Cost effective bricks in construction: a performance study.

Vijayaraghavan, C. ; James, Jijo ; Marithangam, S. 等

Nomenclature

R--Traditional Brick

A--Mud Brick

B--Mud Brick with Slag

C--Mud Brick with Quarry Waste

D--Fly Ash Brick with Slag

[E.sub.1]--FaL-G Brick

CS--Compressive Strength

WA--Water Absorption

E--Efflorescence

w/c--Water Cement Ratio

FA--Fly Ash

CM--Cement Mortar

Introduction

General

The basic concern of a Civil Engineer is the design, construction, supervision and maintenance of different types of structures. A key element in field practice is to deal with different types of materials. This entails drawing up of detailed specifications, selecting materials, storage, sampling and testing, maintaining materials and inventories, etc. A study of these aspects of materials and their application in construction is very important for any Civil Engineer.

Rise in Demand for Materials

Construction activities have increased manifold, after independence of the country in all sectors. In the housing sector alone, the activities have increased substantially, but still are not able to meet the demand of the day. Demands have increased due the following reasons:

(i) Population explosion

(ii) Splitting of joint families

(iii) Desire to possess a house

(iv) Improved standard of living

Causes for Rise in Prices

Over the past two to three decades the prices of construction materials as well as raw materials have increased ten to thirty times. The various reasons for increase in process are:

(i) Heightened construction activity

(ii) Big demand supply gap

(iii) Acute shortage of raw materials

Need for Alternate Materials

In the situation when the production of traditional materials cannot be increased to match the demand for holding the price level it becomes necessary to search for substitutes without compromise on performance and durability of the material. Substitutes also help in reducing the cost thus bringing the materials at affordable rates for all sections of the society.

Materials and Method

General

Selection of materials is an important adjunct of use. It is necessary before, during and after construction. Test may be destructive, as in strength tests up to failure, or nondestructive where the selection is not rendered unusable. As it is impossible to test all materials, sampling is resorted to arrive at the properties of the lot. Testing follows standard procedures to obtain uniformity of results for purposes of comparison.

Materials

The various raw materials selected for the study includes mud, slag, cement, fly ash, river sand, gypsum, and lime.

Methodology

The methodology adopted for casting of bricks has been described in this section. Though it differs for each material adopted, the general process is the same.

Site Selection

The site selection plays an important role in manufacture of the bricks. Proper site selection ensures availability of raw materials at all times and availability of labour. It also ensures that the site is well connected for shipment of finished materials.

Preparation of Mix

This involves suitable proportioning of the mix with due consideration to the quantum of water to be added. Once the required mix proportion has been fixed, the materials are weighed out as per requirement and mixed into a plastic mass by adding the required quantum of water.

Moulding of Bricks

Bricks may be moulded in any one of the following processes:

(i) Hand Moulding

(ii) Machine Moulding

(iii) Semi-Dry Process

In this study, hand moulding process as adopted. Machine moulding will be more suited for mass production on a large scale and also will ensure good control over quality of bricks.

Curing

After 24 hours, the bricks are dried by natural drying process and curing is done by sprinkling of water for 28 days.

Mix Proportions

Different mix proportions were tried out for the various alternate brick combinations. All the bricks were cast to a size of 23cm x 11cm x 8.5cm. The mix proportions of different bricks are tabulated in the following tables.

FaL-G brick was also cast with a mix proportion of 70% Flyash, 25% Lime and 5% Gypsum as sample [E.sub.1].

Testing

A brick is subjected to various tests to find out its suitability. According to IS: 34951976 clay bricks should be tested for the following:

(i) Compressive Strength

(ii) Water Absorption

(iii) Efflorescence

Compressive Strength

The specimen brick is immersed in water for 24 hours. The frog of the brick is filled flush with 1:3 mortar and the brick is stored under a damp jute bag followed by immersion in clean water for days. The specimen is then stored in between the plates of the compression testing machine and load id applied axially at a rate of 14N/mm2 and the maximum load at which the specimen fails is noted for determination of the compressive strength of the brick.

Compressive Strength = ([L.sub.max]./A)

Where,

[L.sub.max]. = Maximum load at failure

A = Loaded area of the Brick

Test for Water Absorption

In cold water test, the specimen is dried in a ventilated oven at 110 - 115[degrees]C till it attains a constant mass. Then it is kept immersed in clean water at 27[degrees]C for 24 hours. It is weighed again to determine the weight of water absorbed and the water absorption is calculated as follows:

Water absorption = ([W.sub.w]/[W.sub.d]) x 100 %

Where,

[W.sub.w] = Weight of water absorbed [W.sub.d] = Weight of dry specimen

Test for Efflorescence

No preconditioning is required for this test. The brick is placed on end on a plate and is immersed in water to a depth of 25mm in a warm well ventilated room. Until all the water evaporates. When the brick appears dry, it is again filled with water to a similar depth. The brick is checked for white patches after the second evaporation to determine the efflorescence.

