Er. Kaushal Kishore

By
Kaushal Kishore, Materials Engineer, Roorkee

INTRODUCTION :
About one crore 10 lakhs all types of new vehicles are added each year to the Indian roads. The increase of about three crores discarded tyres each year pose a potential threat to the environment. Tyres are recycle yet significant number are added to existing tyre dumps or landfills. The generation of waste tyres far exceeds than now being recycle. Waste rubber tyres cause serious environment problems all over the world. This accumulated waste materials can be used in Civil Engineering Construction.

Early studies on the use of worn out tyres in asphalt mixes were very promising, not much attention has been given to the use of rubber from scrap tyres in portland cement concrete. So far no research has been done in the use of rubber crumb for RCC and RB roof slab water proofing.
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By
Kaushal Kishore
Materials Engineer, Roorkee

Polymer-modified Concrete (PMC) has also been called polymer-Portland cement-concrete (PPCC) and latex-modified concrete (LMC). It is defined as Portland cement and aggregate combined at the time of mixing with organic polymers that are dispersed or redispersed in water. This dispersion is called latex; the organic polymer is a substance composed of thousands of simple molecules combined into large molecules. The simple molecules are known as monomers, and the reaction that combine them is called polymerization. The polymer may be a homopolymer if it is made by the polymerization of one monomer, or a copolymer when two or more monomers are polymerized.

Of various polymer-modified mortar and concrete, latex-modified mortar and concrete have superior properties, such as high tensile and flexural strength, excellent adhesion, high waterproofness, high abrasion resistance and good chemical resistance, to ordinary cement mortar and concrete. Accordingly they are widely used in many specialized applications in which ordinary cement mortar and concrete have been employed to a lesser extent till now. In these applications, the latex-modified mortars are widely used rather than the latex-modified concrete from the viewpoint of a balance between their performance and cost.
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By Kaushal Kishore
Materials Engineer, Roorkee

The acceptance criteria of quality of concrete is laid down in IS:456-2000. The criteria is mandatory and various provisions of the code have to be complied before the quality of concrete is accepted. In all the cases, the 28-days compressive strength shall alone be the criterion for acceptance or rejection of the concrete. In order to get a relatively quicker idea of the quality of concrete, optional test for 7 days compressive strength of concrete be carried out.

6 Cubes of 150 x 150 x 150 mm size (the nominal size of aggregate does not exceed 38 mm) shall be cast, 3 for 7-days testing and 3 for 28-days testing. A set of
3 cubes (specimen) average strength will be a sample. The individual variation of a set of 3 cubes should not be more than ± 15% of the average. If more, the test result of the sample is invalid.

Note:- For aggregates larger than 38 mm, bigger than 150 mm moulds are to be used. See IS:10086-1982
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By
Kaushal kishore
Materials Engineer, Roorkee

The scarcity and availability at reasonable rates of sand and aggregate are now giving anxiety to the construction industry. Over years, deforestation and extraction of natural aggregates from river beds, lakes and other water bodies have resulted in huge environmental problems. Erosion of the existing topography usually results in flooding and landslides. Moreover, the filtration of rain water achieved by deposits of natural sand is being lost, thereby causing contamination of water reserves used for human consumption. Hence, to prevent pollution authorities are imposing more and more stringent restrictions on the extraction of natural aggregates and its crushing. The best way to overcome this problem is to find alternate aggregates for construction in place of conventional natural aggregates. Rubber aggregates from discarded tyre rubber in sizes 20-10 mm, 10-4.75 mm and 4.75 mm down can be partially replaced natural aggregates in cement concrete construction.

About one crore 10 lakhs all types of new vehicles are added each year to the Indian roads. The increase of about three crores discarded tyres each year pose a potential threat to the environment. New tyre is made of natural rubber (also called virgin rubber), styrene-Butadien Rubber (SBR), Polybutadienc Rubber (PBR), Carbon black, Nylon tyre cord, rubber chemicals, steel tyre card and Butyl rubber.
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By
Kaushal Kishore
Materials Engineer
Roorkee

INTRODUCTION:
SCREENERS companies near Dehradun and elsewhere have set up highly sophisticated as well as, eco-friendly screening and washing plants for the production of uncrushed (Shingle) coarse aggregates and coarse sand direct from river bed. These plants are producing and supplying uncrushed (Shingle) aggregates of sizes 40 mm, 20 mm, 12.5 mm and river coarse sand, which complies to the specifications of
IS : 383-19702.

