research paper investigation of no-fines … of no-fines concrete in building blocks more than 40...

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Int. J. Struct. & Civil Engg. Res. 2014 K Satham Ushane et al., 2014

INVESTIGATION OF NO-FINES CONCRETE INBUILDING BLOCKS

More than 40 million residential units are needed to house millions of homeless people in India.Blocks are important components in residential buildings. Even though bricks made of soil havebeen widely used so far, there is very good scope for using blocks made of cement, sand andcoarse aggregates because bricks are not available at all places to the desired requirements. Aconcrete block is primarily used as a building material in the construction of walls. A concreteblock is one of several precast concrete products used in construction. Major advantage ofconcrete blocks is that their strength can be engineered as per requirement, thus making themrelatively stronger than masonry with bricks walls by around 15-20%. The market for buildingblock is growing at a rapid rate, especially in the areas where burnt bricks are not easily availableor of poor quality. Unfortunately, rigorous scientific studies have not been made on the strength,durability and economy of concrete building blocks. Lightweight concretes can either be lightweightaggregate concrete, foamed concrete or Autoclaved Aerated Concrete (AAC). Such lightweightconcrete blocks are often used in mason’s house construction, because of their less densityand self-weight, it helps for faster construction.

Keywords: No-fines concrete, Building blocks, Investigation

1 M.E. Student, Department of Civil Engineering,, Nandha Engineering College, Erode, Tamil Nadu, India.2 Assistant Professor, Department of Civil Engineering, Nandha Engineering College, Erode, Tamil Nadu, India.3 Assistant Professor, Bannari Amman Institute of Technology, Sathyamangalam, Tamil Nadu 638401, India.

INTRODUCTIONNo-Fines Concrete is a method of producinglight concrete by omitting the fines fromconventional concrete. No-fines concrete asthe term implies, is a kind of concrete fromwhich the fine aggregate fraction has beenomitted. This concrete is made up of onlycoarse aggregate, cement and water. Veryoften only single sized coarse aggregate, ofsize passing through 20 mm retained on 10

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Int. J. Struct. & Civil Engg. Res. 2014

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mm is used. No-fines concrete is becomingpopular because of some of the advantages itpossesses over the conventional concrete. Thesingle sized aggregates make a good no-finesconcrete, which in addition to having largevoids and hence light in weight, also offersarchitecturally attractive look. No-finesconcrete is generally made with the aggregate/cement ratio from 6:1 to 10:1 Aggregates usedare normally of size passing through 20 mm

K Satham Ushane1*, K J Pradeep Kumar2 and C Kavitha3

*Corresponding Author: K Satham Ushane, [email protected]

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and retained on 10 mm. Unlike theconventional concrete, in which strength isprimarily controlled by the water/cement ratio,the strength of no-fines concrete is dependenton the water/cement ratio, aggregate cementratio and unit weight of concrete. The water/cement ratio for satisfactory consistency willbe used. Water/cement ratio must be chosenwith care. If too low a water/cement ratio isadopted, the paste will be so dry thataggregates do not get properly smeared withpaste which results insufficient adhesionbetween the particles. On the other hand, ifthe water/cement ratio is too high, the pastef lows to the bottom of the concrete,particularly when vibrated and fills up thevoids between the aggregates at the bottomand makes that portion dense. This conditionalso reduces the adhesion betweenaggregate and aggregate owing to the pastebecoming very thin. No standard method isavailable, like slump test or compacting factortest for measuring the consistency of no-finesconcrete. Perhaps a good, experiencedvisual examination and trial and error methodmay be the best guide for deciding optimumwater/cement ratio. No-fines concrete, whenconventional aggregates are used, may showa density of about 1600 to 1900 kg/m3, butwhen no-fines concrete is made by using lightweight aggregate, the density may come toabout 360 kg/m3. No-fines concrete does notpose any serious problem for compaction.Use of mechanical compaction or vibratorymethods is not required. Simple roding issufficient for full compaction.

AIM and Scope of Investigation

AIMThe main objectives of the project are as follow:

1. To identify the strength of no-fines concretespecimen.

2. To identify the most economical mix forblocks.

3. To study the durability of these concreteblocks.

Scope of Investigation1. Reduction in dead loads making savings

in foundations and reinforcement.

2. Improved thermal properties.

3. Improved fire resistance.

4. Savings in transporting and handlingprecast units on site.

5. Reduction in formwork and propping.

MATERIALSGeneralMaterial investigation is done to test thevarious materials that are used in makingconcrete cubes. According to these test resultsobtained we designed the mix ratios for thematerials and prepared the concrete cubes,beams and cylinders. The information aregiven below,

CementOPC of 43 grades in one lot was procured andstored in air tight container. The cement usedwas fresh, i.e., used within three months ofmanufacture. It should satisfy the requirementof IS12262. The properties of cement aredetermined as per IS4031:1968 and resultsare tabulated.

TEST ON CEMENTCement is the most important ingredient ofconcrete. One of the important criteria for the

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and vertical motion for a period of 15 minutes.Mechanical sieving devices may also be used.The residue left on the sieve is weighed. Theweight shall not exceed 10% for ordinary test.

