Test of Concrete on site

Here we use many test of concrete for determine the strength of concrete and workability. here are the 6 types of concrete test

          (1) Compressive Test.

          (2) Slum Cone Test.

          (3) Compaction Test.

          (4) Water permeability Test.

         (5) Water Absorption Test.

         (6) Initial Surface Water Absorption Test.

   Here we are discuss only 2 test of concrete bcz. this test is mostly use in the world on the site

     (1) Compressive Strength Test:-

     (a) Equipment:- 
                                  Compressive test machine , Needle vibrater  , 3 Specimen 150x150mm , Concrete ratio M15.

    (b)  Procedure:-

                                  In this test we check the quality of concrete. we take the ratio of M15( 1 : 2 : 4)  and mixing concrete proper after we fill up concrete in the specimen and similar fill up concrete in 3 specimen and needle vibrater  use in specimen properly. vibrater is properly settle down concrete and air voids remove from the concrete after we will curing for 24 hours . after 24 curing specimen keep in the water for 7 days. In the 7 days concrete is get good strength and good workability . After 7 days we will do test of all 3 specimen by compressive test machine( CTM). Now specimen is put in the CTM and apply load gradually . reading is note before cracks the specimen. Ex. if the compressive load is 90KN. then

                                                    Compressive Strength = Compressive load / Cross-section area of specimen
                                                                                        = 90 / 225

                                                                                        = (90x100) / 225   = 400kg / cm2

Similar we take the three reading and check the average . The average is the compressive strength of concrete.

      (2) Slum-Cone Test:-

      (a) Equipment:-

                                 Slum-Cone , Tamping road , Concrete(M15) , Metallic mold ----(Slum-cone test by check the workability of the concrete . Slum-cone test is the popular test. The slum-cone size is bottom dia.(diameter) 20cm and top dia. 10cm and the height is 30cm with the base plate . the full slum-cone make by metallic mold. steel tamping rod dia. 16mm and the height 60cm.)

   (b) procedure:-

                             Frist we will take M15( 1 : 2 : 4 ) and mixing proper and become a right concrete . The concrete is fill up in the slum-cone by four layer . The each layer is fill up 1/4 of height. when we fill up one layer of concrete in the slum-cone then tamping 25 times of concrete by the tamping road. similar the fill up four layer . After the complete all layer finish the top by towel. here we check the slum. the slum is check by remove slum-cone.

Here make three slum.

(1) True slum.
(2) Shear slum.
(3) Collapsible slum.

                                  

After remove the slum-cone if slum is true slum then concrete workability is good.

NOTE:-
                Now we check the how many concrete is required for slum cone?

              > Volume of slum-cone test (V) = pixh / 3 ( R^2 + Rxr + r^2)

                                                                  = pix30 / 3 ( 10^2 + 10x5 + 5^2)

                                                                  = .005495m^3

                  we know that ------Density  = Mass / Vol.

                                          2400kg/m^3 = Mass / .005495 m^3

                                             Mass  =   2400  x .005495

                                                       =  13.188 kg.

             50% wastage of concrete then = 50% x 13.188    =>  6.594 kg.

          Total concrete = 13.188 + 6. 594

                                  = 19.782kg ~ 20kg.  

 

          > Sum of ratio 1 + 2 + 4 =>  7

 

          > Mass of cement     => 2.85kg.

          >  volume   => 20 kg.

    Now

             weight of cement    =>  (1 / 7)x 20

                                             => 2.85 kg.

             Weight of sand   =>   (2 / 7) x 20             

                                        =>   5.70 kg.

          Weight of aggregate  => (4 / 7) x 20

                                            => 11.40 kg.