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Impact of fine materials content on the transport of dust suppressants in gravel road wearing courses
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Highway and Railway Engineering (closed 20110301).
Dalarna Högskolan .
2011 (English)In: Journal of materials in civil engineering, ISSN 0899-1561, Vol. 23, no 8, 1163-1170 p.Article in journal (Refereed) Published
Abstract [en]

A significant problem when dust-suppressing agents are used on gravel roads is that they tend to leach during rainfall. The purpose of this study is to illustrate this problem by using laboratory studies and studies in situ. Both capillary rise and leaching of suppressants were examined by using cylinders filled with wearing course material. Chloride was more prone than lignosulphonate to transport upwards by means of capillary rise, and therefore, it showed a more effective performance over a longer period of time. Optimal percentages of fine material for minimal lignosulphonate and chloride leaching were found to be 15% by weight and 10-15% by weight, respectively. Ions of calcium chloride seemed to flocculate clay particles, which probably prevents them from leaching. To study the in situ longevity of fine material in general, calcium carbonate, mesa, was used as a marker. The fine material in gravel wearing courses must be replenished regularly. Mesa loss was up to 80% after 1 year.

Place, publisher, year, edition, pages
2011. Vol. 23, no 8, 1163-1170 p.
Keyword [en]
Gravel roads, Dust suppressants, Vertical transportation, Leaching, Fine material content
National Category
Vehicle Engineering
URN: urn:nbn:se:kth:diva-12358DOI: 10.1061/(ASCE)MT.1943-5533.0000282ISI: 000293533100005ScopusID: 2-s2.0-79961073162OAI: diva2:309925
QC 20100616. Updated from submitted to published 20120326. Previous title: Transport of Dust Suppressants in Gravel Road Wearing Courses Related to Fine Material ContentAvailable from: 2010-04-09 Created: 2010-04-09 Last updated: 2012-03-26Bibliographically approved
In thesis
1. Evaluation of Dust Suppressants for Gravel Roads: Methods Development and Efficiency Studies
Open this publication in new window or tab >>Evaluation of Dust Suppressants for Gravel Roads: Methods Development and Efficiency Studies
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Approximately 75 percent (300 000 km) of the total Swedish road network and 20 percent(20 000 km) of the national road network consists of gravel roads. One of the most significantproblems associated with gravel roads is traffic-generated dust emission, which contributes tothe deterioration of the road surface and acts as a major source of particulate matter releasedinto the atmosphere, thereby involving public economics, road safety, human health, andenvironmental quality. In order to bind the fine granular material, which is prone to rise into theair, dust suppressants are applied on roads on a yearly basis.

Methods for evaluating the efficiency of dust suppressants will facilitate in the selection of themost appropriate product and its optimal application rate. For example, methods forsupervision of residual dust suppressant concentration are valuable tools for estimatinglongevity and optimal application rates, and, consequently, effectiveness of different products.

Application of the proper dust suppressant to a gravel road ensures road safety and ridingcomfort as well as creating a cleaner and healthier environment for residents in buildingsadjacent to the road. It also reduces the need and cost for vehicle repair, road maintenanceactivities, and aggregate supplementation.

Both field-based and laboratory research were performed to evaluate the efficiency of varioussuppressants and the influence such factors as product concentration, leaching, and fine materialcontent have on the efficiency of different products. Within the field-based research, a newlydeveloped mobile methodology was used to measure dust emission on numerous test sectionstreated with various dust suppressants. In general, all dust suppressants tested, except apolysaccharide (sugar) and products, which form a brittle surface crust, i.e. lignosulphonate andbitumen emulsion, showed acceptable dust reduction.

Test sections treated with a magnesium- or calcium chloride solution were the most effectivelydust suppressed. The application of solutions instead of a solid salts achieves a more uniformproduct distribution and, therefore, probably a more efficient performance. By applying acalcium- or magnesium chloride solution instead of traditionally used solids, the cost for annualdust control, as well as the environmental impact from the release of these chemicals in theenvironment, can be reduced by 50 percent.

A significant problem when using dust suppressants is their tendency to leach during rainfalldue to their soluble properties. Residual chloride could be detected in the gravel wearing courseover a longer period of time than lignosulphonate and, therefore, showed more effective longtermperformance. Optimal percentages of fine material for minimal lignosulphonate andchloride leaching were found to be 15 percent by weight and 10-16 percent by weight,respectively. Ions of calcium chloride seemed to initiate flocculation of clay particles, therebypreventing them from leaching. Still, the fine material in gravel wearing courses has to be replenished regularly as indicated by studies of the longevity of fine material. Loss up to80 percent was found after two years.

Toxicity tests show that dust suppressant application for dust control purposes, at traditionallyused application rates, does not constitute a threat to sensitive aquatic life. Tests on subsoilwater samples indicated elevated chloride levels, which possibly could cause corrosion to pipes,but not high enough to flavour drinking water.

Place, publisher, year, edition, pages
Stockholm: KTH, 2010. 64, vi p.
Trita-VT. FR, ISSN 1650-867X ; 10:05
Gravel road, dust, particulate matter, PM10, horizontal dust diffusion, deteriorations, maintenance, dust control, dust suppressants, efficiency, application rate, leaching, residual concentration, seasonal variations, salt solution, solid salt, calcium chloride, magnesium chloride, lignosulphonate, polysaccharide (sugar), bitumen emulsion, rape oil, starch, surfactant, mesa, clay, fine material content
urn:nbn:se:kth:diva-12359 (URN)978-92-7415-612-6 (ISBN)
Public defence
2010-04-21, F3, Lindstedtsvägen 26, KT, Stockholm, 10:00 (English)
QC20100616Available from: 2010-04-09 Created: 2010-04-09 Last updated: 2010-06-16

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