scholarly journals Influence of compressive strength and maturity conditions on shrinkage of ordinary concrete

2021 ◽  
Vol 13 (6) ◽  
pp. 168781402110244
Author(s):  
Olga Szlachetka ◽  
Joanna Witkowska-Dobrev ◽  
Marek Dohojda ◽  
Anna Cała
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Drying Shrinkage ◽  
Point Of View ◽  
Early Age ◽  
Volume Changes ◽  
Ordinary Concrete ◽  
Dry Conditions ◽  
Total Elimination

The paper presents results of investigations of compressive strength and shrinkage of concrete samples made on the basis of the Portland cement CEM I 32.5R, after 2, 7, 14, 28, 90, and 365 days of maturation in four different maturation conditions. It was shown that after 28 days the samples cured according to the standard in the cuvettes with water achieved the highest compressive strength, although the early-age compressive strengths after 7 and 14 days were lower than those for the samples cured in building film and in dry conditions. A determined correlation between the compressive strength and shrinkage of the concrete proves that wet curing also allows a total elimination of the shrinkage in the first 28 days. Along with the growth of the compressive strength, the drying shrinkage reduces. Obtained results confirmed that the best way of concrete curing, among the analyzed methods, from the point of view of both compressive strength and volume changes is the wet curing.

Compressive Strength and Shrinkage Behavior of Concrete Produced from Portland Limestone Cement with Water Absorption Polymer Balls

2020 ◽  
Vol 857 ◽  
pp. 83-88
Author(s):  
Ikram F. Ahmed Al-Mulla ◽  
Ammar S. Al-Rihimy ◽  
Mushriq F. Al-Shamaa
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Water Absorption ◽  
Ordinary Portland Cement ◽  
Drying Shrinkage ◽  
Internal Curing ◽  
Early Age ◽  
Portland Limestone Cement ◽  
Limestone Cement ◽  
Shrinkage Behavior

From the sustainability point of view a combination of using water absorption polymer balls in concrete mix produce from Portland limestone cement (IL) is worth to be perceived. Compressive strength and drying shrinkage behavior for the mixes of concrete prepared by Ordinary Portland Cement (O.P.C) and Portland limestone cement (IL) were investigated in this research. Water absorbent polymer balls (WAPB) are innovative module in producing building materials due to the internal curing which eliminates autogenous shrinkage, enhances the strength at early age, improve the durability, give higher compressive strength at early age, and reduce the effect of insufficient external curing. Polymer balls (WAPB) had been used in the mixes of this research to provide good progress in compressive strength with time. Water absorption polymer balls have the ability to absorb water and after usage in concrete it will spill it out and shrink leaving voids of their own diameter before shrinking that lead to provide internal curing. The required quantity of water for the mixes were reduced due to the addition of water from the absorption polymers. Mixes produced from Portland limestone cement in this research show drying shrinkage results and compressive strength results lower than mixes made from ordinary Portland cement.

Effect of Combination of Admixture on the Development of Selected Properties of Concrete and their Comparison

2016 ◽  
Vol 865 ◽  
pp. 206-210
Author(s):  
Klára Křížová ◽  
Rudolf Hela
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Portland Cement ◽  
Modulus Of Elasticity ◽  
Early Age ◽  
Ordinary Concrete ◽  
Guide Value

The paper is involved with effects of admixtures (fly ash, slag) and their combination on selected properties of ordinary concrete. The set of concrete covers seven different containing of Portland cement and approximately 10% of admixed slag and concrete with fly ash and slag contents up to 42 %. At early age of the concrete balanced values of compressive strength were obtained except the concrete with admixture combinations. And on the contrary at 28-day age the concrete with admixture combinations obtained comparable values like concrete with only one type of admixture. The compressive strength was monitored together with modulus of elasticity to 180-day age of the concrete. In the last phase the obtained values were compared with guide value where the slower development of theses parameters with applied admixtures was pointed out.

