The Determination of Bound Water in Waste Phosphatic Clay

Andrew J. Boyd,Mahir Dham,Bjorn Birgisson

doi:10.1155/2009/854701

Andrew J. Boyd, Mahir Dham

Open Access

https://doi.org/10.1155/2009/854701

Copy DOI

Abstract

Phosphatic clay is a by-product of phosphate strip mining, particularly in Florida, USA. This waste material occupies about 100 000 acres of land which could be utilized for other causes. Thus, its use as an alternating cementing material for the addition into the mixing matrix of cement paste and concrete to yield higher strength would be profitable for both materials involved. But the biggest drawback faced is that the phosphatic clay possesses high water holding capacity. The water is thus not available for mixing purposes when added to cement paste and concrete and is thus known as bound water. It is therefore essential to determine the amount of bound water to phosphatic clay which shall not be available for the hydration reaction of cement in cement paste and concrete.

Highlights

Since calcium-silicate-hydrate (C–S–H) is primarily responsible for the strength of concrete, it follows that increasing the proportion of C–S–H will result in a stronger material [1]
The elemental analysis of the waste phosphatic clay from PCS Phosphate companies indicates a presence of a silica source to react with calcium hydroxide (CH) to produce more C–S–H in the cement matrix for improvements in strengths
It can be concluded that the waste phosphatic clay can serve as a source of silica in the cement matrix and has the potential to enhance the compressive and tensile strengths of cement paste and concrete

Summary

Introduction

Since calcium-silicate-hydrate (C–S–H) is primarily responsible for the strength of concrete, it follows that increasing the proportion of C–S–H will result in a stronger material [1]. Phosphatic clay is a by-product of phosphate strip mining, in Florida, USA This waste material occupies about 100 000 acres of land which could be utilized for other causes [2]. Waste phosphatic clay has high water holding capacity, and it follows that the water that is not present for hydration reactions. The determination of this bound water is of utmost importance as it would assist in the determination of water available for the hydration of cementitious materials and should be determined in order for its utilization in cement paste and concrete for enhanced properties

Background

Experimental Approach

Results and Discussion

Conclusions