INFLUENCE OF SILICA-NANO PARTICLES ON PROPERTIES OF RICE HUSK ASH AND CALCIUM CARBIDE WASTE BINDER BASED- MORTAR

ABSTRACT

In the recent time effort has been made to replace Portland Cement (PC) wholly, thus producing  an  alternative  binder.  This  innovation  could  be  due  to  environmental challenges attributed to the green-house gas emission coupled with energy intensity and consumption associated with PC production. The use of Rice Husk Ash (RHA) and Calcium Carbide Waste (CCW) as a binder in the production of mortar has revealed positive results with some drawbacks such as poor initial setting time (IST), final setting time (FST) and early strength gain. This study therefore target at inclusion of silica-Nano particle (SNP) and superplasticizer in RHA-CCW binder with a view to evaluate the influence of SNP inclusion of its performance characteristics. Silica-Nano Particles were extracted by chemical leaching of the RHA and so was the physical and chemical properties of the constituents materials determined before the assessment of the fresh properties of the binder paste. Mortar specimen were thereby made with 60:40 RHA- CCW binder containing varied SNP contents (i.e. 0 to 5 % at 0.5 step increment) for 1:3 binder/sand mix of 0.5 W/B ratio. This was tested for compressive strength, water absorption and abrasion resistance at various curing ages in accordance with BS EN 196-1:2016 for Strength of cement and other established standards. The results shows mortar specimen of 60:40 RHA-CCW binder containing 3% SNP has the best performance in compressive  strength  (having  28  56  and  90   days  values  of  10.94,  13.50  and 15.75 N/mm2) representing an increase in strength 40, 63 and 80 % when compared to the RHA-CCW without SNP. 3% SNP addition in 60:40 RHA-CCW binder at 60/40 1:3 binder sand mortar, with 0.5W/B and 1.5% Superplasticizer by weight of binder was thereby recommended for masonry operations as it conforms to Class N of ASTM C270.

CHAPTER ONE

1.0      INTRODUCTION

1.1    Background of the Study

Concrete is the most widely used building material. With rapid industrialisation and the growth of infrastructure, the demand for cement production is growing, leading to CO2 emissions into the atmosphere, which have a negative effect on the environment (Rao and Navaneethawma, 2016). Studies on alternative binders have been the subject of research for a reduction in the use of cement in construction which will lead to a reduction in CO2  emissions. Extensive work is aimed at the production of some agricultural and industrial waste that is thought to possess certain pozzolanic content. Recent studies on the production of eco-friendly binders by Enejiyon (2018) and Olawuyi et al. (2017) have shown that Calcium carbide waste and Husk Ash from rice has a binder possibility in mortar / concrete. Ash from rice is created by the use of rice husk, which is a rice milling by-product. Reportedly this accounts for 20-24 percent of the produced raw rice. Several research findings on RHA‟s efficiency as cement substitutes have been published (Oyetola & Abdullahi, 2006 & Obilade 2017) Likewise, waste from Carbide is a derivative from the processing of acetylene gas (C2H2). It consists mainly of lime (Ca(OH)2) and solid caustic compounds, and, when pure, is white. The reaction between calcium carbide and water produces a trace of acetylene gas that is used in oxyacetylene welding and Calcium hydroxide CaC2 + 2H2O =  C2H2 + Ca(OH)2 .

However, in many fields of application the use of Nanoparticles in recent years has received particular attention in formulating ingredients with new functionalities, and it has become contemporary area of research in the field of concrete technology (Reddy & Vardhan 2017).

Nanotechnology has been applied for construction purposes to the study of cement and   concrete,   and   is   moving   concrete   science   into   a   new   age.   Countless Nanomaterials (including Nano-sized powders, tubes and fibres) have been developed and incorporated in cement materials. Nano-Silica and Nano-Titanium Oxide have done significant work to date. Nano-SiO2  or NS have not been published. Studies in Nanosilica,  Nano-Calcareous  (Nano-CaCO3),  Nano-  Cement,  Nano-Iron  (Nano- Fe2O3) Nano-Carbon and Nano-Aluminum (Nano-Al2O3) application studies (Kumar and Singh 2018) are the (Sobolev et al., 2009: Huang el.al, 2015) Studies have shown that well-dispersed Nanomaterials can speed up the hydration of cement, i.e. decrease the setting time of paste and mortar (Kumar and Singh, 2018). It further refines micropores concrete and transforms the inner structure of C – S – H gel (like the silicate chains), hence substantially decreasing permeability and enhancing the reliability and durability of the properties (Huang et al., 2015) Nonetheless, one inadequacy of  cement-based  materials  affected  by Nanomaterial‟s is  due to  high specific surface area, the Nano-material will unfavourably affect the workability.

