship between log k and bentonite content was established. These results met or exceeded specification requirements for the aforementioned structures which therefore suggest that the potentials of lateritic soils as a geomaterial for the construction of hydraulic structures can be fully realized when treated with bentonite.

scholarly journals Managing raptors to reduce wildlife strikes at Chicago’s O’Hare International Airport

2016 ◽  
Author(s):  
Craig K. Pullins ◽  
Travis L. Guerrant ◽  
Scott F. Beckerman ◽  
Brian E. Washburn
Keyword(s):  
Significant Risk ◽  
Federal Aviation Administration ◽  
The United States ◽  
Civil Aviation ◽  
Aviation Industry ◽  
International Airport ◽  
The Past ◽  
Wildlife Damage Management ◽  
Wildlife Populations ◽  
The Cost

Nationally, wildlife-aircraft collisions (wildlife strikes) have been increasing over the past 25 years; denoted in the National Wildlife Strike Database that has been maintained by the Federal Aviation Administration (FAA) since 1990. Increasing wildlife populations and air traffic coupled with quieter, faster aircraft create a significant risk to aviation safety; the cost to the civil aviation industry is an estimated $937 million dollars annually. USDA/APHIS/Wildlife Services (WS) provides technical and direct assistance to over 850 airports and airbases around the United States, including Chicago’s O’Hare International Airport (ORD). At ORD, raptors are one of the most commonly struck bird guild and accounted for at least 25% of damaging strikes from 2010-2013. An Integrated Wildlife Damage Management (IWDM) program is implemented at ORD to reduce the presence of wildlife on the airfield, consequently lowering the risk of wildlife strikes. Professional airport wildlife biologists at ORD concentrate much of their efforts on raptor management due to the high strike risk these birds pose to aircraft on the airfield itself. A variety of techniques are currently used to manage raptor populations at ORD. Concurrently, research is being conducted to evaluate the efficacy of the Red-tailed Hawk relocation program at the airport, as well as to assess their movements within the airfield environment.

scholarly journals Performance Evaluation of the Effect of Sodium Hydroxide on Geotechnical Properties of Lateritic Soil for Rural Road Construction

2020 ◽  
Vol 5 (2) ◽  
Author(s):  
Ibrahim I Abdulkarim ◽  
Sa’eed Y Umar
Keyword(s):  
Sodium Hydroxide ◽  
Construction Material ◽  
Energy Levels ◽  
Molar Concentration ◽  
Engineering Properties ◽  
Lateritic Soil ◽  
Rural Roads ◽  
British Standard ◽  
Minimum Requirement ◽  
General Specification

This study explored the potentials of sodium hydroxide (NaOH) for the improvement of the properties of lateritic soil (LS) intended for use as construction material for rural roads in the North-eastern part of Nigeria. The soil was classified as A-6(13) and CL according to the American Association of State Highway and Transport Officials (AASHTO M 145-2012) and the Unified Soil Classification System (ASTM D 2487-2011). The soil is treated to evaluate the effectiveness of NaOH in treating lateritic soil with 1, 3 and 7 molar concentration of NaOH and compacted using two methods of compaction, the British Standard Light (BSL) and British Standard Heavy (BSH). Unconfined compressive strength (UCS) and Californian bearing ratio (CBR) tests were conducted on the compacted specimens. The results obtained show a general improvement in the engineering properties of the soil with increase in molar concentration of NaOH, particularly, when compacted at the BSH energy level. The maximum 7 days UCS values of 909 kN/m2 and 1106 kN/m2 were obtained at 7 molar concentration for the BSL and BSH energy levels. These values are within the range of 750 – 1500 kN/m2 UCS value specified by the Nigerian General Specification (2013) for sub-base materials. In the case of the CBR, at 3 and 7 molar concentrations for BSH effort, CBR values of 33% and 38% were recorded while 34% CBR value was recorded at 7 molar concentration for BSL effort, these values also met the minimum requirement of 30% CBR specified by the Nigerian General Specification for sub-base construction.Keywords— Lateritic, Sodium hydroxide, Soil, Rural roads. 

scholarly journals Reproductive and cost assessment of a seasonal breeding program with Bos indicus in tropical Mexico

