Foamed concrete having a density lower than 1000 kg/m3 would float in water, but its compressive strength would be too low to be used in construction. So the purpose of this research was to determine the optimum MIRHA percentage to be used to increase the compressive strength of liquid foam mortar until it exceeded the minimum compressive strength requirement which is 3.45 Mpa. For the mixture of MIRHA and other pozzolanic material like silica fumes and GOBS, 18 cubes of 55x55x55 mm have been made for compressive strength test, which will be tested for 28 days.
The experimental results show that mix containing MIRRA had higher compressive strength and with the exception of second mix containing 5% MIRHA, all the other six exceeded the minimum required compressive strength. The sixth mix containing 10% MIRHA and 20% slag achieved the highest compressive strength which is 5.6 Mpa which exceeded required strength by 62%. This research was therefore done to find a way to increase the compressive strength of foam concrete with a density lower than water tightness, so that it can be used in construction such as for "Floating House".
This research is focused on the effect of MIRHA, whose material composition is highly reactive, so it can be used as a replacement material for cement, and also on the optimal replacement percentage of MIRHA/OPC required to increase the compressive strength of floating foam mortar. The criteria that had to be met in this research are that the minimum compressive strength is 3.45 MPa, which is a requirement for a non-load-bearing wall structure [3], while the maximum density must still be lower than the density of water, which is 1000 kg/m3. that the mortar floats.
OBJECTIVES
SCOPE OF STUDY
LIGHTWEIGHT CONCRETE
- Advantage of Foamed Concrete
- Disadvantage of foamed concrete
- Wet foam
- Dry Foam
The use of 'The Pantheon' where it uses pumice stone for the construction of cast in-situ concrete is proof of its use. In the United States and England at the end of the nineteenth century, clinker was used in their construction, for example, the 'British Museum' and other low-cost housing. One of its examples is in the form of perlite with its exceptional insulating properties.
It is widely used as loose insulation in masonry construction, where it improves fire resistance, reduces sound transmission, resists rotting and is termite resistant. The preformed foam process for making foam concrete is the most economical and controllable pore formation process, consisting of stable, unconnected air voids. It is generally believed that air voids that determine the porosity of foamed concrete have a significant effect on the compressive strength of the concrete [5].
Foamed concrete with this density is used in roofs and floors as insulation against heat and sound and is applied to rigid floors (ie it is not a construction material in itself). It is used gap filling between masonry sheets in underground walls, insulation in hollow blocks and any other filling situation where high insulation properties are required. The entrapped air takes the form of small, macroscopic, spherical bubbles that are uniformly dispersed in the concrete mixture.
Foam concrete is very reliable as it is almost ageless and eternal material that is not subject to the impact of time. Issue that is readily addressed is injecting foam rather than mixing in the case of an open mixer, or in the case where foam is introduced into a flowing product line, this is not a problem [4) . This equalization of pressure causes the solution to expand into what can best be described as foam similar in appearance to bubble structure and although relatively stable, it is not recommended for the production of low density (blag II 00 kg/m3).
It is also not suitable for pumping long distances or for dumping at great depths [7].
CEMENT REPLACENT MATERIAL
Procedure for Microwave Incineration
It is important to use a proper firing method in order to obtain RHA with a high content of reactive silica. Microwave incinerator as one of the modern incinerators is proposed to produce amorphous RHA with high pozzolanic reactivity as a result, which can significantly improve concrete properties. Microwave heating is defined as the heating of a substance using electromagnetic energy operating in that frequency range.
There is a fundamental difference in the nature of microwave heating when compared to conventional methods of heating the material. Conventional heating relies on one or more of the heat transfer mechanisms of convection, conduction, or radiation to transfer thermal energy to the material. In all three cases, energy is deposited on the surface of the material and the resulting temperature gradient established in the material causes heat transfer to the core of the object.
The temperature gradient thus always takes place in the material, with the highest temperatures at the surface [11. When heated with microwaves, the microwave energy not only interacts with the surface material, but also penetrates the surface and also interacts with the core of the material. Energy is transferred from the electromagnetic field into thermal energy through the entire volume of material penetrated by the radiation.
Microwave heating does not rely on conduction from the surface to bring heat into the core region. Since the heating rate is not limited by conduction through the surface layer, the material can be heated faster. Another important aspect of microwave heating is that it results in a temperature gradient in the opposite direction compared to conventional heating.
This means that the highest temperature occurs in the center of the object, and the heat is transferred to the outer layer of the material [11].
Compressive Strength and Permeability
2005, p. 86) stated that "silica is a by-product of the manufacture of silicon and ferrosilicon alloys from quartz and high-purity coal in an electric submerged arc furnace. The escaping gaseous SiO oxidizes and condenses to form extremely fine spherical particles of amorphous silica (SiO2); from hence the name silica dioxide Glassy (amorphous) silicon is very reactive and the small size of the particles accelerates the reaction with the calcium hydroxide produced by the hydration of portland cement.
