Product development

Housekeeping is essential to extend the life of any structure

Published

3 years ago

October 19, 2021

admin

BV Bhedasgaonkar, Consulting Engineer believes that the lack of housekeeping, non-engineered alteration to structures (particularly steel structures), cutting members and making punctures in slabs for ducts and pipes without adequate structural modifications are major causes of distress.

Kindly explain to our readers in simple terms what is meant by structural restoration or retrofitting of a structure. How does it differ from architectural restoration?

All structural components such as columns, beams, slabs, walls, domes, vaults, retaining walls, load bearing walls, shells of chimneys, silos, tanks, etc that carry the loads in a structure, undergo distress at earlier or later in their life span. Relieving this distress is done by repairing and retrofitting the structural components.

Architectural restoration, on the other hand, concerns mainly with restoring the functional components of the structures such as non-load bearing walls, windows, doors, plasters, tiling, plumbing, electrical etc.

Repairs and retrofitting of RCC structures are representing a substantial portion of total expenditure in RCC Construction. In developed countries this means about 50 to 60 per cent of total outgo. In developing countries like India where most of the construction in industries, mass housing, infrastructure has been done over the last 30 to 40 years, the percentage is less. But this is only likely to go up.

Repairing and retrofitting, as it has been understood and executed till now, has been mainly to restore the structure so that further damage is prevented. With some of the relatively new techniques it is now possible to strengthen the structure so that they perform at their design parameters and in some cases are able to deliver even higher design performance.

Why is structural restoration required at all?

The structures require restoration because they undergo distress. This distress could be on account of several causes, few are listed below:

The structure is under designed meaning some loads are not anticipated or accounted for in the design. This is the flaw at the design stage itself.
Additional loads are envisaged after the structure is in use such as capacity increase, change in earthquake zones requiring higher demand.
Poor quality of concrete in as constructed structure (one of the most common causes).
Corrosion damage, weathering etc.
Some of these causes may lead to functional shortfall (such as leakage) or even structural shortfall leading to structural instability.

As a result of the distress the structure is required to undergo restoration.

What are the different techniques used to assess the health of a structure? Explain in brief.

One of the main techniques for assessment is a very detailed visual observation of the structure. The observation done by an experienced eye can reveal the defects, probable causes of defects and give an idea about possible ways to arrest the damage due to defects and bring the structure back to original condition.

This is usually followed by non-destructive testing of concrete and reinforcement inside concrete. The techniques include rebound hammer, ultrasonic pulse velocity tests, core tests and carbonation tests, etc. on concrete to assess integrity of concrete and strength of concrete. The reliable strength arrived from the tests can be compared with the design grade. For assessing the reinforcement condition Half-cell potential test, resistivity tests are done to assess level of corrosion. Ground Penetration radar scanning is done to map the reinforcement spacings and Diameters which can then be compared with the original drawings. Tomography is used to scan the concrete structure to identify voids, cavities, and honeycombs inside concrete.

In steel structures the NDT includes assessing remaining thickness of corroded steel elements with ultrasonic technique to arrive at remaining cross sections, testing of welds using magnetic particle induction, die penetration tests for welds to check integrity and quality of weld etc.

Third and most important part is assessing the capacity of members and checking whether these are capable of resisting the design loads or there is some shortfall. Reanalysis of structure is required in many cases based on observed and assessed quality (through NDT). Once the shortfall is known a suitable strengthening scheme either for defective elements or for the entire structure (such as seismic capacity shortfall).

How can one arrive at the cost to be incurred on structural restoration?

It is possible to arrive at the cost to be incurred on structural restoration. This can be done after the damages are mapped and quantified after the technique explained above. As built drawings are required for accurate quantification. In absence of the drawings such drawings are required to be made as measured structural drawings and some assumed reinforcement patterns and quantities as per standard design practices. The quantum of damages observed in visual observations can be misleading as the actual damaged areas could be higher during actual repairs once all defective portions are removed, chipped off. Therefore, the accuracy of estimates has limitations. However, with experience an estimate to about 20 per cent accuracy is possible.

