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Early plastic shrinkage cracking of concrete is an important factor affecting the durability of modern concrete structures. Early cracking (within 24 hours after pouring) may become a problem for any concrete structure. It will promote the entry of harmful materials, destroy the beauty of concrete members, and reduce their durability and performance. In addition, due to long-term shrinkage and/or load, these cracks may gradually expand in the service life of components. Scientific research and engineering technicians often have to face the difficulties caused by early plastic shrinkage cracking of concrete. From the aspects of shrinkage mechanism, measurement method, prediction model and strength development, this paper reviews the scientific and technological status of plastic shrinkage and strength development of early-age concrete, and based on this, summarizes the important conclusions in existing research and establishes the relevant concrete strength prediction model.:1 Introduction 2. Shrinkage in concrete 2.1 Classification and mechanism of concrete shrinkage 2.2 Main factors causing concrete shrinkage 2.3 Concluding remarks 3. Plastic shrinkage in early age concrete 3.1 Method for determining the time of initial and final setting 3.2 Mechanism of plastic shrinkage 3.3 Evaporation 3.4 Capillary pressure 3.5 Main factors affecting plastic shrinkage cracking 3.6 Concluding remarks 4. Different methods for determining the resistance to plastic shrinkage cracking 4.1 Rectangular mould test setup 4.2 ASTM C 1579 4.3 Ring test method (NT BUILD 433) 4.4 Capillary pressure test 5. Development of early age strength of concrete 5.1 Mechanical properties 5.1.1 Compressive strength 5.1.2 Tensile strength 5.1.3 Early-age shrinkage of concrete 5.2 Test and prediction model evaluation 6. Test and quantitative model 6.1 pullout tests on early-age concrete 6.1.1 Tests principle 6.1.2 test result 6.2 Compilation of existing pullout capacity prediction models 6.2.1 Strength and pullout force model based on 𝒉𝒆𝒇 6.2.2 Strength and pullout force model based on 𝒉𝒆𝒇 and ∅𝒉 6.2.3 Tensile strength and pullout force model 6.3 Application of existing prediction model in early age concrete 7. Conclusions 8. Literature

The anterior cruciate ligament (ACL) originates from posterior part of the medial side of the lateral condyle of femur to anterior intercondylar notch between a transverse meniscal ligament and medial side of medial meniscus of tibia. Once ACL is disrupted, pain, effusion and atrophy are commonly observable and cause functional disability. Because of the functional limitations, athletic participation is severely restricted. ACL injury is more prevalent in physically active females compared to their male counterparts in the sports of basketball and soccer in high school and collegiate levels. Several attributes of females are considered risk factors for the higher ACL injury incidences and include: anatomy, physiology and neuromuscular/biomechanics. Among them, neuromuscular/biomechanics is the only modifiable risk factor. Performing neuromuscular training may change muscular strength profiles, which may lead to reduction in ACL injury incidence in female athletes. However, this principle was not fully examined. Also, neuromuscular compliance may play a role in muscular strength development and ACL injury incidences. Thus, the purpose of this dissertation was to investigate the effects of neuromuscular training compliance on muscular strength development and ACL injury incidence. The influence of hip abductor, hamstrings and quadriceps strength was examined in this project. The results of these studies indicate neuromuscular training is an effective intervention to reduce ACL injury incidence in female athletes, and there is an inverse dose-response relationship between compliance of the neuromuscular training and number of ACL incidences in female athletes. The effect of compliance on muscular strength development was inconsistent. The results of these studies support that compliance of neuromuscular training is a key to reduce ACL injury incidences; however, more studies are need to conclude neuromuscular training compliance effects on muscular strength development in female athletes.

no / Marls were identified from a range of European sources and assessed for their Cementation Index, as proposed by Eckel. Two were selected for calcination in a laboratory kiln; one from Folwark in Poland (CI 1.75) and one from Lillienfeld in Austria (CI 2.03). Analysis of historical documents, while not revealing precise kiln conditions, does suggest that they were such as not to yield complete decarbonation of the calcite. Consequently, a series of calcinations was undertaken in which the peak temperature control of the kiln was set in the range 730°C to 1100°C, with residence times in the range 150 to 1250 min. The airflow through the kiln was sufficient to maintain a minimum oxygen content of at least 12 %. The resulting clinker was ground to comply with the 19th century Austrian Norme. Pastes were produced at w/c = 0.65 and assessed for setting time and strength development (6 h to 1 year). Both parameters were highly dependent upon calcination conditions with both ¿low¿ and ¿high¿ calcinations producing slower setting and slower strength development than intermediate conditions. Two strength development profiles were identified; one being the expected continuous increase of strength, albeit with a declining rate of increase with time, while the other showed a three-step sequence of high initial strength, a dormant period which could last for many weeks and a final increase in strength to an age of one year. The cements were compared using X-ray diffraction (XRD). Considerable variation in the composition was noted and related to the calcination conditions. Of particular interest is the formation of both ¿'-belite and ß-belite under differing calcination conditions. Clinker particles were also compared using the SEM in back-scattered electron imaging mode and the development of morphology observed.

