Geotechnical and Geoenvironmental Properties of Recycled Construction and Demolition Materials in Pavement Subbase Applications

Abstract

A comprehensive laboratory evaluation of the geotechnical and geoenvironmental properties of five predominant types of Construction and Demolition (C&D) waste materials was undertaken in this research study. The C&D materials tested were Recycled Concrete Aggregate (RCA), Crushed Brick (CB), Waste Rock (WR), Reclaimed Asphalt Pavement (RAP) and Fine Recycled Glass (FRG). The geotechnical assessment included particle size distribution, particle density, water absorption, compaction, Los Angeles abrasion, post-compaction sieve analysis, flakiness index, hydraulic conductivity and California Bearing Ratio (CBR) tests. Shear strength properties of the materials were studied through a series of triaxial tests. Consolidated drained triaxial tests undertaken on the recycled materials indicated that the recycled materials had a drained cohesion ranging from 41 kPa to 46 kPa and a drained friction angle ranging from 49° to 51°, with the exception of FRG and RAP. The response of the materials under repeated load was investigated using repeated load triaxial (RLT) tests. The RLT testing results indicated that RCA, WR and CB performed satisfactorily at 98% maximum dry density and at a target moisture content of 70% of the optimum moisture content under modified compaction. The geoenvironmental assessment included pH value, organic content, total and leachate concentration of the material for a range of contaminant constituents. In terms of usage in pavement subbases, RCA and WR were found to have geotechnical engineering properties equivalent or superior to that of typical quarry granular subbase materials. CB at the lower target moisture contents of 70% of the OMC was also found to meet the requirements of typical quarry granular subbase materials. The properties of CB, RAP and FRG however may be further enhanced with additives or mixed in blends with high quality aggregates to enable their usage in pavement subbases.

Yapim Yikim Atiklarinin Yol Temelleri̇nde Kullanilabi̇li̇rli̇ği̇ni̇n İncelenmesi̇

“…Kompaksiyon eğrisi ve kompaksiyon öncesi ve sonrası yapılan elek analizine göre belirlenen gradasyon değişimi Şekil 8'de sunulmuştur. Malzemenin kompaksiyon öncesi ve sonrasındaki gradasyonları birbirine benzemektedir [3]. YYA malzeme üzerinde optimum, %6 ve %12 su içeriğinde olmak üzere farklı su içeriklerinde CBR deneyi yapılmıştır [33].…”

“…Çalışmada elde edilen sonuçlar aşağıda özetlenmiştir. 3 , su emmesi ise ince danelerde %6,82 kaba daneler için %4,06 çıkmıştır. Malzemenin içerisindeki çimento bazlı danelerin diğer danelere göre su emmesinin yüksek olduğu düşünülmektedir.…”

“…Ülkemizde ise 2012 yılında çıkan 6306 sayılı 'Afet Riski Altındaki Alanların Dönüştürülmesi Hakkında Kanun' ile riskli bulunan yaklaşık 6-7 milyon yapının yıkılması planlanmaktadır. YYA malzemelerin geri dönüştürülerek tekrar kullanılması, çevreye olan etkileri açısından, inşaat endüstrisi tarafından üretilen katı atıkların depolama maliyetlerini düşürmesi, atık depolama gereksinimini azaltması, inşaat için zeminden elde edilen doğal kaynakların kullanımını azaltması, atık malzemelerin daha çok değerlendirilmiş olması, enerji israfını azaltması ve sürdürülebilirliğin artması gibi olumlu etkiler yapabilmektedir [1][2][3][4][5][6].…”

Investigation of the Effect of Recycled Asphalt Pavement Material on Permeability and Bearing Capacity in the Base Layer

“…e percentage of RAP material in blends exceeds 20-25%, and the expected CBR value for the base course decreases as discussed by several authors [4][5][6][7][8][9][10][11][12]. Some researchers reported that the RAP content of the base mixtures should be limited to a maximum of 50% by weight [7,8].…”

Economic and Environmental Evaluation and Optimal Ratio of Natural and Recycled Aggregate Production

“…It has been reported that a developed country like Australia produces 8.7 million tons of waste demolition concrete, 1.3 million tons of waste brick, 3.3 million tons of waste excavation rock, 1 million tons of waste glass, and 1.2 million tons of waste asphalt every year [1]. According to other statistics [2], 42% of all wastes in Australia are related to construction and demolition (C&D) waste, and of this amount 81% is waste concrete.…”