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...

Ngày tải lên: 08/08/2014, 10:23

... with stronger dipole yet short-lived ( 30 60 minutes) forces. Their addition rates are rather higher than for plasticisers and range approximately from 200 to 200 0 ml/ 50 kg depending upon the effect ... 2.5 TYPICAL EFFECT OF PLASTICISING ADMIXTURE ON PROPERTIES OF A VIBRATED CONCRETE PRODUCT The dosage rates vary from 100 to 100 0 ml/ 50 kg cement and each type should be dispens...

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 ... weight) The mix, ash and water variations were as follows: F/C 0 0·25 0 50 1 00 1· 50 2 00 Total water 0 35 0 39 0 43 0 50 0·58 0 65 Table 4.11 lists the 14 day o...

Ngày tải lên: 08/08/2014, 10:23

... cone flower pot units, etc., and when properly constructed and used have a lifetime of 200 – 100 0 uses. Figure 1.6 illustrates a GRP-U-section gulley unit mould where the resin has a white silica ... 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 (includi...

Ngày tải lên: 08/08/2014, 10:23

... concrete colour Both the desk-top 100 mm square sample and the 300 mm 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

... 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 ... devices such as clamp-on and poker vibrators are high-wear-rate pieces of machinery and a sufficient supply of spares should always be kept. 9. Poker vibrators need plenty of room...

Ngày tải lên: 08/08/2014, 10:23

... Science Publishers Ltd 1982 Water 40+ 20+ 30= 90= Added or total water 40= Effective or free water The two W/C ratios are 0 40 and 0 90. 6.1 GENERAL PRECAST WET-CAST PRODUCTION Products in this ... clean 0 4% 0 150kg sand 1 0% 3 0% 100 kg cement 40kg effective water The granite needs 1·2 kg water to cater for its absorption. The sand has 3 0 kg excess water in it, (3 0% –1 0% )...

Ngày tải lên: 08/08/2014, 10:23

... of natural aggregate concrete contains about 200 0 kg aggregate and lightweight aggregate about 1 200 kg, the exotherm from the same cement content will result in a higher concrete temperature ... 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 few hours. An...

Ngày tải lên: 08/08/2014, 10:23

... effect as the following typical readings in m1/ m 2 /s show: 10 min 30 min 1h Non-air-entrained 0 50 0· 30 0· 20 Air-entrained 0 40 0 05 0 01 Fig. 8.18. Defective kerbs with only partial replacement. Copyright ... factor of 10; i.e. 20dBA is about 2× 10 -4 N/m 2 , and so on. Equivalents in real terms are: Less than 10 An eerie silence 10 20 Birds in a garden 20 40 Conve...

Ngày tải lên: 08/08/2014, 10:23

... 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 0 20 0·16 6 0 09 0 07 0 05 One would need to look at the curing ... 10 blocks/day testing: Average of 10 blocks м 0. 9 × specified strength + 0. 62 × standard deviation Day no. Average of 10 Standard 0 9×7 0 Accept/ deviation...

Ngày tải lên: 08/08/2014, 10:23