Durability Of Cement Concrete Research Articles

Investigating the Sway of Marine Brown Seaweed Gel as Natural Polymer in Properties of Concrete

In the present study, the effects of the fresh properties as slump, consistency and setting time and hardened concrete's characteristics such as compressive, split tensile and flexural strength for various ages, the brown seaweed (Sargassum wightii) gel was added to cement throughout differing proportions (1, 2, 3, 4 and 5%) by the mass of concrete. Durability and thermal tests such as water absorption, sorptivity, RCPT, acid attack and thermal conductivity also determined at various ages. Micro structural properties of seaweed gel were found out by SEM, FTIR and XRD analysis. Test results show that seaweed gel act as retarding admixture in cement up to 5% of addition. For instance, 5% alginate collections as a percentage of concrete mass showed a comparable compressive strength of about 42MPa. The use of seaweed gel improved the thermal characteristics of concrete by reducing its thermal conductivity roughly 50% for a 5% addition. The seaweed gels up to 5% addition in concrete will significantly improve the fresh-state properties of concrete without affecting its hardened properties. The future is completely dependent on eco-friendly materials; hence the use of natural organic additives to improve the strength and durability of cement concrete would be the better option for sustainability.

Mechanical Properties of Cement Concrete with Waste Rubber Powder

To investigate the mechanical properties of cement concrete incorporating waste rubber powder, the response surface methodology was employed. The Box–Behnken central composite design was applied to analyze the three primary factors influencing the road performance of cement concrete containing waste rubber powder: the water–cement ratio, sand ratio, and waste rubber powder content. The study determined the impact of these factors on the flexural strength of waste rubber powder cement concrete at both 7 and 28 days. Additionally, the effects of the water–cement ratio, sand ratio, and waste rubber powder content on the performance of cement concrete were analyzed. To investigate the impact of waste rubber powder on cement concrete, various mechanical property tests were conducted, including compressive, flexural, dynamic elastic modulus, and impact performance tests. Furthermore, the study explored the influence of waste rubber powder on the noise reduction capacity of cement concrete using both the rubber ball impact method and ultrasonic method. Lastly, the durability of cement concrete with added rubber powder was assessed through shrinkage tests, frost resistance tests, and chloride ion penetration tests.

The Effect of Municipal Solid Waste Incineration Ash on the Properties and Durability of Cement Concrete.

The aim of this study is to investigate the effect of municipal solid waste incineration bottom ash from a cogeneration plant on the physical and mechanical properties and durability of cement concrete. Part of the cement in concrete mixtures tested was replaced with 0%, 3%, 6%, 9%, and 12% by weight of municipal solid waste incineration bottom ash. Concrete modified with 6% of bottom ash had a higher density (2323 kg/m3), compressive strength at 28 days (36.1 MPa), ultrasonic pulse velocity (3980 m/s), and lower water absorption rate (3.93%). The tests revealed that frost resistance, determined in all-sided testing directions, of concrete modified with 6%, 9%, and 12% of bottom ash added by weight of cement corresponds to strength grade F100. Such concrete can be used in construction works.

Effect of Bio-Inspired Polymer Types on Engineering Characteristics of Cement Composites.

Cement concrete is the most commonly used building and construction material worldwide because of its many advantages. Over time, however, it develops cracks due to shrinkage and tension, which may lead to premature failure of the entire structure. Recently, the incorporation of polymers has been explored to improve the overall strength and durability of cement concrete. In this study, two types of chitosan-based bio-inspired polymers (a-BIP and b-BIP) were synthesized and mixed with cement mortar in different proportions (5–20%). The fluidity of the resulting mixtures and the properties of the hardened samples, such as the compressive and tensile strengths, drying shrinkage, and carbonation resistance, were evaluated. The characteristics of the polymers were tuned by varying the pH during their syntheses, and their structures were characterized using nuclear magnetic resonance spectroscopy, Fourier-transform infrared spectroscopy, and ultraviolet-visible spectroscopy. After 28 days of aging, all samples containing BIPs (35.9–41.4 MPa) had noticeably higher compressive strength than the control sample (33.2 MPa). The tensile strength showed a similar improvement (up to 19.1%). Overall, the mechanical properties and durability of the samples were separately dependent on the type and amount of BIP.