Concrete is one of the world's most widely used building materials,but due to the high carbon dioxide emissions produced by the concretecomponent Portland cement, there is a growing need of alternativeconcrete recipes that require less portland cement. When you replace aportion of the Portland cement in the concrete recipe with an additivematerial such as granulated blast furnace slag, the carbon dioxideemissions decrease, but the strength growth becomes slower. Inconcrete casting, there are currently several working methods foraccelerating strength growth and the purpose of this work is toinvestigate the effect that various hardening accelerating measureshave on slag-based concrete. The work is limited to studying buildingproduction and focuses on the structural parts concrete slabs, wallsand filigree slabs. The study was carried out in collaboration withSkanska AB.To investigate the effect of different hardening accelerating measureson slag-based concrete, concrete casting simulations are compared inthe software Produktionsplanering Betong (PPB). The measures that arestudied in different variations are heating coils, external heating,insulation and elevated casting temperature. A total of 114simulations are planned, which include variations of the investigatedmeasures, outdoor temperature and design geometry. A survey is alsoconducted with the purpose to assess how hardening acceleratingmeasures are applied in swedish building production today. The surveyis spread with a geographical spread to five of the largesthouseproducing construction groups in Sweden. The result of thesimulations performed is that the measure heating loops has achievedthe best result where its effect has been optimized for eachindividual case. The results indicate that heating coils, incombination with insulation, are an effective measure. At the sametime, the survey shows that there is annoyance with the methods thathave proven effective in the simulations performed. Although it is notpossible to draw a conclusion about a universal solution to compensatefor the slower hardening time of the slag concrete, the results stillindicate that today's construction industry has good conditions for atransition to a more environmentally friendly concrete. / Betong är ett av världens mest använda byggmaterial, men på grund av den stora haltkoldioxidemissioner betongkomponenten cement producerar så finns ett ökandebehov att tillämpa betongrecept som kräver mindre cement. Då man ersätter en andelav portlandcementet i betongreceptet med ett alternativt tillsatsmaterial somgranulerad masugnsslagg, minskar koldioxidemissionerna, men hållfasthetstillväxtenblir långsammare. Vid betonggjutning finns i dag flera arbetsmetoder för att påskyndahållfasthetstillväxten och syftet med detta arbete är att undersöka vilken effekt dessaolika härdningspåskyndande åtgärder har på slaggbaserad betong, även kalladslaggbetong. Arbetet begränsas till att studera husproduktion och fokuserar påkonstruktionsdelarna platta på mark, väggelement och filigranbjälklag. Studien ärutförd i samarbete med Skanska Sverige AB.För att undersöka vilken effekt olika härdningspåskyndande åtgärder har påslaggbetong jämförs betonggjutningssimuleringar i programvaranProduktionsplanering Betong, (PPB). Slaggbetongen som undersöks är Skanska GrönBetong, och åtgärderna som huvudsakligen studeras är olika variationer avvärmeslingor, extern uppvärmning, isolering och höjd gjutningstemperatur. 114stycken simuleringar planeras totalt, vilka inkluderar variationer av de undersöktaåtgärderna, uteluftstemperatur och konstruktionsgeometri. En enkätundersökningutförs även med syfte att bedöma hur härdningspåskyndande åtgärder tillämpas isvensk husproduktion idag. Enkäten sprids med en geografisk spridning till fem avde största husproducerande byggkoncernerna i Sverige. Resultatet av de utfördasimuleringarna är att åtgärden värmeslingor uppnått bäst resultat där dess effekt varitoptimerad för varje enskilt fall. Resultatet tyder på att värmeslingor i kombinationmed isolering, är en effektiv åtgärd. Samtidigt visar enkätundersökningen att det finnserfarenhet av de metoder som visat sig effektiva i de simuleringar som utförts. Trotsatt det ej går att dra en slutsats om en allmängiltig lösning för att kompensera förslaggbetongens långsammare härdningstid, tyder ändock resultatet på att dagensbyggindustri har goda förutsättningar för en övergång till en miljövänligare betong.

