Welcome to ConcreteCutting1.Com

“We Specialize in Cutting Doorways and Windows in Concrete Foundations”

Are You in Worcester Massachusetts? Do You Need Concrete Cutting?

We Are Your Local Concrete Cutting Company

Call 508-283-3135

We Service all surrounding Cities & Towns.

Concrete Cutting Worcester MA  

Concrete Cutter Worcester MA     

Concrete Coring Worcester MA   

Core Drilling Worcester MA                      

Concrete Sawing Worcester MA  

Concrete Sawing Worcester Mass

Concrete Cutting Worcester Mass           

Concrete Cutter Worcester Mass 

Core Driller Worcester MA

Core Drilling Worcester Mass

We Perform Concrete Cutting, Sawing, Core Drilling and Coring in Worcester.

For a guide as to the water-cement ratio permissible, we must look to past experience, together with such additional information as brought out by tests. Later, suitable limits for different classes of work will be indicated. In the first chapter there was presented a resume of the basic principles of concrete mixtures in which it was shown how the properties of concrete (plastic concrete) must in the main be dependent on the properties of the hardened cement paste. The properties of the hardened paste, in turn, it was pointed out, were dependent on these three factors:

1. Characteristics of the concrete.

2. The proportion of water to cement—the water- cement ratio.

3. Extent to which chemical reactions of hardening are complete.

In the second chapter these last two points were further amplified. In this chapter data are given showing the soundness of these conclusions as regards compressive strength. Emphasis was placed in the first chapter on the need for a plastic consistency, as the dry, stiff mixes are incapable of proper placement by the usual methods and the thin, watery mixes result in segregation. This precaution is of special importance in the matter of water tightness, but it is also important if the laws of strength developed herein are to apply. All the strength data submitted are limited to those mixtures which are capable of being properly placed and which remain homogeneous when once in the concrete forms. Since Abrams first pointed out the general relationship between quantity of mixing water and compressive strength of concrete there have been many investigations further substantiating his broad conclusions. These further studies have also served to fix more definitely the limits within which the Abrams' law of strength may be expected to apply and to establish the reasons for such limitations. Figure 2 to 10 show the water-cement ratio strength relation for a wide variety of materials and conditions.

These have been specially selected to show the effect of the principal factors which have been found to influence this relationship. A number of tests have been reported from time to time in which variations in the position of the water- cement ratio strength curves for different materials or conditions have been somewhat greater than indicated in the accompanying figures. In many cases, however, these discrepancies have been due to neglect of certain important factors. One of these is the direct loss of water from the mix through absorption, evaporation or leakage from the concrete forms. Another is the change in character of the mix, due to segregation in the mold. Failure to provide for these properly must naturally affect the results. Still another factor is the use of mixes that are too stiff or harsh to place properly. The importance of this has already been pointed out. For ordinary size ranges, size of has no effect on the strength of concrete of a given water-cement ratio. This is shown by Figs. 2, 3 and 4. Fig.2 shows the results of the tests of concrete which the- maximum size of the concrete aggregate varied from to3Jn.Jn.thisthesamecurve between strength and water quantity fits the data for all sizes of concrete aggregate. Other tests bearing on this factor have been complicated by the effect of size of -specimen with respect to size of concrete aggregate particles. The tests in the research from the Concrete with Portland cement Association have shown that when the specimen diameter is less than about four times the maximum particle size there is a falling off in strength. To eliminate this variable the tests in Fig 2 were made R5iEi specimens up to 12 inches in diameter. This large size necessitated making the tests at 14 days, because of the limited capacity of the testing machine.  In Fig. 2, attention should be directed to the points representing the mortar specimens (sand graded from 0.-No. 4).

In these specimens considerable water segregated from the mass and collected at the top. This water was carefully drained off and measured and the true water-cement ratio for the remaining water was calculated. It is this corrected water ratio that is plotted. The perfect continuity in the curve for the three different sizes of concrete aggregate shows the basic character of the water-cement ratio strength relation, when the water ratio is based on the actual water in the concrete as it is finally consolidated in the concrete forms. Figure 3 shows a comparison of concrete aggregates of 1 and 2 in. maximum size. The points for the two sizes fall closely along the same curve, indicating that size of concrete aggregate does not influence the position of the water-cement ratio strength curve. This is true for both 7- and 28- day tests. In Fig. 3 can be seen the effect of non- workability on the strength. The dry mixes at the extreme left fall somewhat below the curve. These tests were for a constant mix, so that changes in water content changed the consistency. Figure 4 shows the water cement ratio strength curve for neat cement pastes. Two by four-inch cylinder molds sealed to prevent loss of water; neat cement pastes, moist cured are similar in character and position to those for corresponding ages in the other figures presented, showing that whether concrete aggregates are used or not the water-cement ratio governs the strength. In these tests the molds were sealed to prevent leakage.

For the wetter mixes there was some accumulation of water at the top of the specimens as in the mortar specimens of Fig. 2. In this series of tests, however, the correction was not made for this amount of water as the tests were not made primarily for this purpose. The effect of such a correction in the curves of Fig.4 would be to move the points for the wettest mixes somewhat to the left and the next point or two slightly in the same direction, thus changing the shape of the curves slightly at the higher water ratios. From the data in Figs. 2 to 4 it is seen that the size of the concrete aggregate is not an important factor in the water- cement ratio strength relation, provided the tests are conducted with due regard for the other variables and the true water-cement ratio of the concrete in place is considered. The grading of the concrete aggregate has much less effect on the water-cement ratio strength relation than is commonly believed. It is probable that many have failed to recognize this fact due to the common practice of comparing different materials on the basis of certain definite mixes. On this basis, grading does affect the strength because of the difference in amount of water which different grading require for the same consistency. When these differences in the amount of water are taken into account, that is, when compared on the basis of water-cement ratios, the differences in strength due to grading are not so important. Too often tests have been made in which non-workability or segregation has been ignored.

This has also served to emphasize the differences in grading. In Fig. 5, the small effect of grading on the water-cement ratio strength relation is well brought out. This figure shows the maximum range in position of the water-cement ratio curve for very wide differences in grading of concrete aggregates having a maximum size of 1 in. The upper curves in Fig. 5 are for coarse concrete aggregates of gravel and the lower curves for limestone. For both coarse concrete aggregates, two separate grading were used. Sands of two grading were used in many cases, 0-No. 4 and 0-No. 14. Each sand was combined with each coarse concrete aggregate in a number of ratios ranging from all sand to combinations in which the coarse concrete aggregate proportion was the largest that could be used and obtained in plotting the data in Fig. 5, only the highest and lowest water-cement ratio curves of the entire set of data are shown for each coarse concrete aggregate.

Are You in Worcester Massachusetts? Do You Need Concrete Cutting?

We Are Your Local Concrete Cutting Company

Call 508-283-3135

We Service all surrounding Cities & Towns.