Foreword When the wall of a house exposed to wind-driven rains allows dampness to penetrate to the interior, damage to the interior finish may be sufficient to require its replacement, a matter of considerable expense. Accordingly, there is great interest on the part of builder and owner in methods of constructing walls which wUl be resistant to the penetration of rain and in methods of "waterproofing" existing walls. An extensive investigation of the rain penetration of masonry construction is in progress at the request of and in cooperation with numerous Federal agencies. This paper gives the results obtained to date. Because of the many kinds and qualities of masonry materials and varieties of design, and the lack of a definite measure of the performance of a wall with respect to rain penetration, the study must be very comprehensive, and the results cannot be adequately summarized in a few words. Of the many factors, worlcmanship is the most important single one. However, attention to many other factors will assist greatly in securing good results. Existing walls may be effectively "waterproofed", but the cost and success of the treatment depend on many factors discussed in detail in this paper.
In a study of the spacing and width of tensile cracks, axially reinforced cylinders were tested by applying tensile forces to the r einforcement and observing the deformations of the concrete and the spacing and the ",idth of cracks. The test data and theoretical equations were in good agreement with res pect to the effects of the principal fact.ors controlling the spacing and the width of cracks. The spacing and t.he width of cracks were found to depend chiefly on the ratio of the diameter to the percentage of reinforcement and the nature of the deformations on the bars. It is concluded that the use of a type of reinforcement bar that will afford more reliable anchorage would result in better control of cracking of reinforced concrete and economy in the u se of r einforcement steel.
A description is given of a series of transverse tests of perlite concrete slabs reinforced with welded wire fabric. The purpose of the tests was to determine the properties of such slabs subjected to short-term and long-term loads. The effect of the reinforcement and the formboard normally used with roof slabs of perlite concrete was investigated.In the short-term tests the slabs were loaded to complete failure, whereas the specimens subjected to the longterm test were loaded with one-half of the estimated maximum load.The results indicate that the minimum concrete strength must be about 1+00 psi in order to develop the full strength of the 1|" by 4in. 12/12 ga welded wire fabric used in the 3-in. thick slabs tested on 36-in. span.The slabs tested under a sustained load for 200 days showed increases over the instantaneous deflections of about 280 and 350 percent for the 230 psi and the 665 psi concrete, respectively, although the instantaneous deflections of the two slabs were nearly equal.
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