Show concrete mixed with accuracy sti strength of Mater material itil Is determined tei ter in ened mined by amount of water employed rw few persons realize verl merlinva inva how great till nil it a difference ir fir tile lio proportion I 1 of water call leave in tile ho mixing ng of concrete con creto there a uro 1 ro ninny many who do not realize that lint for eawh pint of water added to i it concrete mixture tile the strength of wo bo be decreased us as much ns as if two pounds or of porthina por celli ent had been loft left out tin the best mixture la Is that which Is us stiff arlly ns as enn le be mixed con itly bitven this will not lo ho 10 of tile strength which could bo be 4 b slump test cone I 1 obtained tint but n mixture of maximum strength would not bo be practicable for general construction purposes as it would bo be too stiff to bo be worked but a 0 mixture of the lie stiffest consistency can bo be worked will give 70 to 00 ner cent of the strength the accompanying table shows liow flow too much or too little water lc tracts from the strength of concrete con creto by wasting tho the strength of the concrete mass concrete such as Is used for heavy foundation work should not slump to exceed 2 inches reinforced concrete such euch as walls should not slump more than 0 inches concrete con creto roads when finished by hand should not balvo more than it a 4 incho slump I 1 while cement mortar for loor should not have a greater slump than 2 inches inch 08 applying slump test to apply tho slump test estimate tile tho minimum luin that you call uso use and still obtain the consistency in tile tho concrete test the hatches frequently to elleck chuck tile the slump anti and lu in crl asu or decrease tile q quantity of wilter water accordingly consistency of 0 concrete mixtures es la in easily mett und and regul tiled by tile slump test the only apparatus needed tit in ulak ins ing the test Is n 11 pointed mehul rod 21 inches loni an and a piece of sheet for it form forin rolled into tile tho of 0 the fruat llin 0 f a cune cone as shown in III the tile form can call bo be cut from it piece of 16 15 inches wide 26 20 inches long ions und and nut not less leaa than 20 gauge when nhen lied it will bo ba 12 inches lin liea high 4 inches In clita in dia lueter at tile alio top und 8 indies inches in III divinie ter a at t tile bottom pill tills this form with will tile concrete t to 0 bo be tested placing it in layers about 4 inches deep and nd worling it with tile pointed metal rod knelt lanyer r should lie bo exactly 80 30 tittles almea lift oft off th forin immediately and measure alfo sut set clement or baumi of tile tho concrete concrete having a slump of inch will alii con contain condall tall only a 11 little more witter water than necessary tor for strength hut will bo be too stiff for moat construction work woric concrete containing 10 por per cent moro more water than Is required require d for foe greatest strength will give n R slump of 0 3 9 to 4 indies i 25 per cent C excess water gives a slump of 0 to 7 il inches lelles 00 50 per cent excess witter water gives a slump of 8 to 10 inches 10 too little water wastes 27 of the cement 6 10 7 much 10 20 12 20 18 30 26 25 40 81 60 50 12 42 so 60 83 63 70 1 80 72 70 tho the right amount of water for coment cement mixture f maryin g st bength s ia shown in ID the following table cement gravel back of cement I 1 felt 8 cubic foot 5 to gallons 1 1 1 a 11 1 5 A 1 2 3 6 0 W 1 3 4 0 4 1 3 5 7 7 3 a 9 alk as 4 z Z i p K X V using the iho cone in making the slump tact T |