U. S. Department of Commerce National Bureau of Standar ds Re search Paper RP1822 Volume 39, August 1947 Part of the Jo urnal of Rese ar ch of the National Bureau of Standards Some Recent Advances in Our Understanding of the Chemistry of Portland Cement By Robert H. Bogue A revi ew is given of some of the mor e importan t advances that have been made in our under- st andin g of portland cement during the war year s, or more specifically from 1942 to 1946. The fi eld covered is limited st rictly to chemical r esearch , and no attempt is made to include more than the ou tstanding cont ributions. The prese n tatio n is given of thi rteen inv estigational fields of st udy, cl assified in four major divisions. Th e mor e signi fi cant r esults are brou ght together in a s ummar y, 1. Notation The commonly used abbreviated symbols for the cement components are u se d interchangeably with the conventional no tat ion. Thus , C-CaO, S-Si02, A- AI 203, F-Fe20 e, H-H20, N-NazO, K-K20, M- M gO, H en ce, CzAHs -2 CaO.Al20 3.8HzO, etc. II. Introduction Since the clo se of the war , scientists from coun- tries throughout the world have been concerned with catching up on the progress made in other co untries during the years when communi cation was barred. In our laboratories, as in others, our friends seek to lea rn of the advances th at have come from chemical research on portland ce ment. Th e answer is not to be found in anyone place. To meet th at n ee d is one of the purposes of this paper. No attempt is made at a comprehensive pi ct ure. Only a few of the more significant st,udies can be pre sented, and these are confined to the strictly chemical fields. A more extf'nsive treat ment has recently been published elsf'where [I V Many im- porta n t advaD ces likewi se have b een made in the field s of physics, engineering, manufacture, archi- tectUl'e, etc, But what we see in our own fif'ld gives promise of a mo st interesting future. The treatment will be directed to a review of research on phase composition, c ryst al str u ct ure, reactions of hydration, and new technics. 1 Figures in brackets indi cate the literature references at the eud of this paper. Chemistry of Portland Cement III. Phase Composition of Clinker R ecent work upon the phase composition of portla nd ce ment clinker has given new informa- tion along several impor tant directions. 1. Combinations of Potash Although the alkali es in cement ara probably never pr esent in amounts exceeding 2 percent , and usually thell' total is und er 1 percent , yet their pre sen ce in even smaller quanti t les is known to produ ce effe cts which, under cert ain conditions, are the subject of concern. One observed effect [12] is that increasing amounts of alkali in the mix result in in creased difficulty, dUTing manufa ct ur e, in keeping clown the free C;tO. Another [36] is the undue expansion of high-alk ali ce ments with certain types of sili ce ous aggregates. In order to under sta nd the action of the all' alies in cement, it is essential to know the forms in which these elements exist in clinker, and the phase relations by which they may be controlled. In a st udy of the system K20- CaO- Ab0 3' Brownmiller r 5] found that only one compound of pot ash was formed which co uld exist in the gen eral composition-range of portland cemen t. Thl s was the binary compo und KA . 'r aylor [ 39] showed la ter th at t hi s compound was stable in the presen ce of the iron compo und of cement, C4AF . The l atter compound was known to form a solid solution with C2F [1 3], aJid t hi s solid solution was found to act as a pse ndobinary system with the 177 l
Some Recent Advances in Our Understanding of the Chemistry of Portland Cement
Apr 25, 2023
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