BS 6319-12-1992 Testing of resin and polymer cement compositions for use in construction - Methods for measurement of unrestrained linear shrinkage and coefficient of thermal expan.pdf

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1、BRITISH STANDARD BS 6319-12: 1992 Testing of resin and polymer/cement compositions for use in construction Part 12: Methods for measurement of unrestrained linear shrinkage and coefficient of thermal expansionBS6319-12:1992 This British Standard, having been prepared under the directionof the Techni

2、cal Committee B/517, was published under the authority of the Standards Board and comes into effect on 15 October 1992 BSI 08-1999 The following BSI references relate to the work on this standard: Committee reference B/517/8 Draft for comment 90/17981 DC ISBN 0 580 21123 1 Committees responsible for

3、 this British Standard The preparation of this British Standard was entrusted by the Technical Committee B/517, Concrete, to Subcommittee B/517/8, Protection and repair of concrete structures, upon which the following bodies were represented: British Adhesives and Sealants Association British Cement

4、 Association British Railways Board Building Employers Confederation Cement Admixtures Association Concrete Repair Association Concrete Society County Surveyors Society Department of the Environment (Building Research Establishment) Department of Transport Department of Transport (Transport Research

5、 Laboratory) Federation of Civil Engineering Contractors FeRFA Institution of Highways and Transportation Institution of Structural Engineers Plastics and Rubber Institute Sprayed Concrete Association Amendments issued since publication Amd. No. Date CommentsBS6319-12:1992 BSI 08-1999 i Contents Pag

6、e Committees responsible Inside front cover Foreword ii 1 Scope 1 2 References 1 3 Definitions 1 4 Principles 1 5 Apparatus 1 6 Test specimens 3 7 Measurement of shrinkage 3 8 Calculation of shrinkage 3 9 Test report for shrinkage 4 10 Measurement of the coefficient of thermal expansion 4 11 Calcula

7、tion of the coefficient of thermal expansion 4 12 Test report for the coefficient of thermal expansion 5 Figure 1 General arrangement of steel mould and transducers formeasuringdisplacements and typical cross sections 2 List of references Inside back coverBS6319-12:1992 ii BSI 08-1999 Foreword This

8、Part of BS6319 has been prepared under the direction of Technical CommitteeB/517, Concrete. This Part describes a method for measuring the unrestrained dimensional changes of a thin layer of freshly cast polymer mortar or polymer/cement mortar over the first24h after placing. The dimensional changes

9、 depend on the formulation of the mortar and can be due to any combination of water loss, heat loss subsequent to exothermic reaction and molecular rearrangement of the polymer. The measured shrinkage or expansion strains can indicate how the material would behave when used for patch repairs or surf

10、acing to hardened concrete. This Part of BS6319 also describes how the mortar specimen after hardening can be used to measure its thermal expansion. If this measurement is made at early ages, raising the temperature may affect the polymer giving rise to post-cure shrinkage. The effects of temperatur

11、e on these materials are described in Appendix A of BS6319-10:1987. The apparatus used for these tests on polymer mortars may also be used to measure the unrestrained shrinkage and coefficient of thermal expansion of cement mortars when modified by fitting suitable disposable lines to the sliding en

12、ds. This Part of BS6319 should be read in conjunction with BS6319-1 which provides general information and describes a method for preparing test specimens. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their

13、correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. In particular, attention is drawn to the Health and Safety at Work etc. Act 1974 1. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1

14、to 6, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.BS6319-12:1992 BSI 08-1999 1 1 Scope This Part of BS6319 describes the methods for the me

15、asurement of linear shrinkage from initial gel and of the coefficient of thermal expansion of hardened polymer and polymer/cement mortars in the form of unrestrained thin strips (less than20mm in thickness). The methods are suitable for materials that do not contain aggregates larger than3mm used in

16、 thin layers for patch repairs and surfacing applications. 2 References 2.1 Normative reference This Part of BS6319 incorporates, by reference, provisions from a specific edition of another publication. This normative reference is cited at the appropriate points in the text and the publication is gi

17、ven on the inside back cover. A subsequent amendment to, or revision of, this publication applies to this Part of BS6319 only when incorporated in it by updating or revision. 2.2 Informative reference This Part, of BS6319 refers to other publications that provide information or guidance. Editions of

