ANALYSIS AND ASSESSMENT OF FLOW AND STRENGTH
CHARACTERISTICS OF CLSM
33rd Our World in Concrete and Structures (OWICs) - 2008
B C Udayashankar, R.V. College of Engineering, India
A Shashishankar, R.V. College of Engineering, India
Radhakrishna*, R.V. College of Engineering, India
Controlled Low Strength Materials (CLSM); Lyse Rule: Spread Flow test.
Compression test for strength, Phenomenological Model.
Strength is not the only property for which cement based composites are
processed. There are many practical situations where enhanced workability is
required for placement with the requirements of strength being far lower than normal
for which cement mortars and concrete are processed. These are Controlled Low
Strength Materials (CLSM). CLSM is a material that results in a compressive
strength of 8.3MPa or less. Currently CLSM applications require unconfined
compressive strengths in the range of 2 MPa or less, so as to allow future excavation
of previously laid utilities as the need arises. The upper limit of 8.3MPa allows to use
this material for structural fill under buildings where future excavation is unlikely.
CLSM does not require any compaction and can be processed capable of being
excavated, if required. CLSM have the advantages over traditional soil backfill, such
as self-leveling ability, free from settlement after hardening. To cater wide spectrum
of practical situations obtaining flowable characteristics plays a greater role than
imparting potential to development of strength.
Presently the use of CLSM in practice is ahead of development of appropriate
technology to handle a very wide range of practical needs of flowable characteristics
and to handle combinations and variations of the of wide spectrum of materials
involved. In this investigation it is attempted to develop a phenomenological model
within the basic framework of Lyse Rule already explored in concrete technology.
The basic tenet of this law is that the basic property of preset mix is in a particulate
state similar to saturated clays. In this fresh state, shearing resistance of the mix is a
function of total water content similar to saturated clays. Spread flow test on low
cement content and high volume fly ash combinations with sand and rock dust as
fine aggregate and as well as series without any fine aggregate are carried out. The
data is analyzed to advance a phenomenological model. The validity of this model is
verified with an independent set of data generated for this purpose