What is the general impression about different structures in a cement plant that is about 10-12 years old?

Usually in a span of 10 to 12 years, no defects or distress is likely to occur in any structure in a cement plant. If there are any inherent defects at construction stage itself or if there is any gross neglect on housekeeping, then only such defects occur. These include deflection and or cracking in slabs where material gets deposited and not cleaned from time to time. Examples are silo top roofs, conveyor galleries, roofs of conveyor galleries and storage sheds such as stockpiles. The defects could include damage to roofing sheets, deflections of structural steel elements and corrosion of elements embedded inside deposited materials, leakage from silo roofs and formation of lumps of stored material. Plants located in coastal areas may need a review of the condition of the structures after a period of 5 to 6 years.

What are the different structures in a cement plant that are more prone to damage? Why?

The structures that are more likely to get damaged are all the material handling structures such as conveyors, transfer towers, crushers, and material storage structures such as storage gantry structures and clinker stockpiles (usually the underside of the roof of this structure is inaccessible except in shutdown). The defects arise due to vibrations, material depositions, abrasion, exposure to corrosive weather and rains, etc. Storage structures such as silos are also prone to corrosion of reinforcement due to exposure to rainwater. Also, in the Clinker storage structures, the defects are due to abrasion, deposition of dust on structural elements, high temperature etc.

Are housekeeping and structural damage related to each other? How?

Housekeeping is essential to extend the life of any structure. Lack of housekeeping leads to deposition of material which may get wet during rains and keep corroding the concrete or steel structure underneath. Since the condition of the structure is not seen the damages go undetected till one fine day partial or total collapses occur. Leakage arresting is also an essential part of housekeeping in any structure particularly flat portions receiving rains such as silo tops, floors of various platforms and floors etc. Leakages if not checked in time lead to corrosion of reinforcement in concrete as well as corrosion of steel elements (through leakages in roofing sheets). A lot of major retrofitting can be avoided if the housekeeping is done periodically and defects, if any, are attended from time to time.

How typically a restoration work of a silo or a preheater tower is carried out once the damage is ascertained?

In silos the typical defects are due to poor quality of concrete (usually slip forming) and patch repairs. Inadequate reinforcement spacing is also observed in many silos. In prestressed silos, lack of prestress is found to lead to structural damage. In these structures attending all the defective concrete portions and repairing these with polymer modified mortars or micro-concrete is required. Comprehensive anticorrosive treatment to reinforcement inside is essential prior to that.

If the capacity shortfalls are found due to inadequate / corroded reinforcement, then strengthening (usually in hoop direction is required. External post tensioning using steel wires and cables, or Carbon and Glass fiber wrapping are resorted to. Overall protective coating from outside is also essential in silos which are restored.

In preheaters defects mentioned above are encountered. Lack of verticality of structural elements such as columns is required to be assessed. The technique most commonly sided to correct the effect is jacketing. One of the main problems in preheaters is seepage through cracks in slabs. Preheater is usually an open structure and rainwater accumulates on floors. There is also high temperature and there are punctures in slabs for ducts and pipes. Invariably there is severe corrosion of slab reinforcement. This can best be arrested by providing floor impregnation from top, corrosion protection and repairs from soffit side. Sometimes recasting slabs with lost steel formwork is found to be faster and economical.

Have the number of queries you normally receive gone up during pandemic? How are you using technology to reduce the number of visits to a plant location?

The queries have increased in number because the plants have the possibility of getting shut down due to lack of demand during the pandemic. With travel restrictions it is becoming inconvenient to inspect the structure by making a visit. We have been able to arrive at the possible defects using detailed videos and photos shared by clients. In 80- 90% of the cases, it is possible to provide a solution. The clients are also accepting this concept of virtual consultancy.

What are the different techniques / materials you prefer in the restoration job?