Structure, Impermeability and Durability of Cement Concrete

The paper presents the main hypotheses of frost destruction of cement concrete. The influence of cyclic temperature changes and the effect of static and dynamic (shock) loads on concrete on changes in the structure and strength of concreteis considered. The paper provides results of comparative tests of frost resistance of concrete containing a porous additive and a plasticizer, which contribute to an increase in the density and impermeability of its structure. It has been shown experimentally that the introduction of air-entraining additives with an additional effect of hydrophobization is productive from the standpoint of ensuring frost resistance of concrete of relatively low classes (up to C30/37), compressive strength up to 50 MPa and water absorption by mass more than 4.0 %. It is advisable to increase the frost resistance of concrete with greater impermeability and strength by increasing these indicators, in particular, due to the maximum decrease in the initial water content and high-quality compaction. This conclusion is experimentally confirmed by the data presented in the paper, since the “mechanism” of frost destruction of cement concrete is multifactorial, and the growth of its density (impermeability) and strength provide a higher ability to resist “force” effects associated with repeated alternating deformations of concrete, as well as the action of external loads, accumulation of fatigue phenomena, hydrodynamics of liquid filtration under the influence of changing temperature fields, etc. A comparative assessment of concrete frost resistance has been carried out using standardized and patented techniques containing a porous (air-entraining) additive, as well as plasticizing and mineral additives of amorphous micro-silica, introduced into concrete in order to increase its density, impermeability and strength and on this basis – increasing frost resistance. Experimental data are presented, reflecting the relationship and patterns of decrease in frost resistance of concrete subjected to the simultaneous action of static (for compression – different levels from the corresponding indicator of concrete strength) and shock, concentratedly applied dynamic loads. The regularity of the relationship between the accelerated frost destruction of concrete and the action of mechanical loads that cause cracking in its structure has been confirmed.

Influence of Coarse Aggregate Type on the Mechanical Strengths and Durability of Cement Concrete

In this paper, the influence of coarse aggregate on the slump flow and the following mechanical strengths (flexural and compressive strengths), the shrinkage rate, the chloride penetration resistance, and the freeze–thaw resistance were investigated. Water–binder ratios in this study were 0.22, 0.30, 0.34, and 0.45. Sand ratio in this study was 0.45. All samples were cured for 7 d, 14 d, 28 d, and 56 d, respectively. Results indicated that the fluidity of cement concrete with different coarse aggregate increased in this order: gneiss < limestone < basalt < diabase. The mechanical strengths and shrinkage rate increased obviously with the increasing curing age when the curing age ranged from 7 days to 28 days. However, the mechanical strengths and shrinkage rate trended to a stable value when the increasing curing age increased from 28 days to 56 days. The mechanical strengths with different coarse aggregate increased in this order: diabase < basalt < limestone < gneiss. Meanwhile, the shrinkage rate demonstrated this trend of development: diabase < basalt < limestone < gneiss. The resistance to freeze–thaw cycles of cement concrete decreased with the increasing water–binder ratio. Meanwhile, the resistance to freeze–thaw cycles was closely related to the types of coarse aggregate.

Investigation on Durability Behaviour and Optimization of Concrete with Triple‐Admixtures Subjected to Freeze‐Thaw Cycles in Salt Solution

In the seasonal frozen area of northeast China, cement concrete is usually in a working environment of cold climate and chlorine erosion coupling effect. In general, with a reasonable addition of air entraining agent (AEA) and multimineral admixtures such as fly ash, blast furnace slag, and silica fume, the durability of cement concrete under the effects of freeze‐thaw and salt solution can be significantly improved in cold regions. However, due to several more compositions of cement concrete with multiple mineral admixtures, it would take excessive trial mixtures to select the desired mixture proportion based on the conventional method. This means a great deal of costs of raw materials and laboratory experimental time. In this paper, the experimental scheme of mixture proportion for air‐entrained concrete with multimineral admixtures was designed based on the orthogonal experiment design method. Based on the compressive strength, rapid chloride permeability, and weight loss and relative dynamic elastic modulus after salt freeze‐thaw cycles, the influence of different mineral admixtures and their dosages on the durability of concrete subjected to freeze‐thaw in salt solution was analyzed. After that, based on genetic algorithm, an optimization of mixture proportion was proposed, which only requires less trial mixes and accessible optimization process. The test results indicated the superiority of air‐entrained concrete with multimineral admixtures when serving in salt freeze‐thaw environment. Eventually, it was also verified that the optimized concrete in this paper could achieve pleasurable durability performances under salt freeze‐thaw cycles.

