Lightweight cellular concrete (LCC) is a mixture of cement, water and foam, with a density less than 50 pcf. This material is being used increasingly often in a variety of construction applications due to its self-leveling, self-compacting, and self-consolidating properties. LCC may be used as a backfill or structural fill in areas where traditional granular backfill might normally be used. This material may be especially advantageous in areas where the underlying soil may not support the weight of a raised earth embankment. Testing on the behavior of LCC when used as backfill behind retaining walls is relatively limited. The effects of surcharge on the development of active pressure material are unknown. Two large-scale active pressure tests were conducted in the structures laboratory of Brigham Young University. Each test was performed within a 10-ft x 10-ft x 12-ft box that was filled with four lifts of LCC. Hydraulic jacks mounted to a steel reaction frame provided a surcharge load to the LCC surface. In the first test, the LCC was confined on three sides by the reaction frame, while the fourth side was confined by a reinforced concrete cantilever (RCC) wall. Both vertical and horizontal pressures and deflections were measured to determine the effect of the surcharge load on the development of active pressure behind the wall. In the second test, the LCC was confined on three sides and exposed on the fourth. Surcharge was applied to this sample in a similar fashion until the LCC reached ultimate failure. Vertical pressures and displacements, along with horizontal displacements, were measured in this test. Sample cylinders of LCC were cast at the time the test box was filled. These samples were tested periodically to determine the material strength and density. It was observed that the LCC backfill developed active pressure most similarly to a granular soil with a friction angle of 34º and a cohesion between 700 and 1600 psf. The RCC wall was seen to add vertical bearing capacity to the LCC, as well as prevent the catastrophic and brittle failure seen in the free-face test. It was also observed that an induced shear plane in the material dramatically decreased the total bearing capacity when compared to a uniformly loaded specimen with no induced shear plane. The results of this study were compared with design parameters given in previous research, and new design suggestions are presented herein.

The scope of this study is to establish extensive material tests to determine the mechanical properties of cellular concrete and evaluate its potential as energy absorption material against air blast load. This study includes a literature review of existing studies on cellular concrete, proportioning, and its mechanical properties, together with studies on the properties and application of other foams such as aluminium and polymer foams. It is concluded that, unlike other foam materials, there is a lack of systematic studies on the mechanical properties of cellular concrete especially for densities less than 1000 kg/m3. The survey also reviewed the existence of materials being used as a sacrificial layer against air blast load, together with the analytical models proposed to determine the parameters required to design a cladding system. As a result it was found that cellular concrete can maintain most of the properties of the cladding materials and can be applied as a new sacrificial layer against the blast load. Extensive material tests are carried out to characterise the effect of ingredients and density on material properties of cellular concrete. Based on the experimental results, an empirical model is proposed which determines the plateau and densification regime of nominal stress-strain curve of the cellular concrete with different densities. The penetration resistance of cellular concrete with different densities under truncated, conical, flat and hemi-spherical solid indenters are studied experimental. By determining the deformation mechanism of cellular concrete under indentation with application of an X-Ray tomography image system, an analytical model is proposed to determine the resistance of cellular concrete under penetration of flat indenter. Experimental closed range blast tests are performed with 1kg and 3kg C4 explosive to determine the mitigation potential of cellular concrete against air blast load. Numerical modelling of the experimental blast test is carried out using Ansys LS-DYNA to evaluate the feasibility of the numerical modelling techniques to predict the response of cellular concrete against air blast load.

