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Manufactured sand – Our experience

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Restrictions imposed on extraction of natural sand have compelled the construction industry to look for alternative material. Manufactured sand (M-Sand) is one of the foremost alternatives, writes Suhas S Dhuri.

Sand is one of the ?active? ingredients of concrete. It is ?active? in the sense that it has a great bearing on some of the important characteristics of concrete, especially in the fresh state, which ultimately decides the overall performance of the concrete, though it is inert with respect to the various reactions that take place during the bonding of various constituents of concrete.

Traditionally, naturally available river sand has been the choice and generally, there are no issues with this practice. However, with continued use and with ever increasing construction activities, this resource is dwindling globally and restrictions put in place by various governmental agencies, with a view to preserve ecology and environment has brought in severe strains on the construction industry to look for alternate materials. The problem is acute in Mumbai with so much of construction activity around and a practically blanket ban on natural sand dredging.

One of the first alternate materials was crusher fines or crusher dust. This is not a suitable alternative, since the fine material content varies drastically. Its acicular particle shape and rough texture results harsh mixes, which are not cohesive. Added to this material is inconsistent in size distribution.

Manufactured sand on the other hand is a product derived from crushers like crusher fines, but from specially designed crushers and manufacturing process. When rock is crushed and sized in a quarry the main aim has generally been to produce coarse aggregates. This process has left over a proportion of excess fines of variable properties, generally finer than 5-mm size (stone dust/grit). The ready mixed concrete industry has for some time tried to find ways to utilise this material as a controlled replacement of natural sand. Manufactured sand is defined as a purpose-made crushed fine aggregate produced from a suitable source material. Production requires specially designed crushing equipment, screening and possibly washing. It is recognised from both local and overseas experience, that some quarry sources or some rock types within any particular quarry would not be suitable for use as manufactured sand in concrete.

Differences? between M-sand and crusher dust
Aggregates crushing plants vary significantly in their degree of sophistication, in the range and extent of plant process controls and in the degree to which quarry raw feed is controlled to the plant. In simpler plant configurations the quarry raw feed, even when the raw feed is selected on some basis of quality, is processed through two, three or four stages of crushing and shaping and then is separated into a variety of sized aggregates. Usually all aggregate sizes are plus 5 mm and the fines removed at minus 5mm are stockpiled as crusher dust.

Most plants however direct the crushed fines to a single dust stockpile. Provided plant settings are not altered to any great extent and the quarry rock types do not vary excessively, the crusher dusts will settle to a relatively consistent product. Variation in the sizing of the product will result from screen and crusher wear, resetting, and the occasional errors such as a broken screen or screen overflow. Product quality will vary depending on the range and quantity of different type of rock. Manufactured sand is a further development in the use of crushed fine aggregate. The term ?Manufactured Sand? has been developed in world-wide literature to refer to that crushed fine aggregate specifically developed for use as a fine aggregate in concrete. Like any other component of concrete, manufactured sand must be controlled by specification that is suited to the end performance required of the concrete

Natural sand and M-sand
Significant differences between natural sands and manufactured sands result from the geological processes of shaping and sorting that has occurred with most natural sands. The individual grains in natural sands tend to be rounded to sub rounded and have a smooth surface texture. If they are more-mature sediments (i.e., further from the source of erosion) they will tend to be better sorted size-wise, to the point with dune sands that they tend to approach single sized materials. Most natural sands have been abraded to the point that weaker minerals (clays and softer altered minerals) have been separated and removed from the deposits. Abrasion can continue to the point that natural sands become a single mineral material – quartz sands. Better shape and smoother surface texture of most natural sands reduces the inter-particle friction in the fine aggregate component of the concrete mix grading. The consequence is improved workability (usually measured as improved slump). Blending is effective in reducing the level of microfines in the fine aggregate used in the concrete mix compared with the microfines in the manufactured sand. Blending is in fact the simplest and probably the most cost effective means of minimising any adverse properties arising from the typical 10 to 20 per cent passing 150-micron fraction present in most manufactured sands. The microfines are the proportion of the grading most likely to include mineralogy that will increase water demand in the concrete mix.

