11 th INTERNA TIONAL BRICKlBLOCK MASONR Y. CONfERENCE TONGJI UNIVERSITY, SHANGHAI, CHINA, 14 - 16 OCTOBER 1997

SOME PROBLEMS APPEARING IN THE PRACTICES OF MASONRY AND THE CORRESPONDING MEASURES

Liu Y ongxin I

1.Abstract

The masonry has been used in project construction widely. Some factors influencing quality of the buildings in practice are analyzed in detail in this paper. The harm, the consequence, reason of the problems and solution to the problems are proposed. The methods proposed in the paper are simple, applicable and popular. Economic and social effect is obtained in practice.

2.Introduction

With the development of real estate, constantly various new building materiaIs get into use. There are a lot of problems influencing the function and appearance of buildings. The problems are classified as follows: - water leakage of exterior masonry wall, - water leakage at comer of masonry wall in kitchen, toilet, piping shaft, - The damage of space in a masonry wall for pipe or construction tolerance, - Fixing of some materiaIs and components adhere to masonry wall, - The others.

In the past, the solution to the problems was that the problems were deal with after the even. So the normal use of the buildings was influenced, the construction cost increased. The simply, effectively prior measures were proposed in this paper.

Keyword: Masonry; Problem; Measure;

1 M"!ster, Engineer, General Manager, Zhujiang Construction Project Management and

Consuiting Company, 1097 Pudong Avenue, Shanghai, P.R.China.

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3.Problems and measures

3.1 Water leakage of exterior masoory wall The maio causes: The problem is regular in the typhonic region. Water damaged interior ornamentation, the serviceability was impaired. The amount of spalling of interior and exterior wall occured. The exterior claddig system was proposed. The main causes of the problems is that the joints were not filled fully and that some pipes, conduits or construction tolerances were not sealed(Fig.l a,b,c). The other important factors is rain wetting, water leakage, moisture leveis in brick, poor quality exterior coating. The measures: The degree of fill in joint should be more than 80%. The openings should be sealed. It is most important to provide good quality externai coating system to keep out moisture. The type of mortar used in exterior wall should be cement mortar instead of cement-lime mortar. The wall should be wetted before rendering. The wall is rendered with mixture ratio of l :2 to l :3 by two steps(Fig.l d). As the strength of the mortar reached 70% design value, the quality of .rendering such as voids, shrinkage cracks should be checked. If any, the externaI ornamentation should be conducted after dealing.

(a) (b)

ofmortor

(c) (d) Fig.l

3.2. Water leakage at corner of masonry wall in kitcheo, toilet, piping shaft The problem is often presented by residents, and nat solved entirely. There are catchment area at the comer after using. Even if the pour test is qualified, the moisture damages fIoor ornamentation. Under the circumstance, the maintenance cost is considerably expensive. The main causes: Even if the pour test is qualified in accordance with Chinese Standard, if the other

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measures not are used, the water-resisting capacity of masonry and finishing materiaIs is poor. The measures: First, the 120mm to 150mm-thick-plain concrete(grade C20)was cast in the bottom of the masonry as water-proofwall, or the side ofwall was rendered with 120 - 150mm

of water-proof mortar. The rendering should be smooth, and c10sely connected with the floor(Fig.2). Fill the room with 100mm-high-water, and check if there is any leaking after 24 hours.

Fig.2

3.3 The openings in a masonry wall for pipe, conduit or construction tolerance Because the pipes and conduit for electric installation were hidden, the openings were formed after construction. The effective area of section of masonry wall was reduced due to improper construction. Even the masonry waIl failed(Fig.3 a). The main causes: The improper construction. The measures: The openings in masonry wall were formed until the more than 70% strength of masonry was reached(Fig.3b). The diarneter ofthe opening should be less than 60mm, .. otherwise the openings should be hidden with the help of small pseudo-bearn, column and suspended ceiling. The method of construction should be correct.

pick groove ~

_-" ..... -..:II ...... ground(floor)

Fig.3

d ++

_.1...',-, __ ground(floor)

3.4 Fixing of some materiais and components adhere to masonry wall If the fixing of the materiaIs and components, such as doors, windows, frarnes and trace of elevator, was processed improperly, the cracks between the components and masonry would occur, the elevator did not work, the omarnent dropped out, etc.

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The main causes The weak connection of masonry with the materiais and components. The measures Fix the doors and windows frame with iron nails. The embedded erosion-proof wood brick should be used; If the dimension of finishing materiais and omaments is less than 800 x 800mm, the materiais and omaments are fixed by drilling holes after

masonry are rendered with 1:2.5 cement mortar and the 70% strength of mortar is reached. If the dimension of that is more than 800 x 800mm, The concrete base is

cast at the position of connection(FigA). lt is the same for the elevator.

FigA

3.5 the others With different extension and contraction deformation between masonry parapet wall and roofing structure, the cracks occur at the connection of masonry parapet wall and roofing structure after one cold-hot cyc1e.

4. Conc1usions

The measures proposed in this paper to solve some common problems appearing in practices of masonry projects have proved helpful through practical use, but defects and limitations still exist. I wish that this paper may act as a brick which will call for much more previous arguments, so that masonry may have better opportunity to develop. I will be most grateful if experts would like to present their valuable opinion.

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