The techniques and material used for restoration change from problem to problem. But usually for comprehensive anti-corrosive treatment we use thorough cleaning such as sand blasting, migrating corrosion inhibitors, protective coating on old and new reinforcement, epoxy bonding agents and section make up using polymer modified mortar (for thin repairs up to 50 mm ) and micro-concrete( for thicker repairs). Protective coating is also recommended by use depending upon the situation and these include acrylic coating, Epoxy coating and Polyurethan coatings.

For upgrading load carrying capacity we have resorted to Carbon and Glass fiber wrap, Jacketing, shotcreting (for large continuous areas like silos). For silos post tension is also used. In some cases, steel plate jacketing is also convenient.

In your opinion, what are the reasons for poor attention to the structures of a cement plant?

The structures are an equally important part of the plant as the equipment. Equipment gets attended periodically and usually in shutdown most equipment needing overhaul are attended to. Lack of housekeeping, non-engineered alteration to structures (particularly steel structures), cutting members and making punctures in slabs for ducts and pipes without adequate structural modifications are major causes of distress.

For repairs to structures sometimes the shutdown time available is inadequate. Therefore, the structures need to be repaired in running condition. Not adequate fund allocation is done for repairs to structures in the annual budget. Usually for an integrated plant annually about Rs 4 to 5 crore are required to be allocated for structural upkeep, maintenance and protection. A dedicated housekeeping team is required to attend to the plant on a continuous basis.

Do the plants carry out structural audits of the entire plant? Is there any regulation that will compel plants to carry out structural audits at a certain frequency? How is it monitored?

Structural audits have become quite common now. Plants do carry out the audit every 4 to 5 years. However, the implementation of the recommendations on audit are kept on the back burner by not allocating adequate funds. This leads to structural defects getting more severe and resulting in accidents.

The structural stability certificates required to be submitted to the factory inspector periodically are mandatory but usually are not based on comprehensive structural audit. Clients who are conscious of the quality and safety of the structures and personnel carry out comprehensive structural audits including NDT. These are usually done once in 4 to 5 years.

Any typical challenging structural restoration you have carried out? Please give details without mentioning the names.

There are several case studies. These include storage silos in many cement plants including post tensioning using steel cables and Fiber wrapping. Cases with vertical misalignment in slip forming have also been designed. Strengthening of raw mill structure with inherent defects using jacketing was done in a few plants. Strengthening of preheater structure including foundations was carried out in case of a preheater where capacity (and height of preheater was to be increased) enhancement was envisaged. Other few strengthening cases with challenge were to strengthen floor plates in buildings on account of poor concrete which is achieved using additional structural concrete on top and fiber wrapping.

What kinds of damages are seen in the housing colonies of a cement plant? Do you see preventive maintenance happening there?

In housing colonies of cement plants, the defects are usually functional such as cracks in walls, leakage, settlement of floors in black cotton soils etc. Not much structural damage is required to be attended.

Economy & Market

Impactful Branding

Published

1 year ago

July 17, 2023

admin

Advertising or branding is never about driving sales. It’s about creating brand awareness and recall. It’s about conveying the core values of your brand to your consumers. In this context, why is branding important for cement companies? As far as the customers are concerned cement is simply cement. It is precisely for this reason that branding, marketing and advertising of cement becomes crucial. Since the customer is unable to differentiate between the shades of grey, the onus of creating this awareness is carried by the brands. That explains the heavy marketing budgets, celebrity-centric commercials, emotion-invoking taglines and campaigns enunciating the many benefits of their offerings.
Marketing strategies of cement companies have undergone gradual transformation owing to the change in consumer behaviour. While TV commercials are high on humour and emotions to establish a fast connect with the customer, social media campaigns are focussed more on capturing the consumer’s attention in an over-crowded virtual world. Branding for cement companies has become a holistic growth strategy with quantifiable results. This has made brands opt for a mix package of traditional and new-age tools, such as social media. However, the hero of every marketing communication is the message, which encapsulates the unique selling points of the product. That after all is crux of the matter here.
While cement companies are effectively using marketing tools to reach out to the consumers, they need to strengthen the four Cs of the branding process – Consumer, Cost, Communication and Convenience. Putting up the right message, at the right time and at the right place for the right kind of customer demographic is of utmost importance in the long run. It is precisely for this reason that regional players are likely to have an upper hand as they rely on local language and cultural references to drive home the point. But modern marketing and branding domain is exponentially growing and it would be an interesting exercise to tabulate and analyse its impact on branding for cement.

