Use of Agri-Waste in Production of Sustainable Construction Materials

 India generates 500 million tonnes of crop residue annually, according to

 the Union Ministry of New and Renewable Energy. Crop residue is typically used as fodder

 and fuel for domestic and industrial purposes. A surplus of 140 million tonnes, however,

 reportedly remains unattended, out of which 92 million tonnes is burnt each year

Burning crop residue causes severe environmental hazards such as

 greenhouse gas emissions that contribute to global warming, increased

 particulate matter and smog that lead to health hazards and loss of biodiversity.

Thus far, most government interventions have mainly focused on energy production 

out of crop residue, particularly biogas production. 

But development of bio-composites using agricultural residues such as 

rice husks, stalks of most cereal crops, and coconut fibers is also gaining attention.

CSIR-Advanced materials and processes research institute (AMPRI), Bhopal, 

has developed a technology for large-scale recycling of 

parali (paddy straw / stubble) and wheat straw for manufacturing 

hybrid green composite particle / fibreboards on a pilot scale

Indian architect Shriti Pandey recently used agro-waste to construct two COVID-19 care facilities in Bihar and Punjab. The facilities were  built of stubble (or leftover pieces of harvested grain) and are fire-proof, solar-powered  and “inherently thermally insulated. ” What’s more, zero water was used during the construction process — 60 percent  of which took place off-site. Pandey’s efforts reinforce the multifaceted benefit of  agro-waste construction; the project was cost-effective,  non-environmentally intrusive and stable in terms of its physical durability and longevity  — not to mention it aided areas with a rising demand for  hospital beds amidst the pandemic. In this case, a positive change  was made for constructors, environmentalists and community members alike . This has to be done by empowered government agencies

DRONE TECHNOLOGY IN CONSTRUCTION INDUSTRY

 

Emerging digital technologies seem to enhance productivity while also decreasing the overall duration and expense of construction projects.  Drones have just lately been integrated into the construction industry, despite their extensive application in other sectors such as agriculture, public safety, military operations, scientific research, security surveillance, and mining.  Aerial vehicles have been employed in the construction sector for numerous functions, such as inspecting highways, bridges, roads, cell towers, high mast lighting, wind turbines, power transmission lines, building façades and roofs, surveying and mapping, construction oversight, wetland and environmental assessments, drainage and erosion analysis, traffic monitoring, and emergency services.   serve as a few examples.  Operators can disseminate photos to on-site personnel, internal business staff, and remote subcontractors   UAVs provide critical support and cost efficiency through comprehensive surveillance of remote and difficult-to-access locations.  From this viewpoint, UAVs provide optimal access, while 360° panoramas depict a real-time environment   This comparison can be expanded to include real-time recording, reporting, billing, verification, and planning, alongside construction scheduling and cost estimation  UAVs presently offer a significant degree of automation, enabling access to previously inaccessible areas while collecting vast amounts of data in a brief period.  This, however, is not their exclusive application.   Commercial drones are commonly utilized in the construction industry.  A vast array of drones is available on the market.  Drones can be classified into various categories, such as photography drones, aerial mapping drones, military drones, and surveillance drones, among others.  The optimal classification of drones, conversely, may be established according to aerial platforms.  There are four principal groups of drones classified by the type of aerial platform: fixed-wing drones, multi-rotor drones, single-rotor drones, and fixed-wing hybrid VTOL drones.

 

Fly Ash and Slag based cement in terms of durability performance

 

The strength and durability of concrete structure must go hand in hand. Durability is the ability of a structure to resist weathering action, chemical attack and abrasion, while maintaining minimum strength and other desired engineering properties. The commonly observed processes that are responsible, individually or together, for the deterioration of concrete are carbonation, alkali chloride aggregate reaction (AAR), attack, initiated corrosion of reinforcement, sulfate decalcification or leaching and frost or freeze-thaw action. It is generally accepted that under the optimum conditions of effective blending components, transportation, placing, and curing, the addition of mineral admixtures to concrete improves its resistance toward the deteriorating agents.

When mineral admixtures, such as fly ash (FA) or blast furnace slag (BFS) are used, the strength of concrete can be considered as a result of three principal factors, first accounting for the reduction in the quantity of cement (dilution), second heterogeneous nucleation (physical) and third pozzolanic reaction (chemical). The net result is higher long-term strength and durability of the structure. The structures satisfying the requirement of cost, service life, strength and durability require the use high performance concrete (HPC). Judicious choice of chemical and mineral admixtures reduces the cement content and that results in economical HPC.