The very small particles of silica fume can penetrate the space between the cement particles and thus improve packing." Addition of silica fume also reduces the permeability of concrete to chloride ions, which protects the reinforcing steel of concrete against corrosion, especially in chloride-. rich environments such as coastal regions and those of northern roads and runways (due to the use of deicing salts) and salt water bridges. The specific gravity of silica fume is generally 2.20 but it is slightly higher when the silica content is lower.
Using the nitrogen adsorption method, it is indicated that the specific surface of silica fume is about 20 ooom2/kg [4]. As a fine material like silica fume has a very low bulk density which is around 200 to 300 kg/m3• This has resulted in the handling process of silica fume becoming difficult and expensive. Because of this, silica fume is available in the densified form of micropellets (Figure 2), that is, agglomerates of the individual particles (produced by aeration), with a bulk density of 500 to 700 kg/m3.
Another form of silica fume is suspension of equal parts by mass of water and silica fume. Periodic agitation is necessary to maintain a uniform distribution of the silica fume in the slurry. Each of the different forms in which silica fume is available has operational advantages but all forms can be used successfully; claims of significant beneficial effects of either of these forms on the resulting concrete have not been substantiated [4].
GGBS is off-white in color as in Figure 3, resulting in the production of a lighter mortar.
MIX DESIGN
COMPRESSIVE STRENGTH
PROJECT IDENTIFICATION
EQUIPMENT
CONSTITUENT MATERIALS
MIXING PROCESS
The mortar is cured in a closed container of water at room temperature, as shown in Figure 5, so that it can be protected from solar radiation and maintain a high level of humidity.
CONCRETE TEST
HAZARD ANALYSIS .1 List of Hazard
Hazard Prevention
RESULT
From the Graph!, it can be concluded that all the other mix design except the control mix (MO%) and the second mix (M5%) managed to achieve the required minimum compressive strength in 281h days which is 3.45. The control mixture is only able to reach the compressive strength of 1.58 MPa at 28 days, which is equal to 46% of the required strength. For the second mix which is M5%, its 28th day compressive strength also only reaches up to 2.75 MPa which is 78% of the required strength.
For the third mixture (M20%), the compressive strength on the 28th day has reached 4.04 Mpa, exceeding the required strength by 17%. For the fourth mixture, the compressive strength on the 28th day is 4.9 MPa, which also exceeds the required strength by 40%. For the fifth mixture, the compressive strength on the 28th day is 5.1 MPa, which exceeds the required strength by 47%.
Finally, the sixth mix also managed to achieve compressive strength of 5.6 MPa which exceeded the required strength by 62%. The purpose of split tensile test is to meet the requirement of BS 5328: Part 4: 1990 indicated that all mix should have a minimum tensile strength of 0.3. Therefore, from the result it is indicated that control mixture and mixture containing 5% MIRRA cannot be used while other mixture managed to pass the requirement.
DISCUSSION
CONCLUSION
RECOMENDATION
Particle Size Effect on the Strength of Rice Husk Ash Blended Gap Graded Portland Cement Concrete, 2004. 3] Hjh Kamsiah Mohd.Ismail, Mohamad Shazli Fathi, Norpadzlihatun bte Manaf, Study of Lightweight Concrete Behavior, Universiti Bahruud, Malaysia, Johor Skruud 2004. , Malaysia. . Tamilse1van, and Hwee-Sin Lim, Air-Void System of Foamed Concrete and its Effect on Mechanical Properties, ACI Materials JournaVJanuary-February 2006; Title no.
7] PAN Zhihua, Fujiwara Hirorui, Wee Tionghuan, Preparation of high-performance foam concrete from cement, sand and mineral admixtures, College of Materials Science & Engineering, Nanjing Uuiversity of Technology, Nanjing 2006. 9] Kusbiantoro Andre, The effect of microwave-burned Rice Husk Ash (MIRHA) on Concrete Properties, Master Thesis, Uuiversiti Teknologi Petronas, Malaysia, 2007. 13] Kusbiantoro Andre, The Effect of Microwave Incinerated Rice Husk Ash (MIRHA) On Concrete Properties, Master Thesis, Universiti Teknologi Petronas, Malaysia, 2007.
![Figure 1: Mechanism of void filling and transition zone strengthening effect of MIRRA [ 6]](https://thumb-ap.123doks.com/thumbv2/azpdforg/10258318.0/20.853.186.661.452.734/figure-mechanism-void-filling-transition-strengthening-effect-mirra.webp)