Concrete

Indian cement industry is well known for its energy and natural resource efficiency

Published

2 years ago

November 18, 2022

admin

Dr Hitesh Sukhwal, Deputy General Manager – Environment, Udaipur Cement Works Limited (UCWL) takes us through the multifaceted efforts that the company has undertaken to keep emissions in check with the use of alternative sources of energy and carbon capture technology.

Tell us about the policies of your organisation for the betterment of the environment.
Caring for people is one of the core values of our JK Lakshmi Cement Limited. We strongly believe that we all together can make a difference. In all our units, we have taken measures to reduce carbon footprint, emissions and minimise the use of natural resources. Climate change and sustainable development are major global concerns. As a responsible corporate, we are committed with and doing consistent effort small or big to preserve and enrich the environment in and around our area of operations.
As far as environmental policies are concerned, we are committed to comply with all applicable laws, standards and regulations of regulatory bodies pertaining to the environment. We are consistently making efforts to integrate the environmental concerns into the mainstream of the operations. We are giving thrust upon natural resource conservation like limestone, gypsum, water and energy. We are utilising different kinds of alternative fuels and raw materials. Awareness among the employees and local people on environmental concerns is an integral part of our company. We are adopting best environmental practices aligned with sustainable development goals.
Udaipur Cement Works Limited is a subsidiary of the JK Lakshmi Cement Limited. Since its inception, the company is committed towards boosting sustainability through adopting the latest art of technology designs, resource efficient equipment and various in-house innovations. We are giving thrust upon renewable and clean energy sources for our cement manufacturing. Solar Power and Waste Heat Recovery based power are our key ingredients for total power mix.

What impact does cement production have on the environment? Elaborate the major areas affected.
The major environmental concern areas during cement production are air emissions through point and nonpoint sources due to plant operation and emissions from mining operation, from material transport, carbon emissions through process, transit, noise pollution, vibration during mining, natural resource depletion, loss of biodiversity and change in landscape.
India is the second largest cement producer in the world. The Indian cement industry is well known for its energy and natural resource efficiency worldwide. The Indian cement industry is a frontrunner for implementing significant technology measures to ensure a greener future.
The cement industry is an energy intensive and significant contributor to climate change. Cement production contributes greenhouse gases directly and indirectly into the atmosphere through calcination and use of fossil fuels in an energy form. The industry believes in a circular economy by utilising alternative fuels for making cement. Cement companies are focusing on major areas of energy efficiency by adoption of technology measures, clinker substitution by alternative raw material for cement making, alternative fuels and green and clean energy resources. These all efforts are being done towards environment protection and sustainable future.
Nowadays, almost all cement units have a dry manufacturing process for cement production, only a few exceptions where wet manufacturing processes are in operation. In the dry manufacturing process, water is used only for the purpose of machinery cooling, which is recirculated in a closed loop, thus, no polluted water is generated during the dry manufacturing process.
We should also accept the fact that modern life is impossible without cement. However, through state-of-the-art technology and innovations, it is possible to mitigate all kinds of pollution without harm to the environment and human beings.

