MECHANICALBEHAVIOUR OF FLY ASH STABILIZED MUD CONCRETE BLOCKS IN COMPARISON WITH BRICKS,CEMENT BLOCKS, AND CSEB BLOCKS B.G.J. Nipuna Department of civil enginnering,University Of moratuwa Prof R.U.
HalwaturaDepartment of civil enginnering,University Of moratuwa Abstract:Sustainable construction materials are very interested in modern world. Fly ashstabilized mud concrete blocks are under research stage to provide industry as buildingconstruction material. The main components of fly ash stabilized mud concreteblocks are soil, fly ash, Sault, sodium hydroxide. Some researches were done tofind out optimum proportion of these material for blocks. This research focusedon the mechanical behaviour of mud concrete blocks. Tests basically do with thechanging bond thickness, mortar type and bond patterns.
Compressive loads addto the wall panel construct with mud concrete blocks and these values comparewith the test values of bricks, cement blocks, CSEB blocks wall panels. Observecrack patterns and study what to develop for the industrial usage.Simultaneously test do for the bricks, cement blocks, CSEB blocks wall panelsalso to compare the behaviour. Study the blocks dimensions for the optimumsection and mortar quality is main objectives of this research.
Soil can beconsidered as very old building construction material. The process of Developthat material and provide as a sustainable building construction material isvery vital in many ways such as environmentally and economically. This paperpresent test values for the wall panels constructed with different materialsand the best mortar and bond pattern for the wall panel construct form fly ashstabilized mud concrete blocks Keywords:Mud concrete blocks; Bricks; Cement Blocks; CSEB blocks; Stabilization; Fly ashstabilization; Wall panel; Mechanicalbehaviour; 1. IntroductionPeoplestarted to construct buildings from soil at very early stage. After that stepby step it changed to cement and concrete. But now the tread is to use more sustainablebuilding construction material for the constructions. Among sustainablebuilding construction materials soils plays a great role.
Many researchers weredone to find out method to use material like soils in optimum way to userequired quality. Soil stabilization, Mud concrete blocks, Geo polymer concreteare some examples for them. Soil modification is the process ofaddition of a modifier to a sol to improve its strength and durability. The useof alternative cheaper materials as stabilizers will greatly enhance theproduction of blocks with the desired properties at low cost. It will alsodrastically reduce the cost of production and consequently the cost ofconstruction works (Lanka. S,1999) many researches were done tofind out stabilization materials for soils. Alkaline activation effect is themost popular method.
In many develop countries like Sri Lanka is need to findout sustainable and economical materials for the construction. Every countymust have to pay attention not to the development but for sustainabledevelopment.Mudconcrete is similar kind of earth stabilized block build by mixing cement andsoil to build block. The mud in this mixture plays a great role as a fillermaterial and to develop the workability of the mixture. However, the role ofcement in low quantities is to stabilize the soil Mud is one of humankind’soldest and most universally used construction materials. Even at the dawn ofhumanity sustainable development. So to study and do researches in this streamis very vital.Mud concrete blocksMudconcrete blocks plays a great role in sustainable building constructionmaterial.
It is first developed and introduced to the construction field in SriLanka by university of Moratuwa. Basically concrete consists with Concrete iscement, sand, metal and water. Instead of using these materials researchersfound a mixture consists with Soil, stabilizing agent, Water mixture. Mud concrete block which has made byreplacing sand and metal of concrete by fine and coarse aggregates of soil. Thestrength of mud concrete blocks is depend on the proportion of sand and gravelmixture. Cement is also used when preparing mud concrete blocks as a stabilizerin very low quantities.(Udawattha & Halwatura 2016)Firstresearchers invented mixture of clay, soil, water, course and fine sand withsome amount of soil in 2015. In 2017 researchers were found that composition ofsoil, water, salt, and sodium hydroxide.
Mud concrete block has a self-compactingnature. Self-compaction is amethod of compacting by using its own weight. Porosity cause for the strength of the blockand the compaction level cause for the porosity.
Low porosity means high strength. To reduce porosity we have tointroduce compacting technology or materials to improve compaction. (Engineeringn.d.
)Thermal properties also very importantcharacteristics of construction materials. To achieve self-compacting quality,water content is very important. Buthigher water content will lead to reduction in compressive strength of the mudconcrete blocks. So it is very important to maintain considerable water contentwithout affecting to the strength of mud concrete block and self-compacting quality.The optimum proportion for this experiments suggested a water content has to be maintained in range of18% – 20%.(Engineering n.d.)Wall panelcan build by using md concrete blocks with the cement mortar or another mudmortar.
From these two side we have to first initiate the best binder for mudconcrete blocks wall panels. If we maintain precise sand, gravel, water contentand good compaction level we can achieve fare face which will reduce thefinishing cost in wall construction. Compared with other wall materials such asconcrete blocks and burnt bricks mud concrete blocks have good natural colourand aesthetic beauty. In load bearingmud concrete blocks get the highest place. Durability and thermal comfort,keeping the low embodied energy is added advantages of mud concrete blocks. (Udawattha, C. & Halwatura, R.
, 2016). Mudconcrete blocks will become very popular in construction world in future.Because of the easy production process, new appearance, low cost constructionsand the lower energy consumption will cause for the popularity of mud concreteblocks in near future..(Lanka 2015) CSEB BlocksCSEBblocks stands for compressed stabilized earth blocks. CSEB blocks are made fromsand, soil, 10% cement. Bricks stacks and cure 21 days.