Standard Consistency of CementThe standard consistency is defined as thatconsistency which will permit a vicat plungerhaving 10 mm diameter 50 mm length topenetrate to a depth of 33-35 mm form top (or5-8 mm from bottom) of the mould in vicatapparatus. Standard consistency has to beused in determining the initial settling time andfinal settling time.

Coarse Aggregate

The coarse aggregate is strongest and porouscomponent of concrete. Presence of coarseaggregate reduces the drying shrinkage andother dimensional changes occurring onaccount of movement of moisture. The coarseaggregate used passes in 19 mm andretained in 11.4 mm sieve. It is well graded(should of different particle size and maximumdry packing density and minimum voids) andcubical in shape.

BULK DENSITYThe bulk density of the sample is found in rodstate and in loose state, since the weight varieswith respect to the percentage of voids. Thetest shall be carried out in dry material whydetermining the voids, but during the bulkingtest a small amount of water may be imparted.The weight of empty weight container is foundand is then filled with water to obtain the volumeof container.

In Rod StateThe metal container shall be filled about withone third with thoroughly mixed aggregate

selection of cement is its ability to produceimproved microstructure in concrete. Some ofthe important factors which play a vital role inthe selection of the type of cement arecompressive strength at various ages,fineness, heat of hydration, alkali content,tricalcium silicate (C3S) content, tricalciumaluminates (C3A) content, dicalcium silicate(C2S) content and compatibility withadmixtures, etc. Nowadays, practically in site,most of the constructions are being done byOrdinary Portland Cement (OPC).

Fineness TestThe fineness of cement has an importantbearing on the rate of hydration and hence onthe rate of gain of strength and also the rate ofevolution of heat. Finer cement offers a greatersurface area for hydration and hence faster thedevelopment of strength. Maximum number ofparticles in a sample of cement should have asize less than about 100 microns. The smallestparticle may have a size of about 1.5 microns.By and large average size of the cementparticles can be taken as about 10 micron. Theparticle size fraction below 3 microns has beenfound to have the predominant effect on thestrength at one day while 3-25 micron fractionhas a major influence on 28 days. Increase infineness of cement is also found to increasethe drying shrinkage of concrete. It is suggestedthat there should be about 25-30% of particlesless than 7 micron in size.

Procedure

100 gram of cement is correctly weighed andis taken on a standard IS sieve No. 9 (90microns). Air-set lumps in the sample, ifpresent, are broken down with fingers. Thesample is continuously sieved giving circular

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and tamped 25 times with tamping rod.Further, a similar quantity is added and againit is subjected to 25 times of tamping. Theremaining one third also filled in the sameway. The net weight of the aggregate ismeasured and bulk density in rod state iscalculated.

In Loose StateThe metal container is filled up to overflowingby discharging the aggregates from a heightof not more than 50 cm from the top ofmeasure. Care should be taken to preventsegregation. The surface is leveled and netweight is calculated.

MIX DESIGNGeneralMix design can be defined as the process ofselecting suitable ingredients of concrete anddetermining their relative proportions with theobject of producing concrete of certainminimum strength and durability aseconomically as possible. The main objectiveis to stipulate the minimum strength anddurability. The mix design proportionsadopted in our project for the grade of M40are.

1. 6 1453 1365

2. 12 1484 1360

3. 20 1443 1345

Table 1: Bulk Density Value

S.No.

Size ofAggregate

(mm)

Bulk Densityat Rodv State

(kg/m3)

Bulk Densityat Loose

State (kg/m3)

WaterOrdinary drinking water available in theconstruction laboratory was used for castingall specimens of this investigation. Water helpsin dispersing the cement even, so that everyparticle of the aggregate is coated with it andbrought into ultimate contact with theingredients.

It reacts chemically with cement and bringsabout setting and hardening of cement. Itlubricates the mix and compact property.Potable water, free from impurities such asoil, alkalis, acids, salts, sugar and organicmaterials were used. The quality of water wasfound to satisfy the requirement if IS 456-2000.

Figure 1: Mixing, Casting and Curing

S. No. Mix Proportions

1. 1:6

2. 1:8

3. 1:10

Table 2: Mix Proportion

CastingMould PreparationThe cube mould was placed in position on aneven surface. All the interior faces and sideswere coated with mud oil to prevent the stickingof concrete to the mould.

MixingThe concrete with grade M30 (1:1.02:2.26)with water cement ratio 0.38 is used. Concreteis mixed in roller type of mixing machine.

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Placing ConcreteConcrete is properly placed beneath and alongthe sides of the mould with help of trowel.

CompactionHand compaction was done for all the cubesused in the test. The damping mild steel rodshaving point ends were used to poke theconcrete and it is placed in vibrating table tomake compaction complete.

CuringThe mould is striped after 24 hours. The testcubes were cured for duration of 7 and 28 daysin a curing tank. After the wet curing thespecimens were air cured for minimum period2 Hours under laboratory conditions.

TEST RESULTSTesting of concrete plays an important role incontrolling and confirming the quality of cementconcrete. Cube, beam and cylinder are testedfor its strength characteristics.

