Compression Test Lab Report

Compressive Strength Test in accordance to ASTM C39 / C39M:

After the removal of the specimens from the moist storage, compression test of moist-cured specimens was done.

The specimens were placed in a manner with its hardened face up, on the table or platen of the testing machine directly under the spherically seated (upper) bearing block.

The bearing surfaces of the retaining ring or rings and the center of the unbounded cap or caps on the cylinders were cleaned. It was aligned carefully in the axis of the specimen with the center of thrust of the spherically seated block. The load was applied continuously without shock. The compressive load was applied until the load indicator showed that the specimen displays a well-defined fracture pattern.

Diametrical lines were drawn on the two ends of the specimen to ensure that they were on the same axial place. The weight and dimension of the specimen were noted. The compression testing machine for the required range was set. The plywood strip on the lower plate was kept and the specimen was placed. The specimen was aligned so that the lines marked on the ends are vertical and centered over the bottom plate. The other plywood strip was placed above the specimen. The upper plate was brought down to touch the plywood strip. The load was applied continuously without a shock at a rate of approximately 14-21kg/cm2/minute (Which corresponds to a total load of 9900kg/minute to 14850kg/minute). The breaking load (P) was noted.

Young’s Modulus of Elasticity Test in accordance to ACI 318 The young’s modulus of concrete was computed using the method of Elastic Modulus provided by the code ACI 318.

The compressive strength is the measured maximum resistance to axial loading, express as force per unit of cross sectional area in pounds per square inch (psi). Modulus of Elasticity can be estimated from compressive strength.

Ec=Elasticity of Concrete fc=Compressive Strength of Concrete

Wc=Unit Weight (Density) of the concrete

Ec=33Wc1.5f1/2 (PSI lb/ft3) (ACI 318)

Ec=.04.Wc1.5f1/2 (MPA kg/m^3) (ACI

The outside joints of the mold and the contact lines of the mold and base plate were sealed to prevent loss of the mixing water from a freshly molded specimen. The interior surfaces of the mold were thinly covered with mineral oil. The 1 x 11.25 x 1 inches mold and reference bar were used. The reference bar of 11.25 inches in size was placed in the instrument in the same position each time a comparator reading was taken. The dial gauge setting of the measuring device was set by the reference bar during the start and end of the readings. It was made within half a day when the apparatus was kept in a room maintained at a constant temperature. It was checked more often when it was kept in a room where the temperature was not constant. Comparator Readings were obtained by slowly rotating the specimens in the measuring instrument while the comparator reading is being taken. The minimum reading of the dial was recorded only if the rotation causes a change in the dial reading. Specimens were placed in the instrument with the same end up each time a comparator reading was taken. It obtained the comparator readings of specimens stored moist, the hole in the base of the comparator was cleaned into which the gauge stud on the lower end of the bar fits. The comparator indication of the length of the reference bar was read and recorded. One bar was taken out of immersion, pins were blotted, the bar in the comparator was placed, the indication was read, and