CN-112881123-B - Method for calculating cement strength of cement stability test cake

CN112881123BCN 112881123 BCN112881123 BCN 112881123BCN-112881123-B

Abstract

The invention relates to the technical field of cement testing, in particular to a method for calculating cement strength of a cement stability test cake, which comprises the following steps of 1, preparing materials, preparing cement, pouring water, stirring to prepare cement standard-consistency clean slurry, taking out a part of the prepared cement standard-consistency clean slurry, and dividing the part of cement standard-consistency clean slurry into two equal cement slurries; step 2, manufacturing a test cake, namely, agglomerating a cement paste in the step 1 into a sphere, putting the sphere on a glass plate coated with a layer of butter in advance, slightly vibrating on a table top, simultaneously wiping the sphere from the periphery to the center through a knife to enable the cement paste to form a circular test cake with the diameter of 70mm to 80mm, the center thickness of about 10mm and the edge of the circular test cake being gradually thinned, testing the stability of cement through a test cake method, testing the pressure value of the test cake through a pressure testing machine, and then bringing the pressure value into a linear relation value K, so that the strength of cement can be calculated, two tests of a set of procedures are completed simultaneously, and time and cost are greatly saved.

Inventors

ZHU LIHONG
ZHU ZHIYONG
LI KUNXIA
CHEN WEIGUO
GAO CHAO
JIA KE

Assignees

广东财贸建设工程顾问有限公司

Dates

Publication Date: 20260512
Application Date: 20210121

Claims (3)

1. The method for estimating the cement strength of the cement stability test cake is characterized by comprising the following steps of: Step 1, preparing materials, preparing cement, pouring water, stirring to prepare cement standard-consistency clean slurry, taking out a part of prepared cement standard-consistency clean slurry, and dividing the part of prepared cement standard-consistency clean slurry into two equal cement slurries; Step 2, making a test cake, namely, agglomerating a part of cement paste in the step 1 into a sphere, putting the sphere on a glass plate coated with a layer of butter in advance, then slightly vibrating on a table top, and simultaneously wiping the sphere from the periphery to the center through a knife to enable the cement paste to form a circular test cake with the diameter of 70mm to 80mm, the center thickness of about 10mm and the edge of the circular test cake being gradually thinned; step 3, curing the test cakes, namely placing the test cakes prepared in the step 2 into a moisture curing box for curing for 24+/-2 hours; step 4, boiling the test cake, taking out the test cake from the curing box, taking the test cake off the glass plate, observing the appearance of the test cake to be defect-free, and putting the test cake on a test frame of the boiling box for boiling when the test cake is defect-free of cracking and warping; Step 5, detecting stability of the test cake, opening a box cover after boiling, taking out the test cake after the test cake is cooled to room temperature, observing and judging, and considering that the stability of the test cake cement is qualified when the test cake is visually inspected and has no crack and the bottom surface of the test cake is measured by a ruler and has no bend; Step 6, detecting the pressure value of the test cake, preparing a steel ring with the inner diameter of 30 cm and the diameter of 50-60mm, placing the qualified cement test cake on the steel ring, placing the test cake and the steel ring under the pressure ball of the pressure testing machine, applying pressure by the pressure machine, and reading and recording the pressure value; step 7, performing cement compression and fracture tests on the other cement slurry in the step 1, preparing test blocks by the cement slurry according to the standard requirements, placing the test blocks into a moisture curing box, curing for 28 days, taking out the test blocks, obtaining the distance between supports when the test pieces are broken through a fracture tester, and obtaining the limit load of the test pieces through the pressure tester; step 8, obtaining the bending strength of the test piece, and bringing the distance between the supports and the limit load data obtained in the step 7 into a test piece bending strength formula, wherein the test piece bending strength= (limit load x distance between the supports)/(test piece width x test piece height), and calculating and recording a test piece bending strength value; And 9, performing linear relation, namely respectively performing the same operation on the cements with different labels according to the mode to obtain a plurality of groups of cement stability pressure values and cement flexural tensile strength values, performing linear correlation data processing on the pressure values and the flexural tensile strength values, and finally obtaining a linear relation value K between the cement stability pressure values and the cement compressive and flexural strength values to obtain a calculation formula for calculating the cement strength of the cement stability test cakes.
2. The method for estimating a cement strength according to claim 1, wherein in step 6, the pad is placed under the pad before the pad is placed on the steel ring, and then the pad-placed pad is placed on the steel sheet.
3. The method for estimating the cement strength of the cement stability test cake according to claim 1, wherein the test piece flexural tensile strength is measured by taking an average value of 3 test pieces as a measurement value, taking a median value when the test piece with the highest strength is more than 15% of the test piece with the median strength or the test piece with the lowest strength is less than 15% of the test piece with the median strength, and taking a test piece with the highest strength is more than 15% of the test piece with the median strength and the test piece with the lowest strength is less than 15% of the test piece with the median strength.