Compression TestThe cubes of size 150 x 150 x 150 mm areplaced in the machine such that load is applied

on the opposite side of the cubes as casted.Align carefully and load is applied, till thespecimen breaks. The formula used forcalculation

Compressive Strength = Total Failure Load/Area of the Cube

Compressive Strength Results

Figure 2: Mixing of Coarse Aggregate

Split Tensile TestThe test is carried out by placing cylinderspecimen of dimension 150mm diameter and300mm length, horizontally between theloading surface of compression testingmachine and the load is applied until failure ofthe cylinder along the vertical diameter. Thefailure load of the specimen is noted.

The failure load of tensile strength of cylinderis calculated by using the formula

Tensile strength = 2P/3.14 DL6.2.2

where,

P – Failure of the specimen

D – Diameter of the specimen

L – Length of the specimen

Table 3: Compressive Strength for 7 Days

S. No

1. 23 27

Normal Concrete(N/mm2)

No Fines Concrete(N/mm2)

Table 4: Compressive Strengthfor 14 Days

S. No

1. 32 37



Table 5: Compressive Strengthfor 28 Days

S. No

1. 28 42



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Figure 3: Split Tensile Test

Split Tensile Strength Results

Flexural Strength = Pl/bd2

P – Failure load of the prism

b – Breadth of the prism

d – Depth of the prism

Table 6: Split Tensile Strength for 7 Days

S. No

1. 0.989 1.257




S. No

1. 2.26 2.857




S. No

1. 3.68 4.24



Flexural TestThe test is carried out to find the flexuralstrength of the prism of dimension 100 x 100x 500 mm. The prism is then placed in themachine in such manner that the load isapplied to the uppermost surface as cast inthe mould. Two points loading adopted onan effective span of 400 mm while testingthe prism .The load is applied until the failureof the prism. By using the failure load ofprism.

Figure 4: Flextural Test on Prism

Flexural Test Results

Table 9: Flexural Strength for 7 Days

S. No

1. 5.24 6.4




S. No

1. 7.24 8.2




S. No

1. 8.64 9.48



RESULTS AND CONCLUSION• 1:6 mix proportions gives more

compressive strength than the other two mixproportions.

• The effect of water/cement ratio havegreater impact on ultimate strength as

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0.45% water content gives more strengththan other water content used in thisinvestigation.

• The use of water content more than 0.45%causes the flow of cement to the bottom ofthe specimen.

• The use of different size aggregates alsohave greater impact on the ultimate strengthas 12 mm size aggregate gives morestrength than other sizes namely 6 mm and20 mm.

• The use of 6 mm aggregate causesincrease in dry density.

• The use of 20 mm aggregate causes morevoids inside the concrete thereby reductionin strength.

• The ultimate strength of no-fines concreteis of the range between 5 N/mm2-12 N/mm2.

• From the investigation, the mosteconomical mix with high strength identifiedwas 1:6 mix ratios with 12 mm aggregateand 0.45% water content.

SUGGESTION FOR FUTUREWORK• The ultimate strength of conventional

concrete blocks is of the range between 1.3N/mm2-9.5 N/mm2.

• The ultimate strength of no-fines concreteblocks were higher compared with nominalconcrete blocks.

• The water absorption percentage is of therange 5.5-8.5 for no-fines concrete blocksand 8.5-17 for nominal concrete blocks.

• The durability of no-fines concrete blockswere higher compared with nominalconcrete blocks.

• The cost of manufacturing of no-finesconcrete blocks were 3.5-5 rupees but fornominal concrete blocks it was 4.5-6.5rupees.

• Hence, the no-fines concrete blocks weremore economical than nominal concreteblocks.

REFERENCES1. Bing Chen and Juanyu Liu (2004),

“Properties of Lightweight ExpandedPolystyrene Concrete Reinforced withSteel Fiber”, Cement and ConcreteResearch, Vol. 34, pp. 1259-1263.

2. Ducman V, Mladenovic A and Suput J S(2002), “Lightweight Aggregate Based onWaste Glass and its Alkali-SilicaReactivity”, Cement and ConcreteResearch, Vol. 32, pp. 223-226.

3. IS: 456-2000 “Code of Practice for Plaina of Indian Standards”, New Delhi.

4. Mehmet Gesoglu, Turan O Zturan andErhan Guneyisi (2004), “ShrinkageCracking of Lightweight Concrete Madewith Cold-Bonded Fly Ash Aggregates”,Cement and Concrete Research, Vol. 34,pp. 1121-1130.

5. Niyazi Ugur Kockal and Turan Ozturan(2011), “Durability of LightweightConcretes with Lightweight Fly AshAggregates”, Construction and BuildingMaterials, Vol. 25, pp. 1430-1438.

6. Siva Linga Rao N (2011), “Properties ofLight Weight Aggregate Concrete withCinder and Silicafume Admixture”, Vol. 04,No. 06, SPL, pp. 907-912, ISSN: 0974-5904.

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7. Yun K J, Song H-W and Park S-S, ByunK-J, Song H-W and Park S-S (1998),“Development of Structural Lightweight

Foamed Concrete Using Polymer FoamAgent”.

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