The carbonation refers to the precipitation of calcite (CaCO,) as well as other CO,-based solid phases, through the reaction of penetrating atmospheric COz with the calcium ions in the pore solution. The main consequence of carbonation is the drop in the pH of the pore solution of concrete so that the passive layer that usually covers and protects the reinforcing steel against corrosion becomes unstable. The continuous diffusion of CO, inside concrete may also lead to decomposition of calcium silicate hydrate (C-S-H), the principal strength giving phase in concrete. The consequences are loss of strength, shrinkage, cracking and increase in the porosity of concrete. In concrete with mineral admixture, where the amount of calcium hydroxide (CH) is reduced due to pozzolanic or cementitious reaction, the carbonation is dependent on permeability and the resultant lower permeability hinders the ingress of COz:

The aggregate containing certain dolomitic or siliceous minerals react with soluble alkalies in concrete and sometimes result in detrimental expansion, cracking and the premature loss of serviceability of concrete structures affected. This phenomenon is known as alkali aggregate reaction or AAR. All kinds of concrete structures may be affected, although structures in direct contact with water, such as dams and bridges, are particularly susceptible to AAR. The mineral admixtures replacing cement, such as BFS and FA, mitigate or eliminate AAR in concrete.

Under marine conditions, chloride ions penetrate through porous concrete and build up around the reinforcement and the alkalinity (pH) of the surrounding pore solution falls substantially. At that stage, the protective ironoxide film around reinforcing bars depassivates and cracks, exposing the steel. The exposed steel gets corroded in the presence of water and oxygen, resulting in the formation of expansive corrosion products (rust) that occupy several times the volume of the original steel consumed. The expansive corrosion products create tensile stresses on the concrete surrounding the corroding steel reinforcing bar, leading to cracking and spalling of concrete cover. The addition of FA and BFS to concrete inhibits corrosion of reinforcement, improving the resistance toward chloride penetration and reducing the quantity of free (soluble)chloride in concrete. Besides delaying the initiation, the corrosion propagation period is also extended.

The deterioration of concrete due to external sulfate attack is a commonly observed phenomenon, when structures are exposed to sulfate solutions or built in sulfate bearing soil and/or ground water. All commonly obtained water soluble sulfates are deleterious (Mg > Na> Ca) to concrete, but the effect is severe when it is associated with Mg cations. The concrete with mineral admixtures, exposed to Na, SO, environment, in general, shows lower expansion.

it is attributed to the lower content of CH and the formation of secondary C-S-H due to pozzolanic/ cementitious reactions, with the addition of FA and BFS. The lower availability of CH in hardened concrete is believed to create a negative effect, during magnesium sulfate attack. However, that is often offset by the reduced permeability and densification caused by the use of mineral admixtures. The decalcification described by dissolution of otesta lss usually CH (also called portlandite) and C-S-H in hydrated cement systems exposed to water. It results in surface deposits of CaCO3 termed efflorescence, and secondary precipitations of monosulfate, ettringite and calcite, deep within concrete.

The efflorescence or surface deposits develop on new constructions with Portland cement concrete masonry units, including bricks and tiles, which have been bonded with Portland cement. It is normally not damaging but aesthetically undesirable. It has negative effect on the compressive strength of concrete. The use of mineral admixtures, combined with adequate curing, decreases the permeability of concrete leaching and decalcification. It is relevant to hydraulic structures, and radioactive disposal facilities, wherein long-term stability must be guaranteed.

Methods Of Design Of Concrete Structures

 Introduction: A structure refers to a system of connected parts used to support forces (loads). Buildings, bridges and towers are examples for structures in civil engineering. In buildings, structure consists of walls floors, roofs and foundation. In bridges, the structure consists of deck, supporting systems and foundations. In towers the structure consists of vertical, horizontal and diagonal members along with foundation.

A structure can be broadly classified as (i) sub structure and (ii) super structure. The portion of building below ground level is known as sub-structure and portion above the ground is called as super structure. Foundation is sub structure and plinth, walls, columns, floor slabs with or without beams, stairs, roof slabs with or without beams etc are super structure. Many naturally occurring substances, such as clay, sand, wood, rocks natural fibers are used to construct buildings. Apart from this many manmade products are in use for building construction. Bricks, tiles, cement concrete, concrete blocks, plastic, steel & glass etc are manmade building materials.