Description

Method for calculating cement strength of cement stability test cake Technical Field The invention relates to the technical field of cement testing, in particular to a method for calculating cement strength by using a cement stability test cake. Background Cement stability is also called "cement volume stability", and one of the important indexes of cement quality. The cement contains excessive free lime, magnesia or sulfur trioxide, and the cement has uneven volume change during setting and hardening and unstable phenomena such as cracking, bending, crispness, collapse and the like. The strength of cement is an important index for evaluating the quality of cement and is the basis for classifying the strength grade of cement, and the strength of cement refers to the capability of the cement mortar hardening test body to bear the damage of external force. When the existing cement is constructed, stability and strength tests are needed, after one set of stability test flow is utilized, the other set of flow is adopted to test the cement strength (compression resistance and fracture resistance), and the two sets of flow are long in time consumption and high in cost. Disclosure of Invention The invention aims to overcome the defects of the prior art and provides a technical scheme capable of solving the problems. The method for estimating the cement strength of the cement stability test cake comprises the following steps: Step 1, preparing materials, preparing cement, pouring water, stirring to prepare cement standard-consistency clean slurry, taking out a part of prepared cement standard-consistency clean slurry, and dividing the part of prepared cement standard-consistency clean slurry into two equal cement slurries; Step 2, making a test cake, namely, agglomerating a part of cement paste in the step 1 into a sphere, putting the sphere on a glass plate coated with a layer of butter in advance, then slightly vibrating on a table top, and simultaneously wiping the sphere from the periphery to the center through a knife to enable the cement paste to form a circular test cake with the diameter of 70mm to 80mm, the center thickness of about 10mm and the edge of the circular test cake being gradually thinned; step 3, curing the test cakes, namely placing the test cakes prepared in the step 2 into a moisture curing box for curing for 24+/-2 hours; Step 4, boiling the test cake, taking out the test cake from the curing box, taking the test cake off the glass plate, observing the appearance of the test cake to be defect-free, and putting the test cake on a test frame of the boiling box for boiling when the test cake has the defects of cracking, warping and the like; Step 5, detecting stability of the test cake, opening a box cover after boiling, taking out the test cake after the test cake is cooled to room temperature, observing and judging, and considering that the stability of the test cake cement is qualified when the test cake is visually inspected and has no crack and the bottom surface of the test cake is measured by a ruler and has no bend; Step 6, detecting the pressure value of the test cake, preparing a steel ring with the inner diameter of 30 cm and the diameter of 50-60mm, placing the qualified cement test cake on the steel ring, placing the test cake and the steel ring under the pressure ball of the pressure testing machine, applying pressure by the pressure machine, and reading and recording the pressure value; step 7, performing cement compression and fracture tests on the other cement slurry in the step 1, preparing test blocks by the cement slurry according to the standard requirements, placing the test blocks into a moisture curing box, curing for 28 days, taking out the test blocks, obtaining the distance between supports when the test pieces are broken through a fracture tester, and obtaining the limit load of the test pieces through the pressure tester; step 8, obtaining the bending strength of the test piece, and bringing the distance between the supports and the limit load data obtained in the step 7 into a test piece bending strength formula, wherein the test piece bending strength= (limit load x distance between the supports)/(test piece width x test piece height), and calculating and recording a test piece bending strength value; And 9, performing linear relation, namely respectively performing the same operation on the cements with different labels according to the mode to obtain a plurality of groups of cement stability pressure values and cement flexural tensile strength values, performing linear correlation data processing on the pressure values and the flexural tensile strength values, and finally obtaining a linear relation value K between the cement stability pressure values and the cement compressive and flexural strength values to obtain a calculation formula for calculating the cement strength of the cement stability test cakes. Preferably, in step 6, the pad is placed under the pa