Ultra-high performance concrete (UHPC) has progressively gained interest because of its favorable strength and durability properties. Literature shows that curing temperature has a significant effect on the resultant mechanical properties of UHPC, generally resulting in increased compressive strength. However, limited datasets are currently available to ascertain the degree of change related to compressive strength as a function of curing temperature and conditions. This study investigates the effect of isothermal and submerged curing temperature conditions, ranging from 10°C to 90°C, on the compressive strength and elastic modulus development of UHPC and generates a numerical model to capture these effects. The extent and rate of compressive strength development in Cor-Tuf UHPC was found to increase with curing temperature, while only the rate of elastic modulus development increased with curing temperature. The numerical model shows reasonable agreement when compared with the experimental results and was successfully implemented in finite element analysis software.

Vid underhållsarbeten av trafikerade tunnlar stängs trafiken av. Därav sker dessa arbeten oftast nattetid. För att kunna släppa på trafiken igen så snabbt som möjligt eftersträvas effektiva förstärkningsarbeten. Av säkerhetsskäl kan utökade hållfasthetskrav förekomma för sprutbetong som förstärkningsmetod. Om betongen hinner uppnå det krav som ställs för hållfastheten snabbare kan antal nätter som tillägnas förstärkningsarbeten reduceras. Detta examensarbete ska undersöka hur olika tillsatser av typen acceleratorer kan påskynda den tidiga hållfasthetsutvecklingen för sprutbetong. Utav de acceleratorer som utreds ska en slutsats kunna dras om dessa typer av tillsatser lämpar sig för förstärkningsmetoden våt sprutbetong. För att utreda acceleratorernas påverkan på sprutbetong har fullskaliga tester utförts. Vid testning sprutades olika betongrecept i testlådor. På lådorna kunde sedan hållfasthetstester utföras enligt gällande standarder. Testerna undersöker endast betongens tidiga hållfasthet, vilket blir en av arbetets avgränsningar. Resultatet av testerna visas i form av grafer och diagram. Därefter diskuteras metodernas osäkerhet och hur skiljande parametrar påverkar resultatet. Ur graferna kan en positiv effekt utläsas för recepten med tillsatt hållfasthetsaccelerator jämfört med recepten där endast sprutbetongaccelerator användes. Den positiva trenden syns tydligast inom de första fyra timmarna, efter detta framträder osäkerheten i mätvärdena. Slutsatser om acceleratorernas verkan för hela testet kan inte dras utan en statistisk hypotesprövning mellan de olika recepten. En sådan prövning utesluter om det statistiskt går att skilja resultaten åt. Dessutom rekommenderas företaget utföra mindre kompletterande tester på provkroppar i laborativ miljö, där skiljande parametrar kan elimineras och säkrare utdata erhållas. / During maintenance work in trafficked tunnels, the traffic must be halted. Therefore, such efforts often take place night-time. In order to enable a quick release of traffic again, it is crucial to have an effective reinforcement work. Due to the safety risks of using shotcrete as a reinforce method, there is a chance of adding additional strength-requirement can exist due to safety risks. If the concrete achieves the strength requirements sooner than expected, the number of nights dedicated to maintenance work can be reduced. This study intends to investigate how different types of admixtures, so called accelerators, can expedite the shotcrete’s initial strength development. Furthermore, the study will include a conclusion of the suitability for the accelerators that have been applied in the shotcrete. To investigate the effects of these accelerators, extensive tests has taken place. During these tests, shotcretes with different recipes were sprinkled into test boxes. Thereafter, tests of strength development could be performed on these boxes in agreement with prevailing standards. To delimitate the study, the selected methods only show the early strength-development of shotcrete. The results from these tests will be presented in graphs. Uncertainties regarding measurement data and how separated physical parameters affect the test results will be discussed as well. By reading the data presented in the graphs, a positive development can be identified in recipes with added hardening accelerators compared to recipes containing only shotcrete accelerators within the first four hours. Following the first four hours, a significant uncertainty in measurements will be noticed. Finally, due to high irregularity in measured values, conclusions of the accelerators’ effect cannot be confirmed solely by the results from these tests. Therefore, a hypothesis trial is necessary as it would exclude if the recipes statically can be separated. Furthermore, the company recommends performing additional small-scale tests in a laboratory environment. Through laboratory tests, a more certain result can be received.

