Permeability plays a crucial role in determining the durability of concrete structures, particularly their susceptibility to corrosion. This study explores the potential of sulfur concrete as a protective insulator for concrete surfaces. A comparative analysis is conducted to assess the permeability of sulfur concrete (SC), conventional concrete covered with 1 mm sulfur cover (CC-SC), and conventional Portland cement concrete (CC). The investigation includes evaluations of water absorption, void percentage, and accelerated corrosion tests. The time taken for crack initiation and propagation to reach a 1 mm width is recorded. The results demonstrate that sulfur concrete exhibits lower porosity and water absorption, highlighting its waterproof properties and ability to reduce permeability. Significantly, sulfur concrete effectively blocks current flow in the accelerated corrosion test, acting as an insulating barrier. Additionally, cracks in the Portland cement concrete specimens appear after 6 and 9 days for initial crack formation and a 1 mm crack width, respectively. However, when a 1 mm sulfur layer is applied to the surface of the Portland cement concrete, the first crack occurs after 7 days, with a 1 mm crack width observed after 12 days. This indicates that the sulfur cover provides protection for the reinforced concrete and delays the corrosion process. It is important to note that although the sulfur cover delays corrosion in Portland cement concrete, it does not entirely prevent it. Further research and the implementation of additional preventive measures are recommended to address this limitation and enhance corrosion resistance.
The main disadvantage of high-strength concrete is its highly brittle behavior and this can beovercome by adding fibers to the concrete. This would also improve some other mechanical properties of high-strength concrete such as tensile strength and compressive strength. These properties are not very well established for high-strength steel-fiber reinforced concrete (HSFRC) yet. In this study the influence of silica fume on the properties of HSFRC were investigated by using silica fume of two different percentages and three different hooked-end fibers namely, 30/0.50, 60/0.80 and 50/0.60 length/diameter (mm/mm). Fibers were added to concrete in three different volume percentages of 0.5, 1.0 and 2.0 by volume of concrete. The results indicated that there is a linear function between splitting tensile strength (F splt) and volume percentage of fibers (V f) [i.e. F plt = A(V f) + B, where A and B are correlation coefficients] as well as between splitting tensile strength (F splt) and compressive strength (F c) of plain series A concrete [i.e. F splt = C (√F c) + D, where C and D are correlation coefficients]. These relations can describe the development of splitting tensile strength of HSFRC containing no silica fume, 5% silica fume and 10% silica fume by weight of cement. On the other hand, although silica fume has an effect on compressive strength, volume percentage and aspect ratio of steel fibers has little effect.
Compression toughness tests were carried out on concrete cylinders reinforced with three different aspect ratios of hooked-end steel fibers 60, 75, and 83 and six different percentages of steel fibers 0.5, 1.0, 1.25, 1.5, 1.75, and 2.0% by volume of concrete. The w/c ratio used for the normal strength steel fiber reinforced concrete mixes (NSSFRC) was 0.55, and the water-cementitious ratio (w/c+s) for the high strength fiber reinforced concrete mixes (HSSFRC) was 0.31. For each mix, three test cylinders were tested for compression specific toughness. The effect of fiber reinforcement index: volume of fibers × length/diameter ratio on compression specific toughness and also on the relationship between these two properties is presented in this paper. As a result, (a) equations are proposed to quantify the effect of fibers on compression toughness ratio of concrete in terms of FRI, (b) equations obtained in terms of FRI and compression specific toughness of plain concrete to estimate both compression specific toughness of NSSFRC and HSSFRC (N.m), (c) equations obtained which represent the relationship between compression toughness index and FRI for NSSFRC and HSSFRC, respectively, and (d) equations obtained to quantify the relationship between compression specific toughness index and fiber reinforcement index for NSSFRC and HSSFRC, respectively. The proposed equations give good correlation with the experimental values.
This paper investigates the effects of cement content and water/cement ratio on workable fresh concrete properties with slump changing between 90 to 110 mm, and determines the relations among fresh concrete properties such as slump, compacting factor, VeBe, unit weight and setting times of mortar with temperature history. The experiments were conducted under laboratory conditions on eight different concrete mixtures prepared from ordinary Portland cement (cement contents of 300, 350, 400, 450, 500, 550, 600 and 650 kg/m3) and crushed limestone coarse and fine aggregates. Relations such as (a) VeBe time/unit weight/slump/K-slump/compacting factor/w/c ratio for cement content, (b) K-slump/compacting factor/unit weight/VeBe time for slump, (c) aggregate/cement ratio/unit weight/VeBe time for compacting factor, and (d) penetration resistance for elapsed time were determined. It was observed that increasing the cement content causes increase in the slump, K-slump, compacting factor and fresh concrete unit weight, and reduces VeBe time. Proposed fresh concrete relationships are quite appropriate for concretes without using any mineral or chemical admixtures. Key words: Fresh concrete, slump, compacting factor, VeBe time, unit weight, setting time.
This paper presents the results of an investigation on the effect of Portland cement replaced by fly ash or granulated blast-furnace slag on the concrete strength at different curing temperatures. Compressive strength results are analysed according to the hyperbolic strength-age function by introducing a power indexn. The regression analysis is done considering different n values andt o (final setting times) values.