Cement concrete is a composites building material made from combination of aggregates (coarse and fine) and a binder such as cement. The most common form of concrete consists of mineral aggregate (gravel & sand), Portland cement and water. After mixing, the cement hydrates and eventually hardens into a stone like material. Recently a large number of additives known as concrete additives are also added to enhance the quality of concrete. Plasticizers, super plasticizers, accelerators, retarders, pazolonic materials, air entertaining agents, fibers, polymers and silica furies are the additives used in concrete. Hardened concrete has high compressive strength and low tensile strength. Concrete is generally strengthened using steel bars or rods known as rebars in tension zone. Such elements are 'reinforced concrete' concrete can be moulded to any complex shape using suitable form work and it has high durability, better appearance, fire resistance and economical. For a strong, ductile and durable construction the reinforcement shall have high strength, high tensile strain and good bond to concrete and thermal compatibility. Building components like slab walls, beams, columns foundation & frames are constructed with reinforced concrete. Reinforced concreted can be in-situ concreted or precast concrete.

Photogrammetric Surveying

 Photogrammetric Surveying

It is the branch of surveying in which maps are prepared from photographs taken from

ground or air stations. Photographs are also being used for interpretation of geology,

classification of soils, crops, etc. 

The art, science, and technology of obtaining reliable information about physical

objects and the environment through process of recording, measuring, and interpreting

photographic images and patterns of recorded radiant electromagnetic energy and

phenomenon.

Originally photogrammetry was considered as the science of analysing only

photographs. 

Advantages and Disadvantages: 

Some advantages of photogrammetry over conventional surveying and mapping methods are: 

 It provides a permanent photographic record of conditions that existed at the time the

aerial photographs were taken. Since this record has metric characteristics, it is not only

a pictorial record but also an accurate measurable record. 

 If information has to be re-surveyed or re-evaluated, it is not necessary to perform

expensive field work. The same photographs can be measured again and new

information can be compiled in a very timely fashion. Missing information, such as

inadequate offsets for cross sections, can be remedied easily. 

 It can provide a large mapped area so alternate line studies can be made with the same

data source can be performed more efficiently and economically then other

conventional methods. 

 It provides a broad view of the project area, identifying both topographic and cultural

features. 

 It can be used in locations that are difficult, unsafe, or impossible to access.

Photogrammetry is an ideal surveying method for toxic areas where field work may

compromise the safety of the surveying crew. 

 An extremely important advantage of photogrammetry is that road surveys can be done

without closing lanes, disturbing traffic or endangering the field crew. Once a road is

photographed, measurement of road features, including elevation data, is done in the

office, not in the field. 

 Intervisibility between points and unnecessary surveys to extend control to a remote

area of a project are not required. The coordinates of every point in the mapping area

can be determined with no extra effort or cost. 

 The aerial photographs can be used to convey or describe information to the public,

State and Federal agencies, and other divisions within the Department of

Transportation. 

Some disadvantages are: 

 Weather conditions (winds, clouds, haze etc.) affect the aerial photography process and

the quality of the images. 

 Seasonal conditions affect the aerial photographs, i.e., snow cover will obliterate the

targets and give a false ground impression. Therefore, there is only a short time

normally November through March, that is ideal for general purpose aerial

photography. A cleared construction site or a highway that is not obstructed by trees, is

less subjected to this restriction. These types of projects can be flown and photographed

during most of the year. 

 Hidden grounds caused by man-made objects, such as an overpass and a roof, cannot

be mapped with photogrammetry. Hidden ground problems can be caused  by tree

canopy, dense vegetation, or by rugged terrain with sharp slopes. The information

hidden from the camera must be mapped with other surveying methods. 

 The accuracy of the mapping contours and cross sections depends on flight height and

the accuracy of the field survey. 

History of Photogrammetry: 

1851: French officer Aime Laussedat develops the first photogrammetrical devices and

methods. He is seen as the initiator of photogrammetry. 

1858: The German architect A. Meydenbauer develops photogrammetrical techniques for

the documentation of buildings and installs the first photogrammetric institute in 1885 

(Royal Prussian Photogrammetric Institute). 

1885: The ancient ruins of Persepolis were the first archaeological object recorded

photogrammetrically. 

1889: The first German manual of photogrammetry was published by C. Koppe. 

1911: The Austrian Th. Scheimpflug finds a way to create rectified photographs. He is

considered as the initiator of aerial photogrammetry, since he was the first succeeding to 

apply the photogrammetrical principles to aerial photographs 

1913: The first congress of the ISP (International Society for Photogrammetry) was held

in Vienna. 

1980: Due to improvements in computer hardware and software, digital photogrammetry

is gaining more and more importance. 

