Development of Heavyweight Self-Compacting Concrete and Ambient-Cured Heavyweight Geopolymer Concrete Using Magnetite Aggregates

Abstract

Heavyweight self-compacting concrete (HWSCC) and heavyweight geopolymer concrete (HWGC) are new types of concrete that integrate the advantages of heavyweight concrete (HWC) with self-compacting concrete (SCC) and geopolymer concrete (GC), respectively. The replacement of natural coarse aggregates with magnetite aggregates in control SCC and control GC at volume ratios of 50%, 75%, and 100% was considered in this study to obtain heavyweight concrete classifications, according to British standards, which provide proper protection from sources that emit harmful radiations in medical and nuclear industries and may also be used in many offshore structures. The main aim of this study is to examine the fresh and mechanical properties of both types of mixes. The experimental program investigates the fresh properties of HWSCC and HWGC through the slump flow test. However, J-ring tests were only conducted for HWSCC mixes to ensure the flow requirements in order to achieve self-compacting properties. Moreover, the mechanical properties of both type of mixes were investigated after 7 and 28 days curing at an ambient temperature. The standard 100 × 200 mm cylinders were subjected to compressive and tensile tests. Furthermore, the flexural strength were examined by testing 450 × 100 × 100 mm prisms under four-point loading. The flexural load-displacement relationship for all mixes were also investigated. The results indicated that the maximum compressive strength of 53.54 MPa was achieved by using the control SCC mix after 28 days. However, in HWGC mixes, the maximum compressive strength of 31.31 MPa was achieved by 25% magnetite replacement samples. The overall result shows the strength of HWSCC decreases by increasing magnetite aggregate proportions, while, in HWGC mixes, the compressive strength increased with 50% magnetite replacement followed by a decrease in strength by 75% and 100% magnetite replacements. The maximum densities of 2901 and 2896 kg/m3 were obtained by 100% magnetite replacements in HWSCC and HWGC, respectively.

Experimental Study on the Workability and Stability of Steel Slag Self-Compacting Concrete

“…The segregation resistance is often considered as the index of stability of SCC, which also can be classified as static stability and dynamic stability. At present, the evaluation and test methods of the workability of SCC mainly includes a slump flow (SF) test incorporating slump flow time (T500) measurements [13][14][15][16][17][18][19][20][21][22][23][24][25][26], a V-funnel test [14,15,17,[19][20][21][22]24,26], a L-box test [13,15,19,21,23,24,26], a U-shape meter test [14,17,22], and a J-ring test [15][16][17][18][19]24,25], etc. Stability tests conducted for SCC mixture involved a sieve analysis test [15,17,20,25], flow table test [27], segregation probe test [20], and static settlement column test…”

“…The results show that with the increase of slag content, the self-compacting performance of concrete gradually reduces, and when the replacement rate is low, the self-compacting performance of concrete still remains. Valizadeh et al [18] used magnetite aggregate to replace the natural coarse aggregate of SCC and general concrete with the volume ratio of 50%, 75% and 100% in the study of heavyweight SCC. The slump test and J-ring test results show that the workability of fresh concrete decreases gradually with the increase of the amount of magnetite aggregate.…”

Influence of Water Content on Mechanical Strength and Microstructure of Alkali-Activated Fly Ash/GGBFS Mortars Cured at Cold and Polar Regions

“…In addition, raw materials of geopolymer are mostly by-products of industrial products with abundant reserves and low prices. Compared with OPC, geopolymers have better mechanical, chemical, thermal properties, and durability [6,[8][9][10][11][12]. Based on the above-mentioned characteristics, geopolymer is a better option for the development of sustainable products such as building materials, fire-retardant coatings, fiber-reinforced composite materials, and fixed solutions for chemical and nuclear industrial wastes.…”

Development and analysis of highly workable high‐strength heavyweight concrete using magnetite aggregates

“…To explain the observed trend, the higher water absorption capacity of heavyweight aggregate rather than normal weight aggregate, 8 and more compact microstructure 10 are the key parameters. However, at lower w/c ratios, by increasing the magnetite aggregate (up to 50% for w/c ratio equal to 0.25, and 75% for w/c ratio equal to 0.2), and subsequently increasing density, the compressive strength would reduce comparing to the control samples, indicating that higher water absorption capacity of heavyweight aggregates is an inhibitor for propagation of the internal structure of the concrete (calcium‐silicate‐hydrate gel) and gaining strength 46–48 . Notwithstanding, 100% magnetite content would increase the compressive strength even at lower w/c ratio which may be contributed to the more compact microstructure of the concrete 10 …”