Introduction:

Mortar test hammer is specially used in testing the compressive strength of mortar in building brick component.

The detennination of the characteristic strength of masonry and its components in historic buildings requires in situ testing methods which are simple to use, reliable and nondestructive. The basic principles of a nondestructive testing method to determine the strength of mortar in the masonry  wall are shown. The rebound hammer, model Schmidt, is modified  by fixing a triangular plate to the bolt of the hammer. Test results show that the number of millimeters the plate is driven into the mortar layer between the first and the tenth impact characterises the strength of the mortar in the masonry wall. A reliable result cannot be obtained by measuring the rebound factor itself.

Standards: ENV1996-1-1

Specification:

1）Center rod use imported materials, high precision, wear proof.

2）Shell made from super hard aluminum, perfectly protect instrument from damage on site work, and prolong use life.；

3）Pointer slider is outside ring structure, easy to adjust friction, and assure the equal friction between pointer slider and axis, so that assure the accuracy of instrument. Compare with other brand similar product, it’s better accuracy, longer use life.

Parameter:

Test range: 1.0~25Mpa

Standard impact energy: 0.196J(0.02kgf.m)

Stroke of rebound hammer: 75mm

Friction of pointer slider: 0.4N~0.6N

Sphere radius of rebound pole SR: 25mm

Average rebound hammer on steel anvil: 74±2

Size: Φ54*268mm

Weight: ≈1KG

• Mortar

 

The mixing proportions of the mortar used are given in Tab. I. In the first half of the test programme, a complete set of three mortar bars (40x40xl60 mm3) was cast for each mix. They were stored under the same conditions as the masonry pillars. Due to the results of the first part only a few mortar bars were cast in the second half of the programme.

 

Tab. 1: Mixing proportions of the mortar used

 

Mortar Number	Cement [kg]	Lime [kg]	Aggregate (0/8) [kg]	Water [I]
Ml	1.0	3.0	20	4.7
M2	0.6	1.8	30	5.0
M3		3.5	35	5.75
M4		6.0 (slaked lime)	18	2.0
M5		5.0 (slaked lime)	30	2.0
M6		5.0	30	6.5.

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