Cost Comparison

The costs of all the alternate bricks tested in comparison to the traditional bricks were all economical and could work out significant cost savings truly living up to its name of being cost effective materials.

Results

The results of all tests are tabulated and the corresponding graphs are shown.

[FIGURE 3.1 OMITTED]

[FIGURE 3.2 OMITTED]

Conclusion

The results are a clear indication in favour of the alternate material bricks on all counts. The material bricks are stronger, absorb less moisture and as per our tests slightly heavier than traditional bricks. Hence it can be cleanly recommended for cost effective construction for low cost housing.

References

[1] B.R.E, Digests, Building materials, The Constructionpress, London, 1970.

[2] Civil Engineering Materials, Technical teachers' Training InstituteChandigarh, Tata McGraw-Hill Publishing company limited-New Delhi.

[3] Dr. R. Udhayakumar, Handbook on cost effective building technologies, Rural technology Centre, Gandhigram Rural Institute--Deemed UniversityGandhigram.

[4] Proceedings of workshop on "Special Concretes" 9th & 10th March 2007, organized by Indian Concrete Institute, Tamil Nadu centre, Anna universityChennai -25.

[5] HRB (1943) "Use of soil cement mixtures for base course" Highway Res. Bd. Wartime Problems. No.7, Washington, D.C.

C. Vijayaraghavan (1), Jijo James (2) and S. Marithangam3

(1) Asst. Professor and Head of the Department of Civil Engineering, Tagore Engineering College Rathinamangalam, Vandalur Post, Chennai, Tamil Nadu. PIN: 600 048 India E-Mail: Vijayaraghavan_c@yahoo.com

(2,3) Lecturer in Civil Engineering, Tagore Engineering College Rathinamangalam, Vandalur Post, Chennai, Tamil Nadu. PIN: 600 048 India

(2) E-Mail: jijo_blitz@yahoo.co.in

(3) E-Mail: smarithangam@yahoo.co.in

Table 2.1: Mud Brick.

Sample      Mix (%)        w/c

[A.sub.1]   Mud 60 CM 40   0.115
[A.sub.2]   Mud 70 CM 30   0.124
[A.sub.3]   Mud 80 CM 20   0.134
[A.sub.4]   Mud 90 CM 10   0.124

Table 2.2: Mud Brick with Slag.

Sample      Mix (%)                w/c

[B.sub.1]   Mud 25 Slag 50 CM 25   0.085
[B.sub.2]   Mud 36 Slag 40 CM 24   0.090
[B.sub.3]   Mud 49 Slag 30 CM 21   0.096
[B.sub.4]   Mud 64 Slag 20 CM 16   0.102
[B.sub.5]   Mud 81 Slag 10 CM 09   0.111

Table 2.3: Mud Brick with Quarry Waste

Sample      Mix (%)              w/c

[C.sub.1]   Mud 25 QW 50 CM 25   0.085
[C.sub.2]   Mud 36 QW 40 CM 24   0.090
[C.sub.3]   Mud 49 QW 30 CM 21   0.096
[C.sub.4]   Mud 64 QW 20 CM 16   0.102
[C.sub.5]   Mud 81 QW 10 CM 09   0.111

Table 2.4: Fly Ash Brick with Slag.

Sample      Mix (%)              w/c

[D.sub.1]   FA & CM 50 Slag 50   0.076
[D.sub.2]   FA & CM 40 Slag 60   0.078
[D.sub.3]   FA & CM 30 Slag 70   0.080
[D.sub.4]   FA & CM 20 Slag 80   0.083
[D.sub.5]   FA & CM 10 Slag 90   0.086

Table 3.1: Traditional Brick.

Specimen    CS               WA (%)   E
            (N/[mm.sup.2])

[R.sub.1]   4.300            10.982   Nil
[R.sub.2]   4.420            10.892   Nil
[R.sub.3]   4.356             9.580   Nil
[R.sub.4]   4.456            10.850   Nil
[R.sub.5]   4.305            10.265   Nil

Table 3.2: Mud Brick.

Specimen    CS               WA (%)   E
            (N/[mm.sup.2])

[A.sub.1]   7.115             7.498   Nil
[A.sub.2]   5.928             7.475   Nil
[A.sub.3]   5.138             7.568   Nil
[A.sub.4]   2.480            10.000   Nil

Table 3.3: Mud Brick with Slag.

Specimen    CS               WA (%)   E
            (N/[mm.sup.2])

[B.sub.1]   8.300             6.290   Nil
[B.sub.2]   7.905             6.378   Nil
[B.sub.3]   5.534             6.527   Nil
[B.sub.4]   4.866             6.630   Nil
[B.sub.5]    2976            10.000   Nil

Table 2.3: Mud Brick with Quarry Waste.

Specimen    CS               WA (%)   E
            (N/[mm.sup.2])

[C.sub.1]   8.458             6.896   Nil
[C.sub.2]   7.114             6.921   Nil
[C.sub.3]   5.417             7.002   Nil
[C.sub.4]   4.348             7.018   Nil
[C.sub.5]   3.557            10.000   Nil