Page 28 - Concrete-Technology-Interacted_Book_Prof-MIK_Neat

PART 1

Testing

Core sampling and
testing

5.1 Introduction

This chapter sets out to describe the currently used procedures for sampling and testing
concrete cores and details the necessary planning and preliminary work, locating and
sampling cores, examination, measurement, preparation prior to testing, interpretation
and reporting the results.

The first half of the chapter is devoted to current practice that emanates from the
relevant current standards that have been in play for some time as well as recent updates.
Data from research carried out in 1997 suggests that the strength gain in concrete structures
is not as currently documented. These data also include cementitious blends thus increasing
the database beyond the present limit of just considering Portland cement concretes.

The last part of the chapter considers the new data, new ways of assessing core
properties and their influence on strength and how this data might be interpreted.

5.2 The current situation regarding standards and
guidance

For the last twenty years core sampling and testing in the UK has been carried out via
reference to three documents, i.e. Concrete Society Technical Report No. 11 (1976) and
the Addendum (1987) which is referred to as CSTR No. 11: British Standard BS 1881:Part
120:1989, and BS 6084:1981 Guide to assessment of concrete strength in existing structures.
In the USA the standard used has been ASTM C.42 Standard Method of obtaining and

test2in8g cores and sawed beams of concrete.