Mix together the graham cracker crumbs and melted butter; press into the bottom of a 9-inch pie dish. Line the bottom of the pie crust with 1 layer of strawberry halves.
Place the remaining strawberries in a saucepan and crush (there should be about 1 cup of crushed berries); stir the rhubarb, sugar, water, and cornstarch into the crushed berries. Bring the mixture to a boil over medium-low heat, stirring often, until the mixture thickens and becomes translucent. Turn off the heat, let the mixture stand until slightly cooled, about 2 minutes; stir in the lemon juice.
Pour the mixture into the pie dish over the strawberry halves.
Refrigerate until completely chilled, about 1 hour.