18、 these publications current at the time of issue of this standard are listed on the inside back cover, but reference should be made to the latest edition. 3 Definitions For the purposes of this Part of BS6319 the definitions given in BS6319-1:1983 apply. 4 Principles 4.1 Shrinkage test A freshly mix

19、ed sample of polymer mortar or polymer/cement mortar is placed in a shallow steel trough shaped mould with sliding ends, the inside of which has been treated to prevent adhesion by the mortar. The trough has sliding ends which bond to the mortar and are free to move as the mortar expands or contract

20、s. Linear displacement transducers attached to the ends enable the shrinkage to be measured. A temperature sensor attached to the mould enables its temperature and so that of the mortar to be measured. 4.2 Coefficient of thermal expansion test Samples of hardened polymer mortar or polymer/cement mor

21、tar, prepared as for the shrinkage test, are subjected to a number of temperature cycles while movements of the ends and changes in temperature of the mortar are monitored. Correction is made for changes in the length of the mould. 5 Apparatus 5.1 Mould, comprising a400mm long pressed steel trough s

22、upported on an insulating base and fitted with sliding ends, as shown inFigure 1. The tolerances on the dimensions of the trough shall conform to clause3 of BS6319-1:1983. The ends shall fit the cross section of the trough with a clearance of0.1mm. The inside of the trough is coated with polytetrafl

23、uoroethylene (PTFE). Disposable linings which have surfaces prepared to enable the mortar samples to adhere to them are attached to the inner faces of the sliding ends. NOTEA bond-fin or mechanical linkage may be needed for some mortars. The probes of linear displacement transducers (5.2) are attach

24、ed to the outer faces of the sliding ends. A thermocouple (5.4) is attached at the centre of the underside of the mould 5.2 Linear displacement transducers, capable of measuring to an accuracy of0.01mm over a range of at least5mm and producing an output that can be recorded automatically. NOTEThese

25、should be linear variable differential transformers that remain stable during fluctuations in temperature and humidity. The force required to move the probe should not exceed8g. 5.3 Environmental chamber, large enough to contain the mould (5.1) in a horizontal position. Air shall be able to circulat

26、e freely around the mould. The chamber shall be capable of maintaining a temperature to within 1 C over the range25 C to+50 C. A thermocouple (5.4) is used to record the air temperature inside the chamber. NOTEThe relative humidity of the room in which the environmental chamber is used should be not

27、 less than50% r.h. 5.4 Thermocouples, connected into a signal conditioning unit, with automatic cold junction compensation, that gives a linear output proportional to temperature that can be monitored automatically.BS6319-12:1992 2 BSI 08-1999 Figure 1 General arrangement of steel mould and transduc

28、ers for measuring displacementsand typical cross sectionsBS6319-12:1992 BSI 08-1999 3 6 Test specimens 6.1 General Any pre-conditioning of the constituents used in preparation of the specimens shall be declared in the test report. Each specimen shall be representative of the polymer or polymer/cemen

29、t mortar being assessed. Where more than one specimen is to be tested, the specimens shall be taken from the same batch of mortar made from the same batch of constituent materials. 6.2 Preparation of specimens Carry out the preparation of specimens, including sampling, conditioning, proportioning an

30、d mixing of constituents, the conditioning and filling of moulds and curing as described in BS6319-1:1983 unless the specification for a particular material requires otherwise. Any variations shall be declared in the test reports. 7 Measurement of shrinkage 7.1 Specimens Test a minimum of three spec

31、imens at each prescribed test temperature. NOTEThe specimens may all be tested sequentially or at the same time depending on the availability of apparatus. 7.2 Conditioning First spray the mould (5.1) using a silicone aerosol. Then condition the mould and mortar constituents in the chamber (5.3) at

32、the prescribed temperature 2 C. Monitor the temperature of the chamber using a thermocouple (5.4). Conditioning is completed when the thermocouple in the chamber and the thermocouple attached to the mould correspond within1 C. Set the transducers (5.2) at mid-stroke and clamp the sliding ends in thi

33、s position during casting. 7.3 Casting Immediately prior to casting, place a small fillet of silicone wax at the junction of the sliding ends and the trough to prevent escape of polymer. Mix the mortar, place and compact it to form a layer not more than20mm deep in the mould set up on a level surfac

