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Material Testing

Why is multiple packer test instead of single packer test sometimes adopted in testing permeability of rock?

Packer test is used in unlined drillholes in rock to test the permeability. In single packer test, the hole is drilled to the bottom of first test section and the top of the test section is sealed off by a packer. Water is then delivered to the test section and it is kept at constant pressure and the flow is measured.

In highly fractured rock there is a high chance that water tends to leak around the packer which gives inaccurate result. As such, multiple packers are adopted instead in which three sections of the drillhole are sealed up and water is pumped to them at equal pressure. This eliminates the tendency for water to flow around the packers from the middle section.

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Hence, a more accurate result could be obtained by measuring flow from the middle section alone.

Illustration of multiple pack

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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Simple Testing Of Admixtures And Surface Coating For Permeability To Water.

By
Er. Kaushal Kishore ,
Materials Engineer, Roorkee

This method of test describes the procedures for determining concrete permeability to water by capillary absorption method for comparison between controlled specimens and the specimens containing admixtures having surface coatings. This method gives the waterproofing efficiency of admixtures and coating, thus also of the greatest interest for durability of concrete offers protection to reinforcement from corrosion.

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Setting Up Small Testing Laboratory at Field

By
Er. Kaushal Kishore ,
Materials Engineer, Roorkee

Designers and builders of construction projects no longer can consider quality control testing an option or convenience. In the past decade, testing for the quality of materials and finished construction has become a necessity that no responsible builder can neglect.

The truth of this statement is proved not only by construction delays and cost overruns but also by catastrophic failures of major structures. Such catastrophies include dam failures, collapses and foundation breakdowns in multi-storeyed office and apartment structures; and other failures in stadia, factories, schools, auditoria, public buildings and bridges.

Each construction project determines its own individualized testing needs. A variety of factors influence the type of testing required. Among these factors are size of the structures, terrain, type of soil and subsurface conditions at the construction site and other conditions peculiar to the specific location. The expertise of the construction engineers and technical personnel working on the project will also have an influence on the testing and inspection need.
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Various Lab Test On Soil

Soil inspection or say geotechnical inspection is very important in understanding the physical properties of soil and the rocks beneath. This is required to ascertain the the type of foundation required for the proposed construction. Various tests are done to explore the sub surface and surface characteristics of soil .Some of these are given below.

Just click on the link to go to the details of that particular test

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