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Land Ventures t,LLC Land Venturcs I,LLC <br /> Projed 614-08095 ProjeU 814-08095. <br /> November 19,2014 November 19,2014 <br /> Page 12 Page 13 <br /> D.4. Interior Slabs <br /> Even small amour�tr of frost-rela�ed differentiai mwerntnt at walkway Jolnts or cracks ran treate <br /> tripping hazards.Several subgrade impravement optbns can be explored to address th(s condition.The <br /> � <br /> most conservative and potentially most oos[Iy subgrade Improvement optlon to he�p IImR tMe potential <br /> DA.a. Moistun Vepor Protectlon <br /> If floor coverings or coatw�gs less permea6le than the tontrete slab wlll be used,we recommend that a �r heaving,but rrot eliminate It,would be to remove any frost-susteptible sofls present below the <br /> vapor retarder or vapor barrler be placed lmmediately beneath the slab.Some contractors prefer to bury extertor s{a6s"footprinY down m the bottom-of-footing grades or to a maximum depth of 5 Teet bebw <br /> the vapor retarder or barrier be�eath e layer of sand to reduce curAng end shrinkage,but this practice subgrade elevatbns,whicheve►fs less.We retommend the resulting excavatfpn then be retiEled with <br /> risks trepping water betwten the slab and vapor retarder or barrler. sand or sandy grevel having less than 50 percent of the particles by welght passing the#40 sieve and less <br /> than 5 percent of the particles by vreight passing a�200 sfeve. <br /> Regardless of where the vapor retarde�or barrier is piaced,we recommend consulting wtth floor <br /> covering manufacturers regarding the approprlate type,use and instaMatlon of the vapor retarder or <br /> Another subgrade improvement option would be to but4d In a traraitian zone between those wils <br /> considered to be irast-suscepdble and those that are not to somewhaY contro)where any dEfferential <br /> barrier to preserve warranty aswronces. movement may oaur.Such troruitlons could exist between exterior slabs and pavements,hetween eMry <br /> D.4.b. Radon <br /> way slabs and sidewalks,and abng the sidewalks themselves.For thts option,the frost-suscepdble so�s <br /> In preparetion for radon mitigation rystems,we reoommend that slabs on grode be constructed over a in critipl areas would 6e removed to a depth of at least 4 feet bebw grade as discttssed above.The <br /> layer of gas permeable materlai cor�sti�of a minimum of 4 inches of etther clean aggregate,or sand excavation trelow the f�tprint of the sidewa(ks or other s]abs would then 6e sloped upward at a <br /> underlain wnh a geotextile matting sukable for venttng the subgrade.TF�e clean aggregate material gradient rw steeper than 3:1(horizontal:vertical)toward the less mtical areas.The bottom of the <br /> should corisist of sound rodc no larger than 2 incfies and no smaller than YJ41nch.Sand shou�have less excavatfo�should then be sloped tovrard the cer�ter so tliat arry water ent�ing tF�exp,�at�n tou(d� <br /> than 50 percent of the particles by weight passing a#40 sieve and less than 5 percent of the particles by quickly dratned to ttre deepest area for removal.In the deepest areas of the excavation,a series of <br /> perFarated drainpipes will need to he instalkd to collect and dispose ofsurface water infiltration and/or <br /> welght pauing a#200 sieve. groundwater that could aaumulete wlthln the bacicfill.The piping uroukl need to be connected to a <br /> Above the gas permeaDk�gregate or sand,a Qolyethylene sheeting(6 mil minlmum)sfiould be placed. storm sewer o�a sump to remove any aaumulated uuater.ff the water Is not removed,k is ouropinfon <br /> fie sheetfng should be properly lapped artd penetratfons thruugh the sheeting�aled.Penetratiorts this option wIN not be effective in cvntrolif�g heave. <br /> through the slab and fou�datfon walis shouid also be sealed. <br /> Regardless of what is done to the walkway or pavemerrt area wbgrade,It will be critftal the end-user <br /> D.S. Exterior Slabs <br /> devebp a detelled maintenance program to seal and/or fill any crecla and Joints that may develop during <br /> the useful Itfe of the vdrious s�trface features.Concrete and bitumkfous wTil ezperience episodes of <br /> ays or lean cla 7hese soils normal thermo-expansian and thermo-contredbn during its useful Iife.Dur{ng this time,cracks may <br /> All or some of the exterior slabs wfll be underlain with mostly sandy kan cl ys. <br /> are mnsidered to be moderately to Mghly frost s6sceptible.Soils ofthis type can retain masture and devebp and Jolnts may open up,which will e�ose the wbgrade and allow any waterflowing overland to <br /> heav2 upon freezing.In general,thfs characterlst9c is nat an issue unless these soils betome seturated errterthe subgrade and either saturatt the subgrade soRs or ro become perched atop It.This otturrence <br /> due to surFace ninoff or infl4tration or are excessively wet in-situ.Once hozen,these soils rould heave �ntreases the potential ior heave due to freezfng conditlons i�the gene2l vlcin'ity of the crack or jant. <br /> and also result in unfavorable heaving of related sufia�e features that are supported by these soils.This 71�is type of heave has tfie potential m become excessive if not addreued as part of a maintenance <br /> type af heaving could fmpact design dralnage patterns and the performance of the paved areas or program.Speciai atterKion should be paid to areas where disslmNar materfals abut one anotlier,where <br /> exter4or sFabs.To address most of tfie heave related Issues.we recammend the general sfM grades and ��utittlon Jofnts oavr and where shrinkage crarks devebp. <br /> g►ades forsurface features be setta direct surface drainage away fram buNdin�s,across large paved <br /> areas and eway from vrapcways to Iimk the poterrtial for saturatlon of the sui�grede and amr wbsequerit <br /> heaving.General gredes should also have enough"sbpe"shown to tolerete potential larger areas of <br /> fieave whkh may not fully settle when thawed. <br />