Ethereum miner cu_k1
Preparation of the samples The materials used for the manufacture of agroindustrial solid waste-based bricks ASWBs consisted of raw clayrich material, cocoa shell, sawdust, rice husk and sugarcane. The clayey soil is currently used by this company to make fired bricks of different shapes and sizes with dimensional tolerances that conform to ASTM Standards.
Agroindustrial solid wastes were obtained from the supply and storage center Centroabastos , Santander Colombia. Their use should be promoted as an appropriate and alternative low cost but high quality building technology.
December, Figure 2. SEM images of the agroindustrial wastes. Figure 3. Experimental scheme followed for manufacturing ASWBs. The units of ASWBs were manufactured with cuboidal shape and standard size 60 x 50 x 90 mm. All tests were carried out according to ASTM standards and the results reported are the mean of three values. In order to obtain comparable results, a total of 12 ASWBs 3 for each mixture were prepared for testing four different series.
The shape and size tolerances have been respected. Too much clay will cause cracks in the blocks while too much sand will cause the blocks to crumble. The suitable soil must contain the right proportions of sand, silt, clay and water. Sample preparation, mix compositions and testing Fig. The raw clay-rich material was naturally dried during 3 weeks under the following environmental conditions: average temperature of 24 o C and relative humidity of The agroindustrial residues were dried for 24 hours under the direct sunlight to remove the excess moisture.
Then, they were cut in fragments of different average dimensions. In order to determine the effect of the addition of agroindustrial residues on the engineering properties of ASWBs. The mix proportions were prepared based on the dry weights of the ingredients. The quantities of the dry materials obtained from the mix design were measured in each case with the aid of a weighing balance.
First, the dry materials were mixed by hand with a spade on a hard surface until they reached a uniform color. Then, water was added and mixing continued until a homogeneous mixture was obtained. The resultant mixtures were compacted manually in appropriate molds using predetermined masses corresponding to the maximum density found from standard compaction tests.
Figure 4. Stages during preparation of ASWBs. A loading steel roller identical to the two described above was set on top of the ASWBs. The load was applied via a steel roller, identical to those described above, directly onto the ASWBs. The maximum load until the occurrence of the first crack was recorded as flexural strength. Upon crack occurrence, the strength decreased. MR can be calculated according to Varela et al. Immediately after the fabrication of the ASWBs, their dimensions were recorded and at the end of the day curing period, a record of their dimensions was also taken.
There was no significant dimensional or volume increase in any of the ASWBs. No defects such as cracks and bloating were observed after firing. However, a texture characterized by black cores are developed after firing, which can be attributed to organic matter that is not completely burned during firing []. In general, the color of the fired samples was reddish, which is similar to that observed in the formulas without wastes, although somewhat lighter as the proportion of waste increases.
Engineering tests were conducted in a computerized device for mechanical assays according to the ASTM C standard [28]. A Universal Testing Machine MTS with a maximum load of N was used in the testing procedure, taking into account its accuracy 0. Data were recorded automatically to the computer system which the user can manipulate the collected results. The compressive strength test was conducted with a crosshead speed of 0. The test was carried out as follows: ASWBs were placed between two steel bearing plates on the top and on the bottom , which were identical length, width and thickness were respectively x 40 x 5 mm.
The load strain reading at failure was recorded; it was the maximum load the specimen could carry in compression. The threepoint bending flexural strength test was conducted with a cross head speed of 0. The procedure performed on the ASWBs was as follows: two cylindrical steel rollers length of mm and diameter of 5 mm were set at a distance of mm apart on the bottom steel support plate length, width and thickness were respectively x 40 x 5 mm.
After 28 days of curing time, the dry specimens were weighed. Then, they were subjected to 24 h submersion. The water of absorption can be determined from the moist weight of specimens after submersion according to the standard ASTM C [28]. The ASWBs containing residues expanded slightly when fired at oC, resulting in a typical behavior of porous bodies. This may be due to the high content in quartz of the clay that is inert at the studied temperature which reduces the contraction of the piece, as well as to the increase in porosity due to the high content in organic matter in the organic residues.
All ASWBs showed a contraction at this temperature. The weight loss experienced by the samples upon temperature increased with respect to the residue content at oC for all types of wastes. This weight loss could be due to the elimination of the organic matter from the clay and residue by means of combustion and to the elimination of water content from clay mineral due to dehydroxylation reactions in the clay as suggested by Eliche-Quesada et al.
Table 1. Average results for compressive and flexural strength tests of the ASWBs. MR MPa 2. Table 2. According to Romero et al. The temperature decreased the porosity of the ASWBs. The changes in this property were notable with the addition of sawdust, while the addition of cocoa shell, rice husk and sugarcane produced minor differences in apparent porosity similar to results obtained by Eliche-Quesada et al.
The addition of agroindustrial wastes increased the porosity of the ASWBs, however this effect is expected, since the organic matter of the wastes were eliminated during the thermal process, leading to an increase in the open porosity of the ceramic bodies.
IR single-crystal spectra of several nominally anhydrous calcium silicate garnets, both "end-member" and solid-solution compositions, were recorded at room temperature and 80 K between and cm The various spectra are rich in complexity and show several OH-stretching modes at wavenumbers between and cm The data, together with published results, were analyzed and modes assigned by introducing atomic-vibrational and crystal-chemical models to explain the energy of the OH-dipole and the structural incorporation mechanism of OH-, respectively.
The basic substitution mechanism is the hydrogarnet one, where H 4 O 4 4- SiO 4 4-, and various local configurations containing different numbers of H 4 O 4 4-groups define the cluster type. Some spectra also possibly indicate the presence of tiny hydrous inclusion phases, as revealed by OH-modes above about cm
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