Hammer blow method

SAS mixes are optimized using a slightly modified Marshall Method (ASTM Method D 1559) and represent a series of trade-offs between stability and flow, air voids content and permeability and fatigue life [15]. The major departure from the Marshall Method is that only 2 hammer blows rather than the conventional 75 blows per face are used. The light compaction is used only to expel entrapped air and to achieve more uniform sample configurations without disturbing sulfur soldification within the aggregate voids. 

Phenylethanol (Benzylcarbinol). CgHs.CH2.CH20H, mw 122.16, colorl oil, bp 219-221° at 750mm, d 1.023g/cc at 13/4°, sol in ale and eth. Methods of prepn are given in Beil. Nitration of this product resulted in an oily product which expld from a hammer blow. It was probably impure trinitrophenylethanol (see below)... 

Probing methods commonly used are dynamic (e.g. Mackintosh Probes, which is also commonly known as JKR dynamic cone penetrometer, shown in Figure 3.2) or static (e.g. Cone Penetration Tests). Probes comprise sharpen steel rods that are driven (by hammer blow) or pushed into the soil (by static load). Investigation depth is limited by thrust available for pushing the penetrometer into the ground or when dense/coarse gravel is encountered. Soil type, strength and compressibility can be assessed from available correlation charts developed for the respective methods. 

If the object is only to investigate the depth of overburden, geophysical methods can advantageously be applied. In a case where the overburden is of a loose or fairly soft character, seismic measurements, more particularly by means of the hammer blow technique, are very suitable, as they can be performed quickly and inexpensively. However, this technique does require a relatively level surface of the limestone. If the surface is very irregular, e.g., as a result of underground water percolation, this method of investigation cannot be used. The application of the hammer blow technique in conjunction with penetration tests is especially to be recommended. 

With greater overburden thicknesses it is alternatively possible to use a geo-electric method (based on contrasts in theelectrical resistivity of strata), which can be very effective more particularly when used in combination with the hammer blow technique. 

Hammer blow and geo-electric methods represent two simple geophysical techniques which can be used with relatively little effort and expense for determining the depth of overburden, the thickness of consolidated and unconsolidated strata, the detection of waterbearing strata, and ascertaining the ground water table. In addition, determination of the velocity of sound transmission in the ground provides indications as to whether the material can be broken out by ripping. 

The valve tap on the cylinder is very tightly closed it is best released by attaching the valve lever and gently tapping the lever end with a hammer in short sharp blows with gradually increasing force until the ammonia starts to escape. This method is easier and is to be preferred to continuously applied hand pressure. 

A driven anchor is generally pounded into the soil to a design depth by repeated blows with a hammer. While this method is usually associated with pile anchors, it has been used to install plate anchors with the aid of a mandrel and follower. 

The initiators are sensitive to friction and shock (blow). The percussion sensitivity is measured by the drop-hammer method where a 2 kg steel ball is dropped from increasing heights tmtil detonation occurs. The amount of electrical energy needed to initiate the detonation depends on the initiator. 

The SPT is the most widely used of all in situ tests and is carried out in boreholes formed by cable tool percussion methods or by washboring. It involves the hammering of a standard split spoon into the ground and measuring the number of blows required to do this, using a standard hammer weight and drop height. 

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