Project Abstract

<p> </p><p>High cost of cement has caused serious impact on housing delivery due to increase in<br>energy costs and high demand which attracted many research interests in sourcing other<br>alternatives cheaper materials. The use of rice husk powder in composites cement system<br>was investigated. Paste of neat and blended Portland cement with 5%, 10%. 15%, 20%,<br>25%, 30%, 35%, 40%, 45%, 50%, and 55% rice husk powder were cured in air under the<br>same temperature and humidity condition. Compressive strength of the various mix<br>proportions at 28 days were determined using standard compressive strengths testing<br>machine. The hydration products of the high percentage replacement composite cement<br>pastes were identified by x-ray diffraction analysis and compared with those made from<br>100% ordinary Portland cement pastes. Results indicate that only lower percentage<br>replacement level such as 5% and10% rice husk powder contained the required amounts<br>of silica which aided the hydration process producing samples with compressive<br>strengths of 19.72N/mm2 and11.57N/mm2when compared with control sample with<br>33.33N/mm2. However, result of the x-ray diffraction analysis showed that the observed<br>hydration products were mostly as expected due to the high replacement levels but the<br>degree to which crystal phases were identified in one of the samples was unusual. The<br>unusual behavior may be due to the fact that the calcium hydroxide initially formed was<br>consumed during the curing period confirming the important pozzolanic reactions of the<br>rice husk powder at such high replacement.<br>– 7 –</p><p>&nbsp;</p> <br><p></p>

Project Overview

<p> 1.0 Introduction<br>Portland cement is the essential binding agent in cement composite systems, which in turn<br>is the most commonly used construction material worldwide due to its many advantages<br>including lower relative price, durability and other properties. (Escalante and<br>Sharp,2004). Its cost is increasing due to the increase in energy cost and high demand of<br>the product. However, to meet this demand other alternative cheaper materials are being<br>sourced. (Escalante and Sharp,2004 ).<br>Materials of natural origin such as volcanic ash (VA) or industrial by product, like<br>granulated blast furnace slag (GBFS) and pulverized fuel ash (PFA) have been widely<br>used as partial replacement of Portland cement in concrete construction (Escalante and<br>Sharp, 2004). Similarly, an agricultural waste rice husk has been described as a pozzolana<br>with promising cementing properties when used with Portland cement. (Amjad and<br>Abdul, 2004).<br>The advantages of these replacement materials are improved technical properties, lower<br>cost and a reduction of waste accumulation. For instance, replacement of 5% of the<br>aforementioned materials can provide a decrease of about 75×106 tons of CO2. (Escalante<br>and Sharp, 2004).<br>– 17 –<br>The idea of adding pozzolana to Portland cement or Portland cement concrete is widely<br>practiced because it does not only reduce cost and conserves energy, but decreases the<br>heat of hydration, increases compressive strength and durability. (Amjad and Abdul,<br>2004).<br>The introduction of replacement materials in Portland cement produces additional<br>complexity to the chemical reactions developed during hydration of the composite<br>cements. (Escalante and Sharp, 2004). It has been observed that both latent hydraulic and<br>pozzolanic materials participate in the overall hydration process and in the development<br>of microstructure. The dominant product of these reactions is C – S – H gel, which is<br>principally responsible for the mechanical properties of the hydrated cement. C – S – H<br>gel is generated by the interaction of the replacement materials with Portlandite (CH),<br>liberated during the hydration of the alite and belite present in the cement (Escalante and<br>Sharp, 2004).It is evident from many studies that variation in curing condition affects<br>pozzolanic reactivity of the composite cement. (Amjad and Abdul, 2004). However, little<br>or no attention has been paid to investigate how composite cement systems react at<br>fluctuating weather conditions of Zaria.<br>1.1 Statement of the Problem<br>Cement consumption is generally considered as an indicator of the growth of the Gross<br>National product (GNP) of a country. In Nigeria, it is estimated that the demand for<br>cement is about 18 million tones annually used mainly in the construction and building<br>industries. (Dadu,2008). While local production for the past 10 years is between 2.5 to<br>– 18 –<br>6.5 million tones annually. However, to meet this demand an alternative and cheaper<br>material is desirable.<br>Rice-husk, a pozzolanic materials and agricultural waste are land filled and burnt in open<br>piles which is not environmentally friendly. An easy and efficient way of utilizing this<br>waste is by using it with cement to serve the construction and building industries.<br>1.2 Aim of the Research<br>The study aims at investigating the compressive strength and identifying the crystal<br>phases of the composites.<br>1.3 Objectives<br>1. Determining the compressive strength of the composite by using standard compressive<br>strength testing machine.<br>2. Identifying the crystal phases of the hydration products by x-ray diffraction analysis.<br>1.4 Scope<br>The scope of the study embraces the crystal phase identification of the composite cement<br>and the determination of its compressive strength.<br>1.5 Significance of the Research<br>The result obtained from this research will advance and possibly open new frontiers of<br>knowledge in the production of cement composites by utilizing local raw materials. If<br>implemented, it would amount to saving cost on procurement of construction materials<br>like cement and also will help in controlling environmental problems that are associated<br>with the<br>– 19 –<br>burning of waste in rice production.<br>1.6 Delimitation of the Study<br>The investigation is delimited to production of composites from mixture of ordinary<br>Portland cement with rice husk powder.<br>1.7 Limitation of the Study<br>Some of the problems encountered in carrying out the study were lack of some research<br>facilities like;<br>1. Differential Thermal Analyzer: For examining the heat change during hydration<br>of the cement paste.<br>2. Scanning Electron Microscope: This is useful in the study and characterization of<br>the composite.<br>1.8 Research Question/Hypothesis<br>1. What are the crystalline phases of the composites and their relative proportion?<br>2. What are the measures of the compressive strength of the composites?<br>1.9 Basic Assumptions<br>a. That the crystalline phases and their relative proportions would comply with the<br>International Centre for Diffraction Data (ICDD) standards.<br>b. That the compressive strength achievable through mixing method would yield<br>satisfactory results. <br></p>