LAB TEST

Lab Test

Outline

We have conducted 10 different experiments to familiarize ourselves with the scientific processes. The purpose of the experiments is to have the hands on experience with the given experiments. These lab tests were conducted as prescribed by the teacher taking all safety measures.

Table of Contents

Chapter 1: Introduction4

Chapter 2: Experimental Methods5

Chapter 3: Results and Findings45

References58

Chapter 1: Introduction

An experiment is an investigation in which one or more variables may be altered under controlled circumstances to study the effects of altering variables.

In this report we have conducted 10 experiments. For each experiment appropriate apparatus were used to get the results. Also, the methods and procedures used were in accordance to the rules and regulations provided with respect to that experiment.

Chapter 2: Experimental Methods

Lab Test 1: Strength and Slump of Concrete

Loss of workability of concrete with time, often referred to as slump loss, is very important in construction practice, particularly with ready-mixed concrete where long haul times and delays on site are common. Slump loss occurs due to the effects of cement hydration, evaporation, and absorption of water in the case of dry aggregate; its rate is influenced mainly by cement characteristics, cement content, water/cement ratio, ambient and concrete temperature, initial slump and presence of admixture. The coarse and fine aggregates generally occupy 70-80% of the concrete volume and have an important influence on its fresh and hardened properties. Most normal-weight aggregates (fine and coarse) have absorption capacities in the range of 1-2% by weight of aggregate.

A major difference between conventional concrete and HSC is the use of chemical and mineral admixtures that reduce the water content, thereby reducing porosity within the hydrated cement paste . The reduction in water content to very low value can be achieved by using high dosage of chemical admixtures. However, it is undesirable since the effectiveness of chemical admixtures such as super-plasticizer (SP) depends on ambient temperature, cement chemistry, and fineness of aggregate. On the other hand, mineral admixtures act as puzzolanic materials as well as fine fillers resulting in a denser and stronger microstructure of the hardened cement matrix. The mineral admixtures are generally industrial by-products and their usage can provide major economic benefits. Thus, judicial use of SP and mineral admixtures can lead to economical HSC with enhanced durability.

The actual compressive strength of concrete is unknown during the early life of the structure. Also, the concrete market is generally very competitive and it turns out that concrete companies have only restricted budgets to spend in mix-design, although from this fundamental stage comes a great deal of consequences for the site operations and for the structure to be built.

Furthermore, in laboratory, to obtain desired concrete strength with suitable workability, technical personnel must try several mix proportions. This time consuming procedure increase the wastage of material and cost of concrete production. The water absorption rate of typical limestone aggregates is high when the aggregates are first wetted but rapidly decreases with time.

Slump loss, affected by the moisture condition of aggregates, is expected to be greater with ...