O estado do Rio Grande do Sul é o terceiro maior produtor de pedras preciosas do Brasil, atrás apenas de Minas Gerais e da Bahia, destacando-se a produção de ágatas na região de Salto do Jacuí. Na lavra e beneficiamento são produzidos grandes quantidades de resíduos que estão a espera de destino e utilização ambientalmente correta. De modo específico, este trabalho avaliou a possibilidade de utilização do resíduo de ágata rolada na fabricação de blocos de concreto celular espumígeno (BCCE), utilizados como blocos de vedação na construção civil. Adicionalmente, desenvolveu-se uma mistura de dois agentes espumígenos provenientes de ácidos graxos de coco, como agente incorporador de ar, pela adição de espuma pré-formada. A metodologia de produção foi baseada no modelo de produção dos blocos de uma pequena indústria na Região de Passo Fundo/RS, que produz e comercializa BCCE. Em um estudo prévio de bancada, foram estudadas a composição da espuma, a granulometria do resíduo, o teor de água e o tempo de mistura. Os materiais componentes do BCCE são resíduo de sílica de pedras roladas de ágatas (SiO2 - 92,5%), espuma preparada com ácidos graxos de coco, água de qualidade potável e cimento como agente aglomerante. Nos testes de bancada, foram confeccionados 36 corpos de prova, em forma cilíndrica, de tamanho 50 mm de diâmetro por 100 mm de altura, com diferentes volumes de ar incorporado, divididos em três grupos. As amostras foram deixadas durante 28 dias à temperatura ambiente, em processo de cura, e após foram analisados quanto à resistência à compressão, densidade e distribuição das bolhas de ar. Os resultados foram avaliados pela Análise de Variância e demonstraram que o Grupo II apresentou densidade de 430 Kg/m3, e resistência de 0,92 MPa. Este resultado está próximo do atendimento aos requisitos da norma para classe de resistência de < 400 Kg/cm3 (NBR 13438, 2013). / The state of Rio Grande do Sul is the third largest producer of gemstones in Brazil, only losing to the states of Minas Gerais and Bahia, and agate production stands out in the region of Salto do Jacuí. Great amounts of waste, which are waiting for environmentally correct destination and use, are produced in mining and processing. Particularly, this study assessed the potential use of rolling waste of agates in civil construction, and the manufacturing of foam concrete blocks as a full substitute for sand. Additionally, a mixture was made of two foaming agents derived from coconut fatty acids as air-developer agent, and as hydraulic binder the Portland CP V ARI-RS cement. The production methodology was based on the production model of the blocks in a small industry, which produces and sells foam concrete blocks in the region of Passo Fundo, RS, Brazil. In a previous bench study the parameters foam composition, residue granulometry, water content, and mix time were adequate and later replicated industrially. The materials composing foam concrete blocks are rolled agate stones silica (SiO2 – 92.5%), foam from coconut fatty acids, fresh water, and cement as binder. In bench tests, 36 cylindrical specimens were produced, with 50 mm of diameter and 100 mm of height, with different volumes of incorporated air, divided into three groups. The samples were kept at room temperature for 28 days with healing process, and after that, the resistance to compression, density, and air bubbles distribution were analyzed. Results were assessed by Analysis of Variance, and showed that Group II presented density of 430 Kg/m3 and resistance of 0.92 MPa. This result is close to meeting the requirements of the norm for resistance class of < 400 Kg/cm3 (NBR 13438, 2013).

Submitted by Marlucy Farias Medeiros (marlucy.farias@unipampa.edu.br) on 2018-02-06T14:51:48Z No. of bitstreams: 1 EDUARDO CESAR PACHLA - 2017.pdf: 13664238 bytes, checksum: 1ee80147db8a398f429417a34a366ed3 (MD5) / Approved for entry into archive by Marlucy Farias Medeiros (marlucy.farias@unipampa.edu.br) on 2018-02-06T15:33:47Z (GMT) No. of bitstreams: 1 EDUARDO CESAR PACHLA - 2017.pdf: 13664238 bytes, checksum: 1ee80147db8a398f429417a34a366ed3 (MD5) / Made available in DSpace on 2018-02-06T15:33:47Z (GMT). No. of bitstreams: 1 EDUARDO CESAR PACHLA - 2017.pdf: 13664238 bytes, checksum: 1ee80147db8a398f429417a34a366ed3 (MD5) Previous issue date: 2017-12-21 / Visando desenvolver produtos com elevado desempenho térmico-acústico, foram produzidos compósitos introduzindo-se resíduos da indústria orizícola em uma matriz de concreto celular. O intuito do trabalho foi averiguar o efeito da adição desses subprodutos à matriz. No total, foram analisadas dez misturas, uma delas de concreto celular, contendo apenas casca do arroz, e as demais, sendo combinações da casca com a palha do arroz em três diferentes comprimentos e percentuais. Assim, o compósito com melhor desempenho foi estudado quanto à adição das fibras saturadas. Todos os compósitos foram avaliados quanto ao desempenho mecânico, acústico e térmico. A partir das análises de resistência mecânica, verificou-se que a adição de casca do arroz reduziu a resistência à compressão axial e aumentou a resistência à tração na flexão. Contanto, a substituição de parcelas de casca por palha do arroz manteve os resultados de resistência à compressão axial estatisticamente semelhantes até o volume de 10%, porém, a partir de 15% de adição de palha, os mesmos foram reduzidos. No que diz respeito à resistência