scholarly journals Autogenous and drying shrinkage of mortars based on Portland and calcium sulfoaluminate cements

2020 ◽  
Vol 53 (5) ◽  
Author(s):  
Davide Sirtoli ◽  
Mateusz Wyrzykowski ◽  
Paolo Riva ◽  
Pietro Lura
Keyword(s):  
Portland Cement ◽  
Water Demand ◽  
Ordinary Portland Cement ◽  
Rapid Evolution ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
High Water ◽  
Early Age ◽  
Volume Changes ◽  
Calcium Sulfoaluminate

Abstract Calcium sulfoaluminate (CSA) cement can be used as an alternative binder in concrete, partially or fully replacing ordinary Portland cement. While CSA cement considerably accelerates the mechanical properties development, the rapid evolution of the microstructure together with the high water demand cause rapid and large volume changes at early ages. As volume changes may lead to early-age cracking, measures to reduce them may be required In this paper, autogenous and drying shrinkage are studied in mortars prepared with Portland cement, CSA cement or a 50/50 blend as binder. Very fast self-desiccation and high autogenous shrinkage of the CSA-based mortar were observed compared to the mortar made with Portland cement. On the other hand, the early-age volume changes can be limited if a blend of the two cements is used. The blended system revealed a bi-modal trend in the evolution of self-desiccation and autogenous shrinkage, in which the initial fast self-desiccation and shrinkage enter the dormant phase after the first couple of days and again start after about 28 days.

scholarly journals Influences of shrinkage reducing admixture on the mechanical properties, drying shrinkage, water absorption and porosity of Portland cement mortar

2021 ◽  
Vol 15 (3) ◽  
pp. 55-67
Author(s):  
Nguyen Van Chinh
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Portland Cement ◽  
Water Absorption ◽  
Drying Shrinkage ◽  
Effective Porosity ◽  
Minor Effect ◽  
Wide Range ◽  
Shrinkage Reducing Admixture ◽  
A Minor

Drying shrinkage is the main cause of early age cracking of concrete and mortar. A wide range of research has been conducted to reduce the drying shrinkage, including using fibres or chemical admixtures. This paper investigated the effect of shrinkage reducing admixture on the flexural strength, compressive strength, drying shrinkage, water absorption and porosity of mortar. The mix compositions were ordinary Portland cement (OPC) : sand : liquid = 1: 1: 0.38 in which liquid consisted of water and shrinkage reducing admixture (SRA). SRA was used at the proportions of 2%, 4%, and 7% by weight of cement. The test results show that SRA reduces the flexural and compressive strengths of mortar. The reduction in flexural strength and compressive strength at 28 days is 14% and 25%, respectively at 7% SRA dosage. In addition, SRA significantly reduces the drying shrinkage and water absorption of mortar. At 7% SRA dosage, the drying shrinkage at 53 days is reduced by 60% while the water absorption rate at 24 hours is reduced by 54%. However, SRA has a minor effect on the pore size distribution, effective porosity, and cumulative intrusion volume of mortar.

scholarly journals Characteristics of Hollow Compressed Earth Block Stabilized Using Cement, Lime, and Sodium Silicate

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Walid Edris ◽  
Faris Matalkah ◽  
Bara’ah Rbabah ◽  
Ahmad Abu Sbaih ◽  
Reham Hailat
Keyword(s):  
Compressive Strength ◽  
Portland Cement ◽  
Sodium Silicate ◽  
Low Cost ◽  
Construction Material ◽  
Early Age ◽  
Compressed Earth Block ◽  
Earth Block ◽  
Lower Production ◽  
Northern Jordan

