A Self-Learning Manual - Institution of Engineers Mauritius

A Self-Learning Manual
Mastering Different Fields of Civil Engineering Works (VC-Q&A Method) Vincent T. H. CHU
Level One (Core FAQs)
Part I: Concrete Material
1. Can grout replace concrete in normal structure?
The mixture of cement and water alone cannot replace concrete (Longman
Scientific and Technical (1987)) because:
(i) Shrinkage of grout is several times that of concrete with the same
mass.
(ii) The effect of creep of grout is far more than that of concrete.
(iii) Heat of hydration of cement with water is more than normal concrete
and this leads to the problem of severe cracking.
2. What are the differences between epoxy grout, cement grout and
cement mortar? (CM1)
Epoxy grout consists of epoxy resin, epoxy hardener and sand/aggregates.
In fact, there are various types of resin used in construction industry like
epoxy, polyester, polyurethane etc. Though epoxy grout appears to imply
the presence of cement material by its name, it does not contain any
cement at all. On the other hand, epoxy hardener serves to initiate the
hardening process of epoxy grout. It is commonly used for repairing
hairline cracks and cavities in concrete structures and can be adopted as
primer or bonding agent.
Cement grout is formed by mixing cement powder with water in which the
ratio of cement of water is more or less similar to that of concrete [63].
Owing to the relatively high water content, the mixing of cement with water
produces a fluid suspension which can be poured under base plates or into
holes. Setting and hardening are the important processes which affect the
performance of cement grout. Moreover, the presence of excessive voids
would also affect the strength, stiffness and permeability of grout. It is
versatile in application of filling voids and gaps in structures.
Cement mortar is normally a mixture of cement, water and sand (typical
proportion by weight is 1:0.4:3). It is intended that cement mortar is
constructed by placing and packing rather than by pouring. They are used
as bedding for concrete kerbs in roadwork. They are sometimes placed
under base plates where a substantial proportion of load is designed to be
transferred by the bedding to other members.
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