Naturally concrete shrinks when it is subjected to a drying environment. If this shrinkage is restrained, tensile stresses develop and concrete may crack. Plastic shrinkage cracks are especially harmful on slabs. One of the methods to reduce the adverse effects of shrinkage cracking of concrete is by reinforcing concrete with short randomly distributed fibers. The main objective of this study was to investigate the effect of fiber volume and aspect ratio of hooked steel fibers on plastic shrinkage cracking behavior together with some other properties of concrete. In this research two different compressive strength levels namely 56 and 73 MPa were studied. Concretes were produced by adding steel fibers of 3 different volumes of 3 different aspect ratios. From this research study, it is observed that steel fibers can significantly reduce plastic shrinkage cracking behavior of concretes. On the other hand, it was observed that these steel fibers can adversely affect some other properties of concrete during fresh and hardened states.
In this lecture note it has been tried to gather a lot of data about advanced materials of construction in different aspect.
Abstract Using Test Method for Time of Setting of Concrete Mixtures Paste by Penetration Resistance (ASTM C 403), Proctor penetration resistance was determined under isothermal curing temperatures ranging from 6 to 80°C for concretes containing up to 50% of fly ash or ground-granulated blast-furnace slag. The results show that as the temperature increases, the initial and final setting times decrease for all types of concrete, with fly-ash concrete having the longest setting times. At high temperatures, slag concrete has shorter setting times than Type I cement concrete. Relationships are presented for setting time as a function of penetration resistance, temperature, and cement replacement level.
Sulfur concrete represents a promising sustainable alternative to traditional Portland cement due to its rapid setting time, superior chemical resistance, and recyclability. Nonetheless, inherent brittleness and susceptibility to long-term deterioration limit broader applications, necessitating effective modifiers to improve mechanical and durability performance. This study investigates the influence of incorporating high density polyethylene (HDPE) and linear low-density polyethylene (LLDPE) at dosages of 5, 10, 15, and 20 wt.% into sulfur concrete containing 30 wt.% sulfur. Comprehensive evaluations included mechanical testing (compressive, flexural, and tensile strength), non-destructive testing methods (ultrasonic pulse velocity and rebound hammer), accelerated corrosion assessments via impressed voltage technique, and microstructural analyses (SEM, FTIR, and XRD). Results revealed optimum mechanical performance at 5 wt.% polymer content, with LLDPE modification achieving maximum compressive, flexural, and tensile strengths of 25.24 MPa, 3.31 MPa, and 1.75 MPa, respectively, compared to the control’s 20.6 MPa, 2.75 MPa, and 1.21 MPa. Corrosion resistance significantly improved with polymer additions, notably at 20 wt.% LLDPE exhibiting the lowest current intensity (~0.03 A). SEM analysis confirmed enhanced matrix density with HDPE modification, whereas FTIR and XRD analyses indicated no chemical interactions, affirming physical blending. These findings highlight that carefully selected polymer modifications significantly enhance the mechanical integrity and durability of sulfur concrete for sustainable infrastructure applications.
Abstract There are many test methods to measure the impact resistance of fiber-reinforced concrete that are complicated, time consuming, and expensive. A practical test method has been developed to measure the impact resistance of high-strength fiber-reinforced concrete (HSFRC). The equipment developed can also be used for testing aggregate impact values by simply changing the base plate of the machine. A machine was developed to measure the surface abrasion resistance of HSFRC. Testing fiber-reinforced concrete for surface abrasion resistance was found to be extremely difficult if realistic and practical results were desired. In this study the influence of silica fume on the properties of HSFRC was investigated by using silica fume at two different percentages and with three different hooked-end fibers, namely, 30/0.50, 60/0.80, and 50/0.60 length/diameter (mm/mm). Fibers were added to concrete in three different percentages of 0.5, 1.0, and 2.0% by volume of concrete. The results show that including fibers in high-strength concrete improves impact resistance, surface abrasion, and splitting tensile strength.
Copper mining and processing activities at an abandoned mine in the Lefke-Xeros area of Cyprus have created a huge environmental contamination problem in the locality. As an alternative mitigation and management measure, we reported in previous studies that these tailings could be used as a concrete making material. In this paper, results of an experimental investigation of the reinforcement corrosion performance and cost efficiency of 0.57 and 0.50 w/b ratio concrete containing copper tailings either as a cement replacement or an additive material are presented. The time to initiation of corrosion and half-cell potential (HCP) of reinforcements were measured. Actual corrosion status of extracted reinforcement bars was also verified by visual inspection. Results showed that while early corrosion initiation occurred in some samples containing tailings as a cement replacement material, delayed corrosion initiation was observed in all samples containing copper tailings as an additive. Although HCP values became slightly more electronegative as tailings content of samples increased, no substantial reinforcement corrosion was observed. Based on corrosion performance and cost efficiency analyses, utilization of 5% pre-wetted tailings either as a cement replacement or an additive material is the best tailings reuse approach. Increased tourism-related businesses associated with reduced pollution of the Lefke-Xeros coastal area would have a positive impact on the socioeconomic status of the community.