2021 ◽  
Vol 26 (2) ◽  
pp. e2130
Author(s):  
José Francisco Martínez-Albarrán ◽  
Carlos Salvador Galina-Hidalgo ◽  
Ivette Rubio-Gutiérrez ◽  
Wendy Leticia Balam-Villarreal ◽  
Manuel D. Corro-Morales
Keyword(s):  
Pregnancy Rate ◽  
Breeding Season ◽  
Phase 1 ◽  
Bos Indicus ◽  
Fixed Time ◽  
Breeding Program ◽  
Tropical Region ◽  
Two Phases ◽  
One Year ◽  
The Cost

Objective. To compare the reproductive performance of postpartum and open Bos indicus cows and to study the cost effectiveness of retaining non-pregnant animals after a short breeding season in tropical region of Mexico. Material and Methods. A total of 128 Bos indicus were included, 87 postpartum cows (PP) with ≤90 days after calving and 41 open cows (OC) with >90 days open. The study was divided into three phases: 1) Estrus synchronization followed by FTAI (day 0-10), 2) Estrus detection and AI (day 11-45) and 3) Natural mating (day 46-90). For the first phase, all animals were synchronized and AI at fixed time (day 10). Cows displaying overt signs of estrus (day 11-45) were AI. Open cows during the previous two phases were exposed to the bull. Results. Pregnancy in phase 1 was different (p<0.01) for PP and OC groups, 58.6% and 34.1%, respectively. Overall pregnancy percentage over the second service was 42.5% (p>0.05). No differences (p>0.05) were observed at phase 3, average 44.2%. By the end of the breeding season, the cost of OC, was 3 times more than PP cows. Conclusions. Pregnancy rate at first phase was higher in PP cows than OC cows. At the end of breeding season, a pregnancy rate of 80% was found. Incorporation of open cows from previous breeding season was more expensive than PP cows in all phases of the breeding program. Retaining an open cow for rebreeding one year or more could not be economically feasible.

scholarly journals Improvement of Collapsible Soil Behavior of a Lateritic Soil Using Rice Husk Ash

2015 ◽  
Vol 668 ◽  
pp. 290-296 ◽  
Author(s):  
Luiza P. Fagundes ◽  
Jhaber D. Yacoub ◽  
Andrey C. Lima ◽  
Flávia R. Nakatsuchi ◽  
José A. Lollo ◽  
...  
Keyword(s):  
Rice Husk ◽  
Rice Husk Ash ◽  
Combined Effect ◽  
Building Construction ◽  
Lateritic Soil ◽  
Soil Behavior ◽  
Collapsible Soil ◽  
Lateritic Soils ◽  
Environmental Friendly

Great areas of Brazil present lateritic soils, such as the northeast and the south. Some of these soils have, as main characteristic, instable structures that can present considerable volumetric deformation in the presence of water. This behavior, also named collapse, is responsible for several problems on the building construction such as cracks and fractures that can damage the safety of structures. The aim of this paper is to assess the possibility of improvement of collapsible behavior of a lateritic soil using rice husk ash (RHA). A previous characterization of soil and RHA was performed in order to assess the combined effect of soil/RHA. The results are so promising, showing a new alternative to reduce the collapsible behavior of soils using an environmental friendly technology.

From statistics, through new requirements to mathematical modelling of SAT aircraft safety

2018 ◽  
Vol 90 (4) ◽  
pp. 659-666
Author(s):  
Bartosz Dziugiel ◽  
Zdobyslaw Jan Goraj
Keyword(s):  
Mathematical Model ◽  
Business Models ◽  
Federal Aviation Administration ◽  
Safety Level ◽  
Content Type ◽  
Technical Specifications ◽  
Safety Estimation ◽  
The Cost ◽  
The Impact ◽  
Small Aircraft

Purpose The purpose of this study is to investigate the influence of the technical and operational specifications of the Small Aircraft Transport System (SAT/SATS) to the achieved safety level. Design/methodology/approach Safety estimation was made with the use of mathematical model of safety of light aircraft in commercial operations developed on the basis of Federal Aviation Administration (FAA) data. The analysis was conducted for two different SATS business models based on Direct AiR Transport (DART) concept. It allowed for the investigation of the impact of technical specifications of the aircraft included into the SATS fleet as well as the selected elements of the applied business model on SATS safety level. Findings It was found that the proposed changes to DART system resulted in a significant improvement of safety. Mean Time Between Incidents and Accident (MTBIA) increased by 200 per cent. Additionally, the introduced alterations impacted the weights of particular domains and pilot’s error became less critical than the technical reliability. Practical implications It was shown that the application of new requirements influences both the safety level and the cost of operation, which was demonstrated within the ESPOSA and DART projects. Additionally, it was indicated that further effort to improve the light aircraft safety is absolutely necessary. Originality/value Originality consists in combining in one mathematical model both the aircraft configuration and the rules for business operation. Optimization of selected parameters of the system leads to a significant reduction in the accident number and to keeping the cost increment at a reasonable level. It was also found that the resulted improvement sometimes cannot be sufficient to consider a small aircraft operation fully safe, mainly owing to the numerous restrictions because of its small weight and loading capacity.