The cement made thebond between sand stabilizing bricks. The Compaction add required density tothe blocks. Compressed stabilized earth blocks are behave more likely to thebricks.Soil StabilizationStabilizationmeans the process of blending and mixing materials with soil to achieve requiredsoil strength and durability. The main weakness of earth as a buildingmaterial lies in its low resistance to water.
Overhanging eaves and verandashelp considerably, but tropical rains of any intensity can damage unprotectedwalls. Because of the clay fraction, which is necessary for cohesion, wallsbuilt of unsaturaded soil will swell on taking up water and shrink on drying.This may lead to severe cracking and difficulty in getting protectiverenderings to adhere to the wall (Jegandan, Liska, Osman, & Al-Tabbaa, 2009).Stabilizing process can do withinclude blending soils to have a desired gradation or mixing commerciallyavailable additives that may change gradation, change strength and durability,or act as a binder to cement the soil. Final out comes of thestabilization process are· To reduce plastic index · Increase the durability · Increase the strength · increased durability · Give a good working platform for anywhether conditions (Force n.d.)Various Methods of SoilStabilizationMechanical, cement, lime,bituminous, thermal & electrical methods are some example for soilstabilizing methods.
In mechanical stabilizing method change the gradation ofsoil. Mixing soil with cement is also a stabilizing method. Soil can bestabilized by adding lime to the soil and the method is called limestabilization. This method is widely used in clayey soil. Using asphalt alsogood stabilizing method. But due to the low viscosity it is not easy to use andnot cost effective. Thermal Stabilization is also good stabilizing method andit can be done either from extreme heating to extreme cooling of the soil.
Chemical stabilization is done by using chemicals functioning as compactionaids, water repellent, binders. The reaction between the chemical additives andthe soil particles can bind the soil grains by the strong network. Usingchemical stabilizing agents, the soil produced with better quality is comparedwith the mechanical and physical techniques, (Zaliha et al. 2013) Fly ash Fly ash isthe remaining fine particle come after the coal combustion. Fly .It consists ofvery fine particles of · Silicon Dioxide (SiO2)(Amorphous & Crystalline)· Aluminium Oxide (Al2O3)· Iron Oxide (Fe2O3)· Calcium Oxide (CaO)Fly ashuse in various type of purposes in construction field. Fly ash uses in Concrete,production of Cement Clinkers, as a soil stabilizing agent, Mineral Filler inBituminous Concrete, etc. (Trivedi et al.
2013)Fly ashcan classified in to two categories called F type and C type based on chemical composition.Class F fly ash is produced by burning anthracite and bituminous coal, andclass C fly ash is produced by burning lignite and sub-bituminous coal. Amountof calcium and silica composition is themain difference between F and C. Class C fly ash, in addition to havingpozzolanic properties, also has some cementitious properties and it has beensuccessfully used as part of the binder in stabilized base applications.(Degirmenci et al. 2007)Fly ash as a stabilizer Chemicaland physical properties of soil may change according to the original soilproperties by adding fly ash. Following properties changed when adding fly ashto the soil.· Soil texture, · Bulk density,· Water holding capacity · Soil pH Based onthe source fly ash may show alkaline or acidic characteristics.
It could beused to buffer the soil pH. The hydroxide and carbonate salts give fly-ash thecapability of neutralizing the acidity in soils. (Trivedi et al. 2013) Alkaline Effect Many researches were done to study the alkaline effect. Inprevious research, it has been observed that the alkaline activation ofmaterials containing silica and alumina can be used as an alternative to cementin construction.(Glendinning et al.
2011)Alkaline activation is a chemical process in which a powderedaluminosilicate such as fly ash is mixed with an alkaline activator to make apaste capable of setting and hardening in a fairly short period of time. Theproperties like strength, shrinkage, and acid and fire resistance of theresulting materials depend upon the type of the aluminosilicate used and thevariables of the activation process.Alkaline activation of fly ash is environmentally friendlybinders having similar properties or increasing the characteristics ofconventional materials.(Palomo & Fernández-Jiménez 2011)SodiumHydroxide additiveThe main advantage of sodiumhydroxide is that it can use as a great compacting It provide greater density for the same compacting effortwhen it reacts with water.(Zaliha et al. 2013)In theprocess of strength gain activated system NaOH concentration plays a veryimportant role. To increase strength have to increase NAOH concentration.
(Cristelo, Glendinning, Miranda, et al. 2012)MethodologyThe mainaim of this research is to find out the possibility of inventing a new “mudblock” and study the mechanical behaviour of them to develop for industryusage. To develop mud concrete blocks which has required strength for loadbearing walls while satisfying less weight and low cost together with simplemanufacturing process.To findout optimum mortar combination for bond and study the crack patters Thefollowing methodology will follow in this research.· Construct Mud concrete blocks with predesigned proportions· Collect other materials bricks, cementblocks, CSEB blocks for the wall panel construction· Construct wall panel with 3 mortar mixproportions.
· Tests wall panels to check the mechanicalbehaviour · Study the crack patterns and recordvalues · Compare them with the other material typevalues ConclusionVarious researches were conductedto improve the behaviours of bricks, Mud concrete blocks plays a great role insustainable construction material. This researched based on mechanicalbehaviour of mud concrete blocks wall with the comparison to the brick wallpanels, CSEB blocks wall panels. Of Also researches here basically testes thecrack patents and maximum compressive strength bond pattern but proper researchon mechanical behaviour of fly ash stabilized mud concrete blocks in comparisonwith bricks, cement blocks.
AcknowledgementThehelp received from the department of Civil Engineering in University ofMoratuwa highly appreciated. Professor Halwathura and Cr chameera udawatthayour contribution for this research is highly appreciated.ReferencesCristelo,N., Glendinning, S., Fernandes, L., et al.
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