Precast concrete materials, manufacture, properties and usage - Chapter 7 pptx
Precast concrete materials, manufacture, properties and usage - Chapter 7 pptx
... expansion and a lower modulus of elasticity than a flint gravel
concrete, and both these factors will result in reduced stresses.
7. 2 RELEASE AGENTS AND RETARDERS
Release agents for heat-cured concrete ... up and gains strength slowly; a warm-starting concrete, say 25°C,
warms up and gains strength more quickly; and a concrete starting at,
say 40°C, can be handled within a...
Precast concrete materials, manufacture, properties and usage - Chapter 6 pptx
... process a 4- or 8-drop would take place about every 15
seconds.
6.6.3 Wet and earth-moist mix presses
In the production of floor tiles the wet and earth-moist mix mentioned
for the five-stage process ... risks of freezing and thawing and the use of de-icing chemicals. A
typical mix design could be:
2 7 parts of 10 mm hard stone or crushed rock
1·5 parts of natural sand or sand-gra...
Precast concrete materials, manufacture, properties and usage - Chapter 0 pot
... concrete
I. Title
691′·3 TA683 7
ISBN 0-2 0 3-4 905 7- 6 Master e-book ISBN
ISBN 0-2 0 3 -7 988 1-3 (Adobe eReader Format)
ISBN 0-8 533 4-9 9 4-0 (Print Edition)
WITH 40 TABLES AND 109 ILLUSTRATIONS
© APPLIED ... Publishers Ltd 1982
PRECAST CONCRETE
Materials, Manufacture,
Properties and Usage
M.LEVITT
ARCS, BSc, DIC, PhD
Head—Materials Scie...
Precast concrete materials, manufacture, properties and usage - Chapter 1 pdf
... relevant
to precast concrete manufacture leaving mix design to Chapters 5 and 6.
1.5.1 Cement types
The most common cements used are ordinary and rapid-hardening
Portland (including white), sulphate-resisting ... pre-wetted prior to mixing with the
cement and additional water. Some limestones and sandstones have
a slower absorption rate, and workability requirements need to be
m...
Precast concrete materials, manufacture, properties and usage - Chapter 2 pot
... and ordinary Portland cements with levels of C3A well under
10% and sulphate-resisting cements are the only types that will
apparently benefit. The choice is between the use of plasticising and
superplasticising ... Science Publishers Ltd 1982
2
ADMIXTURES
This chapter covers the range of admixtures used in precast concrete
products and mortars used with precast masonry. T...
Precast concrete materials, manufacture, properties and usage - Chapter 3 ppsx
... concrete colour
Both the desk-top 100mm square sample and the 300mm square hand-
portable samples are misleading in the case of unpigmented materials,
and for coloured concretes and mortars they seldom ... agents should be water-in-oil emulsion creams or
chemical release agents. Ordinary mineral mould oils and oil-in-
water emulsions promote streaking and staining.
(c) Pan-type...
Precast concrete materials, manufacture, properties and usage - Chapter 4 pot
... 0· 37 0·50 0·63 0 75
Total water 0·28 0·32 0·34 0·36 0·38 0·40
Observed and cost-corrected-relative-to-control failing loads (flexure)
are shown in Table 4.13. It can be seen that F/C over 0· 37 ... the
user, and in this respect vibrated concrete can only take a few per cent of
ash and it is hardly economic to set up a second silo in a precast concrete
factory to handle such a...
Precast concrete materials, manufacture, properties and usage - Chapter 5 ppt
... accurate and consistent quantity of
concrete into the mould.
In some precast processes tilting tables are used both to cast the
concrete and lift the mould and concrete into the near-vertical ... 240V or three-phase supply under closely supervised
nominally dry conditions.
13. Re-vibration of concrete is beneficial if the concrete is re-vibratable
and the cost of double ha...
Precast concrete materials, manufacture, properties and usage - Chapter 8 pdf
... particles. The 0 7 is a rapid decay and indicates a silting up and
capillary blocking process.
Open-textured and honeycombed concretes cannot be tested by this
method but the vast majority of precast ... is no solution to the resistance-to-
sulphate problems when concrete is not properly made. The
intermediate-permeability concretes are those categorised by (c), and
even with sul...
Precast concrete materials, manufacture, properties and usage - Chapter 9 ppt
... strength + 0.62 × standard
deviation
Day no. Average of 10 Standard 0·9 7 0 Accept/
deviation (
σ
) +0·62
σ
reject
51 7 4 0·5 6·61 A
52 7 3 0·6 6· 67 A
53 7 1 0·8 6·80 A
54 7 0 1·0 6·92 A
55 ... knowledge,
‘know-how’ and ‘alchemy’, and if one does not know what the variables
are doing at any one time control is lost. One can list the factors and
control variables one would use i...