Slumps of the concrete cone in ccntimetres and the

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: the detachable cable connected to the vibrometer and a control switc!). A photograph of the apparatus under operation is given in Fig. 2. ~-3. PROCEDURE A-3.1 A slump test as described in Appendix G of *IS: 456-1957 is perThe glass formed in the sheet metal cylindrical pot of the consistometer. 2 4 6 VEE-BEE 8 IO DEGREES FIG.3 RELATION BETWEEN SLUMP IN CM AND VEE-BEE DEGREES *Second revision in 1964. 37 I IS : 457 - 1957 disc attached to the swivel arm is moved and is placed just on top of the slump cone in the pot and before the cone is lifted up the position of the concrete cone is noted by adjusting the glass disc attached to the swivel arm. ? he cone is then lifted up and the slump is noted on the graduated rod by lowering the glass disc on top of the concrete cone. The electrical vibrator is then switched on and the concrete is allowed to spread out in the pot. The vibration is continued until the whole concrete surface uniformly adheres to the glass disc as indicated in Fig. 2 and the time taken for this to be attained is noted with a stop-watch. The time is recorded in seconds. ‘i-4. RESULT A-4.1 The consistency of the concrete is expressed which are equal to the time in seconds under A-3.1. A-4.2 The required slump scale given in Table II. is obtained on the basis in Vee-Bee of the degrees consistency A-4.2.1 The curve in Fig. 3 indicates the relationship between slump in cm and the degrees covered by the consistency scale given in Table Il. TABLE CONSISTENCY M&t earth Very dry II NUMDEX OP VEE-UER 20 to IS to 10 to 7 ta c Plastic 5 to 4 to 3 Semi-fluid 3 to 2 to 1 Fluid More fluid than 1 SCALE CHAR.XTERISTICS DEGP.EES 40 to 25 to 20 IO CONSISTENCY Particles 01 coarse aggregate in the concrete are Risk of adhesive, but concrete does not clot. segregation. Concrete has the consistency of yery stiff porridge, forms a stiff mound when dumped, and barely tends to shake or roll itself to form an almust horizontal surface when conveyed for a long time in, say, a wheel-barrow Concrete has the consistency of stiff porridge, forms a mound when dumped, and shakes or rolls itself to form a horizontal surface when conveyed for a long time in, say, a whcclbarrow. Co!xrcte can be shaped into a ball bctwccn the palms of the hands an? adheres to the skin. Concrete cannot be rolled int(l a haK1 between the palms of the hands, but spreads out even though slowly and without affecting the cohesion of the constituents so that segregation does not occur. Concrete spreads uut rapidly and segrcgatlon takes place. 38 JS : 457 - 1957 APPENDIX I3 ( Clause 7.5.2 j METHOD B-l. OF SECURING HARDENED SPECIMENS CONCRETE FROM THE STRUCTURE OF SCOPE B-l.1 This method covers the procedure for securing, preparing and testing specimens of hardened concrete from structures and pavements. B-2. PRECAUTIONS I B-2.1 A specimen to be tested for stretlgth shall not be removed from the structure until the concrete has become hard enough to permit its removal without disturbing the bond bet...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online