1996: 83 years after its first conference, the ISPRS comes back to Vienna, the town,

where it was founded. 

Classification of Photogrammetry: 

Photogrammetry is divided into different categories according to the types of photographs or

sensing system used or the manner of their use as given below: 

I. On the basis of orientation of camera axis:  

a. Terrestrial or ground photogrammetry 

When the photographs are obtained from the ground station with camera axis horizontal

or nearly horizontal         

b. Aerial photogrammetry

If the photographs are obtained from an airborne vehicle. The photographs are 

called vertical if the camera axis is truly vertical or if the tilt of the camera axis is less

than 3 degree

. If tilt is more than (often given intentionally), the photographs are

called oblique photographs. 

II. On the basis of sensor system used:  

     Following names are popularly used to indicate type of sensor system used:  

 Radargrammetry: Radar sensor  

 X-ray photogrammetry: X-ray sensor  

 Hologrammetry: Holographs  

 Cine photogrammetry: motion pictures  

 Infrared or colour photogrammetry: infrared or colour photographs  

III. On the basis of principle of recreating geometry:  

When single photographs are used with the stereoscopic effect, if any, it is

called Monoscopic Photogrammetry.  

If two overlapping photographs are used to generate three dimensional view to create relief

model, it is called Stereo Photogrammetry. It is the most popular and widely used form of

photogrammetry.  

IV. On the basis of procedure involved for reducing the data from photographs: 

Three types of photogrammetry are possible under this classification:  

a. Instrumental or Analogue photogrammetry: It involves photogrammetric

instruments to carry out tasks.  

b. Semi-analytical or analytical: Analytical photogrammetry solves problems by

establishing mathematical relationship between coordinates on photographic image and

real world objects. Semi-analytical approach is hybrid approach using instrumental as

well analytical principles.  

c. Digital Photogrammetry or softcopy photogrammetry: It uses digital image

processing principle and analytical photogrammetry tools to carry out photogrammetric

operation on digital imagery.  

V. On the basis of platforms on which the sensor is mounted:

If the sensing system is space borne, it is called Space Photogrammetry, Satellite 

Photogrammetry or Extra-terrestrial Photogrammetry. Out of various types of the

photogrammetry, the most commonly used forms are Stereo Photogrammetry

utilizing a pair of vertical aerial photographs (stereo pair) or terrestrial photogrammetry

using a terrestrial stereo pair.   

Application of Photographic Survey: 

Photogrammetry has been used in several areas. The following description give an overview

of various applications areas of photogrammetry  

a. Geology: Structural geology, investigation of water resources, analysis of thermal patterns

on earth's surface, geomorphological studies including investigations of shore features.  

• Stratigraphic studies 

• General geologic applications 

• Study of luminescence phenomenon 

• Recording and analysis of catastrophic events

• Earthquakes, floods, and eruption.  

b. Forestry:  Timber inventories, cover maps, acreage studies 

c. Agriculture: Soil type, soil conservation, crop planting, crop disease, crop-acreage.

d. Design and construction: Data needed for site and route studies specifically for 

alternate schemes for photogrammetry. Used in design and construction of dams,

bridges, transmission lines.  

e. Planning of cities and highways: New highway locations, detailed design of

construction contracts, planning of civic improvements.  

f. Cadastre: Cadastral problems such as determination of land lines for assessment of

taxes. Large scale cadastral maps are prepared for reapportionment of land. 

g. Environmental Studies:

h. Land-use studies.

i. Urban area mapping.

j.  Exploration: To identify and zero down to areas for various exploratory jobs such as 

oil or mineral exploration. 

k. Military intelligence: Reconnaissance for deployment of forces, planning manoeuvres, 

assessing effects of operation, initiating problems related to topography, terrain

conditions or works.  

l. Medicine and surgery: Stereoscopic measurements on human body, X-ray

photogrammetry in location of foreign material in body and location and examinations

of fractures and grooves, biostereometrics.  

m. Mountains and hilly areas can be surveyed easily.

n. Miscellaneous 

Classification of Photographs:    

The following paragraphs give details of classification of photographs used in different

applications     

A. On the basis of the alignment of optical axis  

 Vertical: If optical axis of the camera is held in a vertical or nearly vertical position. 

 Tilted: An unintentional and unavoidable inclination of the optical axis from vertical

produces a tilted photograph.  

 Oblique: Photograph taken with the optical axis intentionally inclined to the vertical.