Abstract This research aims to produce a Compressed Earth Block (CEB) product using locally available soil collected from northern Jordan. The CEB mixture was further stabilized using Portland cement, lime, and sodium silicate. The research significance is based upon the urgent need of most developing countries (e.g. Jordan, Egypt…etc) to build more durable and low-cost houses by using locally available materials. As a result, CEB was identified as a cheap and environmentally friendly construction material. CEB specimens were thoroughly characterized by studying the mechanical properties and durability characteristics. Blocks of 30 x 15 x 8 cm with two holes of 7.5 cm in diameter have a potential for higher enduring, higher compressive strength, better thermal insulation, and lower production cost. Blocks were manufactured with an addition of 8 % for either Portland cement or lime, as well as 2 % of sodium silicate to the soil. The results showed that the addition of 8 % of cement to the CEB achieves satisfactory results in both mechanical and durability properties. Also, the addition of sodium silicate was found to enhance the early-age compressive strength however it affected negatively the durable properties of blocks by increasing the erosion rate and deterioration when exposed to water.

scholarly journals Preparation and properties of magnesite aggregate radiation - proof concrete

2018 ◽  
Vol 175 ◽  
pp. 01003
Author(s):  
Bingquan Sun ◽  
Jiajia Sun
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Pore Structure ◽  
Water Content ◽  
Radiation Protection ◽  
Point Of View ◽  
Crystal Water ◽  
Ordinary Concrete ◽  
Mixing Water

This paper, from the point of view of improving compactness of density and crystal water content of radiation-proof concrete, using magnesite with high crystal water content as aggregate and alkaline potential water as mixing water, prepared ordinary density radiation-proof concrete and studied its mechanical properties, resistivity and pore structure. The results show that, compared to base ordinary concrete, the prepared concrete has better 28d compressive strength and resistivity, overall porosity decreases by 17%, and pore gradation at all ages improves significantly. It is indicated that the prepared magnesite aggregate radiation concrete has good density and durability, improves concrete radiation protection performance.

Influence of Early Age Volume Changes on Long-Term Concrete Shrinkage

1998 ◽  
Vol 1610 (1) ◽  
pp. 28-32 ◽  
Author(s):  
Erika E. Holt ◽  
Donald J. Janssen
Keyword(s):  
Concrete Slab ◽  
Drying Shrinkage ◽  
Early Age ◽  
Volume Changes ◽  
Test Procedures ◽  
Cracking Behavior ◽  
Concrete Shrinkage ◽  
Cracking Potential ◽  
Partially Restrained

Volume changes can occur in concrete during the first 24 hr and are generally missed in laboratory shrinkage evaluations. Unfortunately these early age volume changes are present in real pavements and structures and can contribute to the cracking behavior of the concrete at later ages. Early age volume changes can occur in two forms: drying shrinkage before the start of curing and autogenous volume changes. Although these early age volume changes are often dismissed as being insignificant, recent work in Europe has identified magnitudes for early age volume changes of some concretes that are equal to or greater than 28-day drying shrinkage measurements. Expansions have also been identified in some cases. The results of some investigations of volume changes in concrete during the first 24 hr under both drying and nondrying conditions are presented. An example of potential long-term cracking under partially restrained conditions (concrete slab-on-grade modeled by a concrete ring cast around a hollow steel ring) is used to illustrate the magnitude of influence of early age volume changes on concrete cracking. Both test procedures employ nonstandard methods to quantify the cracking potential of concrete.

Alkali Activation of Granulated Blast Furnace Slag

2010 ◽  
Vol 158 ◽  
pp. 1-11 ◽  
Author(s):  
Zi Qiao Jin ◽  
Xian Jun Lu ◽  
Shu Gang Hu
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Portland Cement ◽  
Blast Furnace Slag ◽  
Ordinary Portland Cement ◽  
Hydration Product ◽  
Early Age ◽  
Hydration Products ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

