The Structural Engineer > Archive > Volume 7 (1929) > Issues > Issue 1 > Recent Improvements in the Strength and Constructive Value of Portland Cement - Discussion on Mr. Bu
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Recent Improvements in the Strength and Constructive Value of Portland Cement - Discussion on Mr. Butler's Paper

Mr. R. H. HARRY STANGER (Vice-president), who proposed a vote of thanks to Mr. Butler, said he hoped the members of the Institution would not assume from the paper that the British Engineering Standards Association had sat still since the last revision of the specification. A panel consisting of representatives of various testing houses had been working on this matter-he would not say continuously- and the first meeting of that panel was held soon after the revised specification was published. Dealing with the efforts of the B.E.S.A. Committee to introduce more scientific methods into cement testing, he said they were trying to deal with the personal equation in certain directions. They had not quite reached agreement, but tests had been and were being carried out by the various laboratories which would ultimately represent a substantial advance. Mr. Stanger was in absolute agreement with Mr. Butler’s suggestion that the 28 day test should be dispensed with. It was very rarely that cements were tested for 28 days because it meant delay and the locking up of too much capital. As a rule a 3 day test was substituted. He very frequently accepted cements after they had been subjected to 3 day and 7 day tests. To meet the needs of engineers who had been accustomed to carrying out a 28 day test, to ascertain increase in strength, he suggested that in addition to the 3 day and 7 day test, a test of about 14 days’ duration might be applied. Rapid hardening cements were subjected to 1 day, 3 day and 7 day tests as a rule. He thought that only rapid hardening cement would be used in a few years’ time. There were several specifications in use for rapid hardening Portland cements. A specification which he worked to regularly provided for a strength of 300 lbs. per square inch after 1 day and 550 lbs. per square inch after 7 days. Mr. Butler had recommended a strength of 600 lbs. per square inch after 7 days, and no doubt that could be obtained, but the testing houses must exercise care in the way in which they cured the briquettes. The independent testing houses had not been idle, but had met in committee and had tried to arrive at some arrangement amongst themselves as to how this cement should be tested. They were not yet quite in accord, perhaps because they had not gained sufficient experience when they had met to discuss the matter, but they were getting towards agreement, and they would get there quicker, he believed, after the next revision of the B.E.S.A. specification, which would give a lead as to the directions in which more scientific control must be applied in their methods. With regard to Ciment Fondu, Mr. W. Muirhead, the Chairman of the Concrete Sectional Committee of the Institution, had asked him to say that the Committee was preparing a speclfication for an aluminous cement, and it was hoped that that specification would be issued by the end of the present session. Mr. Stanger expressed a little disappointment that Mr. Butler had not sa