However in the current situation, where natural sand is simply not available, total replacement of natural sand is imperative. Despite the improvements made to the properties of manufactured sand, cent percent use of manufactured sand has the risk of concrete segregation in high workability mixes. This problem can be taken care of by use of mineral admixtures like fly ash and designing mixes appropriately. Chemical admixture industry has been working on this issue as well and they have come out with products to address this problem. Thus today, it is possible to produce high strength pumpable concrete mixes replacing natural sand completely and this has been done in several projects.

It is even possible to replace natural sand totally in plaster work, with appropriate admixtures and proportions.

The author is CEO of e Cube Consultants.

Comparison of manufactured sand (Crushed sand) and grit (stone dust)
Parameters Manufactured sand Grit / stone dust/ crusher fines/
Crusher waste
Product Manufactured using special equipment By product of aggregate quarry
Equipment used for production VSI : Vertical Shaft Impactor No special equipment : Produce during
aggregate manufacturing process –
waste materials passing 6 mm sieve
Particle size distribution Consistent In-consistent
Grading Control No control over grading
Material passing 75 microns (wet
sieving)
Control over fine content ? Passing 75 microns max 15 percent No control over material passing
through 75 microns
Percent Passing 150 microns In the range of 12 to 20 In the range 15 to 60
Particle shape Cubical Flaky and elongated
Water demand Moderate over natural sand High due to shape & fine content
Use in Quality Concrete Possible to replace 100% instead of Natural river sand Not advisable to use in quality concrete
Packing density Improvement in packing density Poor packing density
Typical properties of mixes in use with cent per cent manufactured sand:
Proportion / Property Mix No. 1 M35 Mix No. 2 M60
Binder content kg per cu.m (including SCMs) 450 565
Water to binder ratio by weight 0.36 0.24
Manufactured sand (% of total aggregate by weight) 41 38
Compressive strength Mpa 28 day IS:516 41.2 70.3
Flexural strength Mpa 28 day IS:516 4.9 8.1
Split Tensile strength Mpa 28 day IS:5816 4.7 7.8
Modulus of Elasticity (Chord) GPa 28 day ASTM C469 33.12 42.20
Drying shrinkage percent linear (IS: 1199) 0.028 0.012
Moisture movement percent linear (IS: 1199) 0.004 0.0036
Water permeability mm EN 12390 Part 8 (DIN:1048) 16 6
Initial Surface Absorption ml/m2/sec (BS:1881) 0.0116 0.0012
Water absorption percent @ 10 min (BS:1881) 2.88 0.8
Rapid Chloride Permeability coulomb (ASTM 1202) 28 d 2210 448
Rapid Chloride Permeability coulomb (ASTM 1202) 90 d 1467 236
Note: Above mixes were with Mumbai aggregate and OPC 53 with fly ash (and microsilica for M60)

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Price hikes, drop in input costs help cement industry to post positive margins: Care Ratings

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Region-wise,the southern region comprises 35% of the total cement capacity, followed by thenorthern, eastern, western and central region comprising 20%, 18%, 14% and 13%of the capacity, respectively.

The cement industry is expected to post positive margins on decent price hikes over the months, falling raw material prices and marked drop in overall production costs, said an analysis of Care Ratings.

Wholesale and retail prices of cement have increased 11.9% and 12.4%, respectively, in the current financial year. As whole prices have remained elevated in most of the markets in the months of FY20, against the corresponding period of the previous year.

Similarly, electricity and fuel cost have declined 11.9% during 9M FY20 due to drop in crude oil prices. Logistics costs, the biggest cost for cement industry, has also dropped 7.7% (selling and distribution) as the Railways extended the benefit of exemption from busy season surcharge. Moreover, the cost of raw materials, too, declined 5.1% given the price of limestone had fallen 11.3% in the same aforementioned period, the analysis said.

