building materials properties performance and applications pdf
Building material is any material which is used for a construction purpose. Apart from
naturally occurring materials, many man-made products are in use. The manufacture of
building materials is an established industry in many countries and the use of these materials
is typically segmented into specific specialty trades, such as carpentry, plumbing, roofing and
insulation work. This new book presents a wide variety of research on issues facing the
building industry today.
A study on the use of syntactic foams as a building material is presented. The acoustic performance of building materials with respect to their insulative properties is also analyzed. Other topics include the performance of building stones in relation to salt weathering, the behavior of building materials submitted to fire, the problem of microbe invasion into building materials and a study to develop a series of experimental methods to determine the moisture transport and storage properties of building materials.
Chapter 1 – Syntactic foams as building materials are studied. Various manufacturing
parameters contributing to syntactic foam composition in relation with the ‘pre-mould’
method were identified and inter-related. An equation based on lattice unit cell models with
the minimum inter-microsphere distance concept for a relation between volume expansion
rate of bulk microspheres in aqueous starch and microsphere size was derived and
successfully used to predict experimental data.
A simple method for estimation of syntactic foam density prior to completion of manufacture was suggested. Shrinkage of syntactic foam precursor was discussed in relation with different stages such as slurry, dough and solid. Also, the ‘post-mould’ buoyancy method involving mixing starch particles and ceramic hollow microspheres in water is discussed in relation with composition and properties.
It was found that starch particles tend to adhere to hollow microspheres during mixing, forming
agglomerations. A transition in the formation of mixture volumes in water was found to take
place at a calculated relative density value of 1 for an agglomerate consisting of multiple
starch particles and one microsphere.
A Simple Cubic cell model for the starch-microsphereinter-distance was adopted to quantitatively explain various effects on starch content in agglomeration such as hollow microsphere size, initial bulk volume of hollow microspheres and water volume. Further, the following were found for syntactic foams: (a) volume fraction of starch in foam is of linear relation with starch content in binder for a given experimental data range and (b) shrinkage of syntactic foam precursor is relatively high for small hollow microspheres with high starch content.
Compressive failure behaviour and mechanical properties of the manufactured foams were evaluated. Not much difference in failure behaviour or in mechanical properties between the two different (pre- and post-mould)
methods was found for a given binder content in syntactic foam. Compressive failure of all
syntactic foams was of shear on plane inclined 45° to compressive loading direction. Failure
surfaces of most syntactic foams were characterised by debonded microspheres. Compressive
strength and modulus of syntactic foams were found to be dependant mainly on binder
content but independent of microsphere size. Some conditions of relativity arising from
properties of constituents leading to the rule of mixtures relationships for compressive
strength and to understanding of compressive/transitional failure behaviour were developed.
The developed relationships based on the rule of mixtures were partially verified.
Novel sandwich composites made of syntactic foam core and paper skin were developed.
Interface bonding between syntactic foam core and paper skin was controlled by varying starch content. Two different microsphere size groups were employed for syntactic foam core manufacturing. Properties of skin paper with starch adhesive on were found to be affected by
drying time of starch adhesive. Skin paper contributed to increase up to 40% in estimated flexural strength over syntactic foams, depending on starch content in adhesive between syntactic foam core and paper skin. Small microsphere size group for syntactic foam core was found to be advantageous in strengthening of sandwich composites for a given starch content in adhesive.