The classic test for soil or aggregate bearing capacity in road construction is the CBR test. The results of the CBR were determined for gravelly sand and sand with the addition of 1.5% cement, as well as for their mixtures with 18 mm long polypropylene fibres in the amounts of 0.1%, 0.2% and 0.3%. The effect of compaction and time of curing of samples stabilised with hydraulic binder were also determined. The natural soil without cement and fibre additions had relatively high CBR values. The additions of 0.1% and 0.2% polypropylene fibres to the dry mass of the soil resulted in an approximately 2-fold increase in the CBR value for the samples compacted using the standard method. Increasing the amount of fibres to 0.3% caused a reduction in the CBR value to that obtained without fibre addition. For samples compacted using the modified Proctor method, the observations are different. Only the sample with 0.2% fibre addition achieved a slightly higher CBR value. Moreover, the addition of 1.5% cement and the length of treatment increased the CBR values.
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One of the methods of strengthening the subgrade under the road pavement construction is its stabilization with a hydraulic binder. The technology of stabilization with binders is well known in the road engineering, however, it is still beneficial in terms of economical and organisational aspects while considering methods for improvement of the load-bearing capacity of the subsoil. The advantages of this technology are, among others, the possibility of using materials both from recycling and local materials, resulting in the possibility of waste production limitation by the use of weak material (soil) in place. The article presents a case study and the results of research obtained during the process of optimizing the thickness stabilized with a hydraulic binder. Comparative tests were carried out to reveal that non-chemical soil enhancement with the use of aggregate is as important as chemical one with the binder in terms of the quality of the final subgrade for road construction. The results were afterwards confirmed in field with use of heavy machines and full-scale soil stabilisation, leading to economic and environmental benefits.
Road construction relies on natural material exploitation and it is necessary to find new ways of reducing its negative environmental impact. Simultaneously, number of tyres placed on Croatian (and world) market is constantly growing and the need for waste tyres management will begin to increase due to the wear and tear of tyres in use at the moment. This paper presents a review of latest international and domestic researches on waste rubber application in road construction with special emphasize on Croatian researches within this topic. Preliminary results of ongoing research on waste rubber application in cement bound mixtures are also presented.
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Przeprowadzone badania dotyczą metod odlewania budowli z ziemi, jako część programu badawczego poświęconego budowlom ziemnym. Badano wpływ dwóch inhibitorów pęcznienia ziemi zawierającej glinę: poli(tlenku etylenu) [PTE] i karboksymetylocelulozę [KMC], aby była możliwa jej stabilizacja cementem CEM I 42,5N. Ziemię zawierającą 14% gliny, kwarc i kalcyt, stabilizowano 10% dodatkiem cementu. Dodawano równocześnie 3% plastyfikatora polikarboksylanowego w stosunku do masy cementu, aby ziemia uzyskała zdolność do płynięcia. Uzyskane wyniki wykazały, że PTE i KMC – inhibitory pęcznienia gliny, zmniejszyły to pęcznienie o około 30% i 40%, przy czym maksymalne pęcznienie odpowiadało po 90 dniach odpowiednio 24% i 46% wytrzymałości na ściskanie. Omówiono interakcję gliny z cementem i inhibitorami pęcznienia. Znalezione zależności pozwoliły na korzystne zastosowanie tych materiałów do wytwarzania elementów budowlanych, zastosowanych we wznoszeniu budynków na obszarach pustynnych.
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This study is concerned with the method of cast earth as part of an investigation series on earth construction. The effect of two clay swelling inhibitors; polyethylene glycol [PEG] and of carboxymethyl cellulose [CMC] on the swelling of a clay-bearing soil are studied to enable the stabilization of the soil with CEM I 42.5 N. The soil composed of 14% clay, quartz, and calcite, is stabilized with 10% cement. 3% polycarboxylate superplasticizer is added relative to the mass of the cement, to gain the soil pourable properties. The results show that the PEG and CMC clay-swelling inhibitors reduce the expansion of the soil by ~30 and ~40% and lead to a maximum increase of 24 and 46% in the 90-day compressive strength respectively. The interactions between clay, cement, and swelling inhibitors are discussed. The findings allow advantageous applications for producing building units for construction purposes in desert areas.
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W artykule przeanalizowano wyniki kilkuset badań płytą statyczną na podłożu stabilizowanym cementem, na mieszance związanej cementem, a także na podbudowie nawierzchni ułożonej na podłożu lub nasypach stabilizowanych cementem. Ocenianym parametrem nośności był wtórny moduł odkształcenia E2. Stwierdzono, że stabilizacja podłoża cementem umożliwia osiągnięcie wymaganych wartości E2≥120 MPa. Wyższa skuteczność stabilizacji dotyczyła mieszanek związanych cementem (90% punktów powyżej 120 MPa) niż rodzimego podłoża stabilizowanego cementem (66%). Podbudowa nawierzchni wykonana z kruszywa łamanego ułożona na podłożu lub nasypach stabilizowanych cementem wykazywała wysokie wartości E2, a jedynie 3% punktów nie osiągało wartości 120 MPa, co świadczy o skuteczności stabilizacji cementem podłoża nawierzchni.