34、e in the door opening of the chamber(5.3). Level the top surface of the mortar. Minimize the period for which the chamber door is open. As soon as casting has been completed, free the ends and place the mould in the chamber. Take the initial reading of the transducers and thermocouples immediately t

35、he chamber door has been closed. 7.4 Duration of test Record the readings for sliding end displacement and mould temperature at5min intervals until1h after gelling of the mortar has taken place (gelling can normally be detected by monitoring inward movements of the ends). Record further readings at1

36、5min intervals during the next23h and at hourly intervals during the subsequent24h. On completion of the test, measure and record the length of the hardened specimen, L s , at ambient temperature and the length of the mould between the centre lines of the transducer bases, L m , to the nearest0.1min

37、. NOTEOwing to the exothermic reaction, the temperature will rise to a maximum and the trough will expand, thus exaggerating the degree of shrinkage at this stage. Corrections can be made for this expansion but are not usually required as the trough returns to ambient temperature by the time maximum

38、 shrinkage has occurred. 8 Calculation of shrinkage Calculate the change in length of each specimen,%L s , from the equation where where Then calculate the shrinkage strain, s m , as a percentage, from the equation where %L s= 1+ 2 3 (1) 1and 2 are the transducer readings (in mm) (positive towards t

39、he centre of the specimen); 3 is the thermal expansion of the mould given by 3= L m %T s (2) L m is the length of the mould (in mm); %T is the change in temperature of the mould from ambient to the prescribed temperature (in K) (values less than5K can be ignored); s is the coefficient of thermal exp

40、ansion of steel (11 10 6m/mK). (3) L s is the effective length of the hardened mortar specimen at ambient temperature (in mm). s m L s L s -100 =BS6319-12:1992 4 BSI 08-1999 9 Test report for shrinkage The following information shall be included in the test report: a) identification of all the const

41、ituents of the mortar including manufacturers name, code numbers if applicable, type description and date of production; b) temperature and duration of pre-conditioning of the constituents and any variations from the procedure for specimen preparation described in BS6319-1:1983; c) date and location

42、 of mortar specimen preparation and test; d) the prescribed temperature for the test (environmental chamber temperature); e) the apparatus reference number and details of the monitoring system(s) used; f) the effective lengths of the specimens to the nearest millimetre; g) tabulation of the results

43、of shrinkage against time, specifying whether or not temperature correction has been applied, and natural log scale graphs of these results; h) the calculated maximum value of shrinkage strain and the time to reach this value from completion of mixing the constituents for each specimen and their mea

44、n values; i) the time intervals from completion of mixing the constituents to identification of initial gel. 10 Measurement of the coefficient of thermal expansion 10.1 Specimens Prepare and cast specimens for measuring the coefficient of thermal expansion as described in clause7. The casting temper

45、ature shall be15 C unless a different temperature is stated in the specification for a particular material. Record the casting, curing and storage conditions and age at test. Ensure that the specimen is bonded to the linings of the sliding ends and that these linings are firmly attached to the ends.

46、 NOTESpecimens made for shrinkage measurements can be used for determining the coefficient of thermal expansion without removing them from the mould. 10.2 Procedure Place the mould containing the specimen into the chamber (5.3) locating the chamber thermocouple immediately adjacent to the specimen.

47、Set the chamber to the initial temperature T 1which shall be not higher than the casting temperature for the specimen under test. Condition the mould and specimen at T 1until the mould and chamber temperatures correspond within1 C and are stable for at least1h. Record the mean of the two thermocoupl

48、e readings as T 1 . Then subject; the specimen to the following cycles. a) Stage 1. Record the chamber control setting for the initial temperature accurately and also the transducer settings. Adjust the chamber control to produce a reduction in temperature of between20 C and25 C. Maintain this setti

49、ng until both thermocouples indicate the same temperature within1 C for at least1h and record their mean as T 2 . Then return the chamber control to the initial temperature setting and repeat this temperature cycle twice. b) Stage 2. Set the chamber control to the initial temperature. When stability has been reached, adjust the chamber control to give a rise in temperature of between20 C and25 C. Maintain this setting until both thermocouples indicate the same temperature within1 C for at least1h and record their mea