Influence of Hybrid Nano-Particles on Properties of Cement Mortar

Development of voids is one among the important properties that deprive the strength and durability of cement concrete. Voids not only been developed between heterogeneous ingredients of concrete but as well among the homogenous ingredients due to improper compaction and poor quality of materials etc. In this study, an attempt has been taken to study the effect of reduction in voids among the homogenous materials on strength properties of cement mortar. To counteract formation of voids, a Nano-material (Ceric Ammonium Nitrate H8N8CeO18) is being loaded over another Nano-material (Silica SiO2) each having different properties to act as a single Hybrid Nanomaterial (HN). Pore volume analysis, Infra-red test, and SEM analysis were performed to study the properties of HN. On the other hand, various tests like setting time, compressive strength and split tensile strength were performed on cement mortar specimens upon addition of HN by 3%, 5%, 7%and 10% by weight of cement. Results reveal that strength of mortar with HN is higher compared to mortar with Nano silica as well as conventional cement mortar specimens.

Checking the conformity of the grain-size composition of road cement concrete mixtures

The article is devoted to operational quality control of grainsize composition of cement-concrete road mixtures for use on highways of Ukraine. The results of the experimental research are presented, which testify to the non-conformity of the planned grain composition to the actual production composition, as well as the influence on it of a number of factors that significantly affect the quality of the mixture and the durability of cement concrete.

Durability of cement concrete under chemical erosion

This paper launches the study on how the sulfate particle and chloride ions interact to impact the concrete durability. It is analyzed that there is a diffusion law of two particles in concrete, whether the concrete presents corrosion resistance and permeability as contacts with them. The findings reveal that the content of chloride ions decreases with the deepening of the concrete profile. The presence of sulfate ions does not break up the diffusion trend of chloride ions in concrete, but in the case when Cl- and SO42- act together, the content of chloride ions at a constant profile depth is less than that under the action of a single Cl-. When sulfate ions permeate the cement, they will react with hydrate product of cement to generate new chemical substances that fill the inner pores of the cement, thereby suppressing the diffusion of chloride ions. The higher the concrete water-binder ratio, the lower the compression strength; the more inner pores, the weaker its resistance to chemical attack. When mineral admixtures are added to the concrete, the sulfate ions can react with the hydrate products of the cement and mineral admixtures to generate new crystals that largely fill the original pores in the concrete and make it more compact. In this way, the concrete corrosion resistance is built up. Concrete gets most vulnerable to sulfate attack at an ambient temperature of 21-24°C, and relieved at 30- 35°C. Lower relative humidity, high temperature environment are the decisive factors that accelerate the concrete erosion.

The Effect of Exposition Conditions on the Durability of Cement Concrete with Dolomite Aggregate Sourced Near Kraków, Poland

Some dolomite aggregates exposed to a wet environment may decompose. The presence of sodium, magnesium, calcium and sulfate ions in the corrosive medium and the higher temperature can increase the rate of aggregate decomposition.The results of a study on the impact of defined environmental exposition to a H2O, Mg(OH)2, MgSO4, Na2SO4 solutions in various temperature conditions on the susceptibility to dedolomitisation processes of cement concrete made with selected dolomite aggregate are presented in the paper. The observation of linear extension as well as changes in compressive strength and surface alteration due to corrosive exposition conditions were the key diagnostic features adopted for this examination.

Study on Freezing-and-Thawing Durability of Cement Concrete Based on Experimental Investigation of Air-Void Parameters

This paper studies the freezing-and-thawing durability of cement concrete on the basis of experimental investigation of air-void parameters, which has a significant influence on the durability of concrete. More specifically, this research firstly discusses the effect of air-entraining agent types on the air-void parameters feature, and then a rapid freezing-and-thawing test is conducted to assess the durability of the concrete specimens, so as to observe the relationship between the frost resistance performance evaluation index, which is applied as durability factors in this study, and the air-void parameters of concrete, such as the air void spacing factor and the air content of cement concrete.