By
Er. Kaushal Kishore ,
Materials Engineer, Roorkee

There is no direct method for the determination of Fly Ash content in the PPC. However, based on the past test results of insoluble Residue in the PPC, Fly Ash content in the supplied PPC may be obtained.

REAGETS

1. Hydrochloric acid – Sp gt 1.16 (conforming to IS : 265-1976)
2. Dilute Hydrochloric acid with distilled water 1:99 (by volume)
3. 2N Sodium Carbonate Solution.

DETERMINATION OF INSOLUBLE RESIDUE
The sample of the PPC shall be moisture free and taken as per requirements of IS : 3535-1966. The representative sample of the cement selected as above shall be thoroughly mixed before using.

Take one gram of the above PPC sample add 25 ml of cold water and while the mixture is stirred vigorously add 5 ml of hydrochloric acid, if necessary, head the solution and grind the material with flattened end of a glass rod until it is evident that the decomposition of the cement is complete. Dilute the solution to 50 ml and digest for 15 minutes at a temperature just below boiling. Filter and wash the residue thoroughly with hot water. The filter paper with the residue shall be proceeded for further test.

Digest the filter paper containing the residue in 30 ml of hot water and 30 ml of 2N sodium carbonate solution maintaining constant volume, the solution being held at just below the boiling point for 10 minutes. Filter and wash with dilute hydrochloric acid (1:99) and finally with hot water till the residue is free from chloride. Ignite the residue in a tarred crucible at 900 to 10000C, cool in a desicator and weight

From the figure the insoluble residue obtained from the above test, Fly Ash content in the supplied PPC may be obtained. Read references to conduct experiments and find conclusions.

REFERENCES

1. IS : 3535 – 1966 – Method of sampling hydraulic cements, BIS, New Delhi.
2. IS : 265-1976 – Specification for hydrochloric acid (second revision BIS, New Delhi)
3. IS : 4032 – 1985 – Method of chemical analysis of hydraulic cement (First Revision) BIS, New Delhi.
4. IS : 1489 (Part-I) : 1991- (Reaffirmed 2005) (Third Revision) Portland Pozzolana Cement – Part-I Fly Ash based BIS, New Delhi.
5. Nagele, E (1981) – Application of the flotation method to analytical problems of concrete technology Diss, Universitat Karlsruhe, FRG.
6. Hilsdorf, H.K., Nagele, E (1980) a new method for cement content determination of fresh concrete, Cem. Concr. Res. 10, 23-34.

We are thankful to Sir Kaushal Kishore for sharing this important research paper here on the website.

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.

For all test specimens materials, proportions, workability, mixing, compaction, casting, curing, temperature and testing method should be kept identical for conclusive comparison between controlled and admixture/coated specimens.

Casting of Specimens
10cm cubes of the following mix are to be cast by hand compaction filling the cubes in two layers each layer to be rammed 35 times by ramming rod 16mm dia 600mm in length one end bullet pointed. A set of 3 cubes shall be prepared with the recommended dosage of admixture. The other set of 3 cubes shall be made without any admixture (controlled cube). In case of surface coating is to be tested, then all the six cubes shall be made of the same mix.

Mix Proportions
OP Cement 43 grade = 200 Kg/m³
Sand Zone II = 850Kg/m³
20-5mm aggregate = 1115lg/m³
Water= To give slump of 40⁺_-5mm or compaction factor of about 0.90.

The above is a suggested mix of sand and aggregate having specific gravity of 2.6. Mixes may be designed as per local aggregates.
Cement:Aggregate ratio should be kept 1:9 to 1:10

Liquid admixtures usually reduce the water demand, but in very lean mixes there shall not be much reduction in mixing water.
The water of the liquid admixture should be accounted in the mixing water. A few trials of controlled concrete workability will be required for getting the exact quantity of mixing water for obtaining required workability. As far as possible this controlled concrete mixing water should not be exceeded with the admixture mix. The lean mix as recommended above will be desirable for this type of test.

Procedure of Testing
After 24 hours of casting, all the cubes shall be demoulded and cured in clean water in the same curing tank for 28 days. After 28 days of curing all the cubes shall be dried in a ventilated oven at the temperature of 100^oC to ⁺_-10^oC till constant weight. If surface coating is to be tested, then as per recommendations of the manufacturer three cubes to be surface coated at one face and upto the height of 5 cm on all the four faces. After coating and conditioning, these cubes along with the controlled cubes shall again be died in the oven at a temperature of 50^oC to ⁺_-2^oC till constant weight. Coated cubes faces should be kept upward while keeping them in oven, sot that coating should not be damaged. The coating after its application should withstand without any physical and chemical change a temperature of 50^oC, which is a temperature normally reached of concrete surfaces exposed to sun at most places of India during summer. A coating sensitive to this temperature should not be tested with this method.

All the six weighted cubes shall be placed in the same glazed or glass flat tray, so that the cubes are dipped up to a level of 1.2cm. The level of the water shall be maintained throughout the experiment by adding fresh water from time to time. Evaporation of water from exposed cubes surfaces and tray is prevented by covering the entire set up by polythene. Care should be taken that polythene should not disturb the set up. Determine the gain in weight of the cube at different intervals till the weight of cube become constant.