This thesis presents how to establish a theoretical model to predict risk of thermal cracking in young concrete when cast on ground or an arbitrary construction. The crack risk in young concrete is determined in two steps: 1) calculation of temperature distribution within newly cast concrete and adjacent structure; 2) calculation of stresses caused by thermal and moisture (due to self-desiccation, if drying shrinkage not included) changes in the analyzed structure. If the stress reaches the tensile strength of the young concrete, one or several cracks will occur. The main focus of this work is how to establish a theoretical model denoted Equivalent Restraint Method model, ERM, and the correlation between ERM models and empirical experiences. A key factor in these kind of calculations is how to model the restraint from any adjacent construction part or adjoining restraining block of any type. The building of a road tunnel and a railway tunnel has been studied to collect temperature measurements and crack patterns from the first object, and temperature and thermal dilation measurements from the second object, respectively. These measurements and observed cracks were compared to the theoretical calculations to determine the level of agreement between empirical and theoretical results. Furthermore, this work describes how to obtain a set of fully tested material parameters at CompLAB (test laboratory at Luleå University of Technology, LTU) suitable to be incorporated into the calculation software used. It is of great importance that the obtained material parameters describe the thermal and mechanical properties of the young concrete accurately, in order to perform reliable crack risk calculations.  Therefore, analysis was performed that show how a variation in the evaluated laboratory tests will affect the obtained parameters and what effects it has on calculated thermal stresses.

Vid gjutning av bostadsbjälklag är formbyggnad och stämprivning ett viktigt moment. Inombyggbranschen råder vissa tveksamheter angående när och hur stämpen skall rivas. Instruktioner förhur det skall gå till finns att tillgå men de är ofta svårtolkade och i viss mån utdaterade. Det leder tillatt de i många fall inte följs. Hjälpmedel som mätinstrument och simuleringsprogram för detta finnsmen används sparsamt. För att undvika olyckor och säkerställa att betongens hållfasthet är tillräckligutan hjälpmedel används överdrivna tidsmarginaler och detta leder sannolikt till att stämp blirståendes längre än vad som krävs.Under arbetets gång studeras stämp och gjutningsprocessen i detalj för att kunna skapa en tydligbild över hur de ingående faktorerna vid valvgjutningar påverkar varandra. Syftet är att föreslå enlämplig tidpunkt för stämprivning vid valvkonstruktioner. Detta utförs för att kunna avgöra ifall detfinns någon större förbättringspotential, dels när det gäller att motverka slösaktighet av resurser ochförbättra arbetsmiljön men även för att se över instruktionerna för tillvägagångssättet vidformrivning.De metoder som används för att nå resultatet är:● Litteraturstudie av de dokument som beskriver tillvägagångssättet vid stämprivning.● Mätningar med instrument som beräknar hållfasthet vid gjutningar av bostadsbjälklag.● Simuleringar av hållfasthet i programmet Hett 11.● Intervjuer av sakkunniga inom branschen.Resultatet av studien visar på stora skillnader mellan hur länge stämpen står i praktiken och hurlänge de enligt teorin behöver stå. En anledning till detta är att uttorkningstiderna är styrande underproduktionen. Detta medför att högre betongkvaliteter och snabbare härdningstider än de somprojekterades används i byggandet, speciellt vid låga temperaturer. Slutsatsen är att det finnsförbättringspotential inom området. Säkerhetsstämpning kan utföras endast ett par dagar eftergjutning vid goda förhållanden. Fördelarna med detta är att antalet stämp kan minskas, vilket ledertill minskade hyror, samt att framkomligheten för kommande yrkesgrupper och arbetsmoment kanförbättras. / When casting a residential floor, formwork and shore removal is an important element. There aresome doubts in the industry about when and how to remove the shores. There are instructionsavailable but they are often outdated and difficult to interpret. As a result, they are often notfollowed. Appliances such as measuring equipment and simulation software are available but areused sparingly. To avoid accidents and to ensure that the strength of the concrete is sufficientwithout appliances, excessive time margins are used. This will most likely result in unnecessarily longshoring times.During the course of the work, the subject will be studied in detail to create a clear picture of howthe many different factors of the casted floor influence each other. The purpose is to propose asuitable time to remove the shores. This is done in order to determine if there is improvementpotential, partly to improve the working environment, but also to review the instructions of theapproach.The methods used to reach the result are:• Study of the documents describing the procedure of shoring and reshoring• Calculate the compressive strength of the concrete with the device “BI Distant”• Simulate the compressive strength of the concrete in the program Hett 11.• Interviews by experts in the industry.The results show that the shores could theoretically be removed earlier compared to when they areusually removed in practice. One reason for this is that drying times are governing during theproduction. This means that increased concrete qualities and faster curing times than those thatwere planned, were used in construction, particularly at low temperatures. The conclusion is thatthere is an improvement potential in this area. Reshoring can be done only a few days after castingunder good conditions. The advantages of this are that the number of shores can be reduced. Thisleads to reduced rents, and the accessibility for the subsequent professionals and operations can beimproved.

