I have inspected the place in company with Plain Clothes Constable Kelly, from whom I received two samples, one of cement, the other part of the broken concrete cover last Saturday morning.
I have made briquettes out of part of the cement supplied, and find that the cement used (Hammonia brand) is of good quality, having stood a tensile strain of 270 lbs to the square inch after three days. I examined the other materials used in the mixing of the concrete. The screenings are of a good quality, the toppings are also fairly clean, but contain a good deal of fine material which would retard the setting of the cement.
The sand may be called a fair sample, although it contained some vegetable matter, some fine sand, and some dark patches of fine sand more or less impregnated with iron.
I have examined the specifications and drawings, a copy of which was handed to me by Plains Clothes Constable Kelly, and think the dimension and construction of the drain cover is suitable for all requirements; in fact, with richer material, I would have been prepared to construct a cover only 4ins. thick.
In inspecting the drain, I ascertained that previous to the removal of the centering, and while the concrete was still green, filling material to a depth of about 15 ins. was thrown over the cover: this operation in itself would tend to disintegrate the composition, which would be partly wet.
Another strong factor against the proper setting of the cement was the cold prevailing during the clear nights which preceded the accident. While three days may be considered a fair lapse of time for removing centering in hot weather it would take double that time in cold frosty weather.
I was told by the contractor that the lagging was removed after 62 hours, the cover having been partly leaded to the extent of 15ins. the day before the centering was removed.
The weight of the concrete would be about 75lbs. per square feet, that of the earth about 110lbs, or a total of 185lbs. per square foot, or nearly 4cwt. per foot run of the drain on each side of each support: this weight the outside supports could not resist, and the concrete was sheared or cut above the support.
Taking all factors into consideration, I think that the 62 hours in cold weather was insufficient time for allowing the cement to set properly: it should at least have been four days.
The leading of the cover on the second day after construction retarded the and actually disturbed the crust of concrete already set, but the great weight of the earth placed on the cover was the principal cause of the collapse. No earth should have been placed over the concrete for at least 7 days in cold weather.
The fact which confirms me in these conclusions is that the cover near the East end which, presumably, was the last made and the first stripped is still standing apart from the portion which has been forcibly removed for experimental purposes: this part had stood because no extra burden of filling material has been places on it.
In further evidence dated May 16, 1912, Carlo followed up some points from his original deposition.
I supplement the strain on the cement – that yesterday I broke two brickettes made of the same making which averaged 450 lbs to the square inch which proved the cement was setting well and was of good quality. When the mass of concrete was handed to me last Saturday it could be broken into small pieces easily and now it has set hard showing that the process of waiting has made it hard. I produce a copy of these specifications.
To Insp Crowe. The lagging is removed when you think the concrete is strong enough to bear its own weight.
To the Coroner Undoubtedly the weather had something to do with it. Three days is the usual time allowed, as there was a clear line between the other cement and the one that broke showed that there was not time for the cement to join. A cement that sets quickly is not a good cement –as the cement that sets slowly is the best. I passed the plans. There was nothing on the flat surface if all the others conditions had been carried out.
To Mr Moir I made the plan produced. I know the contract made out that the cement should be of the approved Portland cement. The Hammonis cement is good. I do not think that one barrel ought to be better than another but one barrel may be injured. The cement was reinforced with wires and the steel bars were to be set at an angle of 45° according to the specification. If this had been left to set for 4 to 5 days it would have been standing now. When I got the cement last Saturday it could have been crumbled with the fingers.
To Mr Rundle. I visited the scene of the accident. I saw indications that the mortar was not set. I examined the concrete and found that it was crumbly at the time. I think if the men had looked at the concrete they would have seen that it was not set. The fact that the concrete was crumbly was an indication that it was not ready to have the loading put in it and if a person had a proper knowledge of concrete [they] ought to have known that.
To Mr Hunt. I did not find any provision in the specifications as the drawing of the laggings. The piece of concrete produced had been in my office and in my room. It had not been exposed to the air outside. I did not notice that the tar was burst off the longitudinal bars. In my opinion the reinforcement was good enough for the purposes. I did not see any trace of tar on the cross bars, they were rusty in parts. If the bars were fastened at the sides that would be an improvement.
To the Coroner. I am satisfied that if it had been allowed time, it would have been all right. (3)
Who was George Hunt?
George's body was identified by his father Thomas and this is his sad evidence -
Thomas Hunt, Watchman, Mary Street Fairfield
I saw the body of the deceased at the morgue and I identified it as that of my son George Hunt. He was aged 31 years and was married. He lived with me. He was employed at the Albert Park Drainage by Messrs Watt and Hancock. I last saw him alive about 7am last Thursday morning. I met him at the railway station and said “How are you”. He said “Never better in my life.”
To Mr Moir: He had only one full arm. He had a hook on the right arm.
To the Coroner: That did not affect him in his work at all.
Thomas Hunt had married Margaret Bradley on May 19, 1876 at the Registrar of Marriages in Gore Street, Fitzroy. Thomas was a 25-year old cab driver, born in Devonshire England, the son of Joseph and Mary Ann (nee Bradley) Hunt. Margaret was a 28-year old housekeeper, born in Hamburg, Germany; the daughter of John and Margaret (nee Walker) Bradley. (7) It is possible that the two were cousins.