The permeability of each cube of a set shall be found by determining the coefficient of water absorption with the help of the formula:

A= M_w/t
Where A – Coefficient of water absorption.
M_w – Amount of water absorbed per unit area.
T – Time in second for absorption

From the test results the effectiveness of admixtures and coating may be compared with controlled specimens. This method is simple for testing waterproofing admixtures and coating without any special equipment.

This paper by Er. Kaushal Kishore was first published in NBM&CW magazine.

Abstract:
History itself is the evident that from the years together the people moves to the region where they can satisfy their needs and wants with fewer efforts and more opportunities. This thought lead to accumulation of people in some areas resulting in urbanization. As this urban area contributes highly in nation’s economy even the government announce a far reaching progamme of investments in urban development. However, these urban agglomerations manifest generally unsustainable ecologies. The depletion of material resources, the accumulation of waste, and the over-expenditure of non-renewable energy are direct consequences of the predatory expansion of urbanization.

Out of this the major contribution goes to construction industry as the data reveals that Construction is responsible for 40% of the total world flows of raw materials such as sand, gravel and clay. It takes one quarter of all virgin wood, 40% of energy use, 16% of water withdrawals, and produces 17% of all waste generated. If this practise goes on uninterruptible it will cause total exhaustion of natural resource and will create a great question for generations to come for their survival.

This paper aims to add up a new dimension in vision for sustainable development by considering a combined effort of government and industry both. Strategy for the same considers the sustainable development in three phases such, first is the consideration of various tool to achieve it that are Means such as procurement, Design, Innovation etc. Second stage basically defines the ends out of it such as mitigation in climatic changes, water conservation; reduce in wastage and overall optimum use of resources. Final is the controlling stage which is supposed to achieve by using the tools such as implementations of rules for carbon emission and wastage made, formation of government agencies for environmental auditing etc.
This view for Sustainable Construction lays out specific actions by industry and by Government which will contribute to the achievement of overarching targets within each of the main areas covered by the sustainability agenda.
Continue Reading »

By
Er. Kaushal Kishore ,
Materials Engineer, Roorkee

INTRODUCTION
Waterproofing is a treatment of a surface or structure to prevent the passage of water under hydrostatic pressure. Waterproofing barrier system may be placed on the positive or negative side. Damp proofing is a treatment of a surface or structure to resit the passage of water in the absence of hydrostatic pressure. A damp proofing barrier system is used to perform the same functions as a waterproofing system but cannot be used to protect against water pressure. Water may be forced through building members by hydrostatic pressure, water vapour gradient, capillary action, wind-driven rain, or any combination of these. This movement is aggravated by porous concrete, cracks or structural defects, or joints that are improperly designed or installed. Leakage of water into structure may cause structural damage, and invariably cause damage to the contents of the structure.

New roofs RB or RCC slabs must be constructed specified by the designer. Roof waterproofing is a widely misunderstood subject. Often inadequate attention given during the construction of RB or RCC roof slab, wrong products used for waterproofing and generally insufficient treatment given, lead to leakage. Movement because of structural deflection, settlement, etc. and steep temperature variation being exposed, cause development of cracks in the roof slab and water start leaking from these cracks.

While constructing RCC roof slab, it should be borne in mind that the practice of using concrete which is not watertight and placing too much reliance on the waterproofing measures is not desirable. Concrete should be made watertight in itself and the waterproofing method should be looked upon as additional safety devices.

The grade of roof slab concrete shall be strictly as specified by the designer. The concrete materials should be properly proportioned, maintaining the specified maximum water, cement ratio, minimum cement content and required workability. The concrete should be admixed with a Superplasticiser.
Continue Reading »

By
Er. Kaushal Kishore ,
Materials Engineer, Roorkee

NEW CEMENT
Portland cement, is made by a calcareous material, such as limestone or chalk, and from alumina and silica found as clay or shale. The process of manufacture of cement consists essentially of grinding the raw materials, mixing them intimately in certain proportions and burning in a large rotary kilin at a temperature of up to about 14500C. When the material sinters and partially fuses into balls known as clinker, the clinker is cooled and ground to a fine powder, with some gypsum added, and the resulting product is the commercial portland cement so widely used through out the world. The manufacturing of this cement release in the atmosphere 0.8 tonnes of CO₂ in the production of one tonne of cement. When water is mixed with cement and aggregates in the production of concrete for use in the construction, each tonne of cement can absorb up to 0.4 tonnes of CO₂ , but that still leaves an overall carbon footprint per tonne of 0.4 tonnes. In the year 2009 about 2000 million tonnes of CO₂ was emitted in the atmosphere in the production of cement.

The above problems have been overcome from researches by Nikolas Vlasopoulos Chief Scientist and his colleagues at Imperial College, London, and they have set up a company of Novacem’s cement which is making cement from magnesium silicate that absorb more CO₂ as it hardens. Valaspoulos responded that magnesium slicates are abundant world wide with 10,000 billion tonnes available. He is confident that material will be strong enough for use in buildings but acknowledge that getting licence to use it will take several years of testing.
Continue Reading »