According to Care Ratings, though the overall sales revenue has increased only 1.3%, against 16% growth in the year-ago period, the overall expenditure has declined 3.2% which has benefited the industry largely given the moderation in sales.

Even though FY20 has been subdued in terms of production and demand, the fall in cost of production has still supported the cement industry by clocking in positive margins, the rating agency said.

Cement demand is closely linked to the overall economic growth, particularly the housing and infrastructure sector. The cement sector will be seeing a sharp growth in volumes mainly due to increasing demand from affordable housing and other government infrastructure projects like roads, metros, airports, irrigation.

The government’s newly introduced National Infrastructure Pipeline (NIP), with its target of becoming a $5-trillion economy by 2025, is a detailed road map focused on economic revival through infrastructure development.

The NIP covers a gamut of sectors; rural and urban infrastructure and entails investments of Rs.102 lakh crore to be undertaken by the central government, state governments and the private sector. Of the total projects of the NIP, 42% are under implementation while 19% are under development, 31% are at the conceptual stage and 8% are yet to be classified.

The sectors that will be of focus will be roads, railways, power (renewable and conventional), irrigation and urban infrastructure. These sectors together account for 79% of the proposed investments in six years to 2025. Given the government’s thrust on infrastructure creation, it is likely to benefit the cement industry going forward.

Similarly, the Pradhan Mantri Awaas Yojana, aimed at providing affordable housing, will be a strong driver to lift cement demand. Prices have started correcting Q4 FY20 onwards due to revival in demand of the commodity, the agency said in its analysis.

Industry’s sales revenue has grown at a CAGR of 7.3% during FY15-19 but has grown only 1.3% in the current financial year. Tepid demand throughout the country in the first half of the year has led to the contraction of sales revenue. Fall in the total expenditure of cement firms had aided in improving the operating profit and net profit margins of the industry (OPM was 15.2 during 9M FY19 and NPM was 3.1 during 9M FY19). Interest coverage ratio, too, has improved on an overall basis (ICR was 3.3 during 9M FY19).

According to Cement Manufacturers Association, India accounts for over 8% of the overall global installed capacity. Region-wise, the southern region comprises 35% of the total cement capacity, followed by the northern, eastern, western and central region comprising 20%, 18%, 14% and 13% of the capacity, respectively.

Installed capacity of domestic cement makers has increased at a CAGR of 4.9% during FY16-20. Manufacturers have been able to maintain a capacity utilisation rate above 65% in the past quinquennium. In the current financial year due to the prolonged rains in many parts of the country, the capacity utilisation rate has fallen from 70% during FY19 to 66% currently (YTD).

Source:moneycontrol.com

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Wonder Cement shows journey of cement with new campaign

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The campaign also marks Wonder Cement being the first ever cement brand to enter the world of IGTV…

ETBrandEquity

Cement manufacturing company Wonder Cement, has announced the launch of a digital campaign ‘Har Raah Mein Wonder Hai’. The campaign has been designed specifically to run on platforms such as Instagram, Facebook and YouTube.

#HarRaahMeinWonderHai is a one-minute video, designed and conceptualised by its digital media partner Triature Digital Marketing and Technologies Pvt Ltd. The entire journey of the cement brand from leaving the factory, going through various weather conditions and witnessing the beauty of nature and wonders through the way until it reaches the destination i.e., to the consumer is very intriguing and the brand has tried to showcase the same with the film.

Sanjay Joshi, executive director, Wonder Cement, said, "Cement as a product poses a unique marketing challenge. Most consumers will build their homes once and therefore buy cement once in a lifetime. It is critical for a cement company to connect with their consumers emotionally. As a part of our communication strategy, it is our endeavor to reach out to a large audience of this country through digital. Wonder Cement always a pioneer in digital, with the launch of our IGTV campaign #HarRahMeinWonderHai, is the first brand in the cement category to venture into this space. Through this campaign, we have captured the emotional journey of a cement bag through its own perspective and depicted what it takes to lay the foundation of one’s dreams and turn them into reality."

