7100 HARDESON RD 2016-01-01 MF Import

Fisher 6 Sons, Inc. JN 97282 Page 5 August 19, 1997 moisture through the slab is undesirable, a vapor bartier, such as a 6-mil plastic membrane, should be piaced beneath the slab. Additionally, sand shouid be used in the fine-grading process to reduce damage to the vapor barrier, to provide unifortn support under the slab, and to redu:.e shrinkage cracking by improving the concrete curing process. Isolation joints should be provided where the slabs intersect coiumns and walls. Control and expansion joints should also be used to control cracking from expansion and conVaction. The spacing of control or expansion joints depends on the slab shape and the amount of steel placed in it. Use of at least minimal rebar in the slab would hetp to limit differentiai siab settlement and cracking. Reducing the water-to-cement ratio of the concrete and curing the concrete, by preventing the evaporation of free water until cement hydration occurs, will also reduce shrinkage cracking. We recommend proof-rolling slab areas with a heavy truck or a large piece of construction equipment prior to stab construction. Any soft areas encountered during proof-rolling should be excavated and replaced with seiect, imported, structural fill. Pertnanent Foundation and Retaininc Walis Retaining walls backfilled on only one side should be designed to resist the lateral earth pressures impased by the soil they retain. The following recommended design parameters are for walls that restrain level backfill: Parameter Design Value Adive Earth Pressure' 35 pcf ••-•••-•-•-•...----•-+•-•--•-••----•-•-• - •-•---•-••-•-----••... 350 f Passive EaAh Pressure P� ....--••--...--•,-••--•-••--•----••- - ------•-•---•-••--•••-•-• 0.45 Coefficient of Friction - - •-- ---- - •-•--••-••••---•-•--••--•---;...-•-••----•--•-.. Soil Unit UVeight , 130 pcf 1Nherc: (I) pet Is pounds qr eubk foot. and (11) aetiva and pauive �arth pre+�uns arc canputed udng tM pulwNnt nuid pnssuns. • For a restnined wall that unnot deMcl N kad 0.001 thne� kc helght, � u�itam Irieral prouuro pual to 10 pd tMnes the halgM of the wall �hould be +dded to the above +�q�e puW�leM Iluid prauure. The values given above are to be used to design pertnanent foundation and retaining walls oniy. We recommend a safety factor of at least 1.5 for overtuming and sliding, when using the above values to design the walls. The design values given above do not inciude the effects of any hydrostatic pressures behind the walls and assume that no surcharge slopes or loads, such as vehiGes, will be placed behind the walls. If these conditions exist, those pressures shouid be added to the above lateral soil pressures. Also, if stoping backfill is desired behind the wails, we will need to be given the wall ceorecx coNsu�.ravrs, mc.