Lightweight cellular concrete (LCC) is a cement, water, and air entrained mixture that consists of 25-80% voids. The air voids reduce the material strength but also decrease the material weight. Due to its lightweight properties LCC is an attractive alternative to soil backfill for retained structures, such as mechanically stabilized earth (MSE) walls. Although LCC is widely used behind MSE walls, limited information exists regarding the pullout strength of MSE wall reinforcements in LCC backfill. This research attempts to fill the knowledge gap through performing pullout tests on welded wire and ribbed strip reinforcements in MSE walls to determine the pullout friction coefficient (F*), reinforcement pullout behavior, and LCC properties. A large-scale test box (10 feet wide x 12 feet long x 10 feet high) supported by a steel resisting frame, was constructed, and filled with LCC backfill. Both the west and east MSE wall faces consisted of concrete walls. The west wall was supported by 16 ribbed strip reinforcements, while the east wall was supported by nine short, welded wire reinforcements. After backfilling the MSE wall, pullout tests were performed of the 12 ribbed strip reinforcements and all nine welded wire reinforcements. To determine different pullout friction coefficients (F*), different surcharge loads were applied through LCC self-weight, concrete reaction beams, and hydraulic jacks at the top of backfill. After performing the pullout tests on the large-scale test box, additional pullout tests were performed in two smaller (10 feet wide x 6 feet deep x 30 in. tall) MSE walls, each containing four ribbed strip reinforcements to determine the F* of ribbed strip reinforcements at moderate surcharge pressures. Results from these tests produced F* recommendations for ribbed strip and welded wire reinforcements. Additionally, a total of 130 LCC cylinder specimens were used to identify LCC material properties. Results of these tests show that the unconfined compressive strength of LCC is greatly dependent on the cast and cured unit weight, as well as the sample maturity. Comparing the UCS results to other work reveals a wide variation of UCS versus cured density, even though the same ASTM standard was applied for all tests. An equation for the secant modulus of LCC was created using UCS data from this thesis and other research conducted at Brigham Young University (BYU). Direct shear tests were also conducted on LCC cylinders cut to fit the confinement of a direct shear machine. The direct shear test results from this thesis agree with other research conducted at BYU.

Bridges often use pile foundations behind MSE walls to help resist lateral loading from seismic and thermal expansion and contraction loads. Overdesign of pile spacing and sizes occur owing to a lack of design code guidance for piles behind an MSE wall. However, space constraints necessitate the installation of piles near the wall. Full scale lateral load tests were conducted on piles behind an MSE wall. This study involves the testing of four HP12X74 H-piles and four HSS12X12X5/16 square piles. The H-piles were tested with ribbed strip soil reinforcement at a wall height of 15 feet, and the square piles were tested with welded wire reinforcement at a wall height of 20 feet. The H-piles were spaced from the back face of the MSE wall at pile diameters 4.5, 3.2, 2.5, and 2.2. The square piles were spaced at pile diameters 5.7, 4.2, 3.1, and 2.1. Testing was based on a displacement control method where load increments were applied every 0.25 inches up to three inches of pile deflection. It was concluded that piles placed closer than 3.9 pile diameters have a reduction in their lateral resistance. P-multipliers were back-calculated in LPILE from the load-deflection curves obtained from the tests. The p-multipliers were found to be 1.0, 0.85, 0.60, and 0.73 for the H-piles spaced at 4.5, 3.2, 2.5, and 2.2 pile diameters, respectively. The p-multipliers for the square piles were found to be 1.0, 0.77, 0.63, and 0.57 for piles spaced at 5.7, 4.2, 3.1, and 2.1 pile diameters, respectively. An equation was developed to estimate p-multipliers versus pile distance behind the wall. These p-multipliers account for reduced soil resistance, and decrease linearly with distance for piles placed closer than 3.9 pile diameters. Measurements were also taken of the force induced in the soil reinforcement. A statistical analysis was performed to develop an equation that could predict the maximum induced reinforcement load. The main parameters that went into this equation were the lateral pile load, transverse distance from the reinforcement to the pile center normalized by the pile diameter, spacing from the pile center to the wall normalized by the pile diameter, vertical stress, and reinforcement length to height ratio where the height included the equivalent height of the surcharge. The multiple regression equations account for 76% of the variation in observed tensile force for the ribbed strip reinforcement, and 77% of the variation for the welded wire reinforcement. The tensile force was found to increase in the reinforcement as the pile spacing decreased, transverse spacing from the pile decreased, and as the lateral load increased.