Tell us about the impact blended cement creates on the environment and emission rate.
Our country started cement production in 1914. However, it was introduced in the year 1904 at a small scale, earlier. Initially, the manufacturing of cement was only for Ordinary Portland Cement (OPC). In the 1980s, the production of blended cement was introduced by replacing fly ash and blast furnace slag. The production of blended cement increased in the growth period and crossed the 50 per cent in the year 2004.
The manufacturing of blended cement results in substantial savings in the thermal and electrical energy consumption as well as saving of natural resources. The overall consumption of raw materials, fossil fuel such as coal, efficient burning and state-of-the-art technology in cement plants have resulted in the gradual reduction of emission of carbon dioxide (CO2). Later, the production of blended cement was increased in manifolds.
If we think about the growth of blended cement in the past few decades, we can understand how much quantity of , (fly ash and slag) consumed and saved natural resources like limestone and fossil fuel, which were anyhow disposed of and harmed the environment. This is the reason it is called green cement. Reduction in the clinker to cement ratio has the second highest emission reduction potential i.e., 37 per cent. The low carbon roadmap for cement industries can be achieved from blended cement. Portland Pozzolana Cement (PPC), Portland Slag Cement (PSC) and Composite Cement are already approved by the National Agency BIS.
As far as kilogram CO2 per ton of cement emission concerns, Portland Slag Cement (PSC) has a larger potential, other than PPC, Composite Cement etc. for carbon emission reduction. BIS approved 60 per cent slag and 35 per cent clinker in composition of PSC. Thus, clinker per centage is quite less in PSC composition compared to other blended cement. The manufacturing of blended cement directly reduces thermal and process emissions, which contribute high in overall emissions from the cement industry, and this cannot be addressed through adoption of energy efficiency measures.
In the coming times, the cement industry must relook for other blended cement options to achieve a low carbon emissions road map. In near future, availability of fly ash and slag in terms of quality and quantity will be reduced due to various government schemes for low carbon initiatives viz. enhance renewable energy sources, waste to energy plants etc.
Further, it is required to increase awareness among consumers, like individual home builders or large infrastructure projects, to adopt greener alternatives viz. PPC and PSC for more sustainable
resource utilisation.

What are the decarbonising efforts taken by your organisation?
India is the world’s second largest cement producer. Rapid growth of big infrastructure, low-cost housing (Pradhan Mantri Awas Yojna), smart cities project and urbanisation will create cement demand in future. Being an energy intensive industry, we are also focusing upon alternative and renewable energy sources for long-term sustainable business growth for cement production.
Presently, our focus is to improve efficiency of zero carbon electricity generation technology such as waste heat recovery power through process optimisation and by adopting technological innovations in WHR power systems. We are also increasing our capacity for WHR based power and solar power in the near future. Right now, we are sourcing about 50 per cent of our power requirement from clean and renewable energy sources i.e., zero carbon electricity generation technology. Usage of alternative fuel during co-processing in the cement manufacturing process is a viable and sustainable option. In our unit, we are utilising alternative raw material and fuel for reducing carbon emissions. We are also looking forward to green logistics for our product transport in nearby areas.
By reducing clinker – cement ratio, increasing production of PPC and PSC cement, utilisation of alternative raw materials like synthetic gypsum/chemical gypsum, Jarosite generated from other process industries, we can reduce carbon emissions from cement manufacturing process. Further, we are looking forward to generating onsite fossil free electricity generation facilities by increasing the capacity of WHR based power and ground mounted solar energy plants.
We can say energy is the prime requirement of the cement industry and renewable energy is one of the major sources, which provides an opportunity to make a clean, safe and infinite source of power which is affordable for the cement industry.

