Precast concrete materials, manufacture, properties and usage - Chapter 3 ppsx

... concrete colour Both the desk-top 100mm square sample and the 30 0mm 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-typ...

Ngày tải lên: 08/08/2014, 10:23

... concrete I. Title 691′ 3 TA6 83 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 Sci...

Ngày tải lên: 08/08/2014, 10:23

... 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 ... locking piece. The concrete mix used in the mould manufacture is best made of a flint gravel or volcanic rock coarse aggregate and a natural well-graded sand fines with a...

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... reinforced and unreinforced concretes (reinforced units only if permitted by regulations). 2.2 (a) and (c) as 2.1 and pressed and extruded products. 2.2 (b) ready-mixed mortars delivered to site. 2 .3 ... seen that the best results are obtained with a low C3A cement, and ordinary Portland cements with levels of C3A well under 10% and sulphate-resisting cements are the only types...

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... following F/C ratios and approximate total water contents were used: F/C 0 0·25 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 ... rewarding. 4 .3 PNEUMATICALLY TAMPED PRODUCTS In this section are described the experimental findings from a series of works-manufactured, laboratory-tested pneumatic-hammer-compacted p...

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... 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 handling moulds ... 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...

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... 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 ... and the hand process is time- consuming. After the trowelling or rolling-in, the unit is subjected to a wash-off, sand-blast or other suitable technique to expose the aggregate. Fi...

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... 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 f...

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... should be repeated. 8 .3. 2.6 Mineral oil stains Make a smooth stiff paste with powdered talc and tri-chlorethylene as described in Section 8 .3. 2 .3 and apply in the same way. 8 .3. 2.7 Stains from linseed ... and/ or windy climates as rust or organic residue can blow through the tubes and stain the face. 8. Protect concrete against in situ concrete run-downs, bitumen spillage...

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... could well obtain in precast concrete operations. Example 1: Dimensions of cladding unit ex-mould No. 3 where specifications are: x =30 15+0–10 y=2550+0–10 z=150 +3 3 (all in mm) Copyright Applied ... 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 woul...

Ngày tải lên: 08/08/2014, 10:23