Following are different types of oblique photographs:  

i.  High oblique: Oblique which contains the apparent horizon of the earth. 

ii. Low oblique: Apparent horizon does not appear.  

iii. Trimetrogon: Combination of a vertical and two oblique photographs in which

the central photo is vertical and side ones are oblique. Mainly used for

reconnaissance. 

iv. Convergent: A pair of low obliques taken in sequence along a flight line in

such a manner that both the photographs cover essentially the same area with

their axes tilted at a fixed inclination from the vertical in opposite directions in

the direction of flight line so that the forward exposure of the first station forms

a stereo-pair with the backward exposure of the next station.  

ASTRONOMICAL SURVEYING

 ASTRONOMICAL SURVEYING

Celestial Sphere. 

The millions of stars that we see in the sky on a clear cloudless night are all at varying distances from us. Since we are concerned with their relative distance rather than their actual distance from the observer. It is exceedingly convenient to picture the stars as distributed over the surface of an imaginary sphericalsky having its center at the position of the observer. This imaginary sphere on which the star appears to lie or to be studded is known as the celestial sphere. The radius of the celestial sphere may be of any value - from a few thousand metres to a few thousand kilometers. Since the stars are very distant from us, the center of the earth may be taken as the center of the celestial sphere.

Zenith, Nadir and Celestial Horizon.

 The Zenith (Z) is the point on the upper portion of the celestial sphere marked by plumb line above the observer. It is thus the point on the celestial sphere immediately above the observer's station. The Nadir (Z') is the point on the lower portion of the celestial sphere marked by the plum line below the observer. It is thus the point on the celestial sphere vertically below the observer's station. Celestial Horizon. (True or Rational horizon or geocentric horizon): It is the great circle traced upon the celestial sphere by that plane which is perpendicular to the Zenith-Nadir line, and which passes through the center of the earth. (Great circle is a section of a sphere when the cutting plane passes through the center of the sphere)

Terrestrial Poles and Equator, Celestial Poles and Equator. 

The terrestrial poles are the two points in which the earth's axis of rotation meets the earth's sphere. The terrestrial equator is the great circle of the earth, the plane of which is at right angles to the axis of rotation. The two poles are equidistant from it. If the earth's axis of rotation is produced indefinitely, it will meet the celestial sphere in two points called the north and south celestial poles (P and P'). The celestial equator is the great circle of the celestial sphere in which it is intersected by the plane of terrestrial equator.

CO-ALTITUDE OR ZENITH DISTANCE (Z) AND AZIMUTH (A).

It is the angular distance of heavenly body from the zenith. It is the complement or the altitude, i.e. z = (90 - θ) degree. The azimuth of a heavenly body is the angle between the observer's meridian and the vertical circle passing through the body

Trigonometric Leveling

 Trigonometric Leveling

Definition: "Trigonometric levelling is the process of determining the differences of elevations of stations from observed vertical angles and known distances. "The vertical angles are measured by means of theodolite. The horizontal distances by instrument Relative heights are calculated using trigonometric functions. 

● This is an indirect method of levelling.

 ● In this method the difference in elevațion of the points is determined from the observed vertical angles and measured distances. 

● The vertical angles are measured with a transit theodolite and The distances are measured directly (plane surveying) or computed trigonometrically (geodetic survey).

 ● Trigonometric levelling is commonly used in topographical work to find out the elevation of the top of buildings, chimneys, church spires, and so on.Also, it can be used to its advantage in difficult terrains such as mountaineous areas. 

● Depending upon the field conditions and the measurements that can be made with the instruments available, there can be innumerable cases

METHODS OF DETERMINING THE ELEVATION OF A POINT BY THEODOLITE: Case 1. Base of the object accessible.

Case 2. Base of the object inaccessible,Instrument stations in the vertical plane as the elevated object.

Case 3. Base of the object inaccessible, Instrument stations not in the same vertical plane as the elevated object.

Case 1. Base of the object accessible

Note :- it means we can easily measures the distance between the object and instrument station .

Where

A= Instrument station.

B= Point to be observed.

h= Elevation of B from the instrument axis

D =Horizontal distance between A. and the base of object.

h1= Height of instrument (H. I.) 

Bs= Reading of staff kept on B.M.

Alpha = Angle of elevation = angle BAC. Then

Hence we can find RL

Case 2. Base of the object inaccessible, Instrument stations in the same vertical plane as the elevated object.

There may be two cases.

(a) Instrument axes at the same level.

 (b) Instrument axes at different levels.

1) Height of instrument axis to the object is lower.

2) Height of instrument axis to the object is higher. 

 

(a) Instrument axes at the same level:-

Then from figure.

From this we can find out RL