à tração na flexão, a adição de palha do arroz foi positiva. Em relação ao desempenho acústico, a absorção acústica apresentou um acréscimo de aproximadamente 72% com a adição da casca do arroz, e de 83% com a adição de 15% de palha de 3 cm de comprimento. Os resultados de isolamento acústico não se mostraram estatisticamente diferentes, portanto, não foi possível determinar se as fibras vegetais trouxeram ganho na capacidade de isolação sonora. No que concerne o desempenho térmico, constatouse que há redução da condutividade em função do aumento do comprimento da palha do arroz. Por fim, as análises de durabilidade indicaram que os materiais possuem grandes quantidades de hidróxido de cálcio, que por sua vez, em contato com o dióxido de carbono, formam carbonato de cálcio, o que acarreta no surgimento de manchas brancas à superfície dos produtos e acelera o processo de despassivação de reforços metálicos. A concepção dos produtos se mostrou promissora ao obter desempenho térmico-acústico satisfatório, entretanto, é necessário realizar estudos mais minuciosos em relação à durabilidade, e, como alternativa para solucionar essa questão, sugere-se adicionar pozolanas para controlar a formação de hidróxido de cálcio. / Aiming to develop products with high thermal-acoustic performance, composites were produced by introducing waste from the rice industry into a cellular concrete matrix. The purpose of this work was to investigate the effect of adding these byproducts to the matrix. In the total, ten mixtures were analyzed, one of them of cellular concrete, containing only rice husk, and the others, being combinations of the bark and the rice straw in three different lengths and percentages. Thus, the composite with the best performance was studied in the light of addition of saturated fibers. All composites were evaluated for mechanical, acoustic and thermal performance. From the mechanical strength analysis, it was verified that the addition of rice husk reduced the axial compressive strength and increased the tensile strength in the bending. As a result, the substitution of rind plots per rice straw maintained the statistically similar axial compression resistance results up to the 10% volume, but, from 15% straw addition, those results were reduced. Regarding the flexural tensile strength, the addition of rice straw was positive. Considering the acoustic performance, the acoustic absorption presented an increase of approximately 72% with the addition of the rice husk, and 83% with the addition of 15% of straw of 3 cm in length. The results of acoustic insulation were not statistically different; therefore, it was not possible to determine if the vegetal fibers brought positive results to the sound insulation capacity. In terms of thermal performance, it was verified that there is reduction of the conductivity due to the increase of the length of the rice straw. Finally, the durability analysis indicated that the materials have a large amount of the calcium hydroxide, which in turn, in contact with carbon dioxide, forms calcium carbonate, which causes white spots to appear on the surface of the products and accelerates the process of depassivation of metallic reinforcements. The design of the products has shown to be promising due to its satisfactory thermal-acoustic performance, however, it is necessary to carry out more detailed studies on durability and, as an alternative to solve this question, it is suggested to add pozolanas to control the formation of calcium hydroxide.

O estado do Rio Grande do Sul é o terceiro maior produtor de pedras preciosas do Brasil, atrás apenas de Minas Gerais e da Bahia, destacando-se a produção de ágatas na região de Salto do Jacuí. Na lavra e beneficiamento são produzidos grandes quantidades de resíduos que estão a espera de destino e utilização ambientalmente correta. De modo específico, este trabalho avaliou a possibilidade de utilização do resíduo de ágata rolada na fabricação de blocos de concreto celular espumígeno (BCCE), utilizados como blocos de vedação na construção civil. Adicionalmente, desenvolveu-se uma mistura de dois agentes espumígenos provenientes de ácidos graxos de coco, como agente incorporador de ar, pela adição de espuma pré-formada. A metodologia de produção foi baseada no modelo de produção dos blocos de uma pequena indústria na Região de Passo Fundo/RS, que produz e comercializa BCCE. Em um estudo prévio de bancada, foram estudadas a composição da espuma, a granulometria do resíduo, o teor de água e o tempo de mistura. Os materiais componentes do BCCE são resíduo de sílica de pedras roladas de ágatas (SiO2 - 92,5%), espuma preparada com ácidos graxos de coco, água de qualidade potável e cimento como agente aglomerante. Nos testes de bancada, foram confeccionados 36 corpos de prova, em forma cilíndrica, de tamanho 50 mm de diâmetro por 100 mm de altura, com diferentes volumes de ar incorporado, divididos em três grupos. As amostras foram deixadas durante 28 dias à temperatura ambiente, em processo de cura, e após foram analisados quanto à resistência à compressão, densidade e distribuição das bolhas de ar. Os resultados foram avaliados pela Análise de Variância e demonstraram que o Grupo II apresentou densidade de 430 Kg/m3, e resistência de 0,92 MPa. Este resultado está próximo do atendimento aos requisitos da norma para classe de resistência de < 400 Kg/cm3 (NBR 13438, 2013). / The