![]() ![]() When grout compressive strength testing is required, the procedures of ASTM C 1019, Standard Test Method for Sampling and Testing Grout (ref. If there is a decided falling away or shearing off of grout from one side or portion of the grout mass, the test should be disregarded and repeated with a fresh grout sample. The entire test must be completed within 2 ½ minutes, from start of mold filling to measurement. The slump is the vertical distance between the top of the cone and the displaced original center of the top surface of the specimen, as shown in Figure 2. ![]() The mold should not be twisted or moved sideways during lifting. Immediately after striking off and clearing grout from the base of the mold, the mold is lifted in 3 to 7 seconds by raising it vertically using a steady upward lift. Any grout which accumulates around the base of the mold is removed so that it does not interfere with the movement of the slumping grout. After the top layer is rodded, any excess grout is struck off flush with the top of the cone. If the grout level falls below the top of the cone while rodding the top layer, grout is added to keep excess grout heaped above the top of the mold at all times. The middle and top layers are rodded through the depth of the layer, penetrating into the layer below. Each layer is rodded 25 times with a round steel tamping rod to consolidate the grout before the next layer is placed. (156 mm) and the top layer should slightly overfill the mold. The first layer should fill the mold to a depth of about 2 ⅝ in. The technician stands on the mold’s foot pieces to hold the mold firmly in place while filling the mold in three layers of equal volume (see Figure 1). To perform the slump test, the cone, shown in Figures 1 and 2, is dampened and placed on a flat, rigid, nonabsorbent surface. If grout spaces are large, or the lifts are short, slumps in the lower part of the range also can work well. When water will be absorbed at a slower rate, such as with lower absorptive concrete masonry units, grouts in the lower slump range are good selections. ![]() High-slump grouts are advantageous when grout spaces are small or highly congested. When the rate of water loss may be high, such as when temperatures are elevated and/or the concrete masonry units are highly absorptive, slumps in the upper part of the range (i.e., more fluid) may be desirable, although care should be taken that the grout does not segregate because the slump is too high. 5), grout slump must be maintained between 10 and 11 in. (3.9 m) grout lift height is used as permitted in the 2005 edition of Specification for Masonry Structures (ref. (203 and 279 mm) to facilitate complete filling of the grout space and proper performance (ref. The measured grout slump should be between 8 and 11 in. 4), provides test procedures to test grout slump in either the laboratory or the field. Standard Test Method for Slump of Hydraulic-Cement Concrete, ASTM C 143 (ref. The slump test gives an indication of the consistency, water to cement ratio and/or fluidity of the field grout batch. Preparation of compressive strength specimens must begin within 15 minutes of obtaining the final portion. The slump test must be started within 5 minutes of obtaining the final portion. The portions are then combined and remixed to form the bulk sample. If sampled in the field, the incremental samples are transported to the testing location, with care to protect them from sun, wind and other potential sources of evaporation and contamination. To help ensure the sample is representative, the portions should be taken from the middle of the batch no samples should be taken from the first nor last 10% of the discharge. No more than 15 minutes should elapse between obtaining the first and last portion. Two or more grout portions are taken at regularly spaced intervals during grout discharge, and are then combined to form a bulk sample. A minimum bulk sample size of ½ ft³ (0.014 m ) is required for slump and compressive strength tests (ref. Grout should be sampled by a qualified technician. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |