Precast concrete materials, manufacture, properties and usage - Chapter 2 pot

... mortars delivered to site. 2. 3 As 2. 2. 2. 4 Cast stone, coloured and architectural concretes without 2. 2 and 2. 3 present. 2. 5 Vibrated roadside units. 2. 6 Pointing and bedding mortars. In addition ... sections: 2. 1 Vibrated reinforced and unreinforced concretes (reinforced units only if permitted by regulations). 2. 2 (a) and (c) as 2. 1 and pressed and extru...

Ngày tải lên: 08/08/2014, 10:23

... 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 SCIENCE PUBLISHERS LTD 19 82 All ... Publishers Ltd 19 82 PRECAST CONCRETE Materials, Manufacture, Properties and Usage M.LEVITT ARCS, BSc, DIC, PhD Head—Materials Science D...

Ngày tải lên: 08/08/2014, 10:23

... 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 ... series of works-manufactured, laboratory-tested pneumatic-hammer-compacted precast concrete kerbs. The results may be related to any hand machine or mass machine process where earth-m...

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 ... characteristic strengths above 40 N/mm 2 , nor some sandstones above 50 N/mm 2 . (f) Aggregate variations affect physical, chemical and architectural properties and...

Ngày tải lên: 08/08/2014, 10:23

... 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...

Ngày tải lên: 08/08/2014, 10:23

... off up to a 24 0V 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 ... 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 in...

Ngày tải lên: 08/08/2014, 10:23

... required 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. Fig. 6.6. Precast ... N/ mm 2 ) and eject. The backing is the earth-moist mix, and the facing the wet mix, and the two are interdiffused by interface cement and water migration. The backing mix...

Ngày tải lên: 08/08/2014, 10:23

... demoulding and handling. If, for example, one aimed at and achieved a minimum 16 hour flexural strength of 3 N/mm 2 the cube strength at that time would be about 15 N/ mm 2 and about 45 N/mm 2 at 28 ... three different sorts of concrete: Type of aggregate Flint gravel Limestone Lytag Units 28 day cube strength 55 40 30 N/mm 2 28 day flexural strength 6 5 4 N/mm 2 E-value 4...

Ngày tải lên: 08/08/2014, 10:23

... for concrete, 0· 025 for expanded plastics. Solid section: U (solid)=3·08 W/m 2 °C Concrete and plastics: U (sandwich)=0·44 On an area proportionality U (panel)=0·44×0·8+3·08×0 2= 0·97 W/m2 ° C. ... with 10dBA equal to about 2 10 –5 N/m 2 , a very low pressure. An increase by an increment of 10dBA increases the energy level by a factor of 10; i.e. 20 dBA is about 2 10 -4 N...

Ngày tải lên: 08/08/2014, 10:23

... 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 6·9 1·0 6· 92 ... undertaken at 14 28 days old on units covered for the previous 3 days. Day of casting no. 10 min 30 min 1 h 1 0 20 0· 12 0·09 2 0·10 0·07 0·05 3 0·13 0·08 0·06 4 0·09 0·06 0·04 5 0·37...

Ngày tải lên: 08/08/2014, 10:23