state of Rio Grande do Sul is the third largest producer of gemstones in Brazil, only losing to the states of Minas Gerais and Bahia, and agate production stands out in the region of Salto do Jacuí. Great amounts of waste, which are waiting for environmentally correct destination and use, are produced in mining and processing. Particularly, this study assessed the potential use of rolling waste of agates in civil construction, and the manufacturing of foam concrete blocks as a full substitute for sand. Additionally, a mixture was made of two foaming agents derived from coconut fatty acids as air-developer agent, and as hydraulic binder the Portland CP V ARI-RS cement. The production methodology was based on the production model of the blocks in a small industry, which produces and sells foam concrete blocks in the region of Passo Fundo, RS, Brazil. In a previous bench study the parameters foam composition, residue granulometry, water content, and mix time were adequate and later replicated industrially. The materials composing foam concrete blocks are rolled agate stones silica (SiO2 – 92.5%), foam from coconut fatty acids, fresh water, and cement as binder. In bench tests, 36 cylindrical specimens were produced, with 50 mm of diameter and 100 mm of height, with different volumes of incorporated air, divided into three groups. The samples were kept at room temperature for 28 days with healing process, and after that, the resistance to compression, density, and air bubbles distribution were analyzed. Results were assessed by Analysis of Variance, and showed that Group II presented density of 430 Kg/m3 and resistance of 0.92 MPa. This result is close to meeting the requirements of the norm for resistance class of < 400 Kg/cm3 (NBR 13438, 2013).

O estado do Rio Grande do Sul é o terceiro maior produtor de pedras preciosas do Brasil, atrás apenas de Minas Gerais e da Bahia, destacando-se a produção de ágatas na região de Salto do Jacuí. Na lavra e beneficiamento são produzidos grandes quantidades de resíduos que estão a espera de destino e utilização ambientalmente correta. De modo específico, este trabalho avaliou a possibilidade de utilização do resíduo de ágata rolada na fabricação de blocos de concreto celular espumígeno (BCCE), utilizados como blocos de vedação na construção civil. Adicionalmente, desenvolveu-se uma mistura de dois agentes espumígenos provenientes de ácidos graxos de coco, como agente incorporador de ar, pela adição de espuma pré-formada. A metodologia de produção foi baseada no modelo de produção dos blocos de uma pequena indústria na Região de Passo Fundo/RS, que produz e comercializa BCCE. Em um estudo prévio de bancada, foram estudadas a composição da espuma, a granulometria do resíduo, o teor de água e o tempo de mistura. Os materiais componentes do BCCE são resíduo de sílica de pedras roladas de ágatas (SiO2 - 92,5%), espuma preparada com ácidos graxos de coco, água de qualidade potável e cimento como agente aglomerante. Nos testes de bancada, foram confeccionados 36 corpos de prova, em forma cilíndrica, de tamanho 50 mm de diâmetro por 100 mm de altura, com diferentes volumes de ar incorporado, divididos em três grupos. As amostras foram deixadas durante 28 dias à temperatura ambiente, em processo de cura, e após foram analisados quanto à resistência à compressão, densidade e distribuição das bolhas de ar. Os resultados foram avaliados pela Análise de Variância e demonstraram que o Grupo II apresentou densidade de 430 Kg/m3, e resistência de 0,92 MPa. Este resultado está próximo do atendimento aos requisitos da norma para classe de resistência de < 400 Kg/cm3 (NBR 13438, 2013). / The state of Rio Grande do Sul is the third largest producer of gemstones in Brazil, only losing to the states of Minas Gerais and Bahia, and agate production stands out in the region of Salto do Jacuí. Great amounts of waste, which are waiting for environmentally correct destination and use, are produced in mining and processing. Particularly, this study assessed the potential use of rolling waste of agates in civil construction, and the manufacturing of foam concrete blocks as a full substitute for sand. Additionally, a mixture was made of two foaming agents derived from coconut fatty acids as air-developer agent, and as hydraulic binder the Portland CP V ARI-RS cement. The production methodology was based on the production model of the blocks in a small industry, which produces and sells foam concrete blocks in the region of Passo Fundo, RS, Brazil. In a previous bench study the parameters foam composition, residue granulometry, water content, and mix time were adequate and later replicated industrially. The materials composing foam concrete blocks are rolled agate stones silica (SiO2 – 92.5%), foam from coconut fatty acids, fresh water, and cement as binder. In bench tests, 36 cylindrical specimens were produced, with 50 mm of diameter and 100 mm of height, with different volumes of incorporated air, divided into three groups. The samples were kept at room temperature for 28 days with healing process, and after that, the resistance to compression, density, and air bubbles distribution were analyzed. Results were assessed by Analysis of Variance, and showed that Group II presented density of 430 Kg/m3 and resistance of 0.92 MPa. This result is close to meeting the requirements of the norm for resistance class of < 400 Kg/cm3 (NBR 13438, 2013).

