GB1578921A

GB1578921A - Analysing plastic concrete

Info

Publication number: GB1578921A
Application number: GB5273175A
Authority: GB
Original assignee: Duxbury W G
Current assignee: Duxbury W G
Priority date: 1977-03-23
Filing date: 1977-03-23
Publication date: 1980-11-12

Description

(54) ANALYSING PLASTIC CONCRETE (71) I, WILLIAM GEORGE DUXBURY, a British subject of 64 Winslade Road, Sidmouth, Devon, formerly of 15 The Spinney, Camberley, Surrey, do hereby declare the invention for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a method of analysing plastic concrete and to apparatus for use in the method. Plastic concrete is defined as concrete before it has set.

According to one aspect of the invention there is provided a method of analysing plastic concrete as hereinbefore defined comprising the steps of measuring a known amount of plastic concrete sample into a container, removing cement and cement-fine material from the sample by passing a known weight of liquid upwardly through said sample, weighing the liquid with the cement and cement-fine material and using formula (1) as hereinafter defined to determine from the known and measured weights and the specific gravity of the cement the weight of cement and cement-fine material in the sample. Cement-fine material is defined as solid matter having a particle size substantially equal to or less than that of cement.

Preferably the container is an elutriator and the liquid is water.

The sample may be a known weight of concrete and the method may further comprise the step of measuring the volume of the sample and determining the weight of cement-fine material per unit volume of concrete.

The sample may be a known weight of concrete and the method may further comprise the steps of measuring the volume of the sample and using formula (3) as hereinafter defined to determine the weight of water in the sample from the said known and measured volume and weights, the weight of cement and cement-fine material and the specific gravity of the aggregate in the concrete sample.

The method according to the next preceding paragraph may include the steps of determining the ratio of water to cement-fine material of the concrete.

The method according to the two next preceding paragraphs may also include the step of determining the weight of the aggregate in the sample by subtracting the sum of the weights of the cement-fine material and the water from the weight of the sample. The method may also comprise the step of obtaining the ratio of the weight of the aggregate to the weight of the cement-fine material in the sample.

The method may also comprise the step of determining the density of the plastic concrete from the weight and the volume of the sample.

According to another aspect of the invention there is provided apparatus for performing the method according to the first aspect of the invention.

The invention will now be described by way of example with reference to the accompanying drawing, in which: Figure 1 is a schematic view of one apparatus for carrying out the method of testing concrete according to the invention; Figure 2 shows an alternative arrangement of part of the apparatus of Figure 1.

Referring to Figure 1 there is shown apparatus 10 for analysing plastic concrete. The apparatus 10 comprises an elutriator 12 supplied with water through a pipe 15 from a header tank 14, the supply being controlled by a valve 16. The outlet from the elutriator 12 is fed into a collection vessel 20. A sieve 22 at the inlet to the collection vessel 20 is arranged to collect any solid matter having a particle size greater than that of cement so that only cement and cement-fine material pass through.

Figure 2 shows another arrangement of the elutriator 12 and supply pipe 15.

In use, plastic concrete is analysed according to the following method: (a) with valve 16 in the open position, the elutriator 12 is filled with water, any excess going to waste.

(b) with valve 16 in the closed position, water is poured into the header tank 14, until it begins to flow from the over-flow siphons 18.

(c) when the overflow from the siphons 18 stops, the water in the header tank 14 is released by operation of valve 16 and allowed to flow down tube 15, through elutriator 12 and into the collection vessel 20, where it is weighed together with this vessel, to give W1.

(d) the water in collection vessel 20 is discarded and step (b) above repeated.

(e) a sample of 5 to 7 Kg of plastic concrete is weighed, weight=Ws.

(f) this sample is placed in the elutriator 12, and the water overflow collected in a measuring cylinder to indicate the volume V of concrete in the sample.

(g) the water is released from the header tank 14 by operation of valve 16 and flows down the tube 15 and through the elutriator 12, into the collection vessel 20, taking with it the cement and other material of cement fineness.

(h) any material retained on the sieve 22 is returned to the elutriator 12.

(i) the collection vessel 20 and its contents are reweighed, weight W2.

(k) if it is believed that cement still remains in the sample, then the contents of the collection vessel 20 are discarded, the processes in steps (b), (g), (h) and (j) are repeated, and any difference between W, and the new W2 added to the original W2.

(1) from the measured parameters such as the weight Ws of the sample of concrete, the volume of the sample, V, and the difference in weights of the collection vessel and contents, and the known parameter such as the apparent specific gravity or the saturated-surface-dry specific gravity of the aggregate (2.65 in the example which follows), the specific gravity of cement (3.1 in the example), the weight of cement-fine material and some other constituents of the concrete can be calculated.

If the only information required is the cement content per cubic metre of concrete it is not necessary to weigh the concrete sample or to know the specific gravity of the aggregate.

The following example shows a typical example of the results of carrying out the method according to the invention and the method of calculating various parameters from the known and measured parameter of a sample.

Let: Wl=initial weight of collection vessel and contents W2=final weight of collection vessel and contents Weight of concrete sample Weight of cement in concrete sample Weight of water in concrete sample Weight of aggregates in concrete sample V=volume of concrete sample Volume of cement in sample Volume of aggregate in sample Volume of water in sample (=Ww) Sc=specific gravity of cement=3.1 SA=specific gravity of aggregate=2.65 approx.

