Low cost Cement: opportunities and challenges

ABERA DESTA(Quality & OPTIMIZATION Mgr)

Mar.2016

Introduction Review

The process of cement manufacturing has been known for morethan 200 years. Portland Cement clinker is composed of silicates,aluminates and aluminoferrites of calcium, CaO, otherwiseknown as lime. These calcium silicates aluminates and aluminaferrites are hydraulic minerals. This means that when theminerals are mixed with water in a powdered form they undergochemical reactions with that mixing water. The products of thosehydraulic reactions are hydrated calcium silicates andaluminates. The paste of hydrating calcium silicate andaluminate gradually stiffens losing it’s workability until it setsinto a solid mass. That solid mass then develops strength as thehydration reactions continue in the now solid mass.

Clinker

Additives(o-35)GypsumD/f types

of Cement

…cont.. From those early beginnings cement manufacture has

spread to virtually all countries of the world. Consumptionof cement in 2012 reached 3.736 billion tones. In the yearssince 1990 consumption of cement has tripled with acompound annual increase in consumption of 5.74% overthese 22 years. Production is 1.5% higher than consumptionas small inventories of cement are held on cement factoriesand at depots and concrete plants around the world. In theyears since 2000 the rate of cement consumption hasaccelerated with a compound annual increase in worldconsumption of 7.10%.

It is people who consume cement, or more correctly it is the buildings, cities and roads constructed for the use of people which consume cement

The key drivers of cement consumption andcement consumption growth for the development of modern cities and Infrastructure are as follows: -

1. A high and rising population demanding more housing and infrastructure. 2. A rising GDP making improved housing affordable. 3. Increasing urbanization of the population.

The per capita consumption of cement in Ethiopia is lessthan 70kg Ethiopia has good potential for cementmanufacturing, with solid economic growth and a largepopulation of 87 million, while the world average is around500 kg, therefore we are far behind. In case of China, it isover 1,000 kg per head, - that is a very optimistic position infor cement. Fortunately there is no alternate product toreplace cement since it is still the cheapest and bestmaterial, that serves as a binder.

…cont.. Growth of the cement market is mainly because of growth

of the construction industry in Ethiopia and increasedsupport from the Government. The Construction industryof Ethiopia has the potential to create tremendousopportunities that can boost the Cement market. Thecountry is in a crucial phase of development wherenumerous infrastructure projects are underway in differentregions, thus propelling the demand for cementproduction.

Cost reduction Areas increase in production costs are likely to continue. Cost

reduction imperatives are likely to remain a focus area inEthiopian cement industry over the next few fiscals duringwhich Optimization of transportation logistics, Additives,energy, skill manpower is thus an area that could gainenhanced attention. Also, the potential for reducing costsin non-equipment related domains, e.g. materialinventories, consumable consumption rates & tariffs,financial expenses including salary of expatriates (mainlyfor Chinese), etc. is yet to be expected change soon.

..cont… Penetration of alternative fuels in Ethiopia is not yet

started. The average Thermal Substitution Rate(TSR) isnearly zero%. The main alternative fuels considered arebiomass, RDF & MSW. One of the key reasons for this lowpenetration is a lack of awareness , facilitatinginfrastructures to dispose and collect wastes is poor .Therefore; Institutional intervention by private companies/ government agencies in waste classification andsegregation is thus a necessary precursor to accelerateusage.

..cont… Ethiopia has not yet starting to use its own coal and

increasing cost of imported coal would remain a major area of concern .

For instance Messebo has annual purchase of coal with an average 42million USD from South Africa.

…cont… Given the exponential growth in cement capacity in

Ethiopia, shortage of human skills is likely to aggravate andEthiopian Cement companies have had virtually no controlon the cost or consumption of coal, power , transport &manpower. To overcome this handicap, higher attentionneeds to be accorded to Engineering and operation skill,training and creation of improved operating practices bydomestic capacity.

Increase in consumption share of blended cement(low cost cement)

Given the strong benefits associated with the use of blended cement (low cost cement), the industry can initiate corrective action for enhancing its consumption. Some of the likely ways in which this can be done are as follows:

Consuming the natural additives in which Ethiopia has the potential. For example, a pozzolonic material like pumice and limestone.

Increasing customer awareness by organizing training programmes in using blended cement and change the perception of consumer.

…cont.. expensive clinker is substituted with other cementitious materials such

as pumice, limestone or other naturally occurring pozzolanic materials resulting in different types of Blended Cements with unique properties.

The advantages of Blended Cements (Low cost cement) over Ordinary Portland Cement (OPC) are:

Higher cement output for the same clinker production. Lower production costs since the substitute materials are cheaper than

clinker. Superior properties for certain applications because of the strength,

lower hydration heat, and high performance of Blended Cements. Environmentally-friendly due to fuel savings and the reduction of CO2

emission on the basis of per kg product.

…con… The Government can also play a role by taking strategic

initiatives like increasing the concession on excise duty onblended cements benefits accruing to the country from thismove would include greater pollution control (because ofthe effective use of pumice and limestone additives)support to use and Explore local coal, it would also help inimproving the construction quality in the country with lowcost.

Blended cement(Low cost cement) PPC(32.5R):-

*Reduces alkali aggregate reaction

*Increases final compressive strength

*Reduce cost and environmental emission

*Protects steel reinforcement from corrosion

*Lower water requirement with high fluidity

*Increase resistance to chloride and sulphate attack

*Low heat of hydration suitable for use in dams and canals and all mass concreting.

…cont…*Impedes carbonation

*Reduce creep and cracks

*Reduce permeability and voids.

