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What is the difference between Dynamic Probing and Standard Penetration test?

Standard Penetration Test (SPT) is an in-situ dynamic penetration test to provide information on the properties of soil. It may also collect a disturbed soil sample for grain-size analysis and soil classification. SPT involves the driving of a standard sampler through a distance of 450mm into the bottom of a borehole using the standard weight of 63.5kg falling through 760mm.

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Dynamic Probing Test as per BS1377: Part 9: 1990 involves the driving of a metal cone into the ground through a series of 1-metre length steel rods. These rods are driven from the surface by the hammer system on the rig which drops 63.5 kg weight onto the rods through a fall of 760mm. The number of blows that is required to drive the cone down each 100mm increment is then recorded until a required depth is reached or a refusal is achieved. Dynamic Probing has many applications. For instance, it may be used to estimate the depths of at the interface between hard and soft strata and to trace the outline of objects buried underground.

SPT test is used to provide valuable information on soil properties. However, the main use of dynamic probing is to interpolate information between boreholes/trial pits swiftly and to supplement information found from boreholes and trial pits at a low cost. For instance, dynamic probing is carried out close to a borehole where the underground conditions are identified. As such, by using the dynamic probing, the result of borehole can be extended to other areas in between two boreholes.

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This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.

Testing of Concrete Blocks

By
Er. Kaushal Kishore ,
Materials Engineer, Roorkee

INTRODUCTION
Concrete can be converted into precast masonry units such as Hollow and Solid normal and light weight concrete blocks of suitable size to be used for load and non-load bearing units for wallings. Use of such concrete blocks are more appropriate in region where soil bricks are costly, poor in strength and are not available. Depending upon the structural requirements of masonry unit, concrete mixes can be designed using ingredients available locally or if not found suitable then with in the most economical distance. The concrete mix used for normal hollow and solid blocks shall not be richer than one part by volume of cement to 6 parts by volume of combined room dry aggregates before mixing. Hollow concrete blocks for normal work used in masonry when reinforced is used shall not be leaner than 1 part cement to 8 parts room dry sand by volume. The mixes are designed with the available materials to give overall economy and the required properties of the products. The hollow load bearing concrete blocks of the standard size 400 x 200 x 200 mm will weight between 17 and 26 kg (1063 to 1625 kg/m3) when made with normal weight aggregates. Normal weight blocks are made with cement, sand, gravel, crushed stone and air-cooled slag. The grading for sand used in Hollow concrete block shall be as given below:
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Winsor Probe Concrete Test

This procedure I came across in one of the site.Just for info to Beginners. This test is called WINSOR probe test.

When the concrete is done and its up and you want to know the strength of concrete with minimum damage,this is the one of the test.

Engineer will select the location.In this case its in column.

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Determine The In-Situ Dry Density Of Soil By Sand Replacement Method

This test is done to determine the in-situ dry density of soil by sand replacement method as per IS: 2720 (Part XXVIII) – 1974. The apparatus needed is
i) Sand-pouring cylinder conforming to IS: 2720 (Part XXVIII) -1974
ii) Cylindrical calibrating container conforming to IS: 2720 (Part XXVIII) – 1974
iii) Soil cutting and excavating tools such as a scraper tool, bent spoon
iv) Glass plate – 450mm square and 9mm thick or larger
v) Metal containers to collect excavated soil
vi) Metal tray – 300mm square and 40mm deep with a 100mm hole in the centre
vii) Balance, with an accuracy of 1g

sand-replacement

Procedure To Determine The In-Situ Dry Density Of Soil By Sand Replacement Method

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Determine The In-Situ Dry Density Of Soil By Core Cutter Method

This test is done to determine the in-situ dry density of soil by core cutter method as per IS: 2720 (Part XXIX) – 1975.The apparatus needed for this test is

i) Cylindrical core cutter
ii) Steel dolley
iii) Steel rammer
iv) Balance, with an accuracy of 1g
v) Straightedge
vi) Square metal tray – 300mm x 300mm x 40mm
vii) Trowel

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