Sw=specific gravity of water=l Formulae

WA=Ws(Wc+Ww) (5) cement/m3=Wcx 1000/V water/m3=W, x1000/V aggregate/m3=WA x I OOO/V EXAMPLE Let W1=10,000 g W2=10,420 g Ws=5,000 g V=2,080 ml then

WA=50OO(620+365)=401 5 g water/cement ratio=365/620=0.59 aggregate/cement ratio=4015/620=6.48

1000 cement/m3=620x =297.6 kg 2.080 1000 water/m3=365x =175.5 kg 2.080 1000 aggregate/m3=4015x ~1930 kg 2.080 1000 concrete/m3 (plastic density)=5x -2403.8 kg 2.080 Under normal circumstances, only Wc would be required, followed perhaps by Ww, to obtain the water/cement ratio, but the other parameters are clearly easily determined.

The whole operation takes only a few minutes and can be carried out in virtually any location. The only skill required is in the calculations, but these are basic and can be predetermined and presented in graphical form, so that the operator has only to consult a chart instead of doing the calculations.

WHAT I CLAIM IS: 1. A method of analysing plastic concrete as hereinbefore defined comprising the steps of measuring a known amount of plastic concrete sample into a container, removing cement and cement-fine material as hereinbefore defined from the sample by passing a known weight of liquid upwardly through said sample,

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. WA=Ws(Wc+Ww) (5) cement/m3=Wcx 1000/V water/m3=W, x1000/V aggregate/m3=WA x I OOO/V EXAMPLE Let W1=10,000 g W2=10,420 g Ws=5,000 g V=2,080 ml then WA=50OO(620+365)=401 5 g water/cement ratio=365/620=0.59 aggregate/cement ratio=4015/620=6.48 1000 cement/m3=620x =297.6 kg 2.080 1000 water/m3=365x =175.5 kg 2.080 1000 aggregate/m3=4015x ~1930 kg 2.080 1000 concrete/m3 (plastic density)=5x -2403.8 kg 2.080 Under normal circumstances, only Wc would be required, followed perhaps by Ww, to obtain the water/cement ratio, but the other parameters are clearly easily determined. The whole operation takes only a few minutes and can be carried out in virtually any location. The only skill required is in the calculations, but these are basic and can be predetermined and presented in graphical form, so that the operator has only to consult a chart instead of doing the calculations. WHAT I CLAIM IS:

1. A method of analysing plastic concrete as hereinbefore defined comprising the steps of measuring a known amount of plastic concrete sample into a container, removing cement and cement-fine material as hereinbefore defined from the sample by passing a known weight of liquid upwardly through said sample,

weighing the liquid with the cement and cement-fine material and using formula (1) as hereinbefore defined to determine from the known and measured weights and the specific gravity of the cement the weight of the cement and cement-fine material in the sample.

2. A method according to Claim 1, in which the container is an elutriator and the liquid is water.

3. A method according to Claim 1 or 2, further comprising the step of measuring the volume of the sample and determining the weight of cement and cement-fine material per unit volume of concrete.

4. A method according to Claim 1 or 2, in which the sample is a known weight of concrete and the method further comprises the steps of measuring the volume of the sample and using formula (3) as hereinbefore defined to determine the weight of water in the sample from the said known and measured volume and weights, the weight of cement and cement-fine material and the specific gravity of the aggregate in the concrete sample.

5. A method according to Claim 4, including the steps of determining the ratio of water to cement-fine material of the concrete.

6. A method according to Claim 4 or 5, including the step of determining the weight of the aggregate in the sample by subtracting the sum of the weights of the cement-fine material and the water from the weight of the sample.

7. A method according to Claim 6, comprising the step of obtaining the ratio of the weight of the aggregate to the weight of the cement-fine material in the sample.

8. A method according to Claim 3 or any one of Claims 4 to 7 as dependent upon Claim 3, comprising the step of determining the density of the plastic concrete as hereinbefore defined of the concrete from the weight and the volume of the sample.

9. A method of analysing plastic concrete substantially as hereinbefore described.

10. Apparatus when performing the method of Claim 1, comprising a container for containing a measured amount of a plastic concrete sample, means for passing a known weight of liquid through a sample in the container to remove cement and cement-fine material therefrom and means for weighing the liquid with the cement and cement-fine material.

11. Apparatus according to Claim 10, in which the container is an elutriator and the liquid is water.

12. Apparatus according to Claim 10 or 11, comprising means for measuring the volume of the sample and for determining the weight of cement-fine material per unit volume of concrete.

13. Apparatus according to Claim 10 or 11, further comprising means for measuring the volume of the sample and for determining the weight of water in the sample from the said known and measured volume and weight, the weight of cement-fine material and the specific gravity of the aggregate in the concrete sample.

14. Apparatus according to Claim 13, comprising means for determining the weight of the aggregate in the sample and means for obtaining the ratio of the weight of the aggregate to the weight of the cement-fine material in the sample.

15. Apparatus for analysing plastic concrete substantially as hereinbefore described with reference to and as illustrated in Figure 1 or Figure 1 with Figure 2 of the accompanying drawing.