The story begins with a family performing the bhoomi poojan of their new plot. It is the place where they are investing their life-long earnings; and planning to build a dream house for the family and children. The family believes in the tradition of having a ‘perfect shuruaat’ (perfect beginning) for their future dream house. The video later highlights the process of construction and in sequence it is emphasising the value of ‘Perfect Shuruaat’ through the eyes of a cement bag.

Tarun Singh Chauhan, management advisor and brand consultant, Wonder Cement, said, "Our objective with this campaign was to show that the cement produced at the Wonder Cement plant speaks for itself, its quality, trust and most of all perfection. The only way this was possible was to take the perspective of a cement bag and showing its journey of perfection from beginning till the end."

According to the company, the campaign also marks Wonder Cement being the first ever cement brand to enter the world of IGTV. No other brand in this category has created content specific to the platform.

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In spite of company’s optimism, demand weakness in cement is seen in the 4% y-o-y drop in sales volume. (Reuters)

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Cost cuts and better realizations save? the ?day ?for ?UltraTech Cement, Updated: 27 Jan 2020, Vatsala Kamat from Live Mint

Lower cost of energy and logistics helped Ebitda per tonne rise by about 29% in Q3
Premiumization of acquired brands, synergistic?operations hold promise for future profit growth Topics

UltraTech Cement
India’s largest cement producer UltraTech Cement Ltd turned out a bittersweet show in the December quarter. A sharp drop in fuel costs and higher realizations helped drive profit growth. But the inherent demand weakness was evident in the sales volumes drop during the quarter.

Better realizations during the December quarter, in spite of the 4% year-on-year volume decline, minimized the pain. Net stand-alone revenue fell by 2.6% to ?9,981.8 crore.

But as pointed out earlier, lower costs on most fronts helped profitability. The chart alongside shows the sharp drop in energy costs led by lower petcoke prices, lower fuel consumption and higher use of green power. Logistics costs, too, fell due to lower railway freight charges and synergies from the acquired assets. These savings helped offset the increase in raw material costs.

The upshot: Q3 Ebitda (earnings before interest, tax, depreciation and amortization) of about ?990 per tonne was 29% higher from a year ago. The jump in profit on a per tonne basis was more or less along expected lines, given the increase in realizations. "Besides, the reduction in net debt by about ?2,000 crore is a key positive," said Binod Modi, analyst at Reliance Securities Ltd.

Graphic by Santosh Sharma/Mint
What also impressed analysts is the nimble-footed integration of the recently merged cement assets of Nathdwara and Century, which was a concern on the Street.

Kunal Shah, analyst (institutional equities) at Yes Securities (India) Ltd, said: "The company has proved its ability of asset integration. Century’s cement assets were ramped up to 79% capacity utilization in December, even as they operated Nathdwara generating an Ebitda of ?1,500 per tonne."

Looks like the demand weakness mirrored in weak sales during the quarter was masked by the deft integration and synergies derived from these acquired assets. This drove UltraTech’s stock up by 2.6% to ?4,643 after the Q3 results were declared on Friday.

Brand transition from Century to UltraTech, which is 55% complete, is likely to touch 80% by September 2020. A report by Jefferies India Pvt. Ltd highlights that the Ebitda per tonne for premium brands is about ?5-10 higher per bag than the average (A cement bag weighs 50kg). Of course, with competition increasing in the arena, it remains to be seen how brand premiumization in the cement industry will pan out. UltraTech Cement scores well among peers here.

However, there are road bumps ahead for the cement sector and for UltraTech. Falling gross domestic product growth, fiscal slippages and lower budgetary allocation to infrastructure sector are making industry houses jittery on growth. Although UltraTech’s management is confident that cement demand is looking up, sustainability and pricing power remains a worry for the near term.

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