Our construction sites, particularly Govt. Departments hesitates in the use of uncrushed coarse aggregate as so far they are being supplied to them direct from river bed or by manual sieving without washing them with water. Thus neither they are clean nor properly graded. This draw back is not with the uncrushed aggregates produces and supplied from SCREENERS modern plants with regular quality control. In this booklet the readers will find that when quality uncrushed aggregates are available not only economically but locally, our construction sites particularly Govt. Departments should not hesitate in the use of uncrushed aggregates from the river bed and save our environment, as crusher generate pollution. Further in all the Civil Engineering Codes uncrushed aggregates from river bed has been specified to be used in our all Civil Engineering Construction.
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By
Er. Kaushal Kishore ,
Materials Engineer, Roorkee

Concrete Strength
Cement like water, aggregates and some times admixtures is one of the ingredient of concrete. The mixing of these materials in specified proportions produces concrete. Accordingly cement alone is not a building material, it is the concrete which is a building material. For a given cement and acceptable aggregates, the strength that may be developed by a workable, properly placed mixture of cement, aggregates, and water (under same mixing, curing and testing conditions) is influenced by the :

a) Ratio of cement to mixing water
b) Ratio of cement to aggregates, the strength of the mortar, the bond between the mortar and the coarse aggregate.
c) Grading, surface texture, shape, strength, and stiffness of aggregate particles.
d) Maximum size of aggregate.

Strength of concrete is directly related to the structure of the hydrated cement paste. Air in concrete produces voids. Excess of water in concrete evaporate leave the voids in the concrete. Consequently, as the W/C ratio increases, the porosity of the cement paste in the concrete also increases. As the porosity increases, the compressive strength of the concrete decreases.

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By
Er. Kaushal Kishore ,
Materials Engineer, Roorkee

In about 80% of our construction sites, the water in the concrete mixer is added in a very crude manner either direct from a hoze pipe or by some container without any proper measured quantity. Thus no consideration is given to maintain free Water/Cement ration to its correct specified value resulting production of poor quality of concrete. The addition of mixing water in the concrete mixer with these crude methods always add more water then actually required. This excess water in due course evaporated leaving voids and increasing the porosity of the concrete. Such concrete will have lower strength and also will be not durable.

Therefore it is very important to maintain free W/C ration to its correct value in all the batches of concrete. Free W/C ratio means mixing water added to saturated and surface dry aggregates ie, if the site aggregates are dry extra water is to be added in the mixing water as per the absorption of aggregate, and if the site aggregates contains surface water, this surface water is to be deducted from the mixing water. The weight of aggregates should also be adjusted accordingly. A Concrete Mix Design is reported in standard moisture condition of aggregates and this is saturated and surface dry aggregates. If aggregates are being taken by volume bulking of sand should be taken into consideration.

To solve the construction sites mixing water problems, a simple graduated transparent plastic jar of least count 0.5 ltr, as per drawing should be supplied along with the mixer or may be fabricated at site. This Jar be installed at site near concrete mixer as shown in the drawing. The water may be filled in the jar to the quantity of required gauging water. While mixer is running the measured water in the jar slowly drain in the mixer drum through rubber hoze by opening the valve. If ADMIXTURES are to be used and required to be mixed with the gauging water, this may be mixed with water of the jar.

We at engineeringcivil.com thankful to Sir Kaushal Kishore for publishing his paper on “Water Measuring Jar for Concrete Mixer”.

We at engineeringcivil.com are pleased to announce that our website supporter and regular contributor, Sir. Kaushal Kishore have been awarded “NATIONAL (N) ICI-JA LIFE TIME ACHIEVEMENT AWARD – 2011” for his valuable contributions to the field of civil engineering.

We congratulate Sir. Kaushal Kishore and hope his work in civil engineering field gets more and more recognition and we here at engineeringcivil.com continue to get his support and knowledge which will be of tremendous use to the upcoming engineers.

Paper of Efflorescence in Bricks and Efflorescence and Leaching in Concrete by Sir. Kaushal Kishore
Materials Engineer, Roorkee

Efflorescence is the usual terms for deposit of soluble salts, formed in or near the surface of a porous material, as a result of evaporation of water in which they have been dissolved.

EFFLORESCENCE IN BRICKS:
Usually sulphate of magnesium, calcium, sulphate and carbonate (and sometimes chloride and nitrates) of sodium and potassium are found in efflorescence. These salts may be traced to the brick itself, sand used in construction, the foundation soil, ground water, water used in the construction and loose earth left over in contact with brick work. Bricks with magnesium sulphate content higher than 0.05 percent should not be used in construction. Soluble salt content in sand (chloride and sulphate together) should not exceed 0.1 percent.
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By
Er. Kaushal Kishore ,
Materials Engineer, Roorkee

INTRODUCTION:
A green building is that building which is constructed at a well planed location with proper design and sustainable materials. Fitted and painted with eco friendly materials. The building should gives to its occupants healthy and comfortable environment in all climates. It remains cool in summer, warm in winter, inside fully protected from rain, gives natural pollution free air and light through doors, windows and ventilators without any artificial means. For particular requirements it has solar, wind power and eco friendly electrical, mechanical etc. devices.
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