BUILDING COLLAPSE

Evening Post, Volume CX, Issue 1, 1 July 1925, Page 9

BUILDING COLLAPSE

MELBOURNE DISASTER

CORONIAL INQUIRY OPENED

GRAVE DEFECTS ALLEGED.

The inquiry itt.o the , collapse of the British Australasian Tobacco Company's new building in Swanston street, Melbourne, which was in course of construction, and which caused the deaths of four men on 24th April, another man dying subsequently, was opened in the Melbourne Coroner's Court on 18th June. | In opening the case for the Crown, Mr. J.( R. Elsbury eaid (according to tha. Melbourne "Argus"): "It is desirable for me to outline ths evidence indicating what defects are alleged to exist" in the building. The metal screenings used in the concrete wero specified to be half-inch; it appears that right along three-quarter inch motal was used. During the erection of tho building loads of metal vrere condemned, but no witness can say whether that metal was ever taken away. It was specified that the sand used in the concrete was to be clean, sharp; and_ free from loam, salt, or other impurities. Evidence ■will be given by a practical expert of the Country Roads Board that the sand was not suitable building sand, and that if it had been tendered to him be would have rejected ib. The sand did contain/impurities, loam, and various vegetable and organic matters, besides a proportion of oxide of iron. Concrete has been made ,■ from the sand cement and metal found on the building. The proportions specified were oiie part of cement, two of sand, and four of metal, [for the greater part of the bailding, with a reduction to three parts of metal for the columns. The concrete made by the University from the materials found on the building showed, after seven days, a compressive strength of 26631b to the square inch, which was considered good. The sand and metal as it crrived on the job was placed in separate bins and let through trap doors into a hopper. Evi-, dence will be called that it is apparent that, in filling the hopper, the levers had been crossed and the operation of letting the sand and metal at once into the hopper has been the practice on this 30 ' GAUGING QUANTITIES "When the sand and metal were transferred.to the mixer below, wator was let in, and ■ the quantity w,as gauged by a man counting 20. Witnesses will say that by this method of gauging, 12 per cent, of water was allowed in every batch of concrete made. Experts hold that the existence of this . excess of water is responsible for a great part of the weakness of the concrete throughout the building. The normal amount of water allowed was 5.75 per cent., and the existence of 12 per cent, of; water reduced the ; strength of the concrete by nearly 12 per cent., The steel forms or moulds used for the concrete were considered satisfactory except in some places where the join between the plates was large enough to allow the escape of cement. 1n"... some cases the tongs used for the wooden moulding boxes for the beams were not sufficiently rigid. In many, cases the steel reinforcements were out of alignment; in columns; so that the steel was not bearing the proper weight. Insufficient ■ steel rods were were placed in some parts, and in others there were too many. The ligatures binding the steel rods were placed around outside the rods and tied with wire instead of being looped around each rod. The method of placing the conorete in the forms is considered unsatisfactory. The concrete was deposited at various places along the wall and allowed to run leveL With very wot concrete that meant that the cement and water, and sometimes the sand, flowed into the depressions, leaving the metal bare, thus creating sections' of weakness. The roof beams were poursd from five to seven days before (h» roof slabs, leaving a weakness where tho beams met slabs. It is considered thafc little or no ramming of the concrete, when it was in the forms, was done. There will be evidence that on one occasion, at least, during the erection of the wall facing> Stewart street on the floor that collapsed, the hose was turned on the forms, for at least twenty minutes at a time to wash the concrete down into position. ■ . WHITEWASHERS' EVIDENCE The whitewashers,' whose duty it was to strip the concrete, say that" on this job, but on no other, they received an extra l£d a square yard for bagging, which means filling up any apparent cracks in the concrete. When they went on the job to whitewash, the material was often too wet. At other times the mere action of their brushes on/the beams was sufficient to bring away large; pieces, extending from 4ft long to 3£in deep. The concrete that came away would expose the steel reinforcements in the beams; On one occasion the attention of Inghan:., the foreman, was directed to this, and he consulted with the. contractor, Cooper. The plasterers wore 'then brought in to plaster up the holes made in the beams. The plasterers found that the cement would not stick in the holes, but would only bring out further quantities of material, when they placed their hands in the holes dry material, sand, and sometimes a little metal, would pour on the floor. The pieces that fell from the beams crumbled when they struck the floor. One man in charge of the scaffolding will say that a workman said that it was the worst concrete'he had ever seen in his life. Mr. Lowe: "It is unfair to mention such hearsay evidence. .It will create the greatest prejudice." Mr. Elsbury : "The ceilings of the building at several times could not bo lime-washed owing to the damp, and the ceiling of the fourth floor _was quite 'green' when it was stripped. The wall lime-washers will tay ■ that they could see daylight through patches of the screenings, and thobe patches were still apparent in the building. These patches would pour away when touched. At the instruction of Ingham they were plastered up. Holes were knocked in the walls for scaffolding, and instructions were given to knock the holes from the outside and leave an inch, so that the inner wall would not be interfered with. The scaffolders will saj). that they could not make holes without knocking right through; the walls were very soft, and the holes were easy to put in. The duty of the lime-washers was to remove the tie irons from the walls; frequently the irons would pull right through the walls, and at other times would twist around and make large'holes instead of snapping off. CONCRETE ANALYSED Analyses of the concrete in the building were made by the' Railways Department, the State Rivers and Water Sup--ply Commission, the Health Department, j and the Town Hall. .The Railways, tests showed that, the cement was 1 part to 10.5 parts, and 1 part to 15.7 parts of sand and metal. The State Rivers andWater Supply Commission tests showed that the cement was 1 part toilO.ll,'and 1 part to 12.69 parts of sand and metal. The Town Hall < analysis showed that the cement waß in the proportion of. ofj

1 to 9.08 and 1 to 10.94 parts. Physical teats of tho concrete were made at the University. The compressive test stated for concrete nine weeks old is that it should stand a pressure of from '22001b to 24001b to' the square inch. The University test showed that the compressivo strength of the concrete in the building was osolb, 6521b, and 8241b to tho square inefe. One sample was too friable to allow a cube to be made for testing purposes. The Town Hall test showed that the strength of the concrete was 3671b, 7411b, 5631b, and 6471b. On the day of the collapse two men were bagging and lime-washing a column that afterwards collapsed on the fourth floor. After lime -wash ing one of the men noticed a crack. He showed it to the foreman, filled<> the crack up, and limewashed it again. The foreman obtained the contractor, and by the time he arrived the crack had opened out again. There was no wall beam under the fourth floor, as designed, at the light well, where the fourth floor collapsed. The architect said that he supplied particulars of this beam to the contractors. The iJjjht-well wall is 4iri thick up to the fourth, floor, and 6in thick after; it should be 6in all the way. Engineering experts consider that this structural weakness, together with the weakness of the\ concrete, was responsible for tho collapse.