Low-strength cellular concrete is a type of controlled low-strength material (CLSM) which is increasingly being used for various modern construction applications. Benefits of the material include its ease of placement due to the ability of cellular concrete to self-level and self-compact. It is also extremely lightweight compared to traditional concrete, enabling the concrete to be used in fill applications as a compacted soil would customarily be used. Testing of this material is not extensive, especially in the form of large-scale tests. Additionally, effects of skew on passive force resistance help to understand performance of a material when it is used in an application where skew is present. Two passive force-deflection tests were conducted in the structures lab of Brigham Young University. A 4-ft x 4-ft x 12-ft framed box was built with a steel reaction frame on one end a 120-kip capacity actuator on the other. For the first test a non-skewed concrete block, referred to as the backwall, was placed in the test box in front of the actuator. For the second test a backwall with a 30° skew angle was used. To evaluate the large-scale test a grid was painted on the concrete surface and each point was surveyed before and after testing. The large-scale sample was compressed a distance of approximately three inches, providing a clear surface failure in the sample. The actuator provided data on the load applied, enabling the creation of the passive force-deflection curves. Several concrete cylinders were cast with the same material at the time of pouring for each test and tested periodically to observed strength increase.The cellular concrete for the 0° skew test had an average wet density of 29 pounds per cubic foot and a 28-day compressive strength of 120 pounds per square inch. The cellular concrete for the 30° skew test had an average wet density of 31 pounds per cubic foot and a 28-day compressive strength of 132 pounds per square inch. It was observed from the passive force deflection curves of the two tests that skew decreased the peak passive resistance by 29%, from 52.1 kips to 37 kips. Various methods were used to predict the peak passive resistance and compared with observed behavior to verify the validity of each method.

The basic mixture of lightweight cellular concrete (LCC) consists of cement, water, and a stable foaming agent. It is generally classified as having a density of less than 50 pounds per cubic foot (pcf), which is less than both traditional concrete and backfill materials. LCC has gained popularity in construction due to its lightweight, self-leveling, and ease of production and placement. These characteristics have made LCC a popular lightweight backfill material for mechanically stabilized earth (MSE) walls. However, there has been relatively little research on the large-scale behavior of LCC as a MSE backfill. Therefore, large-scale test results defining failure mechanisms and the strength criteria of reinforced LCC are extremely valuable. In this study, a three walled test box (10 ft wide x 12 ft long x 10 ft high) was constructed to contain the LCC. Two 5 ft tall x 10 ft wide MSE wall segments were poured and cured, before being placed as the fourth wall of the test box. The test box was built with a steel reaction frame to reduce lateral deflections during testing of the LCC that was not in the direction of the MSE wall, thus creating a two-dimensional or pseudo "plane strain" geometry. The box was filled with four lifts of Class II LCC 2.5 feet thick with ribbed-strip reinforcements at the center of each lift. After the LCC was cured, two static load tests were performed by applying surcharge to the surface of the LCC using six hydraulic jacks. The static load tests compared the LCC behavior of an MSE wall in comparison with unreinforced LCC without MSE wall panels. Multiple forms of instrumentation were used to understand the behavior of the LCC during surcharge loading. The instrumentation also helped to characterize the strength criteria for LCC based on failure in the large-scale and laboratory testing. This was done to determine the failure mechanism for the MSE wall retaining system with ribbed-strip reinforced LCC backfill. Data was gathered primarily through lateral wall pressures, lateral wall deflections, and forces induced on the ribbed-strip reinforcements. The test results show that an MSE wall with LCC backfill can withstand significant surcharge loading with limited axial and lateral deformations. However, failure occurred at surcharge pressures of about 60% of the unconfined compressive strength. The use of a retaining system significantly increased the failure loads and produced a more ductile failure mode than Class II LCC with a free-face. The active pressures observed are similar to a granular material with a friction angle (ϕ) of 34°, Ka=0.28, and a cohesion of 700 to 1600 psf for Class II LCC. Likewise, failure of the free-face occurred at a value predicted by Rankine theory with ϕ = 34° and c = 1600 psf.