If Nano Particles are combined with paste, mortar, and concrete in Portland cement (PC), products with different characteristics are obtained from conventional materials (Rao & Navaneethawma, 2016). The performance of these cement-based materials depends heavily on solid Nano Particles, such as particles of calcium silicate hydrates and Nano-sized solid porosity are interfacial in between cement and sand particles. Energy, durability and shrinking are some of properties of Nano-sized particles (Alireza et al., 2010) Nevertheless, in view of past studies, an in-depth understanding of the Nano-Silica incorporation mechanism on the hydration of a cement binder and its role in microstructural evolution and in gel chemistry is still lacking (Memon et al, 2010). Likewise, a thorough understanding of the chemistry of CCW combined with RHA to form an agro-industrial waste binder has yet to be developed (Reddy and Vardham 2017). Hence, this study aims to establish understanding of fresh properties and early- age strength properties of Nano-silica-mortar, inclusion in CCW and RHA-based binders.

1.2    Statement of Problem

Because of its adaptability, versatility, durability and ease of manufacture, Concrete is the world’s most popular construction material. The challenge the concrete industry worldwide is therefore to meet the demand of enormous infrastructure requirements, coupled with rapid industrial development and economic growth, as well as urbanization. (Rao & Navaneethawma, 2016) on the other hand, it is sadly found that PC, which forms concrete aggregate’s blending agent, contributes tremendously to the global warming syndrome. Technically, ecologically and economically, there is a need to modify the current concrete production methods in terms of the application of cement.

A significant amount of work has been done on how to remove or reduce the use of PC in concrete without compromising the critical characteristics of cement composite materials. Materials from Pozzolanine like the, Fly Ash, Silica Fume, granulated slag from the earth, RHA and Industrial Timber Ash (ITA) or Saw Dust Ash (SDA) have been found to offer the technological advantages of replacing PCs in terms of new, hardened condition and toughness of concrete. (Ferraro et al., 2017)

The eco-friendly advantage accompanying the use of this material is that it acts as another method of waste disposal, thereby turning the waste into a viable building material. This practice has multiple advantages; the consumption of industrial waste in an environmentally friendly manner, the conservation of natural resources, the moderation  of greenhouse gas  emissions  and,  above all,  the improvement  of the properties of concrete is the culmination of a sustainable community growth. While cost  savings  have  been  made  in  replacing  the  PC  with  this  waste,  the  burden associated with its disposal is also reduced.

Recently, attempts have also been made to replace PC using CCW wholly in combination with Sorghum Husk Ash (SHA) or RHA in mortar and concrete production (Egwuda, 2017 & Enejiyon, 2018).While the analysis yielded a promising result, features such as workability and early strength gain on the SHA / RHA-CCW binder were adversely affected. Therefore, this research aims to include silica Nano particulate matter and superplasticizer in RHA-CCW in order to strengthen the deficiencies of slow hydration and low strength gain found in earlier studies.

1.3    Aim and Objectives

The aim of the research is to study silica and Nano particles’ impact on the properties of  Rice  Husk  Ash  and  Calcium  Carbide  Waste  binder  based  mortar  in  order  to develop an effective proportional combination for good strength output and adequate RHA-CCW bonding hydration. The Objectives are to:

i.      Evaluate the physio-chemical properties of the RHA, CCW and SNP.

ii.      Determine appropriate mix proportions of the constituent materials for fresh properties of mortar made with RHA-CCW and SNP.

iii.     Assess the effect of SNP inclusion on pozzolanic mortar properties made using RHA-CCW.

iv.      Examine the microstructure of the hardened RHA-CCW and SNP binder-based mortar.

1.4    Research Scope of the Study

This Research concentrated on using RHA CCW and SNP as an alternative binder base mortar. With gradual replacement of SNP from 0.5 to 5 percent. The analysis highlights the benefit in fresh and early strength as well as the microstructural properties of alternative binder-based materials, which are believed to be within the limits set by the objectives. The study findings cannot be extended in general terms except for RHA and CCW which have the same index features. The cost efficacy of this analysis was not considered. This does not, of course, intend to neglect the study of the economy to the background, but rather it is believed that performance assessment must be understood and perfected before determining the economic aspect of the study.

1.5    Justification of the Study

Rice husk is one of the common wastes produced from North Central and North West Nigeria rice milling centres. Such wastes are actually disposed of as land-fill material without any economic gain in return, and substantial money is expended on disposal operations. RHA and CCW can be used properly; considerably enrich the mortar and concrete products and other associated building materials to reduce the burden on PC domestic and industrial use (Obilade, 2017).

The use of RHA and CCW as an alternative binder would help to reduce the carbon dioxide (CO2) emissions associated with PC production (Olawuyi et al., 2017). Essentially, a substantial amount of CO2 is released into the atmosphere for every PC output. As this study is aimed at alternative binders in mortar and concrete, it will ideally help balance the environment, reduce disposal costs, reduce the pressure on PC use and conserve the natural resources used in PC production (Obilade, 2017;

Brown, 2017). If the RHA-CCW technology with SNP as additive is properly expressed, the total construction cost can be that, thereby generating green mortar and concrete and making construction affordable. The study is expected to reveal fundamental properties with RHA-CCW and SNP for producing sustainable, high ultimate strength and high durability concrete.

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