Performance Evaluation of Hot-Mix Asphalt Using Rotary Loaded-Wheel Testing

2005 ◽  
Vol 1929 (1) ◽  
pp. 157-164
Author(s):  
M. Shane Buchanan ◽  
Benjamin J. Smith
Keyword(s):  
Hot Mix Asphalt ◽  
Permanent Deformation ◽  
Asphalt Binder ◽  
Hydrated Lime ◽  
New Device ◽  
Proof Testing ◽  
Reasonable Prediction ◽  
The Cost ◽  
Performance Results ◽  
Transportation Agencies

Permanent deformation and moisture damage (i.e., rutting and stripping) are two predominant hot-mix asphalt (HMA) distresses. Rutting can be caused by many factors, including stripping, which result in reduced HMA shear strength. Hot-mix asphalt stripping evaluation is a source of significant industry discussion and debate. Transportation agencies use a number of methods to evaluate stripping, with many methods customized depending on local concerns and environmental conditions. Today, many agencies use some type of loaded-wheel testing, with associated mix “pass–fail” criteria, as part of the mix design acceptance procedure. This process is often referred to as “proof” testing and provides a higher confidence that the HMA mix will perform satisfactorily during service conditions. A new device, the rotary wheel tester, has been developed to evaluate the rutting and stripping performance of HMA mixes. This device operates on a principle similar to that of the Hamburg wheel tester: the main difference is that the specimen is loaded along its diameter instead of from the top. The cost of the rotary wheel tester is less than half that of the Hamburg wheel tester. Testing was conducted to determine whether the rotary wheel tester could distinguish between good- and poor-performing mixes and to determine whether PG 76-22 or PG 67-22 plus hydrated lime improved mix performance. Results indicate that the rotary wheel tester is an easy-to-use testing device that appears to provide reasonable prediction of the rutting and stripping performance of HMA mixes. It also appears that PG 76-22 asphalt binder improves mix performance to a greater extent than does PG 67-22 plus hydrated lime.

Recycling of Waste Originating Form Flexible Pavements for Bound-Base Courses of Flexible Pavements

2020 ◽  
Vol 46 (3) ◽  
pp. 394-408
Author(s):  
Kumari Monu ◽  
G.D. Ransinchung R.N. ◽  
Surender Singh ◽  
Gaurav Singh Raghav
Keyword(s):  
Asphalt Pavement ◽  
Flexible Pavements ◽  
Rutting Resistance ◽  
Reclaimed Asphalt ◽  
Coarse Aggregates ◽  
Long Run ◽  
Indirect Tensile ◽  
Base Course ◽  
The Cost ◽  
Marshall Stability

Reclaimed Asphalt pavement (RAP) is a C&D waste originating from the reclamation of asphalt pavement which has completed its service life. Using RAP would potentially reduce reliance on primary aggregates and lowers the environmental impact of construction. The present study is an attempt made to utilize RAP judiciously as a bound base course of the flexible pavement. Natural coarse aggregates were replaced by RAP in proportions of 50% & 100% with & without Warm Mix Asphalt (WMA), for production of bound-base course mixes. To ensure the long run performance, the aging condition was simulated in the laboratory and mechanical properties such as Marshall Stability, Tensile Strengths, Marshall Stability Retained, Indirect Tensile Ratio, rutting resistance, Fatigue life, and abrasion resistance were considered. With the incorporation of 50-100% coarse RAP, the Marshall Stability, rutting resistance and abrasion were found to be improved by 30-32%, 43-104% and 11-17% respectively. Similarly, total cost saving is about 15-35%, which is quite significant. However, the addition of WMA enhanced the cost by 3-4%, which is insignificant when combined with RAP, furthermore, the reductions in fume emission enhance the sustainability aspect of the technology.

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