scholarly journals THE INFLUENCE OF COARSE AGGREGATE CONCENTRATION ON THE STRENGTH OF CONCRETE AND ON THE POROSITY OF CONCRETE MORTAR/STAMBIOJO UŽPILDO KONCENTRACIJOS ĮTAKA BETONO STIPRUMUI IR SKIEDININĖS DALIES PORINGUMUI

2001 ◽  
Vol 7 (6) ◽  
pp. 446-452
Author(s):  
Gintautas Skripkiūnas ◽  
Vitoldas Vaitkevičius

The results of experiments dealing with coarse aggregate concentration influence on the concrete strength and the structure of hardened cement paste and mortar of concrete are presented in the paper. Experiments were performed on concrete with dense coarse aggregate (crushed granite) which strength is more than strength of mortar and lightweight porous aggregate (expanded clay aggregate) with strength less than that of mortar. Physical and mechanical properties of concrete with dense coarse aggregate are presented in Table 1 and the concretes with the porous coarse aggregate in Table 2. The decrease of entrained air content with the increase of coarse aggregate concentration ϕσt were determined both for concretes with dense and porous coarse aggregate. The entrained air has a significant effect on concrete strength—1% of entrained air decreases the strength of concrete about 5% [11]. The influence of the coarse aggregate concentration on the compressive strength of concrete with the constant air content is presented in Figs 3 and 4. With the increase of coarse aggregate concentration the concrete strength decreases when the entrained air content in concrete is constant. The main reasons of the concrete strength reduction are the stress concentration and structural defects near the coarse aggregate. Coarse aggregate affects the structure of mortar. Dense coarse aggregate has negligible water absorption and does not change water content in mortar of concrete, and capillary porosity of mortar remains constant when the concentration of dense coarse aggregate ϕ st increases (Fig 5). Porous coarse aggregate (expanded clay aggregate) has large water absorption (more than 16%), therefore water content in mortar of concrete is reduced and capillary porosity of mortar is significantly reduced when the concentration of porous coarse aggregate ϕ st increases (Fig 5). The entrained air content in mortar with both dense and porous coarse aggregate decreases inverse proportionally to coarse aggregate concentration ϕ st (Fig 6). The investigations have shown that suitable selection of properties and volumetric concentration of coarse aggregate can reduce stress concentration in concrete and increase the concrete strength.

Author(s):  
Adriane Pczieczek ◽  
Adilson Schackow ◽  
Carmeane Effting ◽  
Itamar Ribeiro Gomes ◽  
Talita Flores Dias

This study aims to evaluate the application of discarded tire rubber waste and Expanded Polystyrene (EPS) in mortar. For mortars fine aggregate was replaced by 10%, 20% and 30% of rubber and, 7.5% and 15% of EPS. We have verified the consistency, density, amount of air and water retentitivity in fresh state. The compressive strength, water absorption, voids ratio and specific gravity have been also tested in hardened state. The application of rubber powder contributed to the increase in entrained air content and in reducing specific gravity, as well as reducing compressive strength at 28 days. The addition of EPS also contributed to the increase of workability, water absorption and voids ratio, and decreased density and compressive strength when compared to the reference mortar. The use of rubber waste and EPS in mortar made the material more lightweight and workable. The mortars mixtures containing 10% rubber and 7.5% EPS showed better results.


Foods ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 228
Author(s):  
Marina Schopf ◽  
Katharina Anne Scherf

Vital gluten is often used in baking to supplement weak wheat flours and improve their baking quality. Even with the same recipe, variable final bread volumes are common, because the functionality differs between vital gluten samples also from the same manufacturer. To understand why, the protein composition of ten vital gluten samples was investigated as well as their performance in a microbaking test depending on the water content in the dough. The gluten content and composition as well the content of free thiols and disulfide bonds of the samples were similar and not related to the specific bread volumes obtained using two dough systems, one based on a baking mixture and one based on a weak wheat flour. Variations of water addition showed that an optimal specific volume of 1.74–2.38 mL/g (baking mixture) and 4.25–5.49 mL/g (weak wheat flour) was reached for each vital gluten sample depending on its specific water absorption capacity.


2021 ◽  
pp. 136943322110093
Author(s):  
Jinqing Jia ◽  
Qi Cao ◽  
Lihua Zhang ◽  
Jiayu Zhou

Concrete made by post-filling coarse aggregate process could reduce the cement content greatly compared with traditional concrete placement method. Thus, it not only lowers the production cost of concrete through lower usage of cement but also reduces the CO2 emissions to the environment. In this paper, the compressive and tensile strength of post-filling coarse aggregate concrete with different post-filling ratios (PFRs) (0%, 10%, 15%, 20%, 25%, 30%) and concrete strength grades (C30, C40, C50) were first studied. Then the flexural performance of nineteen concrete beams with different concrete strength, post-filling ratios, reinforcement ratios was investigated. The experimental results showed that the compressive strength and elastic modulus of the post-filling coarse aggregate concrete increased with the increase of the post-filling ratio of coarse aggregate, reaching the peak value at the filling ratio of 20%. It indicated that there was no obvious difference in the failure mode as well as middle-span deflections between post-filling coarse aggregate concrete (PFCC) beams and ordinary concrete (OC) beams. Ductile failure was observed for all nineteen specimens. Results demonstrated that the cracking load, yield load, and ultimate load of the post-filling coarse aggregate concrete beams all reached the peak value at the post-filling ratio of 20%. In addition, the theoretical predictions of cracking loads and ultimate load carrying capacities matched the experimental results in satisfactory agreement.


