Description
CHAPTER ONE
1.0 INTRODUCTION
1.1 BACKGROUND OF THE STUDY
Concrete is one of the prominent materials in building industries. Concrete is a mixture of aggregates and paste. The aggregates are gravel, sand, or crushed stone; the paste is water and Portland cement (Deng et al., 2019). The use of concrete is developing with a superior performance concrete designed for specific construction and building requirements. Cement, a concrete ingredient, comprises 10 to 15% of the concrete mix by volume. Through a process known as hydration, the water and cement will harden and bind the aggregates to form a rocklike mass. Cement reacts with water in hydration and hydrolysis actions (Deng et al., 2019). A dormant period occurs after the preliminary mixing and the first reaction climax, and prior to the concrete hardening. In structural engineering and civil engineering, serviceability is the condition under which a building will be useful. If the limit states are exceeded, then the structure will be weak. This relates to conditions different from the building strength that make the buildings unfit. Serviceability limit states in the design of structures include factors such as excessive vibration, cracking, deflection, fire resistance, overall stability, and durability. For satisfying the serviceability limit states, a concrete structure should be serviceable and function as expected during its service life. Extreme deflection must not impair the purpose of the structure or be aesthetically improper.
Cement manufacturers mine materials such as iron ore, shale, limestone, and clay; crush and screen the rock; and place it inside a cement kiln. After heating at higher temperatures, these materials will form a tiny ball termed as a “clinker”, which is extremely fine-ground to prepare Portland cement. Silica and lime make up about 85% of the cement ingredients. Other elements present are iron oxide and alumina (Deng et al., 2019). Plasticizers are chemical compounds that help in concrete production with an almost 15% lower content of water. Superplasticizers permit a water content reduction of 30% or higher. Long-term creep prediction has been a main issue in designing concrete structures for some time (Svendsen et al., 2020). Concrete creep is the structure deformation under sustained load. Long-term shrinkage and concrete creep can influence a concrete structure’s lifespan. Reinforced concretes are composite materials made up of various constituent materials with distinct properties that complement each other. Current concrete structures require structural components that have improved mechanical properties and higher durability. This can be achieved by the incorporation of nanostructured materials in concrete materials that can improve their mechanical properties. The use of nanomaterials in concrete structures has been confirmed to provide increased durability and higher mechanical strength, which reduce their maintenance needs or any requirement for quick replacement.
Despite such progress in nanotechnology, proper information regarding nanomaterials’ environmental and human health impacts has been insufficient until now (Svendsen et al., 2020). Thus, a careful approach must be developed when working with these materials. Nanosafety is considered as a growing concern, as the continuous exposure to the engineered nanomaterials is associated with many health effects, including pulmonary inflammation, genotoxicity, carcinogenicity, and circulatory effects. As nanomaterials are difficult to detect as soon as they are released into the environment, they can lead to many types of environmental and health concerns if the remediation system is risky. Therefore, further studies are very important for systematically labeling the structure–function relationship of nanomaterials with regard to their basic chemistry. Moreover, complete risk evaluations must be performed on nanomaterials, which represent a real exposure hazard all during their manufacture or use. Hence, green nanotechnology is also considered to lower the potential ecological and human health dangers from the manufacturing and use of nanosized materials, and to progress toward the replacement of predominant materials with innovative nanosized materials, which are extremely environmentally friendly (Sanzari et al., 2019).
This study on the mechanical properties of nanomaterial concrete uses nanosilica elements as mixture materials in the manufacture of concrete. The fundamental problem studied is how to improve the density and strength the bond between the mortar and the inter-surface zone on the nanosilica concrete. The use of nanomaterials is expected to give simultaneous contribution, in addition to the pozzolanik effect it provides, to provide physical effects, i.e. the packing effect. This effect has an effect in the form of shrinkage of the pores of the concrete, hence denser.
1.2 STATEMENT OF THE PROBLEM
After water, the most often utilised construction material is concrete. However, cement is a very brittle material with low ductility, low tensile strength, early formation, and micro-crack propagation due to shrinkage at young ages. Considering the previous two decades, the output of concrete has been greatly increased by using various supplementary cementitious materials (SCMs) and nanoparticles (such as SiO2, TiO2, Fe2O3, Cr2O3 and Al2O3). Because of their small fragment size and increased surface area, nanomaterials have a high potential for improving concrete. Lot of research have been carried out on the use of nanoparticles in cement but few of them investigated the effect of nanoparticles on the mechanical properties of cement. The inclusion of nanoparticles in concrete and its its effect on the mechanical properties is investigated in this work.
1.3 AIM AND OBJECTIVES OF THE STUDY
The aim of this work is to investigate the use of nanomaterials to enhance the mechanical properties of concrete. The objectives of the work are:
- To carryout an experiment that will determine the effect of nanomaterials in enhancing the mechanical properties of concrete
- To determine the influence of nanosilica in concrete.
- To study the general application of nanotechnology in building.
1.4 SCOPE OF THE STUDY
The scope of the study cover s investigating the compressive strength, modulus of elasticity and splitting tensile test of concrete by partial replacement of cement with nanosilica. Nanosilica with the average diameter of 100 nm were used with four different contents of 2.5%, 5%, 7.5% and 10% by weight.