Lightweight cellular concrete (LCC) is mainly a mixture of water, cement, and foam bubbles. LCC generally has a cast density between 20-60 pcf and an air content between 49-84%. LCC is often used as a fill material because it has a low unit weight which reduces settlement. LCC is increasingly being considered as a backfill behind Mechanically Stabilized Earth (MSE) walls and embankments. Although engineers are using LCC in MSE walls or free face walls (MSE wall without the concrete panels or reinforcements), there is presently a lack of information regarding the performance and behavior of LCC to guide them. This research attempts to answer questions on the design of MSE walls backfilled with LCC and free face LCC walls by providing a well-documented case history and evaluating if LCC can be modeled as a c-ϕ material. A steel frame test box (10 ft wide x 12 ft long x 10 ft high) with a MSE wall on one side was constructed for the research. The box was filled with four lifts of LCC with steel ribbed-strip reinforcements extending into the LCC behind the MSE wall panels at the center of each lift. After the LCC was cured, two static load tests were performed by applying a surcharge load to the surface of the LCC. In one test, surcharge pressure was applied adjacent to the MSE wall to produce failure of the wall system. In a second test, the surcharge pressure was placed adjacent to a free face of the LCC to produce failure. String potentiometers (string pots), load cells, pressure plates, and strain gages were used to measure the behavior of the MSE wall and free face wall during testing. These two tests provided a comparison between LCC behavior with a MSE wall relative to a LCC free face. Failure of the free face wall with unreinforced LCC backfill in this test can be predicted using Rankine’s lateral force equation using a c-ϕ model. Failure angle at the base of the free face wall was between 51-63° which corresponds with an average friction angle (ϕ) of 24° and cohesion (c) of 1575 psf with an upper bound ϕ = 34° and a c = 1285 psf. The presence of reinforcements in the LCC backfill behind the MSE wall increased the capacity of the wall to hold a surcharge load. The presence of reinforcements in the LCC behind MSE walls also led to a much more ductile surcharge pressure vs. lateral deflection curve for the MSE wall compared to the free face wall.

Low-strength cellular concrete consists of a cement slurry that is aerated prior to placement. It remains a largely untested material with properties somewhere between those of soil, geofoam, and typical controlled low-strength material (CLSM). The benefits of using this material include its low density, ease of placement, and ability to self-compact. Although the basic laboratory properties of this material have been investigated, little information exists about the performance of this material in the field, much less the passive resistance behavior of this material in the field.In order to evaluate the use of cellular concrete as a backfill material behind bridge abutments, two large-scale tests were conducted. These tests sought to better understand the passive resistance, the movement required to reach this resistance, the failure mechanism, and skew effects for a cellular concrete backfill. The tests used a pile cap with a backwall face 5.5 ft (1.68 m) tall and 11 ft (3.35 m) wide. The backfill area had walls on either side running parallel to the sides of the pile cap to allow the material to fail in a 2D fashion. The cellular concrete backfill for the 30<&degree> skew test had an average wet density of 29.6 pcf (474 kg/m3) and a compressive strength of 57.6 psi (397 kPa). The backfill for the 0<&degree> skew test had an average wet density of 28.6 pcf (458 kg/m3) and a compressive strength of 50.9 psi (351 kPa). The pile cap was displaced into the backfill area until failure occurred. A total of two tests were conducted, one with a 30<&degree> skew wedge attached to the pile cap and one with no skew wedge attached.It was observed that the cellular concrete backfill mainly compressed under loading with no visible failure at the surface. The passive-force curves showed the material reaching an initial peak resistance after movement equal to 1.7-2.6% of the backwall height and then remaining near this strength or increasing in strength with any further deflection. No skew effects were observed; any difference between the two tests is most likely due to the difference in concrete placement and testing.