Buildings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 300
Author(s):  
Md. Safiuddin ◽  
George Abdel-Sayed ◽  
Nataliya Hearn

This paper presents the water absorption and strength properties of short carbon fiber reinforced mortar (CFRM) composite. Four CFRM composites with 1%, 2%, 3%, and 4% short pitch-based carbon fibers were produced in this study. Normal Portland cement mortar (NCPM) was also prepared for use as the control mortar. The freshly mixed mortar composites were tested for workability, wet density, and entrapped air content. In addition, the hardened mortar composites were examined for compressive strength, splitting tensile strength, flexural strength, and water absorption at the ages of 7 and 28 days. The effects of different carbon fiber contents on the tested properties were observed. Test results showed that the incorporation of carbon fibers decreased the workability and wet density, but increased the entrapped air content in mortar composite. Most interestingly, the compressive strength of CFRM composite increased up to 3% carbon fiber content and then it declined significantly for 4% fiber content, depending on the workability and compaction of the mortar. In contrast, the splitting tensile strength and flexural strength of the CFRM composite increased for all fiber contents due to the greater cracking resistance and improved bond strength of the carbon fibers in the mortar. The presence of short pitch-based carbon fibers significantly strengthened the mortar by bridging the microcracks, resisting the propagation of these minute cracks, and impeding the growth of macrocracks. Furthermore, the water absorption of CFRM composite decreased up to 3% carbon fiber content and then it increased substantially for 4% fiber content, depending on the entrapped air content of the mortar. The overall test results suggest that the mortar with 3% carbon fibers is the optimum CFRM composite based on the tested properties.


AGROINTEK ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 82
Author(s):  
Asnani Asnani ◽  
Abdul Rahim ◽  
Ifall Ifall

<em>This work deals with the effect of banana (sweet plaintain or ‘kepok’ variety) hump flour substituted to wheat flour in the making of noodle, on physical, chemical, and sensory characteristics of noodle.  A completely randomized was employed, with three replicates. Sensory analysis was conducted according to randomized group design. Four proportions of banana hump to wheat flour (10:90, 20:80, 30:70, and 40:60, weight basis) was studied. Results showed that the best physical and chemical characteristics was shown by noodle made from 10:90 proportion of banana hump to wheat flour, with 4.59% water absorption, 0.57% cooking loss, 10.37% water content, 34.21% starch content. However, result of sensory analysis suggested that the most liked noodle was that made from flour proportion of 20:80 with ‘like’ for colour, ‘like very much’ for aroma, ‘like’ for texture, ‘like’ for taste, and ‘like’ for overall preference</em>


2016 ◽  
Vol 8 (1) ◽  
pp. 24-28
Author(s):  
Maya Indra Rasyid

(Chemical and Organoleptic Characteristics of Mung Bean Flakes with The Addition of Fillers and Water) ABSTRACT. The objective of this research was to determine the chemical and organoleptic characteristics of mung bean flakes with the addition of fillers and water. The study was conducted using completely randomized design with two factors namely the addition of fillers and water. The results showed that the addition of fillers and water has significant (P≤0,01) effect on the water absorption ratio and protein levels of mung bean flakes. The best treatment was obtained by the mung bean flour without the addition of fillers with 150% of addition water with water absorption ratio of 204%, water content of 5,7%, protein of 22,01%, starch levels of 61,76%, organoleptic values of aroma of 2,61, color of 2,42, crispness of 2,72 and flavor of 2,83.


2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Qiao-Huan Wang ◽  
Jiong-Feng Liang ◽  
Chun-Feng He ◽  
Wei Li

This paper attempts to explore the effects of recycled coarse aggregate content, steel fiber content, and concrete strength on the axial compressive behavior of steel fiber-reinforced recycled coarse aggregate (RCA) concrete-filled circular steel stub columns. A total of 14 short columns are tested. The results show that using RCA in concrete will reduce the bearing capacity of short columns, but the increase in steel fiber content and concrete strength can eliminate this shortcoming. Not only that, the concrete strength has a great influence on the ductility and stiffness of the specimen.


2017 ◽  
Vol 1 (3) ◽  
pp. 203
Author(s):  
Rohny S. Maail

This research objectives were to investigate possibility of using the waste of sago cortex (Ela sagu/Wa’a) in the manufacture of cement board and to determine the physical properties of cement board based on the comparison in proportion of materials (cement, sago, water)  and catalyst calcium chloride (CaCl2). Method were applied used completely randomesed design with tree replications in 3x3x3, with total 27 samples of cement board. The results shown that the waste of sago cortex ca be applied as raw materials to manufacture of cement board and fulfill the standard of particle board (JIS A 5908, 2003). The board have dencity which is almost equal to the target of dencity, lower value in water content, water absorption and thichness swelling so that have good performance in quality and stability dimensions. The sago cortex in side of base and the catalyst CaCl2 in 6% gave high performance for all physical properties of cement board.


Sign in / Sign up

Export Citation Format

Share Document