Betong är ett av världens mest använda byggnadsmaterial, men kan också vara en stor miljöbov. Cementklinker är en betydande beståndsdel i betong som vid tillverkning frigör stora mängder koldioxid, av den anledningen optimeras betongrecept idag genom att ersätta en del av cementen med flygaska som är en restprodukt från kolkraftsindustrin. I takt med att samhället rör sig mot en fossilfri produktion beräknas tillgången till flygaska att avta och material med liknande egenskaper undersöks som alternativa bindemedel i betong.  Syftet med studien är att, genom litteraturstudier och laboratoriska tester, undersöka huruvida naturliga puzzolaner kan ersätta mängden flygaska i en cementsammansättning utan att försämra betongens hållfasthetsegenskaper. Tryckhållfastheten samt hållfasthetsutvecklingen har undersökts hos 150x150x150 mm provkuber med varierande mängd flygaska samt vulkanaska av isländsk pimpsten respektive jordanska tuffer. Målet med studien är att minska mängden, eller helst ersätta hela andelen flygaska i en klimatförbättrad betongsammansättning.  De laboratoriska testerna har utförts enligt svensk standard där totalt 48 provkroppar gjutits. Referenskuben i undersökningen består av 80% portlandkalkstencement och 20% flygaska. Totalt har 6 olika kombinationer av provkuber gjutits där andelen flygaska ersätts med 20%, 15% eller 10% vulkanaska. Vardera provkub har utsatts för tryckhållfasthetsmätning efter 2, 7 samt 28 dygn.  Resultatet av provtryckningen visade att provkuberna innehållande isländsk pimpsten gav en ökad eller oförändrad hållfasthet vid samtliga mätningar, jämfört med referenskuben. Provkuberna innehållande jordanska tuffer medförde däremot en reducering av hållfastheten vid samtliga mätningar, jämfört med referenskuben. Provkuberna innehållande vulkanaska från isländsk pimpsten gav högst sluthållfasthet då ingen flygaska förekom i sammansättningen och något sämre värden vid inblandning av flygaska, till skillnad från provkuberna innehållande vulkanaska från jordanska tuffer som utan flygaska i princip stannade av i sin hållfasthetstillväxt efter 7 dygn. Skillnaden i resultatet mellan vulkanaska av pimpsten respektive tuffer antyder att vilken typ av material det är samt dess ursprung har betydelse för hur det presterar som bindemedel i betong. / Concrete is one of the most widely used building materials in the world, but it can also be a major environmental culprit. Cement clinker is a significant component of concrete that releases large amounts of carbon dioxide during production. For this reason, concrete recipes are now optimized by replacing some of the cement with fly ash, which is a byproduct from the coal power industry. As society moves towards fossil-free production, the availability of fly ash is expected to decrease, and materials with similar properties are being investigated as alternative binders in concrete.  The purpose of the study is to investigate, through literature review and laboratory tests, whether natural pozzolans can replace the amount of fly ash in a cement composition without deteriorating the strength properties of the concrete. The compressive strength and strength development have been studied on 150x150x150 mm test cubes with varying amounts of fly ash and volcanic ash from Icelandic pumice and Jordanian tuffs. The goal of the study is to reduce the amount, or preferably replace the entire portion, of fly ash in a climate-improved concrete composition. The laboratory tests have been performed according to Swedish standards, where a total of 48 test specimens have been cast. The reference cube in the study consists of 80% Portland limestone cement and 20% fly ash. A total of 6 different combinations of test cubes have been cast, where the proportion of fly ash is replaced with 20%, 15%, or 10% volcanic ash. Each test cube has been subjected to compressive strength measurement after 2, 7, and 28 days. The results of the compression testing showed that the test cubes containing Icelandic pumice provided increased or unchanged strength at all measurements, compared to the reference cube. However, the test cubes containing Jordanian tuffs resulted in a reduction of strength at all measurements, compared to the reference cube. The test cubes containing volcanic ash from Icelandic pumice provided the highest final strength when no fly ash was present in the composition, and slightly lower values when fly ash was added, unlike the test cubes containing volcanic ash from Jordanian tuffs which essentially plateaued in their strength development after 7 days without fly ash. The difference in results between volcanic ash from pumice and tuffs suggests that the type and origin of the material are significant factors in how they perform as a binder in concrete.