What are the current programmes run by your organisation for re-building the environment and reducing pollution?
We are working in different ways for environmental aspects. As I said, we strongly believe that we all together can make a difference. We focus on every environmental aspect directly / indirectly related to our operation and surroundings.
If we talk about air pollution in operation, every section of the operational unit is well equipped with state-of-the-art technology-based air pollution control equipment (BagHouse and ESP) to mitigate the dust pollution beyond the compliance standard. We use high class standard PTFE glass fibre filter bags in our bag houses. UCWL has installed the DeNOx system (SNCR) for abatement of NOx pollution within norms. The company has installed a 6 MW capacity Waste Heat Recovery based power plant that utilises waste heat of kiln i.e., green and clean energy source. Also, installed a 14.6 MW capacity solar power system in the form of a renewable energy source.
All material transfer points are equipped with a dust extraction system. Material is stored under a covered shed to avoid secondary fugitive dust emission sources. Finished product is stored in silos. Water spraying system are mounted with material handling point. Road vacuum sweeping machine deployed for housekeeping of paved area.
In mining, have deployed wet drill machine for drilling bore holes. Controlled blasting is carried out with optimum charge using Air Decking Technique with wooden spacers and non-electric detonator (NONEL) for control of noise, fly rock, vibration, and dust emission. No secondary blasting is being done. The boulders are broken by hydraulic rock breaker. Moreover, instead of road transport, we installed Overland Belt Conveying system for crushed limestone transport from mine lease area to cement plant. Thus omit an insignificant amount of greenhouse gas emissions due to material transport, which is otherwise emitted from combustion of fossil fuel in the transport system. All point emission sources (stacks) are well equipped with online continuous emission monitoring system (OCEMS) for measuring parameters like PM, SO2 and NOx for 24×7. OCEMS data are interfaced with SPCB and CPCB servers.
The company has done considerable work upon water conservation and certified at 2.76 times water positive. We installed a digital water flow metre for each abstraction point and digital ground water level recorder for measuring ground water level 24×7. All digital metres and level recorders are monitored by an in-house designed IoT based dashboard. Through this live dashboard, we can assess the impact of rainwater harvesting (RWH) and ground water monitoring.
All points of domestic sewage are well connected with Sewage Treatment Plant (STP) and treated water is being utilised in industrial cooling purposes, green belt development and in dust suppression. Effluent Treatment Plant (ETP) installed for mine’s workshop. Treated water is reused in washing activity. The unit maintains Zero Liquid Discharge (ZLD).
Our unit has done extensive plantations of native and pollution tolerant species in industrial premises and mine lease areas. Moreover, we are not confined to our industrial boundary for plantation. We organised seedling distribution camps in our surrounding areas. We involve our stakeholders, too, for our plantation drive. UCWL has also extended its services under Corporate Social Responsibility for betterment of the environment in its surrounding. We conduct awareness programs for employees and stakeholders. We have banned Single Use Plastic (SUP) in our premises. In our industrial township, we have implemented a solid waste management system for our all households, guest house and bachelor hostel. A complete process of segregated waste (dry and wet) door to door collection systems is well established.

Tell us about the efforts taken by your organisation to better the environment in and around the manufacturing unit.
UCWL has invested capital in various environmental management and protection projects like installed DeNOx (SNCR) system, strengthening green belt development in and out of industrial premises, installed high class pollution control equipment, ground-mounted solar power plant etc.
The company has taken up various energy conservation projects like, installed VFD to reduce power consumption, improve efficiency of WHR power generation by installing additional economiser tubes and AI-based process optimisation systems. Further, we are going to increase WHR power generation capacity under our upcoming expansion project. UCWL promotes rainwater harvesting for augmentation of the ground water resource. Various scientifically based WHR structures are installed in plant premises and mine lease areas. About 80 per cent of present water requirement is being fulfilled by harvested rainwater sourced from Mine’s Pit. We are also looking forward towards green transport (CNG/LNG based), which will drastically reduce carbon footprint.
We are proud to say that JK Lakshmi Cement Limited has a strong leadership and vision for developing an eco-conscious and sustainable role model of our cement business. The company was a pioneer among cement industries of India, which had installed the DeNOx (SNCR) system in its cement plant.

Concrete

NTPC selects Carbon Clean and Green Power for carbon capture facility

Published

2 years ago

October 12, 2022

admin

Carbon Clean and Green Power International Pvt. Ltd has been chosen by NTPC Energy Technology Research Alliance (NETRA) to establish the carbon capture facility at NTPC Vindhyachal. This facility, which will use a modified tertiary amine to absorb CO2 from the power plant’s flue gas, is intended to capture 20 tonnes of CO2) per day. A catalytic hydrogenation method will eventually be used to mix the CO2 with hydrogen to create 10 tonnes of methanol each day. For NTPC, capturing CO2 from coal-fired power plant flue gas and turning it into methanol is a key area that has the potential to open up new business prospects and revenue streams.