EN
The paper presents the results of several hundred static plate load tests on a soil subgrade stabilized with cement and on a mixture with cement, as well as on subgrade of pavement made on a soil subgrade or on embankments stabilized with cement. Secondary modulus of elasticity E2, which is a parameter of the bearing capacity, was measured. The results have shown that subgrade stabilized with cement reaches E2 ≥ 120 MPa. The greater effectiveness of stabilization concerned mixtures with cement (90% over 120 MPa value) than the cement-stabilized subgrade “in situ” (66%). Road pavement made of coarse aggregate build on the soil subgrade or on embankments stabilized with cement have shown high E2 values, and only 3% of measured values have been under 120 MPa, which proves the effectiveness of cement in stabilizing subgrade of pavement.
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Long-term performance of civil engineering projects mainly depends on the strength of underground layers. When the underground soil layers are problematic or have low bearing capacity and strength against the applied loads, application of soil stabilization methods can be effective. In this study, performance of pile-raft systems using stabilized/reinforced soil under foundation is investigated. For validation, the obtained numerical results were compared with the existing results from analytical and numerical analyses. Using the experimental data available in the literature, the variations of stiffness and strength parameters were simulated by three-dimensional finite element method and then foundation response was evaluated for each case. According to the obtained results, depending on the pile-raft configuration, different strategies of stabilization with cement, reinforcement with polypropylene fibers, or a combination of cement stabilization and fiber reinforcement can be employed to reduce the differential and maximum settlements of foundation and to improve the overall performance. In general, even though reinforcement with fibers has a positive influence on the tensile and shear strength of soil, the effect of cement stabilization on the design parameters of the foundation is more pronounced. Finally, an implementation of cost analysis of stabilization project was proposed to be conducted based on the applied materials and improvement/cost ratio.
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W nawiązaniu do problemu odpowiedniej nośności podłoża pod nawierzchnie drogowe, posadzki, a także fundamenty obiektów budowlanych przedstawiono problematykę stabilizacji słabego gruntu spoistego cementem, z zastosowaniem środka hydrofobizującego. Celem pracy było wykazanie poprawy parametrów gruntów spoistych pod względem wytrzymałości na ściskanie i mrozoodporności.
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The article presents the problem of stabilization poor cohesive soil with application of cement and hydrophobizing agent for increase bearing capacity of pavement, construction of floors and the foundations of buildings. The aim of the study was to improve the parameters of cohesive soils in terms of compressive strength and frost resistance.
Currently, a worldwide dynamic rise of interest in using soil as a construction material can be observed. This trend is evident in the rapid rise of the amount of standards that deal with soil techniques. In 2012 the number of standards was larger by one third than five years prior. To create a full standardization of the rammed earth technique it is necessary to take into account the diversity of used soil and stabilizing additives. The proportion of the components, the process of element production and the research methods must also be made uniform. The article describes the results of research on the compressive strength of rammed earth samples that differed from each other with regards to the type of loam used for the mixture and the amount of the stabilizer. The stabilizer used was Portland cement CEM I 42.5R. The research and the analysis of the results were based on foreign publications, the New Zealand standard NZS 4298:1998, the American Standard NMAC14.7.4 and archival Polish Standards from the 1960’s that dealt with earth material.
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Przeprowadzono badania laboratoryjne w celu oceny przydatności odpadowego granulatu ze wzbogacania rudy żelaznej, jako stabilizowanego cementem kruszywa do wykonywania podbudów drogowych. Zastosowano rozkład Weibulla do przeprowadzenia analizy regresyjnej i opracowania modelu do oceny zachowania się zmęczeniowego tego materiału, w warunkach laboratoryjnych. Uzyskane wyniki porównano z właściwościami podbudów wykonanych ze żwiru, także stabilizowanego cementem. Uzyskane wyniki wykazują, że trwałość zmęczeniowa podbudowy wykonanej z granulatu rudy żelaznej jest gorsza niż podbudowy ze żwiru, przy tym samym poziomie obciążenia. Jednak rozrzut wyników dotyczących trwałości zmęczeniowej maleje gdy stosunek obciążenia do wytrzymałości wośnie. Uzyskane wyniki stanowią podstawę teoretyczną do stosowania odpadowego granulatu rudy żelaznej w wykonywaniu podbudów drogowych.
EN
The laboratory experiments was conducted to characterize the fatigue performance of iron-ore tailings aggregate, stabilized with cement. The Weibull distribution function was adopted to assist the regression analysis and establish the predicted fatigue life model, under laboratory conditions. Furthermore, the comparison was made between the assessed fatigue life and natural gravel stabilized with cement. The results have shown that the fatigue life of iron-ore tailings aggregate stabilized with cement is lower than the fatigue life of natural gravel, also stabilized with cement, at the same stress ratio level. However, the discrepancy in the fatigue life decreases as the stress ratio increases. The results provide theoretical support for the application of cement-stabilized, iron-ore tailings aggregate in the pavement engineering.
W pracy przedstawiono badania zmian konsystencji, właściwości mechanicznych i filtracyjnych pod wpływem oleju napędowego gruntu. Oceniono przydatność cementu do stabilizacji zanieczyszczonego olejem napędowym gruntu.
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The results of researches on the change of consistency, mechanical and filtration properties of soil under the influence of diesel oil are presented in the paper. The usability of cement for the stabilization of soil contaminated with diesel oil has been assessed.
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