6-inch slab would produce a dead load of 6 by 12.5 or 75  pounds  per  square  foot,  excluding  the  weight  of forms.  The  recommended  minimum  construction  live load  to  provide  for  the  weight  of  crew  members  and equipment is 50 pounds per square foot of horizontal projection.  If  powered  concrete  buggies  are  used  in concreting   operations,   it   is   recommended   that   75 pounds   per   square   foot   be   used   as   a   minimum construction live load. Lateral Pressure When  concrete  is  placed  in  the  form,  it  is  in  a plastic  state  and  behaves  temporarily  like  a  fluid, producing a hydrostatic pressure that acts laterally on the  vertical  forms.  If  concrete  acted  as  a  true  liquid, the pressure developed would be equal to the density of the fluid (150 pounds per cubic foot is commonly assumed  for  concrete)  times  the  depth  in  feet  to  the point  at  which  the  pressure  was  being  considered. However,  plastic  concrete  is  a  mixture  of  solids  and water  whose  behavior  only  approximates  that  of  a liquid,  and  then  for  a  limited  time  only.  This  lateral pressure  is  comparable  to  a  full-liquid  head  when concrete   is   placed   full   height   within   the   period required for its initial set. With slower rates of placing, concrete at the bottom of the forms begins to harden, and   the   lateral   pressure   is   reduced   to   less   than full-fluid pressure by the time concreting is completed in the upper parts of the form. The   effective   lateral   pressure,   a   modified hydrostatic pressure, has been found to be influenced primarily by the rate of placing and the temperature of the concrete mix. Other variables that have been found to   have   an   effect   on   lateral   pressure   include consistency   of   concrete,   amount   and   location   of reinforcement,   vibration,   maximum   aggregate   size, and   placing   procedures.   However,   with   usual concreting practices, the range of the effects of these variables is generally small and is either neglected or compensated for in design tables. Lateral  Loads Adequate lateral bracing is extremely important to stability and safety in formwork construction; but all too   often,   it   is   treated   carelessly   or   even   omitted entirely.   Formwork   must   be   braced   to   resist   all foreseeable  lateral  loads,  such  as  those  imposed  by wind, dumping of concrete, or any other impact, such as starting and stopping of equipment. There are many types of braces that can be used to give forms stability. The  most  common  type  is  a  diagonal  member  and horizontal   member   nailed   to   a   stud   or   wale.   The diagonal member should make a 45-degree angle with the  horizontal  member.  Additional  bracing  may  be added   to   the   form   by   placing   vertical   members (strongbacks) behind the wales or by placing vertical members  in  the  corner  formed  by  the  intersecting wales. WALL FORM DESIGN Concrete  forms  must  be  constructed  to  resist  the pressure   exerted   on   them   by   the   freshly   placed concrete   without   deflection   (side   displacement) beyond a specified maximum. This maximum is very small;  for  a  wall  form,  for  example,  the  maximum deflection  of  sheathing,  studs,  and  wales  is  not  over 1/270th  of  the  span. Placing concrete exerts a very considerable lateral (side) pressure on the form sheathing. The pressure at the  bottom  of  the  freshly  placed  concrete  is  greater than that at the top and the pressure increases with the height of the form. When designing formwork, you must ensure that the  sheathing,  the  stud,  and  the  waler  spacing  are designed   to   a   given   pressure   (vertical   rate   of placement). Vertical Rate of Placement To  determine  the  vertical  rate  of  placement  for concrete   wall   forms,   you   divide   the   quantity   of concrete (mixer output) which is placed into the form in an hour (in cubic feet) by the horizontal area of the form space being filled. Suppose you are filling a wall section for a wall 30 feet long by 12 inches thick. The horizontal area would then be 30 square feet. See the formula below. Let’s  take the hourly rate of the 11 S mixer (11 cubic feet per load) which has an hourly output of 4 to 8 cubic yards or from 108 to 216 cubic feet (depending on personnel) in a continuous operation. However, the quantity of concrete placed in the form per hour will depend on how continuous the mixer operation is and how rapidly the mix is transferred from the mixer to the  form.  This  quantity  you  will  have  to  determine according to your knowledge and circumstances at the 3-3