EFFICIENCY OF TILES FOR DRAINAGE

Wanganui Chronicle, 17 November 1949, Page 7

EFFICIENCY OF TILES FOR DRAINAGE

Waimarino Farmers Want An Investigation At a meeting recently of the Waimarino branch of Federated Farmers the subject of-concrete drainage tiles was discussed. It was reported that several members had had the unfortunate experience of some tiles collapsing within two years. It was resolved that members of Federated Farmers be urged to refrain from installing any concrete tiles until the Provincial Executive has had an opportunity to have an investigation made as to the cause of the failure of these tiles. During the last two and a-half years the Massey Agricultural College Drainage Advisory Service has planned and installed tile drainage schemes in the Manawatu district involving' 385,000 tiles, reports a Massey College bulletin. The drainage research section at the college has experimented with a considerable number of field tiles .both earthenware and concrete, and has arrived at the following conclusions: (1) Tiles do not need to be porous, Sometimes attempts are made by New Zealand manufacturers to make a porous tile. This inevitably leads to a weak tile, with consequent likelihood of a large percentage of breakages and the possibility of deterioration in the case of concrete tiles. All this is to no purpose. Only strong tiles should be used. A good tile should stand a man’s weight and even a sharp stamp from the foot dealt to the tile laid lengthwise on the ground. (2) Evidence shows that, properly made, concrete tiles should be just as satisfactory as earthenware, in normal soils. However, poorly-made concrete tiles are likely to bring into disrepute a commodity which should be entirely satisfactory. It has been calculated that if a 10-chain length of tile were laid without joints, water would seep through the walls at the rate of 50 gallons an hour. It is known that from the outlet from a 10-chain length of Ift. tiles laid end to end, as in ordinary practice, flows may be as high as 2000 gallons an hour; thus the 50 gallons an hour which moves through the wall is negligible. In other words, in the field water actually reaches the tile drains 40 times faster than it could if there were no joints; or, put in still another way, it is evident that during high flows at least 97i per cent, of the water must enter through the joints. It is emphasised that only wellmade concrete tiles are likely to be as satisfactory as earthenware ones. By well-made is meant ones that are solid, compact, with as little porosity as possible, made from well-mixed cement and clean sand aggregate in correct proportions and allowed to cure and harden in a satisfactory manner. Emphasis is purposely placed on the need for concrete tiles to be solid, so as to prevent water from moving through their walls to an undue extent. In support of this contention the following may be quoted from the Dictionary of Applied Chemistry, by Thorpe:—“Set cement is the product of the action of water, but it is not indifferent to the further action of water. The products of the hydration of Portland cement and its cogeners are calcium hydroxide, which is soluble in water, and hydrated calcium silicates and aluminates which are decomposable by water. Therefore, when water has free access to set cement and can flow through the concrete or mortar of which it forms part, the cement is dissolved or destroyed .In practice, good concrete is made so nearly impermeable that, except under heavy pressures, no such flow occurs, but if the concrete is loose in texture and the flow of water correspondingly easy, destruction is only a matter of time.” If this statement is accepted as correct (and th e authority is well recognised), then the need for the tiles to be compact is obvious. It is possible that the tiles will become watertight if the walls become clogged with fine soil particles once in the ground, but it is felt that the more porous ones, at any rate, will remain porous and allow water to move through the walls and so induce decay. STOCK ROUTE. “Drovers are obliged to use the stock routes, but the difficulty is to enforce the law in this respect,” remarked Cr. A. M. Gordon at Tuesday’s Borough Council meeting. “Some use the stock route and some do not. Some drive stock through the main street,” he said. Tlie town clerk remarked that the Borough Council had not yet been successful in obtaining the services of a ranger. The meeting decided to advertise again for a ranger. SEAT AT TAXI STAND. “It looks as though we will have to erect another seat at the taxi stand as the present seat is often fully occupied and frequently people are standing,” remarked the Mayor, Mr. E. Loader, at Tuesday's Borough Council meeting. PERSONAL. Cr. F. Wallis, who is a patient at the Wanganui Hospital, was granted leave of absence at Tuesday’s meeting of the Taihape Borough Council. Cr. R. Emery, who has returned from a visit, overseas, was welcomed by the Mayor, Mr. E. Loader. Crs. Emery and N. Ashenden were congratulated on being appointed Justices of the Peace. CARAVANS AND THE LAW. When the question of caravans was under discussion at Tuesday’s council meeting it was pointed out by the town clerk that a caravan does not comply with the borough building bylaws. PAINTING BOROUGH LEASES. “A lot of painting is going on in Taihape and it looks as though the town is taking on a 'new look’ appearance,” remarked a member of the Taihape Borough Council at Tuesday’s monthly meeting. He moved that the lessees be advised that they must carry out the painting clauses of the lease. The town clerk explained that lessees were required by law to paint the buildings once every five years. The motion was carried. SALE OF MUNICIPAL RESERVES “The Borough Council, as a matter of policy, docs not favour the sale °t municipal reserves, declared the Mayor, Mr. E. Loader, at Tuesday’s council meeting.