In order to stimulate the potential cementitious property of granulated blast furnace slag (GBFS), the ground GBFS sample (Wei Fang Iron and Steel Corporation, China) was activated by lime and gypsum under different dosages. The results showed that lime is an effective activator for the slag, and the optimum dosage of lime is about 10% (w/w) of the slag. At the optimum dosage of lime, the 28 days compressive strength of the lime-slag paste is higher than that of 32.5 ordinary Portland cement (OPC). But, the early age strength (3 and 7 days compressive strength) of the lime-slag paste is lower than that of the OPC. Addition of gypsum can effectively improve the early age strength of the lime-slag paste. At the ratio of gypsum:lime:slag of 8.2:9.2:82.6 (w/w), both the early and long-term compressive strengths of the gypsum-lime-slag paste are higher than that of the OPC. According to XRD, TG-DTA and SEM detections of the hydration products of the lime-slag paste, the gypsum-lime-slag paste and the OPC paste, it reveals that the hydration process of the GBFS-based cementitious material is different from the ordinary Portland cement and the presence of ettringite (AFt) contributes to the early age strength of the pastes. The major hydration product of the OPC paste (<7 days) were measured as ettringite (AFt), but the AFt phase was not detected in the hydration product of the lime-slag paste and the major hydration product of the lime-slag paste was determined as amorphous CSH gel. However, AFt was detected in the hydration products of the gypsum-lime-slag paste in the early stages of hydration, and the formation of AFt is favorable for the early strength improvement of the material.

Parameter Analysis of the Reinforcement for the Width and Spacing Control of the Early-Age Cracks in Concrete

2016 ◽  
Vol 691 ◽  
pp. 14-27
Author(s):  
Robert Sonnenschein ◽  
Juraj Bilčík ◽  
Katarína Gajdošová
Keyword(s):  
Drying Shrinkage ◽  
Peak Level ◽  
Parameter Analysis ◽  
Early Age ◽  
Reinforcing Bars ◽  
Volume Changes ◽  
Concrete Element ◽  
Thermal Movement ◽  
Cover Thickness ◽  
Crack Widths

Early-age volume changes in concrete induced by temperature change, hydration, autogenous and drying shrinkage can lead to concrete cracking and this can have lasting effects on serviceability, durability or aesthetics of the structure. The restraint to thermal movement is the product of the coefficient of the temperature fall from a peak level during cement hydration and a restraint factor. In most cases it is not necessary and also not economical to avoid cracks. In these cases, crack widths are limited due to water tightness, durability or aesthetic reasons. If early-age thermal cracking cannot be prevented, crack width can be controlled with reinforcement. The reinforcement distributes cracks and consequently reduces their widths and spacing. As a result, there forms a large number of smaller cracks instead of a few through-cracks. This means, that due to the formation of fine cracks, the strain capacity of a reinforced concrete element before the occurrence of through cracks can be increased with the help of skin reinforcement. This paper discusses the parameters of reinforcement affecting the width and spacing of early-age cracks in concrete. The effect of reinforcement on early-age cracking in concrete was investigated on numerical simulation and in full-scale experiments. The test variables were the reinforcement ratio and the cover thickness of the longitudinal reinforcing bars.

Experimental Research on Mechanical Properties of the early-Age Shotcrete

2011 ◽  
Vol 90-93 ◽  
pp. 2188-2192
Author(s):  
Nan Xie ◽  
Jie Ouyang ◽  
Bing Li ◽  
Jing Hui Lu
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Experimental Research ◽  
Early Age ◽  
Construction Sites ◽  
Exponential Relationship ◽  
Construction Period ◽  
Ordinary Concrete ◽  
Under Construction

Abstract. The compressive strength and elastic modulus of early-age shotcrete have important influence on the safety of tunnel during construction period. In order to investigate the laws of the mechanical properties of early-age shotcrete, experiments on the compressive strength and elastic modulus of early-age shotcrete with two different mixes used frequently on construction sites were carried out. The results show that the compressive strength and elastic modulus of shotcrete develop fairly rapidly and especially the development of elastic modulus of shotcrete is faster than that of ordinary concrete. There is an exponential relationship between the compressive strength and time as well as the elastic modulus development and time. Simultaneously their formulas were derived. The research results of this paper are not only helpful to understand the laws of the mechanical properties of early-age shotcrete, but also provide some reference for the reliability analysis of tunnel under construction.

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