EFFECT OF WATER CEMENT RATIO ON STRENGTH OF CEMENT MORTAR MADE WITH STONE DUST USING ULTRASONIC PULSE VELOCITY (U.P.V)
CHAPTER ONE
INTRODUCTION
1.1 Background of the Study
A well-established fact in the cement industry speaks that excessive water content leads to reduction in strength of cement mortar, but insufficient water content incurs a poor workability. Hence, a method for determining the optimum water content and influence of w/c ratio on cement mortar is obviously desirable. Quality control unit involves tight control of w/c ratio for concrete materials. But in the case of cement mortar, more water is deemed requisite by the mason to make the mixture workable enough for his comfort zone. Therefore, it is appropriate to see the influence of w/c ratio for mortar strength.
Mortar is a masonry product which is matrix of concrete. It consists of binder and fine aggregate and moreover, it is an essential associate in any reinforced structural construction. The strength of mortar is a special concern to the engineer because mortar is responsible to give protection in the outer part of the structure as well as at a brick joint in masonry wall system. Moreover, mortar is used to hold together bricks or stones or other such hardscape components (Aziz 1995). A complete understanding of mortar and its application is huge to accomplish effective execution.
A considerable amount of dust is produced at the time of stone crushing. On the contrary, they are often considered as a waste in the locality. Saving of natural resources and environment is the essence of any advancement (Reddy 2010). Numerous attempts have been made since the ancient time up to the present moment to use the waste materials in construction work. Apart from stone dust, fly ash, silica fume, rice husk etc are other waste materials that have been utilized for construction purposes. Exchange of normal sand by stone dust will assist both solid waste minimization and waste recovery (Mahzuz 2011). Several researches have been made (Ahmed 2010; Lohani et al. 2012) to discover a proper way of using the stone dust without affecting the strength of cementitious product.
Stone dust is a waste material obtain from crusher plants during the process of making of coarse aggregate of different sizes, about 175 million ton stone dust is produced every year, which is kept in abundance. This unused quantity of stone dust requires a suitable disposal site for its easy and safe disposal. A large land area is required to accomplish the requirement which would again be a great problem in a country of thickly populated like Nigeria. Stone dust, being final part of a coarse aggregate is an inert material and may be used in concrete making as partial replacement of fine aggregate. Crusher dust is a byproduct generated from quarrying activities involved in the production of crushed coarse aggregate. It is possible to use such manufactured sand
With respect to feasibility, Masrur (2010) suggested that stone dust is appropriate for medium graded concrete for better performance in terms of strength and economy over normal sand. For Mortar, stone dust is well appropriate to choose it as an alternative of sand. According to Masrur (2010) about 100000 cftof stone dust is generated during stone crushing which is almost equivalent to 1.6 million BDT. With the rapid growth of construction industries consumption of construction material is increased. Again with the industrial development waste material generation is occurring in a massive quantity.
1.2 Statement of the Problem
Water/cement-ratio (w/c-ratio) is an important factor affecting quality of the concrete, which has motivated engineers to do research on determining the w/c-ratio. The traditional way to estimate the w/c-ratio by weighing the cement and water from mix design, the estimated results are usually not accurate as the other factors affect the accuracy such as moisture in the aggregates and water added in the construction site.
Water cement ratio affect the whole properties, the durability, and strength of cement mortar to a great extent. Too much water can increase the workability, but it will also adversely affect the strength and durability of cement mortar and when water used in a small amount, it may also affect the strength development of cement mortar, apart from decreasing its workability. The water cement ratio also contribute to the macro and micro structural arrangement of constituents of cement mortar which in turn could affect strength measurementusing non-destructive means. Hence this study focuses on the effect of water cement ratio on strength of cement mortar made with stone dust using ultrasonic pulse velocity (U.P.V).
1.3 Objectives of the Study
The study sought to know the effect of water cement ratio on strength of cement mortar made with stone dust using ultrasonic pulse velocity. Specifically, the study sought to;
1. examine the strength of cement mortar mixes with various water cement ratios.
2. examine the effect of water/cement ratio on the mechanical properties using compressive strength machine and ultrasonic pulse velocityand split tensile strength of cement mortar.
3. Compare the measured strength from both methods
1.4 Research Questions
1. What is the strength of cement mortar mixes with various water cement ratios?
2. What is the effect of water-cement ratio on the strength of cement mortar?
3. What is the effect of water cement ratio on the non-destructive measurement method?
1.5 Significance of the Study
This study will be of immense benefit to engineers and other researchers who intend to know more on the effect of water cement ratio on strength of mortar and the UPV testing method. This study contributes to knowledge and could serve as a guide for other studies.
1.6 Scope/Limitations of the Study
This study is on the effect of water cement ratio on strength of cement mortar made with stone dust using ultrasonic pulse velocity (u.p.v).
Limitations of study
1. Financial constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet, questionnaire and interview).
2. Time constraint: The researcher will simultaneously engage in this study with other academic work. This consequently will cut down on the time devoted for the research work.
1.7 Definition of Terms
Water Cement Ratio:Water–cement ratio is the ratio of the weight of water to the weight of cement used in a concrete mix.
Cement:Cement is a binder, a substance used for construction that sets, hardens, and adheres to other materials to bind them together.
Mortar:Mortar is a workable paste used to bind building blocks such as stones, bricks, and concrete masonry units, fill and seal the irregular gaps between them, and sometimes add decorative colors or patterns in masonry walls.
Stone Dust: Stone dust is like a coarser version of sand. It is often a byproduct of running stonesthrough a crushing machine to make crushed stone.
Ultrasonic Pulse Velocity: An ultrasonic pulse velocity test is an in-situ, nondestructive test to check the quality of concrete and natural rocks.
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