*Reduces micro cracking

*Autogenously healing, fatigue properties

*Reduces freeze-thaw damages

*Self compression properties

*Increase abrasion resistance

….cont… PLC(32.5R):-

*It has less energy consumption*It reduces the void space of concrete*It improves water demand, bleeding and workability*It improves plastering quality*It improves plasticity and cohesion of Mortar*It decreases wastage of mortar during plastering*It improves surface regularity of screeds*It reduces adverse environmental impact due to reduced co2 emission level.

Comparison between three different PLCs, PPC and OPC cements having the same mix composition.

DescriptionProportion in kg Per m3

35% PLC 25% PLC 20% PLC 25% PPC OPC

Cement 370 370 370 370 370Water 185 185 185 185 185Fine aggregate (Sand) 620 620 620 620 620Coarse aggregate (Gravel) 1265 1265 1265 1265 1265Density (unit weight) , kg/m3 2440 2440 2440 2440 2440Slump, mm 40 30 35 30 35water to cement ratio 0.50 0.50 0.50 0.50 0.50Total aggregate/cement 5.1 5.1 5.1 5.1 5.1Fine aggregate/total aggregate 0.33 0.33 0.33 0.33 0.33Size of coarse aggregate, mm 10 - 25 10 - 25 10 - 25 10 - 25 10 - 25Size of fine aggregate, mm 0.5 - 2 0.5 - 2 0.5 - 2 0.5 - 2 0.5 - 23 day strength, N/mm2 11.9 19.7 19.0 12.2 19.47 day strength, N/mm2 17.5 24.7 28.8 18.2 30.128 day strength, N/mm2 24.0 31.7 39.7 27.6 45.1Expected strength class C-20 C-20 C-20 C-20 C-30Actual strength class C-20 C-30 C-35 C-25 C-45

Types of PLC European EN197-1:2000/Ethiopian ESEN197-1-2013 CEM II/A-L Portland-limestone cement 6 to 20%,

CEM II/A-LL Portland-limestone cement 6 to 20%,

CEM II/B-L Portland-limestone cement 21 to 35%,

CEM II/B-LL Portland-limestone cement 21 to 35%

PLC cement in Ethiopia

Tests carried out in Messebo Cement Factory & AAIT

• PLC cements were produced in different grinding

– Clinker contents with C3A 8 to 12%

– Limestone content 20% to 35%

– Mortar tests and chemical analyses performed

• Concrete made with w/cm ratios 0.4 to 0.6

– Cement content 225 kg/m3 to 420 kg/m3

Practical usage test of PLC Messebo supplies more than 1.5 million quintal to our

customers the assessment result shows us PLC has thefollowing advantages:

-good workability-smooth surface,-easy contact,-least mortar waste, during plastering, -good looking and -no crack at all-it can be applied effectively for C-20 & C-25

grade Concrete works .

PLC for pavement Concrete Pavement Performance Concrete pavement constructed

with PLC (20% limestone) at a Heidelberg cement plant. For thefirst 5 years, de-icing salts were applied to the surface of theconcrete pavement.After 13 years the pavement surface was assessed both visually andwith laboratory tests.

•The results show that:-

The surface was still undamaged by freeze-thaw. No changes inthe concrete due to weathering or loading were observed.

Concrete strength increased with age Since 1997 several bridge decks and highway pavement

projects were completed with PLC in Europe.

Applications of PLC

Hollow concrete Block

Concrete C-20 & C-25

Precast-concretes

Renders &grouts

Drains

Floor screeds

Sewerage pipes

Masonry mortars

Plastering

Paving

Covering lean

etc.

…cont… PLC used successfully in Europe for over 29 years in a

variety of applications and exposure conditions.

PLC is not new. Only new to Ethiopia

There is no good reason not to use Portland limestone cement.

Challenges for today’s Cement Industry High cost of production*being cement production process is energy intensified→→

production cost is high

Environmental pollution

*High emission of CO2 to the atmosphere ,due to:

I) calcinations of limestone (about 44%by mass)

ii) burning of fuels

Recommendations:- Ethiopian cement Industry ,all stakeholders &

Government must consider the following key factors.

1-Investment on Alternative source of energy (Biomass, RDF, MSW).

2-Aggressive improvement in Technical and Managerial skill of the localpeople by different means like by giving O& M contract for limitedperiod, Continous training and establishment of institute which dealswith cement technology .

…cont…3-Government support:- in enhancing productivity and

efficiency of local Cement factories by allocatingresources(electricity ,local Coal ,skill labor , Access roads,strengthen & Support Cement Association, incentives )sufficiently .

The cement industry is highly capital intensive. If it is tohave a sustainable long-term future in Ethiopia, it must beallowed to compete on a level playing field with its globalcounterparts.

…cont…4-Proper utilization of raw materials :- are very important in product

quality, product differentiation, energy and Quarry management of mineral extraction including rehabilitation plan of quarry can be

considered as Key factor.

“Utilization of local energy and indigenization”

5-Exploit and work on Local coal utilization in which Ethiopia has the potential & work in Indigenization

6-Increase market share of Blended cement(PLC, PPC,…) for construction purpose including Highways.

…cont…7-The usage of systems of operation, quality, maintenance,

Environment management systems should be inevitable inall cement industriesinvestment is mandatory to boost the system efficiency toimprove performance, utilization and productivity.

8-Surrounding community and Employee benefit packages &Health and safety programmes shall be established &implemented.

To save foreign currency , to avoid unnecessary cost& to enhance competitiveness indeed to boost ournational economy.

Thank you for your kind attention!

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